Visual Quality Assessment After FS-LASIK Using Customized Aspheric Ablation Profile for Age-Related Accommodation Deficiency Compensation.

PURPOSE: To evaluate clinical outcomes and visual quality 12 months after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) performed with the Custom-Q algorithm for correction of myopia with or without astigmatism and compensate for age-related accommodation deficiency. METHODS: Patients who had Custom-Q FS-LASIK for myopia and myopic astigmatism with age-related accommodation deficiency were included in this retrospective study. Distance, intermediate, and near visual acuities, objective and subjective refractions, Q-factor, corneal higher order aberrations (HOAs), accommodation function, defocus curve, contrast sensitivity, and a subjective questionnaire assessing visual quality were evaluated 12 months postoperatively. RESULTS: Clinical data of 43 cases were analyzed. The mean age was 42.02 ± 1.85 years (range: 40 to 48 years). At the 12-month follow-up visit, there were 43 (100%), 42 (97%), and 33 (77%) patients who achieved a binocular uncorrected distance, intermediate, and near visual acuity, respectively, better than 20/20 separately. Defocus curves revealed better distance vision in the dominant eyes, and the nondominant eyes performed better at intermediate and near vergence (P < .001). The Q-value and corneal spherical aberration coefficient were more positive in the dominant eyes than those in the nondominant eyes (P < .001). The accommodative amplitude and relative accommodation improved binocularly (P < .001). The questionnaire demonstrated high patient satisfaction with near vision, and no one reported having severe visual disturbance. CONCLUSIONS: For myopic patients with age-related accommodation deficiency, the Custom-Q algorithm proved to be an effective way to achieve acceptable near vision without compromising distance vision. [J Refract Surg. 2024;40(4):e245-e252.].

Comprehensive Assessment of Posterior Corneal Asphericity Change Calculated by Tangential Radius of Curvature After FS-LASIK and SMILE.

PURPOSE: To evaluate changes in posterior corneal asphericity (ΔQ) using the tangential radius of curvature after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) procedures. METHODS: One hundred twenty right eyes of myopic patients who underwent either FS-LASIK or SMILE procedures were analyzed using Sirius 3D corneal topography for assessment. The tangential radius was employed to calculate both preoperative and postoperative posterior corneal Q-values across each semimeridian. After both surgical interventions, the ΔQ value variations across the 360° semimeridional regions of the posterior corneal surface were compared. RESULTS: A marked postoperative increase in the posterior corneal Q-value was documented. No significant differences were noted between the postoperative Q-values or ΔQ-values of the two surgical approaches. Among patients with moderate myopia, postoperative Q-value exhibited considerably lower increases and ΔQ-value significantly smaller than their counterparts with high myopia. Moreover, the fluctuation in ΔQ across semimeridional regions was less evident in patients with moderate myopia than in those with high myopia. Notably, the degree of ΔQ fluctuation across semimeridional regions was similar between both surgical categories. These data offer insights into variations in the posterior corneal surface after refractive surgeries depending on the degree of myopia, illuminating their clinical relevance. CONCLUSIONS: Both FS-LASIK and SMILE introduce notable changes to posterior corneal asphericity among patients with different myopia intensities. Furthermore, the influence on the asphericity across the entire posterior surface is similarly distributed between FS-LASIK and SMILE techniques. [J Refract Surg. 2024;40(3):e133-e141.].

Retrospective assessment of accuracy of nine intraocular lens power calculation formulae in eyes with axial myopia.

