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

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.].

SMILE for Hyperopia With and Without Astigmatism: Results of a Prospective Multicenter 12-Month Study.

PURPOSE: To investigate the safety and effectiveness of small incision lenticule extraction (SMILE) in patients who have hyperopia with or without astigmatism. METHODS: This was a prospective multicenter trial including 374 eyes of 199 patients treated by SMILE for hyperopia using the VisuMax femtosecond laser (Carl Zeiss Meditec AG). Inclusion criteria were sphere up to +6.00 diopters (D), cylinder up to 5.00 D, and maximum hyperopic meridian up to +7.00 D, with preoperative corrected distance visual acuity (CDVA) of 20/25 or better. The optical zone was 6.3 mm with a transition zone of 2 mm. The minimum lenticule thickness was set at 25 µm in the center and at 10 µm at the edge. Patients were examined at 1 day, 1 week, and 1, 3, 6, 9, and 12 months after surgery. Standard refractive surgery outcomes analysis was performed. RESULTS: The preoperative spherical equivalent was +3.20 ± 1.48 D (range: +0.25 to +6.50 D). At the 12-month follow-up visit, 81% of eyes treated were within ±0.50 D and 93% of eyes were within ±1.00 D of intended correction. A total of 1.2% of eyes lost two or more lines of CDVA at the 12-month follow-up visit, and 83% were at least 20/20, corresponding to a safety index of 1.005 at 12 months. Of the 219 eyes with plano target, 68.8% had an uncorrected distance visual acuity of 20/20 or better and 88% were at least 20/25 uncorrected at 12 months. There were no statistically significant changes in contrast sensitivity. CONCLUSIONS: SMILE was found to be an effective treatment method for the correction of compound hyperopic astigmatism, demonstrating a high level of efficacy, predictability, safety, and stability. [J Refract Surg. 2022;38(12):760-769.].

Optimized artificial intelligence for enhanced ectasia detection using Scheimpflug-based corneal tomography and biomechanical data.

PURPOSE: To optimize artificial intelligence (AI) algorithms to integrate Scheimpflug-based corneal tomography and biomechanics to enhance ectasia detection. DESIGN: Multicenter cross-sectional case-control retrospective study. METHODS: 3,886 unoperated eyes from 3,412 patients had Pentacam and Corvis ST (Oculus Optikgeräte GmbH; Wetzlar, Germany) examinations. The database included one eye randomly selected from 1,680 normal patients (N), and from 1,181 "bilateral" keratoconus (KC) patients, along with 551 normal topography eyes from very asymmetric ectasia patients (VAE-NT), and their 474 unoperated ectatic (VAE-E) eyes. The current TBIv1 (tomographic-biomechanical index) was tested, and an optimized AI algorithm was developed for augmenting accuracy. RESULTS: The area under the receiver operating characteristic curve (AUC) of the TBIv1 for discriminating clinical ectasia (KC and VAE-E) was 0.999 (98.5% sensitivity; 98.6% specificity [cutoff 0.5]), and for VAE-NT, 0.899 (76% sensitivity; 89.1% specificity [cutoff 0.29]). A novel random forest algorithm (TBIv2), developed with 18 features in 156 trees using 10-fold cross-validation, had significantly higher AUC (0.945; DeLong, p<0.0001) for detecting VAE-NT (84.4% sensitivity and 90.1% specificity; cutoff 0.43; DeLong, p<0.0001), and similar AUC for clinical ectasia (0.999; DeLong, p=0.818; 98.7% sensitivity; 99.2% specificity [cutoff 0.8]). Considering all cases, the TBIv2 had higher AUC (0.985) than TBIv1 (0.974; DeLong, p<0.0001). CONCLUSION: AI optimization to integrate Scheimpflug-based corneal tomography and biomechanical assessments augments accuracy for ectasia detection, characterizing ectasia susceptibility in the diverse VAE-NT group. Some VAE patients may be true unilateral ectasia. Machine learning considering additional data, including epithelial thickness or other parameters from multimodal refractive imaging, will continuously enhance accuracy.

Changes in Light Disturbance Analyzer Evaluation in SMILE for High Myopia and Astigmatism.

