Postoperative Spherical Equivalent Refraction Research Articles

Comparison of objective visual quality between SMILE and FS-LASIK in moderate-to-high myopia.

This study aims to compare the changes in the corneal wavefront aberrations and the objective visual quality resulting from two types of eye surgery-small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK)-in patients with moderate-to-high myopia. A prospective analysis was performed on 98 eyes of 51 patients who underwent SMILE. Additionally, 88 eyes of 45 patients who underwent FS-LASIK were analyzed. All patients underwent ocular examination preoperatively and at 1 day, 1 week, 1 month, and 3 months postoperatively. Corneal aberrations and objective visual quality were measured using the Optical Quality Analysis System II (OQAS II) and Optical Path Difference Scan III (OPD-Scan III). At postoperative 1 day and 1 week, there was a statistically significant difference in uncorrected distance visual acuity (UDVA) between SMILE and FS-LASIK (P < 0.05). Postoperative spherical (S), cylinder (C) and spherical equivalent refraction (SE) were similar between the two groups (P > 0.05). In both groups, the absolute magnitude of total higher-aberrations (tHOA), piston, vertical tilt, vertical coma, and spherical aberration (SA) increased after surgery compared to preoperative values (P < 0.05). There was no significant difference in Δhorizontal tHOA, Δhorizontal tilt, Δhorizontal coma, and Δhorizontal trefoil between the two groups (P > 0.05), and the FS-LASIK had higher Δvertical trefoil and ΔSA (P < 0.05) but lower Δpiston, Δvertical tilt, and Δvertical coma than the SMILE group (P < 0.05). There was a rise in objective scattering index (OSI) and a decline in both modulation transfer function (MTF) cutoff and Strehl ratio (SR) after surgery compared to preoperative values in both groups (P < 0.05). There was a statistically significant difference in the OSI at 1 day and 3 months between the two groups (P < 0.05). Postoperative MTF cutoff and SR were similar between the two groups (P > 0.05). Postoperative OSI was positively correlated with corneal tHOA (0.261 ≤ R ≤ 0.483, P < 0.05) and was negatively correlated with vertical tilt and vertical coma (-0.315 ≤ R ≤ -0.209, P < 0.05) in both groups. While both SMILE and FS-LASIK can effectively correct moderate-to-high myopia, there is an increase in corneal aberrations and a postoperative delay in objective visual quality. The cornea may require a longer recovery period in the SMILE. OPD-Scan III combined with OQAS II is a useful supplementary inspection for assessing the optical quality following refractive surgery.

Performance Evaluation of a Simple Strategy to Optimize Formula Constants for Zero Mean or Minimal Standard Deviation or Root-Mean-Squared Prediction Error in Intraocular Lens Power Calculation

PurposeTo investigate the performance of a simple prediction scheme for the formula constants optimized for a mean (MPE), standard deviation (SDPE) or root-mean-squared refractive prediction error (RMSPE). DesignRetrospective cross-sectional study. MethodsUsing IOLMaster 700 biometric data from 888 eyes treated with the Hoya Vivinex lens and 821 eyes treated with the Alcon SA60AT lens, plus the power of the implanted lens and postoperative spherical equivalent refraction, optimized constants for SRKT, Hoffer Q, Holladay 1, Haigis, and K6 formulae were calculated using an iterative nonlinear optimization for zero MPE and minimal SDPE and RMSPE. Start values were detuned by ±1.5 from the MPE optimized constants and formula constants generated using the simple prediction scheme were compared to the corresponding directly optimized constants. ResultsFor all 5 formulae under test and with both datasets, constants optimized using the simple scheme showed excellent agreement with those from the iterative method with either MPE or RMSPE used as the optimization metric, and good agreement with SDPE as the metric. Constants optimized for zero MPE or minimal RMSPE agreed within 0.05, whereas constants for minimal SDPE could be systematically off by up to 0.6 from the MPE values, making SDPE unsuitable as an optimization metric. ConclusionsThis simple formula constant optimization scheme performs excellently for 4 disclosed formulae and one nondisclosed formula in our 2 monocentric datasets with zero MPE or minimal RMSPE as metrics. Multicentric studies with other study populations and biometers are required to further investigate the clinical applicability.

Performance of a simplified strategy for formula constant optimisation in intraocular lens power calculation.