PURPOSE: To compare the accuracy of nine conventional and newer-generation formulae in calculating intraocular lens power in eyes with axial myopia. SETTING: Tertiary eye care center, Bengaluru, India. DESIGN: Retrospective cross-sectional, comparative study conducted in India. METHODS: Patients undergoing uneventful phacoemulsification in eyes with axial length >26 mm were included. Preoperative biometry was done using Lenstar LS 900 (Haag-Streit AG, Switzerland). Single eye of patients undergoing bilateral implantation was randomly selected. Optimized lens constants were used to calculate the predicted postoperative refraction of each formula, which was then compared with the actual refractive outcomes to give the prediction errors, following which subgroup analysis was performed. The Kane formula, Barrett universal II, Emmetropia Verifying Optical (EVO) 2.0, Hill Radial Basis Function (Hill RBF) 3.0, Olsen formula, along with Wang Koch-adjusted four formulae, that is, Sanders Retzlaff Kraff/Theoretical (SRK/T), Holladay 1, Haigis, and Hoffer Q formula, were compared for intraocular lens power calculations. RESULTS: One hundred and sixty-five eyes that fulfilled all the inclusion criteria were studied. Hill RBF 3.0 had the lowest mean and median absolute prediction errors (0.355 and 0.275, respectively) compared to all formulas. In subgroup analysis (26-28, >28-30, and >30 mm), significant difference was seen only in extremely long eyes (>30 mm). The Hill RBF 3.0 formula generated the maximum percentage of eyes with refractive errors within ±0.25, ±0.5, ±0.75, and ±1 D (46%, 76.2%, 89.9%, and 95.8%, respectively). CONCLUSION: This is the first study evaluating all the formulas exclusively in the myopic eyes. Hill RBF 3 was found to be superior in accuracy to all other formulas.

Quantitative assessment of corneal elasticity distribution after FS-LASIK using optical coherence elastography.

Quantifying corneal elasticity after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) procedure plays an important role in improving surgical safety and quality, since some latent complications may occur ascribing to changes in postoperative corneal biomechanics. Nevertheless, it is suggested that current research has been severely constrained due to the lack of an accurate quantification method to obtain postoperative corneal elasticity distribution. In this paper, an acoustic radiation force optical coherence elastography system combined with the improved phase velocity algorithm was utilized to realize elasticity distribution images of the in vivo rabbit cornea after FS-LASIK under various intraocular pressure levels. As a result, elasticity variations within and between the regions of interest could be identified precisely. This is the first time that elasticity imaging of in vivo cornea after FS-LASIK surgery was demonstrated, and the results suggested that this technology may hold promise in further exploring corneal biomechanical properties after refractive surgery.

Corneal remodeling after SMILE for moderate and high myopia: short-term assessment of spatial changes in corneal volume and thickness.

PURPOSE: To evaluate the early corneal remodeling and its influencing factors after Small incision lenticule extraction (SMILE) for moderate and high myopia. METHODS: This was a retrospective study. Pre- and post-operative (1 week and 1, 3, 6 months) corneal volume (CV), mean keratometry (Km), and corneal thickness (CT) were measured by Scheimpflug tomography. CT at the central, thinnest point, and on concentric circles of 2, 4, and 6 mm diameter was recorded to assess corneal thickness spatial profile (CTSP) and percentage of thickness increase (PTI) in the moderate and high myopia groups, and to explore possible influencing factors. RESULTS: After SMILE, the peripheral CT decreased in the moderate myopia group and central corneal thickness (CCT) increased in the high myopia group at 1 month compared to 1 week (all P < 0.05). The CV, Km and CT were significantly increased at 3 months compared to 1 month (all P < 0.05), but there was no significant change at 6 months compared to 3 months for both groups (all P > 0.05). Patients with high myopia showed greater corneal thickness changes (△CT) and higher PTI than moderate myopia (all P < 0.05). Regression analysis revealed that in addition to refraction, peripheral PTI was negatively correlated with CCT in the moderate myopia group (4 mm: ß = -0.023, P = 0.001; 6 mm: ß = -0.050, P < 0.001), as well as in the high myopia group (4 mm: ß = -0.038, P < 0.001; 6 mm: ß = -0.094, P < 0.001). Moreover, peripheral PTI in the moderate myopia group was negatively correlated with age (4 mm: ß = -0.071, P = 0.003; 6 mm: ß = -0.162, P < 0.001). CONCLUSIONS: After SMILE, the CV, Km, and CTSP showed dynamic changes in the early stage, which stabilized after 3 months. Compared to the moderate myopia group, the high myopia group experienced slower corneal stabilization. The change in PTI at 6 months after SMILE may be related to higher preoperative refraction, thinner CCT and younger age.

Assessment of the biometric modifications of the eye in LASIK during suction.

