Shandong Medical and Health Science and Technology Development Plan Project (202207020806)

The following protocol was reviewed and approved by the Ethics Committee of the Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine (Grant No. HEC-KS-2020002KY), and was strictly adhered to the Declaration of Helsinki. All patients signed an informed consent form.
1. Patient selection
NOTE: 20 patients (38 eyes) with presbyopia treated by excimer laser monocular multifocal bi-aspheric ablation were admitted to the Department of Refractive Surgery of the Eye Hospital Affiliated with Shandong University of Traditional Chinese Medicine. Baseline and follow-up examinations were performed.
<ol>
	<li>Inclusion criteria
	<ol>
		<li>Include patients between 40-55 years of age diagnosed with presbyopia in both eyes.</li>
		<li>Include patients with a sphere range of -1.00 D to -8.00 D and a cylinder range &#8805; -4.00 D.</li>
		<li>Include patients with an ADD range of +1.25D to +2.50 D.</li>
		<li>Include patients with best corrected distance visual acuity &#8805; 0.8 and best corrected near visual acuity 40 cm &#62; J2.</li>
		<li>Incule patients whose monocular test tolerates anisometropia of at least 1 D.</li>
		<li>Include patients with the diameter of the photopic pupil of 2.5-3.5 mm and dark pupil &#62; 4.5 mm.</li>
		<li>Include patients whose corneal spherical aberration at 6 mm &#62; 0.0 &#181;m and the root mean square value (RMS) of corneal higher-order aberration (HOA) at 6 mm &#60; 0.5 &#181;m.</li>
	</ol>
	</li>
	<li>Exclusion criteria
	<ol>
		<li>Exclude patients who have active inflammation or infection of the eyes.</li>
		<li>Exclude patients with abnormal corneal topography and biomechanical examination before operation. Exclude if corneal stroma thickness &#60; 300 &#181;m after ablation and preoperative central corneal thickness &#60; 470 &#181;m.</li>
		<li>Exclude patients with pupil offset &#8805; 0.7 mm.</li>
		<li>Exclude patients with other eye diseases affecting vision except refractive error, history of ophthalmic surgery (including laser corneal refractive surgery), history of trauma, etc.</li>
		<li>Exclude patients with anxiety, depression, and other mental states and with high requirements for postoperative visual quality and vision.</li>
	</ol>
	</li>
</ol>
2. Preoperative preparation
<ol>
	<li>Examine the patient before refractive surgery.
	<ol>
		<li>Identify the dominant eye using a Hole test.
		<ol>
			<li>Adjust both eyes to the best corrected visual acuity (BCVA),straighten the arms. Cross the thumbs and index fingers to form a small triangle, and look at the bow 2.5 m in front.</li>
			<li>Cover the left eye; if the bow is still visible, the dominant eye is the right eye. If the bow is not visible, the dominant eye is the left eye.</li>
		</ol>
		</li>
		<li>Calculate and adjust ADD.
		<ol>
			<li>Select experimental ADD. Calculate it by the formula, ADD =15 - age/4.</li>
			<li>Adjust ADD. Mesaure negative relative accommodation (NRA) and positive relative accommodation (PRA) on an experimental ADD basis. Divide the algebraic sum of NRA and PRA by two plus experimental ADD.</li>
			<li>Determine the final prescription. For individuals whose reading distance is greater than 40 cm, reduce +0.25 D; For patients with reading distance less than 40 cm, add +0.25 D, make several subtle adjustments and try to confirm the final prescription, so that the patient&#39;s vision is clear and comfortable.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Perform other preoperative examinations.
	<ol>
		<li>Include slit-lamp microscopy, comparative sensitivity function, Sirius 3D anterior segment, and corneal aberration analyzer to measure corneal topographic, corneal aberration, and pupil size in light, medium, and dark environments.</li>
		<li>Measure the corneal morphology by three-dimensional anterior segment analysis and assess corneal biomechanics using a corneal visual biomechanics analyzer.Finally, perform cycloplegic refraction and fundus examination.</li>
	</ol>
	</li>
	<li>Plan the surgical design.
	<ol>
		<li>Use the anterior segment and corneal aberration analyzer, with the Aberration Free (AF) mode selected for the dominant eye to eliminate aberrations andtarget refraction of 0.</li>
		<li>The non-dominant eye was&#160;selected as the monocular mode, and according&#160;to the measured pupil size, the optical zone was&#160;set to 6.2-6.7 mm, the distant target was -0.89&#160;D, and the central 3 mm area was introduced&#160;into ADD&#160;(depending on the patient, up to-2.50 D).</li>
	</ol>
	</li>
	<li>Provide preoperative medications.
	<ol>
		<li>Provide preoperative medications 3 days before the operation: levofloxacin hydrochloride eye drops 3 times a day and hydroxoglycoside eye drops 4 times a day.</li>
	</ol>
	</li>
</ol>
3. Surgical procedure
<ol>
	<li>Flush and disinfect the eye.
	<ol>
		<li>Ask the patient to open his eyes and look upward. Rinse the conjunctiva sac with 0.9% normal saline.</li>
		<li>Disinfect the skin within 6 cm around the eyelid center with a skin disinfectant. Apply promethacaine hydrochloride eye drops for ocular surface anesthesia every 10 min, a total of 2 times.</li>
	</ol>
	</li>
	<li>Place the patient supine and put the head in the right position. Lay the surgical towel, expose the surgical eye, and drop artificial tears to moisten the ocular surface. Stick a transparent dressing frame, open the eyelid fissure to fully expose the cornea, and wipe the cornea with a wet sterile sponge (Figure 1).</li>
	<li>Use the femtosecond laser system to create the corneal flap (Figure 2). Attach the negative pressure suction ring to the laser emission window and treatment control panel.</li>
	<li>Select the flap mode and start the treatment steps according to the treatment program on the treatment screen. Ask the patient to look at the green light. Use the operating microscope and operating table joystick to align accurately.</li>
	<li>During alignment, make the watermark just in the center of the contact lens on the negative pressure ring and let it reach about 80%-90%.</li>
	<li>Start the negative pressure suction until the cornea completely adheres to the contact surface of the negative pressure ring. Hear Section On for the end of negative pressure suction, and hear Ready to prepare for the next step.</li>
	<li>Depress the pedal to start ablation, and urge the patient to stare at the green gaze light. Corneal stromal flap parameters: thickness: 100 &#181;m; diameter: 8.1 mm; hinge angle: 90&#176;;intrastromal scan laser energy: 125 nJ; edge cutting scan laser energy: 125 nJ. Once the corneal flap production is completed, release the pedal, disengage the negative pressure suction, and remove the negative pressure suction ring.</li>
	<li>Replace the negative pressure suction head and repeat steps 3.2-3.7 to treat the other eye.</li>
	<li>Guide the patient to the excimer laser surgical bed and place the patient supine. Lay the surgical towel, stick a transparent dressing frame, and open the eyelid fissure to fully expose the cornea. Rinse the corneas with a balanced saline solution and accurately align them with the aid of an operating microscope.</li>
	<li>Separate the corneal flap using a corneal flap separator, insert a light separation from the lateral incision near the hinge, and carefully separate the flap from the corneal stroma in the opposite direction of the pedicle until the corneal flap is completely opened, exposing the stroma. Finally, use the disposable sterile medical sponge to dry surface moisture.</li>
	<li>Use the excimer laser to ablate the corneal stroma (Figure 3). Verify the patient&#39;s information and cut using the excimer laser according to the surgical design. Ask the patient to stare at the gaze light, keep the eyes aligned with the laser, and center the corneal apex to select the corneal apex for the stromal ablation.</li>
	<li>At the end of the treatment, rinse the stroma with a compound electrolyte intraocular irrigating solution. Reset the corneal flap (Figure 4), and apply 0.3% tobramycin and dexamethasone eye drops. Observe the corneal reset under a slit lamp. Repeat step 3.8-3.9 to isolate the other corneal flap and perform stromal ablation.</li>
	<li>Guide the patient out of the operating table, put on a sterile eye mask, and ask the patient for a review the next day after the operation.</li>
</ol>