PURPOSE: To study the objective change in light disturbance around a glare source using the Light Disturbance Analyzer (LDA) (Binarytarget Lda) and correlate this with the validated subjective quality of vision (QoV) questionnaire in small incision lenticule extraction (SMILE) for high compound myopic astigmatism. METHODS: This was a prospective study recruiting 114 patients undergoing SMILE with attempted spherical equivalent refraction (SEQ) correction from -9.00 to -13.00 diopters (D), and cylinder up to 5.00 D. The LDA was used before and 3 and 12 months after surgery to evaluate the Light Disturbance Area, Light Disturbance Index, Best Fit Circle Radius, and Best Fit Circle Irregularity. Patients completed the Rasch-validated QoV questionnaire before and 12 months after surgery. Correlation analysis was performed between the LDA parameters and the QoV frequency, severity, and bothersomeness for halos and starbursts. RESULTS: At 12 months, there was a non-statistically signifcant change of 11.9% for Light Disturbance Area and Light Disturbance Index and 6.5% for Best Fit Circle Radius. There was an increase of 81.9% for Best Fit Circle Irregularity (P = .017). Light Disturbance Area, Light Disturbance Index, and Best Fit Circle Radius correlated with bothersomeness for QoV halos, and with frequency, severity and bothersomeness for QoV star-bursts (P < .05), albeit with a low correlation coefficient (R2 < 0.13). There was no correlation between increase in Best Fit Circle Irregularity and the halo and starburst scores from the QoV questionnaire. CONCLUSIONS: LDA Best Fit Circle Irregularity was found to increase following high myopic SMILE. Other LDA parameters appeared to increase, but a much larger sample would be required to find statistical significance. The change in LDA parameters was only weakly correlated with QoV halo and starburst metrics, representing the wide variation in inter-subject perception. [J Refract Surg. 2022;38(11):725-732.].

Applications of epithelial thickness mapping in corneal refractive surgery.

In this review, we discuss the applications of epithelial thickness mapping in corneal refractive surgery. The review describes that the epithelial thickness profile is nonuniform in the normal eye, being thinner superiorly than inferiorly and thinner temporally than nasally. It is postulated that this is due to the eyelid forces and blinking action on the superior cornea. Changes in the epithelial thickness profile have been found to be highly predictable, responding to compensate for changes in the stromal curvature gradient, using the eyelid as an outer template. This leads to characteristic changes in the epithelial thickness profile that can be used for early screening in keratoconus, postoperative monitoring for early signs of corneal ectasia, and for determining whether further steepening can be performed without the risk of apical syndrome following primary hyperopic treatment. Compensatory epithelial thickness changes are also a critical part of diagnosis in irregular astigmatism as these partially mask the stromal surface irregularities. The epithelial thickness map can then be used to plan a trans-epithelial photorefractive keratectomy treatment for cases of irregularly irregular astigmatism.

Corneal Epithelium Asymmetry in Children With Atopy: The Effect of Hand Dominance.

Purpose: To evaluate the effect of eye rubbing on the epithelial thickness profile in tomographically normal corneas by AS-OCT and to compare right and left eyes in right-handed children. Methods: Thirty right-handed boys (mean age 11.2 years) with ocular allergy and history of eye rubbing were evaluated using Scheimpflug (Pentacam HR, Oculus Wetzlar, Germany) and anterior segment optical coherence tomography. Epithelial thickness (ET) and full corneal thickness (CT) parameters were compared between right and left eyes with a non-parametric Mann-Whitney test. A p-value lower than 0.05 was considered for statistical significance. Results: No eyes had topometric nor tomographic criteria for keratoconus. The min-max ET was lower in right eyes (-2.8 µm vs -3.5; p = 0.02). The difference between inferior and superior (I-S) octants was lower in right eyes (1.1 µm vs 1.9 µm; p = 0.03) as a result of inferotemporal thinning. The highest ET difference was registered between nasal and temporal octants and was more pronounced in the right eyes (2 µm vs 3.1 µm; p < 0.001). Conclusion: AS-OCT analyses reveal different epithelial thickness patterns between the eyes in young atopic patients, likely eye rubbers. Inferior and temporal epithelial thickness seem to be more affected by thinning in the eye on the side of the dominant hand.