PURPOSE: To study the biometric modifications of the eyeball during suction in Laser assisted in Situ Keratomileusis (LASIK). METHODS: Observational and cross-sectional study. We studied 43 patients who underwent surgery for myopia and myopic astigmatism. Mean age was 38.3 ±â€¯11.5 years, and 19 were female (44.2%). Conventional LASIK surgery with a manual microkeratome was performed. Before and during the suction maneuvre the following parameters were measured using an 11 Mhz biometric probe: aqueous depth (AQD), lens thickness (LT), vitreous cavity length (VCL) and axial length (AXL). Paired t-test was used to compare the biometric measurements before and during suction. RESULTS: The mean spherical equivalent refractive error was -4.5 ±â€¯2.3 diopters. During suction, the AQD did not change significantly (p = 0.231). However, AXL and VCL increased by 0.12 mm and 0.22 mm respectively (p = 0.039 and <0.01) and LT decreased by 0.20 mm (p < 0.01). AXL increased in 42% of the eyes and decreased in 16%, VCL increased in 70% of the eyes and decreased in 9%, and the LT was reduced in 67% of the eyes. CONCLUSIONS: Suction maneuvres during LASIK surgery produce changes of little magnitude in the eye globe, mainly a decrease in LT and an increase in VCL and AXL. Therefore, these modifications are expected to produce minimal anatomic alterations.

[Direct assessment of changes in biomechanical properties of the cornea after ReLEx SMILE and FemtoLASIK surgeries]. / Neposredstvennaya otsenka izmenenii biomekhanicheskikh svoistv rogovitsy posle provedeniya operatsii ReLEx SMILE i FemtoLASIK.

The aim of this study was to evaluate corneal biomechanical properties in myopic patients after ReLEx SMILE and FemtoLASIK surgeries using the Corvis ST analyzer. MATERIAL AND METHODS: The SMILE group comprised 23 patients (46 eyes) with spherical refraction -3.8±1.8 diopters (D), the FemtoLASIK group included 18 patients (36 eyes) with spherical refraction -3.5±1.3 D. Analysis of the biomechanical properties of the cornea was carried out using the CORVIS ST device (Oculus, Germany) before and seven days after corneal refractive surgery. RESULTS: In the SMILE group, with intraoperative decrease in corneal thickness of 91.43±19.43 µm, a significant increase in the following parameters was observed: deformation coefficient (DA ratio; p=0.0001), peak distance (PD; p=0.02) and inverse concave radius (ICR; p=0.003); a decrease in the stiffness parameter at first applanation (SP-A1; p=0.0001), Corvis biomechanical index (CBI; p=0.0001), intraocular pressure (IOP; p=0.001). In the FemtoLASIK group, with intraoperative decrease in corneal thickness of 75.33±32.3 µm, we observed a significant increase in DA ratio (p=0.0002), PD (p=0.04), ICR (p=0.0002), a decrease in SP-A1 (p<0.0001), IOP values (p=0.0003). In comparison with the FemtoLASIK group, the deformation amplitude DA changed significantly less in the SMILE group (p=0.04). In the FemtoLASIK group, in comparison with the SMILE group, the DA ratio (p=0.0009) and SP-A1 (p=0.0003) significantly increased. Intraoperative corneal thickness change correlates with ICR both in SMILE (R=0.52) and in FemtoLASIK (R=0.65). CONCLUSION: Corneal biomechanical properties determined with CORVIS ST in eyes with mild to moderate myopia change to a lesser extent after ReLEx SMILE compared to FemtoLASIK.

[Comparison of corneal power assessment methods after small incision lenticule extraction].

Objective: To compare the accuracy of different corneal curvature parameters in assessing the corneal refractive status and tracking corneal power changes after small incision lenticule extraction (SMILE). Methods: This prospective cross-sectional study tracked and recorded total corneal curvature parameters measured by different instruments before and three months after SMILE for myopia. These parameters, including total keratometry (TK) from the IOLMaster 700, total corneal refractive power (TCRP) from the Pentacam AXL, real keratometry (RK) from the CASIA 2, and corrected parameters calculated using the Haigis, Shammas, and Maloney methods, were compared with data obtained using the clinical history method (CHM). Surgically induced changes in TK, TCRP, and RK were analyzed and compared with those in spherical equivalent on the corneal plane (ΔSEco). Results: The study included 40 eyes (40 participants). After SMILE, the difference was smallest between TK [(0.08±0.38) D] and CHM values (P>0.05). However, TCRP, RK, KHaigis, KShammas, and KMaloney were significantly different from CHM data (P<0.05). The width of the 95% limits of agreement of TK (1.49 D) was narrowest, followed by that of RK (1.57 D). Pearson analysis showed that each parameter had a good correlation with CHM data. The differences between the changes in TK, TCRP and RK caused by surgery and ΔSEco were (0.03±0.39) D, (0.17±0.43) D, and (-0.19±0.46) D, respectively. The width of the 95% limits of agreement of ΔTK (1.54 D) was narrowest, and the correlation coefficient of ΔTK (0.951) was highest. Conclusion: The parameter TK of the IOLMaster 700 can provide accurate and objective corneal power evaluation after SMILE.