To investigate the performance of a simple prediction scheme for the formula constants optimised for a mean refractive prediction error. Analysis based on a dataset of 888 eyes before and after cataract surgery with IOL implantation (Hoya Vivinex). IOLMaster 700 biometric data, power of the implanted lens and postoperative spherical equivalent refraction were used to calculate the optimised constants (.)opt for SRKT, HofferQ, Holladay and Haigis formula with an iterative nonlinear optimisation. For detuning start values by ±1.5 from (.)opt, the predicted formula constants (.)pred were calculated and compared with (.)opt. Formula performance metrics mean (MPE), median (MEDPE), mean absolute (MAPE), median absolute (MEDAPE), root mean squared (RMSPE) and standard deviation (SDPE) of the formula prediction error were analysed for (.)opt and (.)pred. (.)pred - (.)opt showed a 2nd order parabolic behaviour with maximal deviations up to 0.09 at the tails of detuning and a minimal deviation up to -0.01 for all formulae. The performance curves of different metrics of PE as functions of detuning variations show that the formula constants for zeroing MPE and MEDPE yield almost identical formula constants, optimisation for MAPE, MEDAPE and RMSPE yielded formula constants very close to (.)opt, and optimisation for SDPE could result in formula constants up to 0.5 off (.)opt which is unacceptable for clinical use. This simple prediction scheme for formula constant optimisation for zero mean refraction error performs excellently in our monocentric dataset, even for larger deviations of the start value from (.)opt. Further studies with multicentric data and larger sample sizes are required to investigate the performance in a clinical setting further.

Comparison of Refractive Prediction Error by Axial Length in Flanged Intrascleral Intraocular Lens Fixation.

To evaluate the refractive prediction error in flanged intrascleral intraocular lens (IOL) fixation using the SRK/T formula and compare the axial length using a single IOL. Seventy-six eyes from 70 patients (45 males and 25 females) were included in this study. The mean age at the time of surgery was 73.4 ±12.3 years. The patients underwent flanged IOL fixation using a PN6A (Kowa). All surgeries were performed by two surgeons (Y. K. and T. O.) between Jan 2020 and Dec 2022 at Jikei University Daisan Hospital. IOL power was calculated using the SRK/T formula with IOL Master 700 (Carl Zeiss) as the bag power. The recommended value of 119.0 was used for the A-constant. The actual refractive spherical equivalent was calculated and compared with preoperative predictions. Refractive prediction errors were defined as the deviation of the actual postoperative spherical equivalent refraction in diopters from the predicted preoperative spherical equivalent refraction. The patients were divided into three groups according to axial length: <22.0 mm (short eyes), 22.0-24.5 mm (medium eyes), and >24.5 mm (long eyes), and the refractive prediction errors and mean absolute errors were compared. The mean refractive prediction error was -0.20 ± 0.52D. The mean absolute error was 0.44 ± 0.33D. The mean refractive prediction errors were not significantly different between the 22.0-24.5 mm (medium eyes) and >24.5 mm (long eyes) groups. (P=0.06) The mean absolute errors were not significantly different between the two groups (P=0.10). The SRK/T formula worked well regardless of whether the eyes were medium or long according to the axial length in the flanged intrascleral IOL fixation.

One-year clinical efficacy evaluation of selective corneal wavefront aberration-guided FS-LASIK correction in patients with high myopia.

To evaluate the effectiveness, safety, predictability, precision and changes of higher-order aberrations (HOAs) on corneal front surface of selective corneal wavefront aberration-guided femtosecond laser-assisted in situ keratomileusis (CW-FS-LASIK) in patients with high myopia 1-year postoperatively. Totally 74 eyes of 37 patients with high myopia or myopic astigmatism in both the eyes who underwent the CW-FS-LASIK procedure in Xi'an Gaoxin Hospital from January 2021 to June 2021 were included. The changes of uncorrected distance visual acuity (UDVA), best corrected visual acuity (BCVA), spherical equivalent refraction (SER), astigmatism, HOAs and Strehl ratio (SR) on the anterior surface of the cornea after 1y of the surgery were analyzed. At postoperative 1y, the UDVA (logMAR) of 74 eyes (100%) reached 0 or better, including 0 in 8 eyes (10.81%), -0.1 in 45 eyes (60.81%), and -0.2 in 21 eyes (28.38%). The effectiveness index was 1.29±0.134. There was no decrease in postoperative BCVA compared with preoperative BCVA in all patients. Postoperative BCVA was the same in 44 eyes (59.46%) as preoperative BCVA, increased by 1 line in 23 eyes (31.08%) and increased by 2 lines in 7 eyes (9.46%) compared with preoperative BCVA. The safety index was 1.11±0.159. The estimated corrected SER before surgery was (-7.76±1.21) D, and the actual corrected SER was (-7.83±1.25) D (Y=0.9811X+0.2156, R2=0.9084). There was a high correlation between the estimated corrected SER and the actual corrected SER. The postoperative SER in 74 eyes (100%) was within ±0.75 D. The postoperative astigmatism of all was within -0.75 D to 0. Root mean square (RMS) HOAs of spherical aberration and SR within 5 mm of the corneal front surface were all increased compared with those before operation (P<0.01). The total coma, horizontal coma and vertical coma were all decreased compared with those before operation (P<0.01). There was no statistically significant difference in horizontal trefoil and vertical trefoil compared with preoperative ones (P>0.05). Selective CW-FS-LASIK for correction of high myopia is effective, safe, predictive, and accurate. For patients with preoperative RMS HOAs over 0.25 defocus equivalent, postoperative coma aberration can be significantly reduced, and SR value can be increased, thus corneal imaging quality can be improved.