The Impact of Epithelial Remodeling on Surgical Techniques Used in Topography-guided Surface Ablation in Irregular Corneas.

PURPOSE: To analyze the optical consequences of epithelial remodeling in irregular corneas and their impact on the choice of different surface ablation techniques. METHODS: Anterior corneal and stromal surface topographies and epithelial thickness maps were analyzed in 24 eyes with irregular corneal optics. On two of the eyes, four different surface ablation techniques were simulated: (1) conventional anterior topography-guided photorefractive keratectomy (PRK), (2) transepithelial phototherapeutic keratectomy (PTK), (3) transepithelial anterior topography-guided PRK, and (4) stromal topography-guided PRK. RESULTS: Stromal surface topographies showed higher keratometric values, astigmatism, asphericity, and corneal higher order aberrations compared to topographies of anterior corneas covered by epithelium. Transepithelial anterior topography-guided PRK and stromal topography-guided PRK both resulted in regularized stromal surface, transepithelial PTK achieved partial regularization corresponding to the smoothing effect of the epithelial remodeling, and conventional anterior topography-guided PRK delivered after epithelial removal resulted in residual stromal surface irregularities. CONCLUSIONS: The difference in optical landscapes between the stromal and anterior surfaces in irregular corneas will represent a source of error when anterior topography-guided treatments are delivered on the deepithelialized stroma, as in conventional PRK. In contrast, anterior topography-guided ablations performed as transepithelial PRK and stromal topography-guided PRK delivered after epithelial removal address the full stromal irregularity, whereas transepithelial PTK alone may be used when topography-guided treatments are not possible. The authors conclude topography-guided PRK of irregular corneas should lead to significantly improved regularization only if it includes the effect of epithelial remodeling. [J Refract Surg. 2022;38(8):529-537.].

Large Population Outcomes of Small Incision Lenticule Extraction in Young Myopic Patients.

PURPOSE: To evaluate the outcomes of small incision lenticule extraction (SMILE) for myopia in a large population of young adults. METHODS: In this retrospective case series, the patient population consisted of the first 4,138 consecutive SMILE treatments using the VisuMax femtosecond laser (Carl Zeiss Meditec) between 2012 and 2018 at the London Vision Clinic. Inclusion criteria were myopic spherical equivalent up to -9.00 diopters (D), cylinder up to 6.00 D, corrected distance visual acuity of 20/20 or better, age younger than 40 years, and follow-up of 12 months. Outcomes analysis was performed using the Standard Graphs for Reporting Refractive Surgery. RESULTS: Data were available at 12 months in 3,722 eyes (90%), and 416 eyes (10%) were lost to follow-up. Mean attempted spherical equivalent refraction (SEQ) was -4.61 ± 1.84 D (range: -1.12 to -9.00 D). Mean cylinder was -0.78 ± 0.66 D (range: 0.00 to -6.00 D). Postoperatively, the mean SEQ relative to target was -0.13 ± 0.30 D (range: -1.35 to +1.25 D) and was within ±0.50 D in 88.1% and ±1.00 D in 99.6% of eyes. Uncorrected distance visual acuity was 20/20 or better in 95.4% of eyes and 20/25 or better in 98.7% of eyes. One line of CDVA was lost in 3.0% of eyes, and 0.08% (n = 3) lost two or more lines of CDVA, for which CDVA was restored following phototherapeutic keratectomy treatment. There was a statistically significant improvement of 0.05, 0.06, 0.07, and 0.07 log units for contrast sensitivity at 3, 6, 12, and 18 cycles per degree, respectively (P < .001). CONCLUSIONS: SMILE achieved excellent outcomes for myopia up to -9.00 D with cylinder up to -5.50 D for a large population in patients without presbyopia. [J Refract Surg. 2022;38(8):488-496.].

Objective and Subjective Quality of Vision After SMILE for High Myopia and Astigmatism.