Assessment of Risk Factors Affecting Refractive Outcomes after Phacovitrectomy for Epiretinal Membrane.

PURPOSE: To investigate factors associated with refractive outcomes after phacovitrectomy for epiretinal membrane (ERM). METHODS: Retrospective review of patients undergoing phacovitrectomy for ERM was done. The main outcome measure was predictive refraction error (PE), defined as observed refraction error - target refraction error, calculated by the SRK/T, Haigis, and SRK II formulae. PE was measured at postoperative 1, 3, and 6 months. Simple and multiple linear regression analysis were used to evaluate factors associated with PE. RESULTS: A total of 53 eyes of 53 patients were included. The mean PEs at postoperative 1, 3, and 6 months were all negative, implying myopic shift in all patients regardless of the intraocular lens formula used. Haigis formula showed the least myopic shift among the three formulae (p = 0.001, Friedman test). There was no significant difference in PE depending on preoperative central macular thickness (CMT) in subgroup analysis. On stepwise multiple linear regression analysis, ERM etiology (ß = 0.759, p = 0.004, SRK/T formula; ß = 0.733, p = 0.008, Haigis formula; ß = 0.933, p < 0.001, SRK II formula), preoperative anterior chamber depth (ß = -0.662, p = 0.013, Haigis formula; ß = -0.747, p = 0.003, SRK II formula), and decrease of CMT (ß = -0.003, p = 0.025, SRK/T formula) were significantly associated with PE at postoperative 6 months. CONCLUSIONS: Myopic shift in PE was observed after combined phacovitrectomy for epiretinal membrane. ERM etiology, preoperative anterior chamber depth, and decrease of CMT were significantly associated with PE at postoperative 6 months. There was no difference in PE after surgery between the two groups defined by CMT (≥500 and <500 µm).

Early Assessment of Circumferential Anterior Segment Structures Following Implantable Collamer Lens V4c Implantation Via SS-OCT.

Purpose: To explore early changes in circumferential anterior segment structures following Implantable Collamer Lens (ICL) V4c implantation via swept-source optical coherence tomography (SS-OCT). Methods: In 103 eyes of 56 myopic patients undergoing ICL V4c surgery, anterior segments were measured via SS-OCT to compute local anterior chamber angle (ACA) parameters on the nasal-temporal (0°-180°), superior-inferior (90°-270°), and superior nasal-inferior temporal (80°-260°) meridians, including angle-opening distance at 500 µm (AOD500), trabecular-iris space area at 500 µm (TISA500), trabecular-iris angle at 500 µm (TIA500), and circumferential ACA parameters, including AOD area at 500 µm (AODA500), trabecular-iris circumference volume at 500 µm (TICV500), and the index and area of iris-trabecular contact (ITC). ACA parameters were compared preoperatively and at 1 week, 1 month, and 3 months postoperatively and compared among quadrants. Mixed-effects model was used to evaluate the parameters correlated with the post-ITC parameters. Results: The mean AOD500, TISA500, TIA500, AODA500, and TICV500 were decreased by 65.4% to 71%, 64.1% to 69.3%, 53.8% to 61.5%, 69.9%, and 69.2%, respectively, at 1 week postoperatively. The ITC index and area values rose from 1.436% ± 4.427% and 0.070 ± 0.254 mm2 to 12.343% ± 13.216% and 0.903 ± 1.304 mm2 (all P < 0.05). No further decreases in ACA parameters were observed beyond 1 week postoperatively (all P > 0.05). Significant differences were observed among quadrants, with the narrowest in the superior-nasal quadrant, followed by the superior quadrant. The 3-month vault was significantly correlated with the ITC index and area at 3 months postoperatively. Conclusions: Anterior segment structures were significantly shallow at 1 week with no further decreases thereafter. In light of anatomical variability, we recommend circumferential meridian scan to assess angle status, with special attention to the superior-nasal and superior quadrants. Translational Relevance: We investigated the early changes in circumferential anterior segment structures following ICL V4c implantation, thus providing a better perspective for understanding anterior segment structural characteristics after ICL V4c surgery.