Excimer Laser Multifocal Double Aspheric Ablation for Presbyopia Correction

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	<li>Wolffsohn, J. S., Davies, L. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Presbyopia:+Effectiveness+of+correction+strategies.">Presbyopia: Effectiveness of correction strategies.</a> Prog Retin Eye Res. 68, 124-143 (2019).</li><li>Frick, K. D., Joy, S. M., Wilson, D. A., Naidoo, K. S., Holden, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+global+burden+of+potential+productivity+loss+from+uncorrected+presbyopia.">The global burden of potential productivity loss from uncorrected presbyopia.</a> Ophthalmology. 122 (8), 1706-1710 (2015).</li><li>Nanavaty, M. A., Daya, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Refractive+lens+exchange+versus+phakic+intraocular+lenses.">Refractive lens exchange versus phakic intraocular lenses.</a> Curr Opin Ophthalmol. 23 (1), 54-61 (2012).</li><li>Soler Tom&#225;s, J. R., Fuentes-P&#225;ez, G., Burillo, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Symmetrical+versus+asymmetrical+PresbyLASIK:+Results+after+18+months+and+patient+satisfaction.">Symmetrical versus asymmetrical PresbyLASIK: Results after 18 months and patient satisfaction.</a> Cornea. 34 (6), 651-657 (2015).</li><li>Shetty, R., Brar, S., Sharma, M., Dadachanji, Z., Lalgudi, V. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PresbyLASIK:+A+review+of+PresbyMAX,+Supracor,+and+laser+blended+vision:+Principles,+planning,+and+outcomes.">PresbyLASIK: A review of PresbyMAX, Supracor, and laser blended vision: Principles, planning, and outcomes.</a> Indian J Ophthalmol. 68 (12), 2723-2731 (2020).</li><li>Pinelli, R., Ortiz, D., Simonetto, A., Bacchi, C., Sala, E., Ali&#243;, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correction+of+presbyopia+in+hyperopia+with+a+center-distance,+paracentral-near+technique+using+the+Technolas+217z+platform.">Correction of presbyopia in hyperopia with a center-distance, paracentral-near technique using the Technolas 217z platform.</a> J Refract Surg. 24 (5), 494-500 (2008).</li><li>Ali&#243;, J. L., Chaubard, J. J., Caliz, A., Sala, E., Patel, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correction+of+presbyopia+by+technovision+central+multifocal+LASIK+(presbyLASIK).">Correction of presbyopia by technovision central multifocal LASIK (presbyLASIK).</a> J Refract Surg. 22 (5), 453-460 (2006).</li><li>Vargas-Fragoso, V., Ali&#243;, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Corneal+compensation+of+presbyopia:+PresbyLASIK:+An+updated+review.">Corneal compensation of presbyopia: PresbyLASIK: An updated review.</a> Eye Vis (Lond). 4, 11 (2017).</li><li>Pallikaris, I. G., Panagopoulou, S. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PresbyLASIK+approach+for+the+correction+of+presbyopia.">PresbyLASIK approach for the correction of presbyopia.</a> Curr Opin Ophthalmol. 26 (4), 265-272 (2015).</li><li>Ryu, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Presbyopia+correction+using+the+monocular+bi-aspheric+ablation+profile+in+myopic+eyes.">Presbyopia correction using the monocular bi-aspheric ablation profile in myopic eyes.</a> J Cataract Refract Surg. 49 (1), 69-75 (2023).</li><li>Fu, D., Zhao, J., Zeng, L., Zhou, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One+year+outcome+and+satisfaction+of+presbyopia+correction+using+the+PresbyMAX&#174;+monocular+ablation+profile.">One year outcome and satisfaction of presbyopia correction using the PresbyMAX&#174; monocular ablation profile.</a> Front Med (Lausanne). 7, 589275 (2020).</li><li>Fu, D., Zhao, J., Zhou, X. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Objective+optical+quality+and+visual+outcomes+after+the+PresbyMAX+monocular+ablation+profile.">Objective optical quality and visual outcomes after the PresbyMAX monocular ablation profile.</a> Int J Ophthalmol. 13 (7), 1060-1065 (2020).</li><li>Braun, E. H., Lee, J., Steinert, R. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monovision+in+LASIK.">Monovision in LASIK.</a> Ophthalmology. 115 (7), 1196-1202 (2008).</li><li>Kohnen, T., B&#246;hm, M., Herzog, M., Hemkeppler, E., Petermann, K., Lwowski, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Near+visual+acuity+and+patient-reported+outcomes+in+presbyopic+patients+after+bilateral+multifocal+aspheric+laser+in+situ+keratomileusis+excimer+laser+surgery.">Near visual acuity and patient-reported outcomes in presbyopic patients after bilateral multifocal aspheric laser in situ keratomileusis excimer laser surgery.</a> J Cataract Refract Surg. 46 (7), 944-952 (2020).</li><li>Uthoff, D., P&#246;lzl, M., Hepper, D., Holland, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+method+of+cornea+modulation+with+excimer+laser+for+simultaneous+correction+of+presbyopia+and+ametropia.">A new method of cornea modulation with excimer laser for simultaneous correction of presbyopia and ametropia.</a> Graefes Arch Clin Exp Ophthalmol. 250 (11), 1649-1661 (2012).</li><li>Baudu, P., Penin, F., Mosquera Arba, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uncorrected+binocular+performance+after+biaspheric+ablation+profile+for+presbyopic+corneal+treatment+using+AMARIS+with+the+PresbyMAX+module.">Uncorrected binocular performance after biaspheric ablation profile for presbyopic corneal treatment using AMARIS with the PresbyMAX module.</a> Am J Ophthalmol. 155 (4), 636-647 (2013).</li><li>Luger, M. H., McAlinden, C., Buckhurst, P. J., Wolffsohn, J. S., Verma, S., Arba-Mosquera, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Presbyopic+LASIK+using+hybrid+bi-aspheric+micro-monovision+ablation+profile+for+presbyopic+corneal+treatments.">Presbyopic LASIK using hybrid bi-aspheric micro-monovision ablation profile for presbyopic corneal treatments.</a> Am J Ophthalmol. 160 (3), 493-505 (2015).</li><li>Luger, M. H., Ewering, T., Arba-Mosquera, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-year+experience+in+presbyopia+correction+with+biaspheric+multifocal+central+presbyopia+laser+in+situ+keratomileusis.">One-year experience in presbyopia correction with biaspheric multifocal central presbyopia laser in situ keratomileusis.</a> Cornea. 32 (5), 644-652 (2013).</li><li>Chan, T. C., Kwok, P. S., Jhanji, V., Woo, V. C., Ng, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Presbyopic+correction+using+monocular+bi-aspheric+ablation+profile+(PresbyMAX)+in+hyperopic+eyes:+1-year+outcomes.">Presbyopic correction using monocular bi-aspheric ablation profile (PresbyMAX) in hyperopic eyes: 1-year outcomes.</a> J Refract Surg. 33 (1), 37-43 (2017).</li><li>El Danasoury, A. M., Gamaly, T. O., Hantera, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multizone+LASIK+with+peripheral+near+zone+for+correction+of+presbyopia+in+myopic+and+hyperopic+eyes:+1-year+results.">Multizone LASIK with peripheral near zone for correction of presbyopia in myopic and hyperopic eyes: 1-year results.</a> J Refract Surg. 25 (3), 296-305 (2009).</li><li>Yebra-Pimentel, E., Gonz&#225;lez-J&#233;ijome, J. M., Cervi&#241;o, A., Gir&#225;ldez, M. J., Gonz&#225;lez-P&#233;rez, J., Parafita, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Corneal+asphericity+in+a+young+adult+population.+Clinical+implications.">Corneal asphericity in a young adult population. Clinical implications.</a> Arch Soc Esp Oftalmol. 79 (8), 385-392 (2004).</li><li>Calossi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Corneal+asphericity+and+spherical+aberration.">Corneal asphericity and spherical aberration.</a> J Refract Surg. 23 (5), 505-514 (2007).</li></ol>