PURPOSE: To report subjective and objective quality of vision (QoV) results for high myopic small incision lenticule extraction (SMILE) between -9.00 and -13.00 diopters (D). METHODS: This was a prospective study recruiting 114 patients undergoing SMILE with attempted spherical equivalent refraction (SEQ) correction from -9.00 to -13.00 D, and cylinder up to 5.00 D. Patients were informed before surgery of the increased risk of QoV symptoms. Patients completed the Rasch validated QoV questionnaire. Objective QoV was assessed by corneal and whole eye aberrations, HD Analyzer Objective Scatter Index (OSI) (Keeler), and contrast sensitivity. Patient satisfaction was assessed on a scale from 0 (very dissatisfied) to 10 (very satisfied). Individual item and total Rasch-scaled scores for the three subscales (frequency, severity, and bothersomeness) of the QoV questionnaire were calculated before and 12 months after surgery. RESULTS: The mean patient satisfaction score was 9.27 ± 1.18 (range: 2 to 10), 8 or higher in 93%, and 7 or higher in 98% of patients. One patient with a satisfaction score of 2 had a simple refractive error re-treatment and then reported a satisfaction score of 10. The total mean ± standard deviation Rasch-scaled QoV score for the frequency, severity, and bothersomeness subscales before surgery was 24 ± 19, 20 ± 16, and 19 ± 18, respectively. Scores increased after surgery to 41 ± 18, 32 ± 16, and 30 ± 21, respectively (P < .001). Corneal aberrations (6 mm, OSI) increased on average by 0.39 µm for spherical aberration, 0.41 µm for coma, and 0.56 µm for higher order aberrations root mean square. OSI increased on average by 0.58. There was a small but statistically significant improvement in contrast sensitivity at 3, 6, 12, and 18 cycles per degree. There were no statistically significant correlations found between subjective scores for starbursts and objective measurements. CONCLUSIONS: Satisfaction was high following SMILE for high myopia. As expected, there was an increase in QoV symptoms, mainly glare and starbursts. The acceptance of QoV symptoms for high myopic SMILE was high, indicating that residual refractive error and visual acuity are the major drivers for patient satisfaction with appropriate preoperative informed consent. [J Refract Surg. 2022;38(7):404-413.].

Epithelial thickness mapping for corneal refractive surgery.

PURPOSE OF REVIEW: As more devices become available that offer corneal epithelial thickness mapping, this is becoming more widely used for numerous applications in corneal refractive surgery. RECENT FINDINGS: The epithelial thickness profile is nonuniform in the normal eye, being thinner superiorly than inferiorly and thinner temporally than nasally. Changes in the epithelial thickness profile are highly predictable, responding to compensate for changes in the stromal curvature gradient, using the eyelid as an outer template. This leads to characteristic changes that can be used for early screening in keratoconus, postoperative monitoring for early signs of corneal ectasia, and for determining whether further steepening can be performed without the risk of apical syndrome following primary hyperopic treatment. Compensatory epithelial thickness changes are also a critical part of diagnosis in irregular astigmatism as these partially mask the stromal surface irregularities. The epithelial thickness map can then be used to plan a trans-epithelial PRK treatment for cases of irregularly irregular astigmatism. Other factors can also affect the epithelial thickness profile, including dry eye, anterior basement membrane dystrophy and eyelid ptosis. SUMMARY: Epithelial thickness mapping is becoming a crucial tool for refractive surgery, in particular for keratoconus screening, ectasia monitoring, hyperopic treatment planning, and therapeutic diagnosis and treatment.

Epithelial thickness mapping for corneal refractive surgery.