Myopia, its prevalence, current therapeutic strategy and recent developments: A Review.

Myopia is a widespread and complex refractive error in which a person's ability to see distant objects clearly is impaired. Its prevalence rate is increasing worldwide, and as per WHO, it is projected to increase from 22% in 2000 to 52% by 2050. It is more prevalent in developed, industrial areas and affects individuals of all ages. There are a number of treatments available for the control of myopia, such as glasses, contact lenses, laser surgery, and pharmaceuticals agents. However, these treatments are less beneficial and have significant side effects. A novel molecule, 7-methylxanthine (7-MX), has been found to be a highly beneficial alternate in the treatment of myopia and excessive eye elongation. Many preclinical and clinical studies showed that 7-MX is effective for the treatment of myopia and is presently under phase II of clinical investigation. We have also investigated preclinical toxicity studies such as acute, sub-acute, sub-chronic, and chronic on rats. In these studies, 7-MX was found to be non-toxic as compared to other reported anti-myopic agents. Moreover, as an ideal drug, 7-MX is observed to have no or low toxicity, brain permeability, non-allergic, higher oral administration efficacy, and low treatment costs and thus qualifies for the long-term treatment of myopia. This review article on 7-MX as an alternative to myopia treatment will highlight recent findings from well-designed preclinical and clinical trials and propose a potential future therapy.

Assessment of biosafety and implantation feasibility of novel phakic refractive lens.

PURPOSE: We investigated the biosafety and implantation feasibility of a new phakic refractive lens (PRL) in rabbit eyes. METHODS: Short PRLs (S-PRLs), large PRLs (L-PRLs), and large-grooved PRLs (LG-PRLs), were prepared by molding medical-grade liquid silicon. The cytotoxicity and cellular adhesion of the PRLs was assessed in vitro. To assess implantation feasibility, the S-PRL, L-PRL, and LG-PRL were implanted in the posterior chamber of rabbit eyes and the relative position was assessed by optical coherence tomography. The intraocular pressures (IOP) were compared between the S-PRL, L-PRL, LG-PRL, and control groups to evaluate the PRL biosafety after implantation. RESULTS: The in vitro assays showed that cell viability and cellular adhesion in the S-PRL, L-PRL and LG-PRL groups was not significantly different to those in the control group throughout the study. After implantation into the posterior chamber of rabbit eyes, there were no obvious signs of inflammation or increases in IOP at each time point relative to the control group, demonstrating good biosafety of the PRL. The relative positions of the L-PRLs and LG-PRLs in the posterior chamber were appropriate and the retention frequencies were high. CONCLUSIONS: The newly developed LG-PRL showed good biosafety with negligible in vitro cytotoxicity, ocular inflammation, or fluctuations in IOP. The LG-PRL provided the best implantation feasibility. The grooves on the LG-PRL provided channels for aqueous humor circulation. The LG-PRL is a promising type of PRL with an appropriate size and surface structure for effective correction of refractive errors in rabbit eyes.

Assessment of Refractive Outcome of Photo Refractive Keratectomy in Myopia and Myopic Astigmatism.