Assessment of refractive outcomes in eyes that underwent intraocular lens implantation in the posterior chamber but not "in-the-capsular bag:" A comparative retrospective study.

The purpose of this study was to report visual and refractive outcomes in eyes that underwent intraocular lens (IOL) fixation in the absence of capsular support. This was a retrospective chart review of cases undergoing posterior chamber iris-fixated IOL (IFIOL) and scleral-fixated IOL (SFIOL) implants from June 2014 to March 2020 with more than 3 months of follow-up and having a preoperative best-corrected visual acuity of 20/80 and more. Records of 120 eyes of 112 patients were reviewed. The mean age of the patients was 46.9 ± 22.3 (14.4-98.0) years, and 62% (n = 70) of participants were male. Most of the eyes (102: 85%) were aphakic at the time of surgery. The mean follow-up was 22.95 ± 17.1 months. The efficacy index of sutured IFIOL and glued SFIOL outperformed sutured SFIOL at 3 months and final visits postoperatively (P < 0.001). All techniques studied here resulted in a similar safety index at 3 months (P = 0.4). The mean predictive error (postoperative spherical equivalent refraction minus intended target refraction) was +0.07 ± 1.5 D and -0.12 ± 1.4 D at 3 months and the final postoperative visit, respectively. The studied techniques have relatively good visual and refractive outcomes in this series. In addition, techniques involving a small corneal incision with foldable IOL fixation to the iris or scleral tissue have superior efficacy and safety indices compared to creating large corneoscleral wounds for rigid IOL fixation techniques.

IMPACT OF GAS/AIR TAMPONADE ON REFRACTIVE OUTCOMES AFTER FLANGED INTRASCLERAL INTRAOCULAR LENS FIXATION.

This study aims to investigate the postoperative refractive outcomes in eyes that underwent the flanged intrascleral intraocular lens (IOL) fixation combined with vitrectomy with or without gas/air tamponade. The eyes were divided into two groups (Group A; eyes that underwent flanged intrascleral IOL fixation with gas/air tamponade, and Group B; eyes that underwent flanged intrascleral IOL fixation without gas/air tamponade). The predicted spherical equivalent (SE) refraction values were calculated using the Sander-Retzlaff-Kraff Theoretical formula. Then, the prediction error was calculated by subtracting the predicted SE refraction from the postoperative objective SE refraction and the absolute prediction error was calculated as the absolute value of the prediction error for each eye. A total of 68 eyes were included in the current study. There was a significant correlation between the predicted and postoperative SE refraction in both groups (Group A, r = 0.968, P < 0.0001, Group B, r = 0.943, P < 0.0001, linear regression analysis). The prediction error demonstrated a mild myopic shift after the flanged intrascleral IOL fixation in both groups (Group A, -0.40 ± 0.96 diopter, Group B, -0.59 ± 0.95 diopter). There was no significant difference in prediction error and absolute prediction error between the two groups ( P = 0.44, P = 0.70, Wilcoxon rank sum test). The postoperative SE refraction after flanged intrascleral IOL fixation was not influenced by gas/air tamponade.

A Simplified Method to Minimize Systematic Bias of Single-Optimized Intraocular Lens Power Calculation Formulas

To provide a simplified method to optimize lens constants to zero the mean prediction error (ME) of an intraocularlens (IOL) calculation formula, without the need to program the formula itself, by exploring the influence of IOL and corneal power on the refractive impact of variations in effective lens position. Theoretical development of an optimized formula and retrospective clinical evaluation on documented datasets. Retrospective data from 8878 patients with cataracts with pre- and postoperative measurements available using 4 IOL models and 6 IOL power calculation formulas were examined. A schematic eye model was used to study the impact of small variations in effective lens position (ELP) on the postoperative spherical equivalent (SE) refraction. The impact of keratometry (K) and IOL power (P) on SE was investigated. A theoretical thick lens model was used to devise a formula to zero the average prediction error of an IOL power calculation formula. This was achieved by incrementing the predicted ELP, which could then be translated into an increment in the IOL constant. This method was tested on documented real-life postoperative datasets, using different IOL models and single-constant optimized IOL calculation formulas. For small variations in ELP, there was an exponential relationship between IOL power and the resultant postoperative refractive variation. The ELP adjustment necessary to zero the ME equated to a ratio between the ME and the mean of the following expression: 0.0006*(P2+2K*P) on the considered datasets. The accuracy of the values obtained using this formula was confirmed on documented postoperative datasets, and on published and nonpublished formulas. The proposed method allows surgeons without special expertise to optimize an IOL constant to nullify the ME on a documented dataset without coding the different formulas. The influence of individual eyes is proportional to the squared power of the implanted IOL.