PURPOSE OF REVIEW: As more devices become available that offer corneal epithelial thickness mapping, this is becoming more widely used for numerous applications in corneal refractive surgery. RECENT FINDINGS: The epithelial thickness profile is nonuniform in the normal eye, being thinner superiorly than inferiorly and thinner temporally than nasally. Changes in the epithelial thickness profile are highly predictable, responding to compensate for changes in the stromal curvature gradient, using the eyelid as an outer template. This leads to characteristic changes that can be used for early screening in keratoconus, postoperative monitoring for early signs of corneal ectasia, and for determining whether further steepening can be performed without the risk of apical syndrome following primary hyperopic treatment. Compensatory epithelial thickness changes are also a critical part of diagnosis in irregular astigmatism as these partially mask the stromal surface irregularities. The epithelial thickness map can then be used to plan a trans-epithelial PRK treatment for cases of irregularly irregular astigmatism. Other factors can also affect the epithelial thickness profile, including dry eye, anterior basement membrane dystrophy and eyelid ptosis. SUMMARY: Epithelial thickness mapping is becoming a crucial tool for refractive surgery, in particular for keratoconus screening, ectasia monitoring, hyperopic treatment planning, and therapeutic diagnosis and treatment.

Heidelberg Anterion Swept-Source OCT Corneal Epithelial Thickness Mapping: Repeatability and Agreement With Optovue Avanti.

PURPOSE: To assess the repeatability of corneal epithelial thickness mapping in virgin, post-laser refractive surgery (PLRS), and keratoconic eyes using a novel swept-source optical coherence tomographer (SS-OCT), and to determine the agreement of the measurements with a validated spectral-domain (SD) OCT. METHODS: Analysis of 90 virgin, 46 PLRS, and 122 keratoconic eyes was performed. Three consecutive measurements of each eye were acquired with the Anterion SS-OCT and Avanti SD-OCT devices, and averages of the epithelial thickness mapping were calculated in the central 2-mm zone and in the 2- to 5-mm and 5- to 7-mm diameter rings. The repeatability was analyzed using pooled within-subject standard deviation (Sw). The agreement was assessed by Bland-Altman analysis and paired t tests. RESULTS: The repeatability ranges of the Anterion and Avanti epithelial thickness mapping measurements were Sw: 0.60 to 1.36 µm and Sw: 0.75 to 1.96 µm, respectively. The 95% limits of agreement of the Anterion and Avanti were 0.826 to 8.297. All values of the thickness measurements with the Anterion were lower than those of the Avanti, with the mean differences being 4.06 ± 1.81, 3.26 ± 2.52, and 3.68 ± 2.51 µm in virgin, PLRS, and keratoconic eyes, respectively (P < .001 for all). CONCLUSIONS: The repeatability of the Anterion's epithelial thickness mapping was higher than that of the Avanti. In terms of the agreement between the Anterion and Avanti, the epithelium measured by the Anterion was always thinner than that of the Avanti, making their interchangeable use unsuitable without corrections. [J Refract Surg. 2022;38(6):356-363.].

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

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.].

New Sizing Parameters and Model for Predicting Postoperative Vault for the Implantable Collamer Lens Posterior Chamber Phakic Intraocular Lens.

PURPOSE: To identify parameters influencing the postoperative vault of the Implantable Collamer Lens (ICL) (STAAR Surgical) using the Artemis Insight 100 very high-frequency (VHF) digital ultrasound robotic scanner (ArcScan, Inc) and develop a model to improve lens vault prediction. METHODS: This was a retrospective analysis of 147 consecutive V4c EVO and EVO+ ICL implantation procedures performed over three phases in myopic eyes. In the initial phase, lens size was defined by published sulcus-to-sulcus and crystalline lens rise measurements (Kojima formula) from VHF digital ultrasound biometry. From these data, a stepwise multivariate regression analysis was performed to develop a model for predicting central vault including the following variables: ICL size, ICL power, sulcus-to-sulcus (STS), ciliary body inner diameter (CBID), zonule-to-zonule, STS lens rise (STSL), ACD, anterior chamber angle, scotopic pupil diameter (SPD), angle-to-angle, and white-to-white diameter. The resulting regression model was used in coordination with the Kojima formula to select the lens size for the next series of eyes. The regression analysis was then repeated and a further series were treated. The postoperative achieved vault at 1 month was compared to the target vault predicted by the formula. A comparison analysis of the new model was made to previously published lens sizing formulas. RESULTS: Statistically significant variables were ICL size, ICL power, CBID, STSL, and SPD. The primary 42 eyes (Kojima formula) achieved a mean vault of 506 ± 233 µm, a range of 810 µm (114 to 924 µm), and an interquartile range (IQR) of 391 µm. Using the Reinstein formula v1.0 for the next 36 eyes, the mean vault relative to target was +7 ± 123 µm, range of 569 µm (-278 to +291 µm), and IQR of 169 µm. Using the Reinstein formula v2.0 for the next 69 eyes, the mean vault relative to target was +67 ± 121 µm, range of 573 µm (-219 to +354 µm), and IQR of 131 µm. The achieved vault was within ±100, ±200, and ±300 µm of target in 33%, 50%, and 74% of eyes, respectively, for the training group, 58%, 89%, and 100% for the Reinstein formula v1.0 group, and 62%, 84%, and 94% for the Reinstein formula v2.0 group. CONCLUSIONS: This is the first report describing the ciliary body inner diameter, which proved to be more highly correlated with vault than STS, and thus CIBD supersedes STS from the previous widely accepted improvement over WTW sizing. The new model also found scotopic pupil size to be a significant predictor, which has not been a part of any previously published model. The significant improvement in vault predictability afforded by these parameters and the new model enables charting attempted versus achieved vault outcomes for the first time. [J Refract Surg. 2022;38(5):272-279.].