All authors have nothing to disclose.

Currently, there are limited effective methods for restoring ocular accommodation, making presbyopia a prominent area of research in refractive surgery. The bi-aspheric ablation profile, a widely recognized clinical modality for presbyopia correction, has shown favorable safety and efficacy with satisfactory postoperative outcomes15,16,17. However, there is a paucity of studies focusing on the monocular mode. In this study, we present a comprehensive guide to the surgical operation of the monocular bi-aspheric ablation profile and assess the postoperative visual outcomes and visual quality.
Preoperative evaluation is particularly important for patients with presbyopia, as multiple measurements are required to determine the dominant eye and the most appropriate ADD. The final choice of ADD is not only related to the measurement results, but also should pay attention to the subjective feelings of the patient, and determine the most suitable power for the patient through try-on.
Multifocal bi-aspheric ablation profile is commonly used to address various ametropia with presbyopia, leading to notable enhancements in UDVA and UNVA in both monocular and binocular eyes postoperatively10,11,12. Luger et al.18 presented one-year postoperative outcomes of bilateral bi-aspheric ablation profile for the correction of myopia or hyperopia with presbyopia, indicating that 70% of patients achieved UDVA &#8805; 0.1 logMAR and 84% attained UNVA &#8805; 0.1 logRAD. In another study by Luger et al.17, the hybrid mode was utilized to correct refractive errors associated with presbyopia. Both eyes underwent multifocal bi-aspheric treatment to introduce varying depths of focus while preserving different diopters. Following surgery, 90% or more of patients achieved UDVA &#8805; 20/20 in both eyes, with 93% of the myopic group and 88% of the hyperopic group achieving UNVA &#8805; J2 in both eyes. In contrast to these studies, our present study focused on the monocular mode, where only one eye received multifocal bi-aspheric treatment considering both distance and near vision. Notably, 95% of patients achieved postoperative binocular UDVA of 0 logMAR or better and a binocular UNVA of J1 or better. These visual acuity outcomes were comparable to those reported by Ryu et al.10. The safety profile of the procedure was underscored by the absence of any patient experiencing a loss of two or more lines of corrected distance visual acuity (CDVA) pre- or post-operatively, mirroring the findings of Chan et al.19.
The previous central Presby LASIK surgery made it difficult to achieve the alignment of the line of sight, the central pupil, and the apex of the cornea, and it was prone to vision aberrations after the operation, which affected the visual quality. The multifocal bi-aspheric ablation profile uses bi-aspheric ablation, and the cornea is multifocal after the operation. The negative spherical aberration is introduced without additional aberrations20. Fu et al.12 studied the objective visual quality of patients after monocular surgery and found that SA increased negatively after surgery, vertical and horizontal coma, trefoil aberration had no significant change, and HOA increased positively but the difference was not statistically significant. The subjects selected in this study were mainly myopic patients with presbyopia. Since the dominant eye was completely corrected for distance vision, the positive SA was significantly increased after surgery, while the non-dominant eye was subjected to multifocal bia-spheric ablation, introducing partial negative SA, which offset the positive spherical aberration produced by correcting myopia, resulting in no significant change in non-dominant ocular aberration. The study results were similar to those of Fu et al.12. Fu et al.11 also conducted another study to evaluate the subjective satisfaction of patients after the monocular profile. The study showed that patient satisfaction was 95% at three months after surgery and 100% at one year after surgery. Three months after surgery, the patient reported dry eyes, halo, and decreased night vision, but with time, these symptoms improved, and the patient gradually adapted to this binocular imbalance.
In the monocular mode, SCHWIND Custom Ablation Manager for Amaris software was used for surgical design, AMARIS 1050RS excimer laser was used for ablation of the corneal stroma, and VisuMax femtosecond laser system was used formaking of the corneal flap. Attention should be paid to the evaluation of the amount of negative SA introduced in the surgical design, so as not to affect the patient&#39;s postoperative visual quality due to excessive SA. At the same time, it should be noted that there is a reversal mode in the surgical design, and if the postoperative patient is unable to tolerate the corneal multifocal state, the reversal mode can be used to eliminate it. The size of the corneal flap needs to cover the ablation range, the ablation center selects the corneal apex, and the AMARIS 1050RS excimer laser machine is used for surgical ablation, which uses 7-dimensional eye-tracking technology to track the rotational movement of the eyeball, which greatly reduces the generation of articulated HOA.
The Q-value represents the corneal aspheric index, and under normal conditions, the cornea assumes a flat elongated elliptical shape with a central protrusion and a flat periphery, characterized by a mean Q-value of -0.23 &#177; 0.0821. Notably, the Q-value exhibits a positive correlation with SA when other factors, such as pupil and curvature, remain constant22. Following surgery, the cornea assumes an elevated central and flat peripheral configuration in a prolate form, leading to a concurrent negative increase in both spherical aberration and Q-value. This alteration enhances the depth of focus and effectively improves near vision22. The findings of this study demonstrated a positive increase in the Q-value in both eyes after surgery, attributable to the correction of myopia in both eyes. Specifically, the dominant eye underwent standard myopia correction, while the non-dominant eye was subjected to a double aspheric design, retaining a certain degree of refractive error alongside myopia correction. Consequently, the Q-value of the non-dominant eye was more negative than that of the dominant eye, thereby contributing to the improvement of the patient&#39;s near vision.
Although the results of the operation were good, there were still shortcomings in the research, such as the small sample size and the lack of a subjective satisfaction survey of patients. Although the results showed that the patients achieved good postoperative vision, but did not summarize and analyze the symptoms of discomfort that occurred after the operation. It is important to note that only preoperative and postoperative were selected. Based on the results of two time points in the next 6 months, it is impossible to make an accurate judgment on the changes in the patient&#39;s vision after the operation.
Monocular bi-aspheric ablation profile has emerged as a primary method for excimer laser correction of presbyopia due to its favorable outcomes in both distance and near vision post-operatively, rapid recovery time, and high patient tolerance. While it does not restore the eye&#39;s accommodative ability, it offers sufficient &#34;pseudo-accommodation&#34; to significantly alleviate near-vision difficulties in patients and enhance the quality of life for individuals with presbyopia.