OBJECTIVES: To determine the refractive outcomes of wavefront optimized photo refractive keratectomy (PRK) in patients having myopia and myopic astigmatism in terms of efficacy, safety, accuracy, stability and predictability of the procedure. STUDY DESIGN: Quasi-experimental study. PLACE AND DURATION OF STUDY: Refractive Surgical Unit, Armed Forces Institute of Ophthalmology, National University of Medical Sciences, Rawalpindi, Pakistan, from October 2013 to August 2018. METHODOLOGY: Patients having myopia and myopic astigmatism, consented to be a part of the study, underwent meticulous screening consisting of detailed medical history, ocular examination and investigations. Each case was compiled and evaluated. Those who satisfied the criteria for refractive surgery were subjected to PRK procedure. Postoperative follow-up was carried out and parameters were recorded at designated intervals of 1 week, 1, 3, 6 and 12 months. RESULTS: This study included 208 eyes of 106 patients with mean age of 25.33 + 5.196 years. At the end of one year, 97% (202 out of 208) eyes had uncorrected distance visual acuity (UDVA) better than 20/25 with efficacy index of 1.009 ± 0.132 and safety index of 1.019 ± 0.126. None of the eyes lost two or more lines. In this study, 207 out of 208 eyes remained within + 0.50 diopter (D) of intended spherical equivalent (SEQ). Results showed 100% accuracy of procedure since all the study patients achieved SEQ within + 1D. CONCLUSION: PRK is an effective, predictable, and safe treatment procedure for correcting myopia and myopic astigmatism. Key Words: Photorefractive keratectomy, Myopia, Refractive surgery, Myopic astigmatism, Uncorrected distance visual acuity.

Comparison of the Cost-Effectiveness of SMILE, FS-LASIK, and PRK for Myopia in a Private Eye Center in Spain.

PURPOSE: To describe and compare the cost-effectiveness of small incision lenticule extraction (SMILE), femtosecond laser-assisted in situ keratomileusis (FS-LASIK), and photorefractive keratectomy (PRK) for treating myopia and myopic astigmatism in a private eye center. METHODS: The perspectives for this cost-effectiveness analysis were for the payer and the health care sector. For the payer's perspective, a decision tree model was made, with a time period of 30 years, and the average weighted utility values and quality-adjusted life years (QALY) were computed for each procedure. The average weighted costs were derived for each procedure and divided by the QALY to obtain the incremental cost-effectiveness ratios (ICER). For the health care sector's perspective, the direct and indirect costs of acquiring the equipment and maintaining the facilities-including consumables and personnel salaries-were obtained to compute the minimum number of patients treated per year. RESULTS: The weighted utility values were 0.8 for SMILE and PRK and 0.77 for FS-LASIK. The weighted QALYs were 24 for SMILE and PRK, and 23.1 for FS-LASIK. The average weighted costs were 335.45, 443, and 346.96€, respectively. The resulting incremental cost-effectiveness ratios were 13.98 €/QALY for SMILE, 18.46 €/QALY for PRK, and 15.02 €/QALY for FS-LASIK. There was a negative correlation between the ICER and the time (in years) after the surgery. To achieve a profit, the minimum number of patients treated per year is 155 for SMILE, 136 for PRK, and 155 for FS-LASIK. CONCLUSIONS: Laser corneal refractive surgery is cost-effective for a person desirous of refractive correction for myopia. SMILE had the lowest ICER, followed by FS-LASIK and PRK. This trend was noted at all time periods. The cost of investing in laser refractive surgery facilities is outweighed by the potential income in high-volume eye centers. [J Refract Surg. 2022;38(1):21-26.].

Examining the Validity of a New Method for the Objective Assessment of Binocular Accommodative Facility (2Q-AF Test): A Comparison with ± 2.00 DS Lens Flippers.

PURPOSE: Recent technological advances have permitted to objectively record the accommodative response while shifting between two different levels of accommodation. This study is aimed at examining the concurrent validity of a new objective method for the qualitative and quantitative assessment of binocular accommodative facility, which is named 2Q-AF test, in comparison to the ±2.00 DS lens flippers. METHODS: Fifty-six individuals took part in this study (36 healthy young adults [24.4 ± 3.2 years] and 20 children [12.2 ± 0.4 years]). Participants randomly performed the 2Q-AF and the ±2.00 DS lens flipper tests. For the 2Q-AF test, a binocular open-field autorefractor was used to record the magnitude of accommodative response during a 60-sec period, while participants repeatedly changed fixation from a 5 m to a 40 cm chart when clarity of vision was achieved at each level. Due to the advantages of the proposed method, we have determined the number of cycles and the 2Q-AF score, with the latter also considering the accuracy of changes in accommodation. A standard procedure was followed for the ±2.00 DS flipper test. RESULTS: Our data exhibited a moderate association between the number of cycles with the ±2.00 DS lens flippers and the number of cycles in the 2Q-AF test in the group of young adults (p = .005, r = 0.46 [0.15-0.68]) and children (p = .007, r = 0.58 [0.19-0.81]), whereas a stronger relationship was observed when considering the number of cycles with the ±2.00 DS lens flippers and the 2Q-AF score (young adults: p < .001, r = 0.83 [0.69-0.91]; and children: p < .001, r = 0.78 [0.52-0.91]). CONCLUSIONS: The current findings show that the 2Q-AF test is a valid method for accommodative facility assessment, as suggested by its good levels of reliability and validity. This method allows to examine the accommodative facility in qualitative terms and solve most of the limitations associated with the ±2.00 DS lens flipper test.