PRESBYOND Laser Blended Vision LASIK in Commercial and Military Pilots Requiring Class 1 Medical Certification.

To report the outcomes of PRESBYOND Laser Blended Vision LASIK (Carl Zeiss Meditec AG) in presbyopic commercial and military pilots requiring Class 1 aeromedical certification. This was a retrospective study of 23 consecutive pilots who underwent PRESBYOND Laser Blended Vision LASIK. Postoperative visits were conducted at 1 day and 1, 3, and 12 months. Standard outcomes analysis was performed using the data at 12 months. Objective quality of vision measures including mesopic contrast sensitivity (CSV-1000; VectorVision), Ocular Scatter Index (HD Analyzer; Keeler), and straylight (C-Quant; Oculus Optikgeräte GmbH) were determined before and 3 months after surgery. A questionnaire to assess the functional vision of pilots before and after surgery was derived to record subjective outcomes. Of the 23 pilots treated, data were available at 12 months for 22 pilots (95.7%) and at 3 months for 1 pilot (4.3%). Median age was 55 years (range: 42 to 65 years). At 12 months, binocular uncorrected distance visual acuity was 20/20 or better in 100% and 20/16 or better in 52% of pilots. Binocular uncorrected intermediate visual acuity was J3 in 73%, J5 in 95%, and J10 in 100% of pilots. Binocular uncorrected near visual acuity was J1 or better in 78% and J2 or better in 100% of pilots. Mean postoperative spherical equivalent refraction relative to the target was -0.04 ± 0.34 diopters (D) (range: -0.63 to +0.63 D), with 93% within ±0.50 D. There was a statistically significant increase in contrast sensitivity at 3, 6, 12, and 18 cpd. C-Quant straylight was 1.07 ± 0.16 before surgery and 1.06 ± 0.16 at 1 to 3 months after surgery (P = .705). All pilots achieved Class 1 medical certification from the United Kingdom Civil Aviation Authority and resumed flying. All pilots reported improved functionality compared to the previous vision correction method. PRESBYOND Laser Blended Vision LASIK enabled presbyopic commercial pilots to continue to fly without the need for glasses. With consideration of the visually challenging cockpit environment, PRESBYOND Laser Blended Vision LASIK provides clear continuous vision for tasks at near, intermediate, and far distance. Class 1 pilots reported a subjective improvement in visual tasks and comfort following surgery. [J Refract Surg. 2023;39(1):6-14.].

Penetrating Keratoplasty Versus Deep Anterior Lamellar Keratoplasty for Advanced Stage of Keratoconus

To compare visual acuity, refractive error, and complications after penetrating keratoplasty (PK) versus deep anterior lamellar keratoplasty (DALK) in the management of advanced stage of keratoconus. Retrospective, comparative, interventional study. This study enrolled 411 consecutive keratoconus eyes with preoperative mean keratometry ≥60 D that received either PK (218 eyes) or DALK (193 eyes). The outcome measures were postoperative visual acuity, refraction, complications, and further surgical interventions. The mean follow-up duration was 77.9±46.5 and 72.9±47.8 months in the PK and DALK groups, respectively (P=0.28). Compared to baseline values, postoperative visual acuity and refraction significantly improved in both groups. Postoperative corrected distance visual acuity was 0.18±0.13 and 0.26±0.19 logMAR in the PK and DALK groups, respectively (P<0.001). Postoperative spherical equivalent refraction was -2.89±2.89 D after PK and -4.58±3.62 D after DALK (P<0.001). Final keratometric astigmatism was comparable between the two groups (P=0.82). Suture-related complications were observed in 48.6% of the PK eyes and 72.0% of the DALK eyes (P<0.001). The incidence of graft rejection was 33.5% after PK and 19.7% after DALK (P=0.002). At the last visit, 98.2% of PK grafts and 94.8% of DALK grafts remained clear (P=0.06). Both techniques of corneal transplantation led to a significant improvement in the visual and refractive variables in eyes with advanced keratoconus. PK resulted in a better visual acuity and refraction with less suture-related complications compared to DALK. However, PK was associated with higher rate of graft rejection. The two techniques were comparable in terms of graft survival.