Presbyopia is an age-related reduction in amplitude of accommodation leading to loss of near vision due to the loss of function of the lens and ciliary muscle1. The global population of presbyopes is projected to exceed 2 billion by 2030, with uncorrected and undercorrected presbyopia affecting socio-economic development2. Correction of presbyopia includes lens correction, surgical approaches, and medication. Corneal surgery is one of the main forms of corneal surgery to correct presbyopia because of its less invasive nature, fewer complications, and faster recovery3.
Ruiz introduced Presby laser-assisted in situ keratomileusis (LASIK) in 1996, which ablates the cornea into a multifocal pattern and increases the negative SA to achieve simultaneous near and distance vision4,5. Depending on the proximity area, Presby LASIK can be categorized into peripheral model6 (peripheral area for near vision and central area for distance vision) and central model7(peripheral area for distance vision and central area for near vision)8,9. The monocular bi-aspheric ablation profile is a hybrid Presby LASIK that combines the advantages of multiple programs, including micro-monocular vision, bi-aspheric, and multifocal. The dominant eye is completely corrected for distance vision, the central zone of the non-dominant eye retains approximately -0.89D of refraction for near vision, the peripheral cornea is ablated for distance vision, and the range of near addition (ADD) is between +1.25D to 2.50D, and aspheric cutting is used in both the central and peripheral zones10,11.
Compared with the previous monovision LASIK, the multifocal morphology of the non-dominant eye after the monocular bi-aspheric ablation profile reduces the anisometropia between the two eyes. The negative increase of SA introduces the depth of focus, which can better improve near vision and, at the same time, improve the intermediate vision, reduce the impact on stereopsis, and improve the patient&#39;s acceptance and satisfaction11,12,13. The monocular mode will lead to complete correction of the dominant eye, which can achieve the fastest postoperative clear full vision, reduce the risk of UDVA decline, and is more suitable for patients with presbyopia who have the same requirements for UDVA and UIVA, while other algorithms are multifocal in both eyes, which need more time for adaptation after surgery and have the risk of UDVA decline14,15,16. This article describes the detailed surgical steps of excimer laser multifocal double aspheric ablation mode as a surgical guide.

<table><tbody><tr><td>0.9% Sodium Chloride Physiological Solution</td><td>Shandong Qidu Pharmaceutical Co., Ltd.</td><td>H37020764</td><td></td></tr><tr><td>AMARIS 1050RS Excimer Laser System</td><td>SCHWIND eye-tech-solutions,DE</td><td>https://www.eye-tech-solutions.com/amaris1050-excimer-laser</td><td></td></tr><tr><td>Compound Electrolyte Intraocular Irrigating Solution</td><td>Shenyang Xingqi Ophthalmic Co.</td><td>http://sinqi.com/html/SYXQ/202006/948671948671019061.html</td><td></td></tr><tr><td>Dexamethasone Eye Drops</td><td>Alcon-Couvreur</td><td>H20150119</td><td></td></tr><tr><td>Dextran 70</td><td>Chengdu Qingshan Likang Pharmaceutical Co.</td><td>6941684920076</td><td></td></tr><tr><td>Glycerol Eye Drops</td><td>Chengdu Qingshan Likang Pharmaceutical Co.</td><td>6941684920076</td><td></td></tr><tr><td>Hypromellose 2910</td><td>Chengdu Qingshan Likang Pharmaceutical Co.</td><td>6941684920076</td><td></td></tr><tr><td>Levofloxacin Hydrochloride Eye Drops</td><td>Shandong Bausch &amp;amp; Lomb Freda Pharmaceutical Co., Ltd</td><td>6924090700180</td><td></td></tr><tr><td>Proparacaine hydrochloride Eye Drops</td><td>Alcon-Couvreur</td><td>H20103352</td><td></td></tr><tr><td>SCHWIND Cutom Ablation Manager for Amaris</td><td>Consorzio Servizi Ortopedici,Turin,IT</td><td>N/A</td><td></td></tr><tr><td>Sirius 3D anterior segment and corneal aberration analyzer</td><td>Consorzio Servizi Ortopedici,Turin,IT</td><td>YM0020207&amp;nbsp;</td><td></td></tr><tr><td>Skin disinfectant</td><td>Jinan Xinyongtai Shiye Co., Ltd</td><td>http://www.sdxyt.cn/zh/products_detail.asp?id=23</td><td></td></tr><tr><td>Sterile Irrigator for Single Use</td><td>Shandong Weigao Group Medical Polymer CO.,Ltd</td><td>https://weigaogroup.com/photo/show-114.aspx</td><td></td></tr><tr><td>Sterile medical sponge for Single Use</td><td>Beijing Kang&#039;an Kelin Technology Co., Ltd</td><td>SS-96A</td><td></td></tr><tr><td>Tobramycin Eye Drops</td><td>Alcon-Couvreur</td><td>H20150119</td><td></td></tr><tr><td>Transparent Film Dressing Frame Style</td><td>Minnesota Mining and Manufacturing</td><td>1624WCN</td><td></td></tr><tr><td>VisuMax femtosecond laser system</td><td>Carl Zeiss Meditec, Inc., Dublin, CA</td><td>20183241728</td><td></td></tr></tbody></table>

correction of presbyopia by monocular bi-aspheric ablation profile

The study aims to evaluate visual acuity and objective visual quality before and after the monocular bi-aspheric ablation profile for correction of presbyopia surgery. This prospective self-control study included 20 cases and 38 eyes of patients who underwent monocular bi-aspheric ablation profile correction of myopia with presbyopia at the Eye Hospital of Shandong University of Traditional Chinese Medicine from January 2023 to January 2024. These patients were selected for observation, and each patient's preoperative and postoperative uncorrected distance visual acuity (UDVA), uncorrected near visual acuity (UNVA), corrected distance visual acuity (CDVA), spherical aberration (SA) (within 6 mm), horizontal and vertical coma (within 6 mm), and corneal aspheric index (Q-value) (within 6 mm) were evaluated. Statistical data analysis was performed at different time points before and after the operation. There were statistically significant differences in UDVA between dominant and non-dominant eyes before and after surgery (Z = -3.784, p &lt; 0.001; Z = -3.817, p &lt; 0.001). Post-operatively, 90% of the non-dominant eyes achieved UNVA of J1 and above, and 95% of the bilateral eyes achieved UNVA of J1 and above. Significant differences were found in the SA of the dominant eyes, which showed a positive increase (Z= -3.784, p &lt; 0.001); however, compared with the dominant eye, the SA of the non-dominant eye was negatively increased, but the difference was not statistically significant (p = 0.08). There was a significant difference in the vertical coma of the dominant eye before and after the operation, but there was no significant difference in non-dominant eyes. There was no significant difference in the change of binocular horizontal coma before and after the operation. There were significant changes in the Q value of both eyes before and after the operation (Z = -3.923, p &lt; 0.001; Z = -3.51, p &lt; 0.001). After the monocular bi-aspheric ablation profile, the cornea of the non-dominant eye showed a prolate shape, negative SA increased, and the UDVA and UNVA improved after the operation.