Assessment of the correlation of the tear breakup time with quality of vision and dry eye symptoms after SMILE surgery.

PURPOSE: It is well reported that dry eye symptoms can increase after many refractive surgery procedures. This study aims to provide a clinical understanding of the correlation of fluorescein tear film breakup time (FTBUT) with quality of vision (QoV) and dry eye symptoms following small incision lenticule extraction surgery (SMILE). METHODS: Patients electing to have SMILE surgery were subdivided into 2 groups: Group 1 included short preoperative FTBUTs of 3 to 6 seconds (s); Group 2 included long FTBUTs of ≥ 8 s. Uncorrected distance visual acuity, corrected distance visual acuity, manifest refraction, FTBUT, QoV and Ocular Surface Disease Index (OSDI) questionnaires were recorded 1 and 6 months postoperatively. RESULTS: Thirty-nine subjects were included in each group. There was no significant difference in visual outcomes between the 2 groups at both the 1- and 6-month postoperative assessments. FTBUT remained significantly lower in group 1. Oxford staining was initially higher for group 1 at 1 month (P = 0.007), but there was no significant difference at 6 months (P = 0.180). There was no significant difference in QoV or OSDI scores between the 2 groups at both postoperative visits. CONCLUSIONS: Low preoperative FTBUT (3-6 s) does not appear to negatively affect postoperative visual outcomes or results in a greater likelihood of dry eye symptoms and poor ocular surface compared to eyes with a longer preoperative FTBUT. These results suggest that a low preoperative FTBUT does not necessarily increase the likelihood of poor visual acuity, dry eyes symptoms, or poor ocular surface outcomes following SMILE surgery.

Assessment of the Vault After Implantable Collamer Lens Implantation Using the KS Formula.

PURPOSE: To examine the vault size after Implantable Collamer Lens (ICL) (KS-AquaPORT; STAAR Surgical) surgery using the KS formula. METHODS: In this prospective study, the postoperative vault was examined using the KS formula in 121 eyes of 65 patients (28 men and 37 women) who underwent ICL implantation for myopia and myopic astigmatism. The mean horizontal angle-to-angle (ATA), anterior chamber depth, and axial length before surgery were 11.83 ± 0.40, 3.25 ± 0.34, and 26.52 ± 1.17, respectively. Anterior segment optical coherence tomography (CASIA2; Tomey Corporation) was used for ATA measurement. RESULTS: Multiple regression analysis of the potential factors influencing the predicted vault error (postoperative vault - predicted vault by KS formula) showed that only ICL size was a significant factor (P < .001, r = 0.36). At an ICL size of 12.1 mm, the postoperative vault was smaller than the predicted vault, and the postoperative vault tended to be larger than the predicted vault at ICL sizes of 13.2 and 13.7 mm. CONCLUSIONS: Vault prediction by the KS formula was generally good, but the ICL size influenced the vault prediction error; therefore, a modified KS formula was created to reduce the error in measurements of the postoperative vault. [J Refract Surg. 2021;37(9):636-641.].

Customized eye modeling for optical quality assessment in myopic femto-LASIK surgery.