Effect of femtosecond laser cutting parameters on the results of small-incision lenticule extraction.

To determine the effect of femtosecond laser cutting parameters on small-incision lenticule extraction (SMILE) results by evaluating cap thickness, interface light scattering, and visual and refractive outcomes. SynsLaser Clinic, Oslo, Norway. Retrospective. 58 right eyes treated with SMILE using a programmed cap thickness of 130 μm were divided into 2 groups according to laser settings: Group 1: 165 nJ pulse energy and 4.5 μm spot separation (n = 36); Group 2: 125 nJ pulse energy and 4.2 μm spot separation (n = 22). The cap thickness was measured within the central 5 mm of the horizontal meridian using spectral-domain optical coherence tomography. Postoperative interface light scattering was graded based on the percentage area showing light scattering: 0: no scattering; 1: ≤25%; 2: 26% to 50%; 3: 51% to 75%; and 4: &amp;gt;75%. At 3 months postoperatively, cap thickness was 138.9 ± 6.2 μm in Group 1 and 149.4 ± 3.5 μm in Group 2 ( P &amp;lt; .001). Interface scattering was 0.9 ± 1.0 in Group 1 and 0.3 ± 0.9 in Group 2 ( P &amp;lt; .05), with no scattering in 33.3% and 86.4% of the eyes, respectively. The postoperative spherical equivalent refraction was -0.03 ± 0.44 diopters (D) in Group 1 and -0.04 ± 0.31 D in Group 2. In Group 1, 83.3% of the eyes were within ± 0.5 D of the desired outcome, and 69.4% achieved an uncorrected distance visual acuity of 20/20 or better. In Group 2, these values were 95.5% and 86.4%, respectively. Lower pulse energy with tighter spots seems to reduce interface light scattering and improve refractive outcomes while also significantly increasing cap thickness.

Theoretical Relationship Among Effective Lens Position, Predicted Refraction, and Corneal and Intraocular Lens Power in a Pseudophakic Eye Model.

PurposeTo ascertain the theoretical impact of anatomical variations in the effective lens position (ELP) of the intraocular lens (IOL) in a thick lens eye model. The impact of optimization of IOL power formulas based on a single lens constant was also simulated.MethodsA schematic eye model was designed and manipulated to reflect changes in the ELP while keeping the optical design of the IOL unchanged. Corresponding relationships among variations in ELP, postoperative spherical equivalent refraction, and required IOL power adjustment to attain target refractions were computed for differing corneal powers (38 diopters [D], 43 D, and 48 D) with IOL power ranging from 1 to 35 D.ResultsThe change in ELP required to compensate for various systematic biases increased dramatically with low-power IOLs (less than 10 D) and was proportional to the magnitude of the change in refraction. The theoretical impact of the variation in ELP on postoperative refraction was nonlinear and highly dependent on the optical power of the IOL. The concomitant variations in IOL power and refraction at the spectacle plane, induced by varying the ELP, were linearly related. The influence of the corneal power was minimal.ConclusionsThe consequences of variations in the lens constant mainly concern eyes receiving high-power IOLs. The compensation of a systematic bias by a constant increment of the ELP may induce a nonsystematic modification of the predicted IOL power, according to the biometric characteristics of the eyes studied.Translational RelevanceOptimizing IOL power formulas by altering the ELP may induce nonsystematic modification of the predicted IOL power.

Applying Information Gain to Explore Factors Affecting Small-Incision Lenticule Extraction: A Multicenter Retrospective Study.