A total of 20 patients who underwent the monocular bi-aspheric ablation profile for correction of presbyopia were analyzed in this study. The preoperative age of the patients was 47 (&#177; 3.36) years, and the preoperative spherical equivalent (SE) of the dominant and non-dominant eyes were -4.47 D (&#177; 2.16) D and -4.34 D (&#177;2.09 D), respectively. All surgeries were completed with no postoperative complications.
Visual acuity results 
There was no significant difference in CDVA between the dominant eye and the non-dominant eye before and after surgery, but there were significant differences in UDVA between the dominant eye, the non-dominant eye, and both eyes before and after surgery(Z = -3.755, p &#60; 0.001; Z = -3.817, p &#60; 0.001; Z = -3.800, p &#60; 0.001) (Table 1).
Preoperatively, 70% of the dominant eye and over 60% of the non-dominant eyes achieved a UNVA of J5 or better, with no patients reaching a near visual acuity of J1. At 6 months post-operatively, 90% of patients in the non-dominant eye achieved a UNVA of J1 or better, while 100% of the dominant eye achieved J5 or better. Additionally, 95% of patients attained a BUNVA of J1 or better (Table 1).
Corneal asphericity index 
The Q values of the dominant and non-dominant eyes were positively changed after surgery, and the changes were statistically significant, and the Q values of the dominant and non-dominant eyes were statistically significant when compared with each other 6 months after surgery(Z = -3.823, p &#60; 0.001; Z = -3.510, p &#60; 0.001; Z = -3.474, p &#60; 0.05) (Table 2).
NOTE: See Table 2.
High order aberration 
Both binocular SA increased positively after surgery; the change in dominant eye SA was statistically significant (Z = -3.784, p &#60; 0.001), the change in non-dominant eye SA was not statistically significant, and the difference in binocular SA compared with each other 6 months after surgery was statistically significant (Z = -3.920, p &#60; 0.001). There was a significant difference in the vertical coma of the dominant eye before and after the operation(Z = -2.503, p &#60; 0.05), but there was no significant difference in the horizontal coma and vertical coma of the non-dominant eye (Table 3).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/67173/67173fig01.jpg" /> 
Figure 1: Patient positioning. Place the patient in the supine position, routinely flush the eyes, disinfect, spread the towel, apply the film and the lid opener to support the lid fissure, and fully expose the cornea. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67173/67173fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/67173/67173fig02.jpg" /> 
Figure 2: Creating the corneal flap. Use the femtosecond laser system to create the corneal flap. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67173/67173fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/67173/67173fig03.jpg" /> 
Figure 3: Corneal stromal ablation. Use the excimer laser to ablate the corneal stroma. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67173/67173fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/67173/67173fig04.jpg" /> 
Figure 4: Flushing and resetting the corneal flap. The stroma is rinsed with a compound electrolyte intraocular irrigating solution, and the corneal flap is reset. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67173/67173fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td></td>
			<td>Eye</td>
			<td>Pre</td>
			<td>After</td>
			<td>Z</td>
			<td>p</td>
		</tr>
		<tr>
			<td>UDVA</td>
			<td>Dom</td>
			<td>1.2 (0.95, 1.28)</td>
			<td>0 (0, 0)</td>
			<td>-3.755</td>
			<td>&#60;0.001</td>
		</tr>
		<tr>
			<td></td>
			<td>Non</td>
			<td>1.1 (0.92, 1.3)</td>
			<td>0.2 (0.2, 0.38)</td>
			<td>-3.817</td>
			<td>&#60;0.001</td>
		</tr>
		<tr>
			<td></td>
			<td>OU</td>
			<td>1.1 (0.9, 1.2)</td>
			<td>0 (0, 0.1)</td>
			<td>-3.8</td>
			<td>&#60;0.001</td>
		</tr>
	</tbody>
</table>
Table 1: Changes in UDVA and CDVA before and after the operation.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td></td>
			<td>Eye</td>
			<td>Pre</td>
			<td>After</td>
			<td>Z</td>
			<td>p</td>
		</tr>
		<tr>
			<td>Q-value</td>
			<td>Dom</td>
			<td>-0.17 (-0.27, -0.12)</td>
			<td>0.59 (0.32, 0.96)</td>
			<td>-3.823</td>
			<td>&#60;0.001</td>
		</tr>
		<tr>
			<td></td>
			<td>Non</td>
			<td>-0.18 (-0.23, -0.13)</td>
			<td>0.46 (0.11, 0.79)</td>
			<td>-3.51</td>
			<td>&#60;0.001</td>
		</tr>
	</tbody>
</table>
Table 2: Changes in Q-value before and after the operation.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td colspan="3">Eye</td>
			<td>Pre</td>
			<td>After</td>
			<td>t</td>
			<td>p</td>
		</tr>
		<tr>
			<td colspan="2">SA</td>
			<td>Dom</td>
			<td>0.24 (0.15, 0.29)</td>
			<td>0.5 (0.44, 0.6)</td>
			<td>-3.784</td>
			<td>&#60;0.001</td>
		</tr>
		<tr>
			<td colspan="2"></td>
			<td>Non</td>
			<td>0.23 (0.18, 0.32)</td>
			<td>0.11 (0.02, 0.32)</td>
			<td>-1.752</td>
			<td>0.08</td>
		</tr>
		<tr>
			<td colspan="2">Horizontal</td>
			<td rowspan="2">Dom</td>
			<td rowspan="2">-0.11 (-0.21, -0.01)</td>
			<td rowspan="2">-0.26 (-0.47, 0.03)</td>
			<td rowspan="2">-1.755</td>
			<td rowspan="2">0.079</td>
		</tr>
		<tr>
			<td colspan="2">Coma</td>
		</tr>
		<tr>
			<td colspan="2"></td>
			<td>Non</td>
			<td>0.13 (0.03, 0.17)</td>
			<td>0.16 (0, 0.27)</td>
			<td>-0.959</td>
			<td>0.338</td>
		</tr>
		<tr>
			<td colspan="2">Vertical Coma</td>
			<td>Dom</td>
			<td>0.15 (0.09, 0.22)</td>
			<td>-0.03 (-0.19, 0.17)</td>
			<td>-2.503</td>
			<td>0.012</td>
		</tr>
		<tr>
			<td colspan="2"></td>
			<td>Non</td>
			<td>-0.13 (-0.29, 0.07)</td>
			<td>-0.14 (-0.44, 0.09)</td>
			<td>-1.681</td>
			<td>0.093</td>
		</tr>
	</tbody>
</table>
Table 3: Changes of Higher-order aberrations before and after the operation.

Author Spotlight: Advancements in Refractive Surgical Correction for Presbyopia and Exploring Postoperative Visual Acuity

This article provides a step-by-step guide to correcting presbyopia with a monocular bi-aspheric ablation profile.

