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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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. 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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 p...

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.

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			<td>6941684920076</td>
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			<td>6924090700180</td>
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			<td>Alcon-Couvreur</td>
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			<td>SCHWIND Cutom Ablation Manager for Amaris</td>
			<td>Consorzio Servizi Ortopedici,Turin,IT</td>
			<td>N/A</td>
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			<td>Consorzio Servizi Ortopedici,Turin,IT</td>
			<td>YM0020207&#160;</td>
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</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.

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

Correction of Presbyopia by Monocular Bi-Aspheric Ablation Profile

We are committed to a refractive surgical correction of presbyopia and exploring its postoperative visual acuity effect and coronal morphology in order to provide a reliable reference value for the clinical application of this technology. The correction technique applied in this paper has improved the phenomenon of insufficient distance vision and difficulty in adaptation after multifocal correction in the past, and is more suitable for patients with high requirements for distance vision. In the future, we will pay more attention to the comparative research of several different correction method and try to provide the best treatment plan for patients with presbyopia in different conditions.

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 dif...

This article provides a step-by-step guide to correcting presbyopia with a 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

Research

JoVE Journal

Medicine

Corneal Flap Creation and Stromal Ablation in Laser Eye Surgery in Humans

To plan the monocular by aspheric ablation profile, open the Amaris software. Select the anterior segment and corneal aberration analyzer with the aberration-free mode for the dominant eye, to eliminate aberrations and target a refraction of zero. For the non-dominant eye, select the monocular by aspheric ablation profile with an optical zone of 6.2 to 6.7 millimeters.Set the target to 0.89 diopters in the distal zone and introduce an ADD in the central three-millimeter zone. After selecting the patient with a monocular biospheric ablation profile, ask the patient to open their eyes and look upward. Rinse the conjunctiva sac with 0.9%normal saline.Disinfect the skin around the eyelid center, using a disinfectant. Place the patient supine with the head properly aligned. Drop artificial tears into the ocular surface to moisten it.Lay the surgical towel and expose the surgical eye. Stick a transparent dressing frame. Open the eyelid fissure to fully expose the cornea and wipe the cornea with a wet sterile sponge.Use the laser system to create the corneal flap. Attach the negative pressure suction ring to the laser emission window and treatment control panel. Select the flap mode and start the treatment steps according to the program displayed on the screen.Ask the patient to look at the green light. Using the operating microscope and joystick, align the watermark in the center of the contact lens on the negative pressure ring, ensuring it reaches about 80 to 90%Start the negative pressure suction until the cornea completely adheres to the contact surface of the negative pressure ring. Listen for a suction on to indicate the end of negative pressure suction and ready for the next step of preparation.Depress the pedal connected to the laser to start the ablation process, and instruct the patient to focus on the green gaze light. After setting the corneal stromal flap parameter, as mentioned, record the corneal ablation process. Upon completion of the corneal flap production, release the pedal, disengage the negative pressure suction, and remove the suction ring.Next, position the patient supine on an excimer laser surgical bed. Place the surgical towel and stick a transparent dressing frame around the patient's eye. Open the eyelid fissure to fully expose the cornea.After rinsing the corneas with saline, align them using the operating microscope. Separate the corneal flap using a flap separator, starting from the lateral incision near the hinge. Gently continue separating the flap from the stroma in the opposite direction of the pedicle until fully opened, exposing the stroma.Dry the stromal surface moisture using a sterile medical sponge. Use the excimer laser to ablate the corneal stroma. After verifying the patient's information, perform the ablation according to the surgical design.Ask the patient to stare at the gaze light while aligning the eyes with the laser, and center the corneal apex to select for the stromal ablation. After treatment, rinse the stroma with a compound electrolyte intraocular irrigating solution. Reset the corneal flap, apply 0.3%tobramycin and dexamethasone eye drops, and observe the corneal reset under a slit lamp.After correction of presbyopia, significant differences in uncorrected distance visual acuity between the dominant, non-dominant, and both eyes before and after surgery were observed. After surgery, the corneal asperity index of both dominant and non-dominant eyes was positively changed, and the changes were statistically significant. Both binocular spherical aberrations increased after surgery, with a statistically significant increase in spherical aberrations in the dominant eye.

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Excimer Laser Multifocal Double Aspheric Ablation for Presbyopia Correction

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