PurposeThis retrospective study aimed to identify the key factors influencing postoperative refraction after small-incision lenticule extraction (SMILE) using information gain.MethodsThis study comprised 2,350 eyes of 1,200 patients who underwent SMILE using a Visumax 500-kHz femtosecond laser (Carl Zeiss Meditec AG) in three ophthalmic centers: Tianjin Eye Hospital (center A), Jinan Mingshui Eye Hospital (center B), and Qingdao Eye Hospital (center C). Anterior segment features, including corneal curvature and central corneal thickness (CCT), were obtained from Pentacam HR (Oculus, Wetzlar, Germany). Information gain was calculated to analyze the importance of features affecting postoperative refraction.ResultsPreoperative and postoperative mean spherical equivalent (SE) refraction were −5.00 (−6.13, −3.88) D and 0.00 (−0.25, 0.13) D, respectively. None of the patients lost more than two lines of corrected distance visual acuity. The safety index was 1.32 ± 0.24, 1.03 ± 0.08, and 1.13 ± 0.16 in centers A, B, and C, respectively. The efficacy index was 1.31 ± 0.25, 1.02 ± 0.08, and 1.13 ± 0.17 in centers A, B, and C, respectively. At least 95% of the eyes were within ±1.00 D of the attempted correction. Postoperative refraction was related to preoperative spherical diopter refraction (r = 0.369, p < 0.001), preoperative SE (r = 0.364, p < 0.001), maximum lenticule thickness (r = −0.311, p < 0.001), preoperative uncorrected distance visual acuity (r = 0.164, p < 0.001), residual stromal thickness (r = 0.139, p < 0.001), preoperative mean anterior corneal curvature (r = −0.127, p < 0.001), preoperative flattest anterior corneal curvature (r = −0.122, p < 0.001), nomogram (r = −0.100, p < 0.001) and preoperative CCT (r = −0.058, p = 0.005).ConclusionsSMILE was considered a safe and effective procedure for correcting myopia. Based on information gain, postoperative refraction was influenced by preoperative mean anterior corneal curvature, CCT, refraction, and residual stromal thickness.

Visual and Refractive Outcomes Following Laser Blended Vision With Non-linear Aspheric Micro-anisometropia (PRESBYOND) in Myopic and Hyperopic Patients.

To report 6-month visual and refractive outcomes following PRESBYOND Laser Blended Vision (Carl Zeiss Meditec) treatment using non-linear aspheric micro-anisometropia laser in situ keratomileusis (LASIK) for the correction of myopic and hyperopic presbyopia. A retrospective, non-comparative study of 139 consecutive patients with a mean age of 53.13 ± 5.84 years (range: 42 to 70 years) treated with LASIK-induced micro-anisometropia using the MEL 90 excimer laser and VisuMax femtosecond laser (both Carl Zeiss Meditec). The target refraction was plano for distance eyes (dominant eye) and between -0.50 and -1.50 diopters (D) for near eyes. Patients were observed for 6 months. A total of 278 eyes (78 myopic and 200 hyperopic) from 139 patients completed the study. Mean preoperative spherical equivalent (SE) was -3.40 ± 1.83 D (range: -0.50 to -8.25 D) for myopic eyes and +1.61 ± 0.98 D (range: -1.25 to +4.63 D) for hyperopic eyes. Mean postoperative SE refraction of distance eyes was +0.20 ± 0.35 D (range: -0.38 to +1.00 D) and -0.14 ± 0.42 D (range: -1.38 to +0.88 D) for myopic and hyperopic eyes, respectively. Mean postoperative SE refraction of near eyes was -0.90 ± 0.44 D (range: -0.13 to -2.25 D) and -1.21 ± 0.48 D (range: -0.13 to -2.25 D) for myopic and hyperopic eyes, respectively. Mean binocular uncorrected near visual acuity was 0.70 ± 0.28 logMAR (range: 0.32 to 1.00 logMAR) and 0.79 ± 0.27 logMAR (range: 0.25 to 1.00 logMAR) for myopic and hyperopic eyes, respectively. Mean binocular uncorrected distance visual acuity was 1.19 ± 0.18 logMAR (range: 0.63 to 1.25 logMAR) and 1.14 ± 0.26 logMAR (range: 0.40 to 1.25 logMAR) for myopic and hyperopic eyes, respectively. Stereoacuity was better than 100 seconds of arc in 79% of myopic eyes and 85% of hyperopic eyes and all vision quality scores were greater than 90 of 100. No eyes lost two or more lines. The non-linear aspheric micro-anisometropia protocol resulted in safe and effective visual outcomes in patients with both myopic and hyperopic presbyopia. [J Refract Surg. 2022;38(5):288-297.].

Accuracy of intraocular lens power calculation for cataract surgery after deep anterior lamellar keratoplasty.

The purpose of this study was to assess the accuracy of intraocular lens power (IOL) formulas for cataract surgery after deep anterior lamellar keratoplasty (DALK). This retrospective study included eyes which had previously undergone DALK and underwent standard phacoemulsification with monofocal IOL implantation between January 2012 and January 2021 at Ospedali Privati Forlì "Villa Igea" (Forlì, Italy). The predicted spherical equivalent (SE) was calculated using the Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Hoffer Q, Hoffer QST, Holladay 1, Holladay II, Kane and SRK/T formulas. Prediction error (PE) was calculated as the actual postoperative SE refraction minus the SE predicted refraction. Eighty-two eyes of 82 patients were included. The mean PE was negative using all formulas. Friedman test revealed a statistically significant difference of the median absolute PE (MedAE) among the different IOL formulas (P=0.005). On the basis of the MedAE, the formulas were ranked as follows: SRK/T (0.805 D), Kane (0.810 D), EVO (0.845 D), Hoffer QST (0.847 D), Barrett (0.895 D), Holladay 1 (0.915 D), Haigis (1.010 D) and Hoffer Q (1.070 D) formulas. All formulas had a tendency towards a myopic refractive shift in post-DALK eyes. Although the SRK/T, Kane, EVO and Hoffer QST formulas were more accurate, predictability of refractive outcomes was lower than in virgin eyes.