Correction of Presbyopia by Monocular Bi-Aspheric Ablation Profile

The study aims to evaluate visual acuity and objective visual quality before and after the monocular bi-aspheric ablation profile for correction of ...

correction-of-presbyopia-by-monocular-bi-aspheric-ablation-profile

Nanyang Technological University

Research

JoVE Journal

Medicine

353 Views.  Shandong University of Traditional Chinese Medicine. We zetten ons in voor een refractieve chirurgische correctie van presbyopie en het onderzoeken van het postoperatieve gezichtsscherpte-effect en de coronale morfologie om een betrouwbare referentiewaarde te bieden voor de klinische toepassing van deze technologie. De correctietechniek die in dit artikel wordt toegepast, heeft het fenomeen van onvoldoende afstandszicht en aanpassingsproblemen na multifocale correctie in het verleden verbeterd, en is meer gesch...

Video: Auteur in de schijnwerpers: vooruitgang in refractieve chirurgische correctie voor presbyopie en het onderzoeken van postoperatieve gezichtsscherpte

Corneal Confocal Microscopy: A Novel Non-invasive Technique to Quantify Small Fibre Pathology in Peripheral Neuropathies

The accurate quantification of peripheral neuropathy is important to define at risk patients, anticipate deterioration, and assess new therapies. Conventional methods assess neurological deficits and electrophysiology and quantitative sensory testing quantifies functional alterations to detect neuropathy. However, the earliest damage appears to be to the small fibres and yet these tests primarily assess large fibre dysfunction and have a limited ability to demonstrate regeneration and repair. The only techniques which allow a direct examination of unmyelinated nerve fibre damage and repair are sural nerve biopsy with electron microscopy and skin-punch biopsy. However, both are invasive procedures and require lengthy laboratory procedures and considerable expertise. Corneal Confocal microscopy is a non-invasive clinical technique which provides in-vivo imaging of corneal nerve fibres. We have demonstrated early nerve damage, which precedes loss of intraepidermal nerve fibres in skin biopsies together with stratification of neuropathic severity and repair following pancreas transplantation in diabetic patients. We have also demonstrated nerve damage in idiopathic small fibre neuropathy and Fabry's disease.

Corneal Confocal microscopy is a non-invasive clinical technique which may be used to quantify C fibre damage to diagnose and stratify patients with increasing neuropathic severity.

The accurate quantification of peripheral neuropathy is important to define at risk patients, anticipate deterioration, and assess new therapies. ...

Thermal Ablation for the Treatment of Abdominal Tumors

Percutaneous thermal ablation is an emerging treatment option for many tumors of the abdomen not amenable to conventional treatments. During a thermal ablation procedure, a thin applicator is guided into the target tumor under imaging guidance. Energy is then applied to the tissue until temperatures rise to cytotoxic levels (50-60 &deg;C). Various energy sources are available to heat biological tissues, including radiofrequency (RF) electrical current, microwaves, laser light and ultrasonic waves. Of these, RF and microwave ablation are most commonly used worldwide.
During RF ablation, alternating electrical current (~500 kHz) produces resistive heating around the interstitial electrode. Skin surface electrodes (ground pads) are used to complete the electrical circuit. RF ablation has been in use for nearly 20 years, with good results for local tumor control, extended survival and low complication rates1,2. Recent studies suggest RF ablation may be a first-line treatment option for small hepatocellular carcinoma and renal-cell carcinoma3-5. However, RF heating is hampered by local blood flow and high electrical impedance tissues (eg, lung, bone, desiccated or charred tissue)6,7. Microwaves may alleviate some of these problems by producing faster, volumetric heating8-10. To create larger or conformal ablations, multiple microwave antennas can be used simultaneously while RF electrodes require sequential operation, which limits their efficiency. Early experiences with microwave systems suggest efficacy and safety similar to, or better than RF devices11-13.
Alternatively, cryoablation freezes the target tissues to lethal levels (-20 to -40 &deg;C). Percutaneous cryoablation has been shown to be effective against RCC and many metastatic tumors, particularly colorectal cancer, in the liver14-16. Cryoablation may also be associated with less post-procedure pain and faster recovery for some indications17. Cryoablation is often contraindicated for primary liver cancer due to underlying coagulopathy and associated bleeding risks frequently seen in cirrhotic patients. In addition, sudden release of tumor cellular contents when the frozen tissue thaws can lead to a potentially serious condition known as cryoshock 16.
Thermal tumor ablation can be performed at open surgery, laparoscopy or using a percutaneous approach. When performed percutaneously, the ablation procedure relies on imaging for diagnosis, planning, applicator guidance, treatment monitoring and follow-up. Ultrasound is the most popular modality for guidance and treatment monitoring worldwide, but computed tomography (CT) and magnetic resonance imaging (MRI) are commonly used as well. Contrast-enhanced CT or MRI are typically employed for diagnosis and follow-up imaging.

A thermal tumor ablation procedure is described. The entire procedure is detailed, including pretreatment planning and imaging studies, anesthesia, adjuvant techniques to facilitate a percutaneous approach, imaging guidance of the ablation device to the tumor, thermal treatment, post-treatment care and follow-up.

Percutaneous thermal ablation is an emerging treatment option for many tumors of the abdomen not amenable to conventional treatments. During a thermal ...

Ultrasound Cyclo Plasty in Eyes with Glaucoma

Glaucoma is a chronic disease caused by the progressive degeneration of the optical nerve fibers, resulting in decreased visual field that can lead to severe visual impairment, and eventually blindness. This manuscript describes a simple, surgeon-friendly, non-incisional technique, named Ultrasound Cyclo Plasty (UCP), for reducing intraocular pressure (IOP) in glaucoma patients. The technique determines a selective coagulation necrosis of the ciliary body; in addition, the stimulation of supra-choroidal and trans-scleral portions of the uveo-scleral outflow pathway has been recently proposed. UCP shows several technical improvements in ultrasound technology compared to previous techniques, providing more precise focusing on the target zone. The procedure is performed in the operating room under peribulbar anesthesia. Briefly, the coupling cone is put in contact with the eye and the ring probe, that contains six piezoelectric transducers which produce the ultrasound beams, is inserted inside it. Their proper centering over the ocular surface represents a crucial step for the correct targeting of the ciliary body. Sterile balanced salt solution is used to fill the empty spaces to ensure ultrasound acoustic propagation. Surgical treatment consists in the sequential automatic activation of each of the six transducers, for a total duration of less than 3 min. The patient leaves the hospital 1 h after the procedure with the treated eye patched. In the present study, 10 patients with open-angle glaucoma were followed-up during at least 12 months after the procedure. IOP was reduced at each interval compared to pre-operative, as well as the number of hypotensive medications. Twenty percent of patients did not respond to the treatment, and needed subsequent surgery to better control IOP. Treatment tolerability was good, with no cases of hypotony or phthisis. The UCP procedure is simpler, faster, safer, and less invasive than traditional cyclodestructive procedures with similar results in reducing IOP.