Refractive surgery is recognized as an effective method for myopia treatment, but it can induce night vision disturbances such as glare. We present an eye modeling method for the optical quality assessment in response to the structural changes in the eyes by femto-LASIK surgery. Customized eye models were built from the measurements of 134 right eyes pre- and post-operatively. Optical performance was evaluated using spot diagrams, point spread functions (PSFs), modulation transfer functions (MTFs), and chromatic aberrations at various fields (0°-30°), different pupil diameters (2-6 mm), and initial myopias (- 1.25 to - 10.5 D). Pupil size and initial myopia are the two major factors that affect visual performance of post-operative eyes. The results of spot diagrams, PSFs, and MTFs indicated that post-operative visual performance deteriorated as the visual field and pupil size increased, and it was significantly influenced by initial myopia. Post-operative chromatic aberrations were also affected by initial myopia. As pupil size increased, the post-operative longitudinal chromatic aberrations tended to decrease slightly, while the transverse chromatic aberrations remained similar. The use of eye modeling for refractive surgery assessment could possibly provide a more personalized surgical approach, could improve the prediction accuracy of refractive surgery outcomes, and promote the invention and development of better surgical methods.

Femto-LASIK outcomes obtained by a fellowship trainee during a refractive surgery training program.

PURPOSE: To report, for the first time, the clinical outcomes and patient satisfaction of laser refractive surgery performed by a trainee during a corneal and refractive surgery fellowship program in Latin America. METHODS: This prospective and interventionist study reviewed the clinical charts of the first 100 consecutive refractive surgery cases performed by a single Cornea Fellowship trainee between March 2018 and June 2018 in the Blindness Prevention Association of Mexico (Asociación para Evitar la Ceguera en Mexico). Femtosecond LASIK was performed in all eyes. Visual and refractive outcomes were evaluated during the first year of follow-up. Patient satisfaction was measured using 5 author-created questions 6 months after surgery. RESULTS: Data of 100 eyes of 50 consecutive patients were evaluated. One year after the surgery, mean uncorrected distance visual acuity (UDVA) was 0.01 logMAR. Spherical equivalent error passed from -3.91 ± 2.28 D preoperatively to -0.22 ± 0.28 D. No eyes lost lines in corrected distance visual acuity (CDVA). Manifest refraction maintained stable during the first year after surgery. The five author-created questions revealed a high level of confidence and patient satisfaction. CONCLUSIONS: Femto-LASIK performed by a corneal and refractive surgery fellowship trainee showed good refractive and visual outcomes, as well as high patient satisfaction and confidence in a refractive surgery centre in Latin America.

Intraocular Lens Power Calculation in Eyes with Previous Excimer Laser Surgery for Myopia: A Report by the American Academy of Ophthalmology.

PURPOSE: To review the literature to evaluate the outcomes of intraocular lens (IOL) power calculation in eyes with a history of myopic LASIK or photorefractive keratectomy (PRK). METHODS: Literature searches were conducted in the PubMed database in January 2020. Separate searches relevant to cataract surgery outcomes and corneal refractive surgery returned 1169 and 162 relevant citations, respectively, and the full text of 24 was reviewed. Eleven studies met the inclusion criteria for this assessment; all were assigned a level III rating of evidence by the panel methodologist. RESULTS: When automated keratometry was used with a theoretical formula designed for eyes without previous laser vision correction, the mean prediction error (MPE) was universally positive (hyperopic), the mean absolute errors (MAEs) and median absolute errors (MedAEs) were relatively high (0.72-1.9 diopters [D] and 0.65-1.73 D, respectively), and a low (8%-40%) proportion of eyes were within 0.5 D of target spherical equivalent (SE). Formulas developed specifically for this population requiring both prerefractive surgery keratometry and manifest refraction (i.e., clinical history, corneal bypass, and Feiz-Mannis) produced a proportion of eyes within 0.5 D of target SE between 26% and 44%. Formulas requiring only preoperative keratometry or no history at all had lower MAEs (0.42-0.94 D) and MedAEs (0.30-0.81 D) and higher (30%-68%) proportions within 0.5 D of target SE. Strategies that averaged several methods yielded the lowest reported MedAEs (0.31-0.35 D) and highest (66%-68%) proportions within 0.5 D of target SE. Even after using the best-known methods, refractive outcomes were less accurate in eyes that had previous excimer laser surgery for myopia compared with those that did not have it. CONCLUSIONS: Calculation methods requiring both prerefractive surgery keratometry and manifest refraction are no longer considered the gold standard. Refractive outcomes of cataract surgery in eyes that had previous excimer laser surgery are less accurate than in eyes that did not. Patients should be advised of this refractive limitation when considering cataract surgery in the setting of previous corneal refractive surgery. Conclusions are limited by the small sample sizes and retrospective nature of nearly all existing literature in this domain.