Clinical Outcomes, Contrast Sensitivity, Reading Performance and Patient Satisfaction Following Bilateral Implantation of AT LARA 829MP EDoF IOLs

PurposeTo evaluate the visual outcomes, contrast sensitivity, reading performance and patient satisfaction after bilateral implantation of AT LARA extended depth of focus (EDoF) intraocular lenses (IOLs).MethodsPatients undergoing phacoemulsification for age-related cataract and satisfying the eligibility criteria underwent bilateral implantation with AT LARA EDoF IOLs (Carl Zeiss Meditec, Jena, Germany). At follow-up visits of 1, 3, 6 and 12 months, binocular uncorrected and corrected distance, intermediate and near visual acuity, reading performance, defocus curve, contrast sensitivity and patient satisfaction for dysphotopsia and spectacle independence were evaluated.ResultsA total of 60 eyes from 30 patients with a mean age of 65.40±7.71 years were included in the study. At 12 months, 83% of patients (n=25) had binocular cumulative uncorrected distance visual acuity (UDVA) of 20/20 or better. Postoperative spherical equivalent refraction accuracy was within ±0.50 D for 95% of eyes (n=57) and refractive cylinder accuracy was within ≤0.50 D in 95% of eyes (n=57). The mean binocular uncorrected near visual acuity (UNVA) was 0.16±0.09 logMAR, and the mean uncorrected intermediate visual acuity (UIVA) at 60 and 80 cm was 0.01±0.09 and 0.03±0.08 logMAR, respectively, at 12 months. Reading speeds at 40, 60 and 80 cm showed improvement over time. No patient had complaints of severe dysphotopsia and none of the patients required glasses for any activity. No eye underwent YAG-laser capsulotomy for significant posterior capsule opacification at the end of mean follow-up.ConclusionIn our limited experience of 30 patients at 12 months, AT LARA EDoF IOLs resulted in excellent visual outcomes for uncorrected distance, intermediate and near visual acuity. The incidence of dysphotopsia and spectacle dependence was low, resulting in good patient satisfaction.Trial RegistryCTRI/2020/08/027105 (www.ctri.nic.in).

Prediction accuracy of standard and total keratometry by swept-source optical biometer for multifocal intraocular lens power calculation

We aimed to compare the refractive outcomes of cataract surgery with diffractive multifocal intraocular lenses (IOLs) using standard keratometry (K) and total keratometry (TK). In this retrospective observational case series study, a total of 302 patients who underwent cataract surgery with multifocal IOL implantation were included. Predicted refractive outcomes were calculated based on the current standard formulas and a new formula developed for TK using K and TK, which were obtained from a swept-source optical biometer. At 2-month postoperatively, median absolute prediction errors (MedAEs) and proportion of eyes within ± 0.50 diopters (D) of predicted postoperative spherical equivalent (SE) refraction were analyzed. There was no significant difference between MedAEs or proportion of eyes within ± 0.50D of predicted refraction from K and TK in each formula. In TFNT00 and 839MP IOL cases, there was no difference between MedAEs from K and TK using any formula. In 829MP IOL cases, MedAE from TK was significantly larger than that from K in Barrett Universal II/Barrett TK Universal II (P = 0.033). In 677MY IOL cases, MedAE from TK was significantly larger than that from K in Haigis (P = 0.020) and Holladay 2 (P = 0.006) formulas. In the subgroup analysis for IOL, there was no difference between the proportion of eyes within ± 0.50 D of predicted refraction from K and TK using any formula. TFNT00 and 839MP IOLs were favorable with TK, with 677MY IOL with K and 829MP IOL being in a neutral position, which necessitates the study that investigates the accuracy of the new TK technology.

Results of thin-cap small-incision lenticule extraction.