Glaucoma is a chronic disease with progressive degeneration of optic nerve fibers resulting in decreased visual field. Elevated intraocular pressure is considered the most important and the only treatable risk factor. This manuscript describes a simple, surgeon-friendly, non-incisional technique, named Ultrasound Cyclo Plasty, for reducing intraocular pressure in glaucoma patients.

Glaucoma is a chronic disease caused by the progressive degeneration of the optical nerve fibers, resulting in decreased visual field that can lead to ...

Behavior

Stereoacuity Improvement using Random-Dot Video Games

Conventional amblyopia therapy involves occlusion or penalization of the dominant eye, though these methods enhance stereoscopic visual acuity in fewer than 30% of cases. To improve these results, we propose a treatment in the form of a video game, using random-dot stimuli and perceptual learning techniques to stimulate stereoacuity. The protocol is defined for stereo-deficient patients between 7-14 years of age who have already received treatment for amblyopia and have a monocular best corrected distance visual acuity of at least 0.1 logMAR. Patients are required to complete a perceptual learning program at home using the video game. While compliance is stored automatically in the cloud, periodic optometry center visits are used to track patient evolution and adjust the game&#39;s stereoscopic demand until the smallest detectable disparity is achieved. The protocol has proved to be successful, and effectiveness is gauged in terms of a two-level gain on a random stereoacuity test (global stereoacuity or cyclopean stereoacuity reference test). Moreover, the random-dot stimuli learning transfers to medial lateral stereoscopic acuity according to a Wirt Circles test, in which success criteria is a final stereoacuity of over 140&#34;, and the attained enhancement corresponds to no less than two levels of stereoscopic acuity. Six months later, a random-dot stereoacuity test recorded no reduction in the stereoacuity that was achieved.

Presented here is a protocol to improve stereoacuity using gamified perceptual learning software based on random-dot stimuli. Patients are stereo-deficient subjects without strabismus. The protocol combines optometry center visits with home exercises using software. Compliance and stereoacuity evolution are stored in the cloud.

Conventional amblyopia therapy involves occlusion or penalization of the dominant eye, though these methods enhance stereoscopic visual acuity in fewer ...

Scleral Cross-linking Using Riboflavin and Ultraviolet-A Radiation for Prevention of Axial Myopia in a Rabbit Model

Myopic individuals, especially those with severe myopia, are at higher-than-normal risk of cataract, glaucoma, retinal detachment and chorioretinal abnormalities. In addition, pathological myopia is a common irreversible cause of visual impairment and blindness1-3. Our study demonstrates the effect of scleral crosslinking using riboflavin and ultraviolet-A radiation on the development of axial myopia in a rabbit model. The axial length of the eyeball was measured by A-scan ultrasound in New Zealand white rabbits aged 13 days (male and female). The eye then underwent 360&#176; conjunctival peritomy with scleral crosslinking, followed by tarsorrhaphy. Axial elongation was induced in 13 day-old New Zealand rabbits by suturing their right eye eyelids (tarsorrhaphy). The eyes were divided into quadrants, and every quadrant had two scleral irradiation zones, each with an area of 0.2 cm&#178; and a radius of 4 mm. Crosslinking was performed by dropping 0.1% dextran-free riboflavin-5-phosphate onto the irradiation zones 20 sec before ultraviolet-A irradiation and every 20 sec during the 200 sec irradiation time. UVA radiation (370 nm) was applied perpendicular to the sclera at 57 mW/cm&#178; (total UVA light dose, 57 J/cm&#178;). Tarsorrhaphies were removed on day 55, followed by repeated axial length measurements. This study demonstrates that scleral crosslinking with riboflavin and ultraviolet-A radiation effectively prevents occlusion-induced axial elongation in a rabbit model.

We demonstrate the effect of scleral crosslinking with riboflavin and UVA on an axial elongation rabbit eye. Axial elongation was induced in 13 day-old New Zealand rabbits (male and female) by suturing their right eye eyelids (tarsorrhaphy).

Myopic individuals, especially those with severe myopia, are at higher-than-normal risk of cataract, glaucoma, retinal detachment and chorioretinal ...

Iris Fixation via External Pentagram Suturing

Extensive anterior synechia of the iris can result in the gradual disappearance of the anterior chamber. It is one of the most common outcomes of both oculopathy and complicated post anterior segment surgery. This can impact visual function and lead to bullous keratopathy, making it one of the most complex clinical problems. Conventional anterior chamber plasty will partially create the anterior chamber, but the anterior chamber disappears again in some cases. The main reasons are: (1) the iris lens diaphragm is loose with atrophied and tension-free iris so that the aqueous humor circulation will push and squeeze the iris forward; (2) the effect of "roller" formed in the process of inflammation or restoration will change the iris structure from peripheral anterior synechia (PAS) to extensive anterior synechia again; (3) the fibration will result in synechia from iris to the cornea. In such cases, corneal endothelium deficiency can't stop the aqueous humor from entering the cornea. This results in persistent corneal edema post-conventional anterior chamber plasty, resulting in progressive rubbing and lachrymation. Therefore, anterior chamber plasty is not the first choice for patients without surgical indications of Descemet's stripping automated endothelial keratoplasty (DSAEK). However, this can be performed in patients with surgical indications who plan to receive DSAEK. A unique method of iris fixation via external pentagram suturing anterior chamber plasty (PSACP) is described here. The present technique is also compared with the conventional anterior chamber plasty. PSACP and DSAEK might be an effective way to cure the bullous keratopathy with extensive anterior synechia of the iris and disappeared anterior chamber.

Iris Fixation via External Pentagram Suturing

The present protocol describes how a 10-0 polypropylene suture crosses the anterior surface of the iris, forming a pentagram to prevent both iris and pupil from moving toward the cornea. This can be combined with subsequent keratoplasty to cure bullous keratopathy with extensive anterior synechia of the iris.

Extensive anterior synechia of the iris can result in the gradual disappearance of the anterior chamber. It is one of the most common outcomes of both ...

Binocular Dynamic Visual Acuity in Eyeglass-Corrected Myopic Patients

Current clinical visual assessment mainly focuses on static vision. However, static vision may not sufficiently reflect real-life visual function as moving optotypes are frequently observed daily. Dynamic visual acuity (DVA) might reflect real-life situations better, especially when objects are moving at high speeds. Myopia impacts static uncorrected distance visual acuity, conveniently corrected with eyeglasses. However, due to peripheral defocus and prism effects, eyeglass correction might affect DVA. The present research demonstrates a standard method to examine eyeglass-corrected DVA in myopia patients, and aimed to explore the influence of eyeglass correction on DVA. 
Initially, standard subjective refraction was performed to provide the eyeglass prescription to correct the refractive error. Then, binocular distance vision-corrected DVA was examined using the object-moving DVA protocol. Software was designed to display the moving optotypes according to the preset velocity and size on a screen. The optotype was the standard logarithmic visual chart letter E and moves from the middle of the left to the right side horizontally during the test. Moving optotypes with randomized opening direction for each size are displayed. The subjects were required to identify the opening direction of the optotype, and the DVA is defined as the minimum optotype that subjects could recognize, calculated according to the algorithm of logarithmic visual acuity.
Then, the method was applied in 181 young myopic subjects with eyeglass-corrected-to-normal static visual acuity. Dominant eye, cycloplegic subjective refraction (sphere and cylinder), accommodation function (negative and positive relative accommodation, binocular cross-cylinder), and binocular DVA at 40 and 80 degrees per second (dps) were examined. The results showed that with increasing age, DVA first increased and then decreased. When myopia was fully corrected with eyeglasses, a worse binocular DVA was associated with more significant myopic refractive error. There was no correlation between the dominant eye, accommodation function, and binocular DVA.