To evaluate the influence of a thin cap in small-incision lenticule extraction (SMILE) for the correction of myopia or myopic astigmatism. Tertiary care private practice. A chart review of 102 eyes of 51 patients was performed. The effect of 120 µm vs 100 μm cap thickness on postoperative spherical equivalent refraction (SEQ), cylinder, corrected and uncorrected visual acuities, and ease of lenticule separation was assessed in a contralateral manner, whereas all other parameters were identical between eyes (including optical zone, minimum lenticule thickness, incision size, and energy and spot settings) using paired t test. At 3 months postoperatively, SMILE with 120 μm cap thickness was undercorrected in SEQ relative to SMILE with 100 μm cap thickness in a cohort of 102 eyes of 51 consecutive patients. The difference of 0.06 ± 0.39 diopter (or 0.7% ± 5.7%) did not reach statistical significance. Postoperative cylinder was not statistically different in both groups. Visual acuity was similar in both groups. Ease of lenticule separation was identical in both groups. Suction time was shorter with a 100 μm cap (P < .005). Postoperative central residual stromal thickness was 20 ± 15 μm thicker with a 100 μm cap (P < .0001). Adverse events were comparable. Postoperative refraction, visual acuity, ease of lenticule separation, and incidence of adverse events were not significantly affected by cap thickness. Surgeons might safely use 100 μm instead of 120 μm caps without nomogram adjustment. Alternatively, after suction loss during the lenticule cut, a second docking with a programmed cap thickness of 100 μm (and a larger optical zone) might be a rescue technique enabling surgeons to still perform the intended SMILE procedure.

Refractive outcomes and accuracy of IOL power calculation with the SRK/T formula for sutured, scleral-fixated Akreos AO60 intraocular lenses.

Scleral fixation of intraocular lenses has become a popular procedure for treating aphakia in the absence of capsular support. However, the lens formulas used to predict refractive outcomes were designed for in-the-bag lens placement. This study evaluates the accuracy of the SRK/T formula in predicting a target postoperative refraction when suturing a scleral-fixated intraocular lens (IOL) implant 3mm posterior to the limbus. This is a retrospective, case series including 20 eyes of 20 patients who underwent scleral fixation of Akreos AO60 IOLs (Bausch & Lomb, Rochester, NY) by a single surgeon at the OSU Wexner Medical Center. Preoperative measurements were performed with optical biometry, and IOL power was calculated with the SRK/T formula. Following surgery, the actual refractive spherical equivalent (SE) was performed and compared with the preoperative prediction. Prediction error (PE), defined as the deviation of actual postoperative SE refraction in diopters (D) from preoperative predicted SE refraction, was the primary outcome measure. The mean attempted (predicted) SE was - 1.12 D (± 0.87). Mean achieved SE was - 0.96 D (± 1.04). Mean PE (actual postoperative SE versus predicted preoperative SE) was 0.16 D (± 0.69). A total of 9 eyes (45%) were within ± 0.5 D of the predicted SE, 16 eyes (80%) were within ± 1.0 D, and all 20 eyes (100%) were within ± 1.5 D. IOL power calculation using the SRK/T formula with optical biometry demonstrates reliable postoperative refractive outcomes in patients undergoing scleral fixation of an IOL (Akreos AO60). Further studies are needed to refine the predictive value of the SRK/T and other formulas for application in scleral fixation of IOLs.

Visual and Refractive Long-Term Outcomes Following Standard Cross-Linking in Progressive Keratoconus Management.

PurposeTo analyze the effectiveness and stability of the refractive, topographic and visual outcomes of the standard cross-linking (SCXL) in keratoconus (KC) management.Patients and methodsThis study was designed as a retrospective non-comparative study that included 28 KC patients (n=49 eyes) who performed SCXL as a single procedure to treat KC and completed five-year follow-up period. The topographic, refractive and visual data were recorded preoperatively and at 12, 24, 36 and 60 months postoperatively.ResultsForty eyes (81.6%) showed achieved postoperative spherical equivalent (SE) refraction better than the attempted refraction. Ten eyes (20.4%) improved by <1 D, 23 eyes (46.9%) improved from 1 D to <2 D and 7 eyes (14.3%) improved by ≥2 D. Both uncorrected distant visual acuity (UDVA) and corrected distant visual acuity (CDVA) showed statistically significant improvement from preoperative 1.34±0.29 (mean±SD) and 0.74±0.23 LogMAR to postoperative 0.99±0.32 and 0.50±0.22 LogMAR (P<0.0001) respectively. Both Kmax and SE refraction showed statistically significant and stable improvement from preoperative 51.95±1.90 and −7.90±3.14 D to postoperative 50.19±1.96 and −6.35±2.49 D (P<0.0001) respectively. Two eyes (4%) showed KC progression at the end of 5th follow-up year.ConclusionSCXL had good effectiveness and stability that halted KC progression over 5-year follow-up period. It had also unexpected improvement in the KC refractive components mainly the spherical and SE components.