The present research demonstrates a method to accurately examine dynamic visual acuity (DVA) in myopic subjects with eyeglass correction. Further analysis indicated that the closer the refraction state to emmetropia, the better the eyeglass-corrected binocular DVA is at both 40 and 80 degrees per second.

Current clinical visual assessment mainly focuses on static vision. However, static vision may not sufficiently reflect real-life visual function as ...

Preventing Posterior Capsular Opacification Through IOL Rotation in Cataract Surgeries

Rotating the Intraocular Lens to Prevent Posterior Capsular Opacification in Cataract Surgeries

Posterior capsule opacification (PCO) is a common postoperative complication of extracapsular cataract surgery, which is caused by the proliferation and migration of lens epithelial cells and can affect long-term visual outcomes significantly. The most effective treatment for PCO is neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulotomy; however, this treatment is associated with posterior segment complication and can break the stability of capsular bag, affecting the position and function of trifocal or toric intraocular lenses (IOLs). Advances in surgical procedures, IOL design, and pharmacy have reduced the rate of PCO in recent years, concentrating on the inhibition of proliferative lens epithelial cells (LECs). This protocol aimed to clear LECs more thoroughly during phacoemulsification and IOL implantation. The first several steps, including clear corneal incision, continuous circular capsulorhexis, hydrodissection, hydrodelineation, and phacoemulsification, were completed as conventional procedures. After placing the IOL into the capsular bag, rotation of the IOL by at least 360&#176; was performed using an irrigation/aspiration tip or a hook, with slight stress on the posterior capsule. Some residuals occurred in the originally transparent capsular bag after rotation of the IOLs. Then, these materials and the viscoelastic were cleared completely using an irrigation/aspiration system. A clear posterior capsule was observed after the surgery in patients undergoing this method. This method of rotating IOLs is a simple, effective, and safe way to prevent PCO by clearing residual LECs and can be carried out without extra tools or skills.

Author Spotlight: Enhancing Visual Outcomes in Cataract Surgery: A Novel Technique to Prevent Posterior Capsular Opacification Through IOL Rotation 

The present protocol describes removing residual epithelial cells by rotating the intraocular lens in extracapsular cataract surgery without extra tools for preventing posterior capsular opacification.

Posterior capsule opacification (PCO) is a common postoperative complication of extracapsular cataract surgery, which is caused by the proliferation and ...

 Evaluating Stereopsis in Unilateral Amblyopia: A Comparative Study

Comparison of Three Clinical Stereoscopic Methods for Measuring Binocular Visual Function During Amblyopic Treatment in Unilateral Amblyopia

This study aimed to compare the measuring stereopsis results of unilateral amblyopia during amblyopic treatment by employing some of the most widely used clinical tests. Thirty-four individuals with previously untreated unilateral amblyopia, aged 8.4 &#177; 2.7 years, were included in the study. Monocular (best corrected visual acuity [BCVA] at distance) and binocular (including Titmus, Random-dot, and Frisby stereopsis) visual functions were measured at baseline and 2-month and 6-month visits after synthetical treatment.
We found that Titmus stereopsis was always significantly better than Random-dot stereopsis (p &#60; 0.001). Frisby stereopsis was also always significantly better than Random-dot stereopsis (p &#60; 0.001). However, there was no significant difference between Titmus stereopsis and Frisby stereopsis (p = 0.562). However, interestingly, there was no significant difference in the mean improvement of the three stereopsis methods from baseline to the 2-month visit, F = 1.158, p = 0.318.
Similarly, a significant difference was also lacking in the mean improvement of the three stereopsis methods from baseline to the 6-month visit, F = 0.302, p = 0.740. We conclude that there will be different results obtained from different stereopsis measuring methods used to measure amblyopia in patients. We recommend performing at least two types of stereoscopic measurements to evaluate each case of amblyopia. However, for observing therapeutic effects, each measurement method has the same performance for clinical results during amblyopic treatment.

Here, we present three common stereopsis measurement methods to measure patients with amblyopia and the comparison of the efficacy of different methods.

This study aimed to compare the measuring stereopsis results of unilateral amblyopia during amblyopic treatment by employing some of the most widely used ...

Focusing of Light in the Eye

Light rays enter the eye through the cornea, a transparent dome-shaped tissue that is the eye&#39;s outermost layer. The cornea bends or refracts, light rays traveling to the pupil. The shape of the cornea determines how much of the light is bent and whether the image will be focused correctly on the retina at the back of the eye. Once the light has passed through both refraction layers, it converges into a single focal point onto a small area. This is where photoreceptors start transforming visible photons into electrical signals sent along nerve fibers up to your brain for interpretation - ultimately resulting in what is known as sight.
The refractive power of the human eye is its ability to bend light rays as they enter the eye to focus them onto the retina at the back of the eye. This is necessary because light entering the eye is initially divergent, but the images we perceive must be clear and focused. The refractive power of the human eye is measured in diopters (D).
The cornea is the primary refractive surface of the eye, providing approximately two-thirds of the eye&#39;s refractive power. The lens of the eye, located behind the iris, provides the remaining one-third of the eye&#39;s refractive power.
The lens can change shape, known as accommodation, allowing the eye to focus on objects at different distances. The eye&#39;s crystalline lens is located directly behind the iris and pupil and further focuses light onto the retina. Unlike a rigid camera lens, our crystalline lenses are elastic and can change shape depending on one&#39;s vision needs for near or far objects.
When looking at an object closer than 20 feet away from you (near vision), your eyes must accommodate by becoming more curved to focus on near objects properly. When looking at an object farther than 20 feet away from you (distant vision), your eyes must become less curved to focus on distant objects properly.
The amount of bend or curve placed upon incoming light rays depends on one&#39;s refractive power index: The higher power index means more curvature required of incoming light, and vice versa. People with myopia (nearsightedness) have too much anatomical curvature in their eyes. This causes incoming light to focus too soon before reaching the retina, causing blurry vision when looking at distant objects. Inversely, people with hyperopia (farsightedness) have anatomical curvature that is too slight in their eyes. This causes incoming light rays to not bend enough before reaching their retinas and, as a result, causes blurry vision when looking at nearby objects.
Some other types of refractive errors can occur in the human eye, including:
<ol>
	<li>Astigmatism occurs when the cornea, the eye&#39;s clear front surface, is shaped like a football instead of spherical, causing blurry and distorted vision at any distance.</li>
	<li>Presbyopia is an age-related condition that typically occurs when the eye lens is less flexible, resulting in difficulty focusing on close-up objects.</li>
</ol>
These refractive errors can be corrected using appropriate glasses or contact lenses or surgery in some extreme cases.

In a normal human eye, as light rays enter, they bend at the cornea, and the lens, to form an inverted image on the retina. The extent to which rays ...

Correction of Presbyopia by Monocular Bi-Aspheric Ablation Profile

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