Small Incision Lenticule Extraction (SMILE) for the Correction of High Myopia With Astigmatism.

PURPOSE: To report the outcomes of small incision lenticule extraction (SMILE) for high myopia between -9.00 and -14.00 diopters (D). METHODS: This was a prospective study of SMILE for high myopia using the VisuMax femtosecond laser (Carl Zeiss Meditec). Inclusion criteria were attempted spherical equivalent refraction (SEQ) between -9.00 and -14.00 D, cylinder up to 7.00 D, corrected distance visual acuity (CDVA) of 20/40 or better, age 21 years or older, and suitable for SMILE. The sub-lenticule thickness was 220 µm or greater, and the total uncut stromal thickness was 300 µm or greater. Patients were to be followed up for 1 year. Standard outcomes analysis was performed using 12-month data where available or 3-month data otherwise. RESULTS: Of 187 eyes treated, data were available at 12 months for 181 eyes (96.8%) and 3 months for 4 eyes (2.1%), and 2 eyes (1.1%) were lost to follow-up. Mean attempted SEQ was -10.55 ± 1.00 D (range: -9.00 to -12.99 D). Mean cylinder was -1.19 ± 0.83 D (range: 0.00 to -4.00 D). Preoperative CDVA was 20/20 or better in 73% of eyes. Postoperative uncorrected distance visual acuity was 20/20 or better in 57% and 20/25 or better in 82% of eyes. Mean SEQ relative to target was -0.22 ± 0.48 D (range: -1.63 to +1.38 D), 66% ± 0.50 D and 93% ±1.00 D. Mean SEQ 12-month change was -0.08 ± 0.34 D (range: -1.75 to +0.88 D). There was loss of one line of CDVA in 4% of eyes, and no eyes lost two or more lines. Contrast sensitivity was unchanged. Patient satisfaction was 8 or more out of 10 in 94% and 6 or more in 99% of patients. CONCLUSIONS: Outcomes of SMILE for myopia greater than -9.00 D at 3 to 12 months showed excellent efficacy, safety, stability, and predictability, with high patient satisfaction. [J Refract Surg. 2022;38(5):262-271.].

Visual Outcomes, Footplate Position and Vault Achieved with the Visian Implantable Collamer Lens for Myopic Astigmatism.

PURPOSE: Report the outcomes of the implantable collamer lens (ICL) in myopic astigmatism using very high-frequency (VHF) digital ultrasound sizing. METHODS: Analysis of 42 consecutive ICL procedures using EVO and EVO+ (Visian V4c) lenses (STAAR Surgical) was done. ICL size was chosen using the ultrasound-based Kojima Formula with Insight 100 VHF digital ultrasound (VHFDU). Standard visual outcomes analysis was performed using 3-month data, also including contrast sensitivity, refractive and corneal vector analysis, and ECC. Postoperative lens position was evaluated using VHF digital ultrasound. RESULTS: Attempted SEQ was -10.83±3.39D (-4.40 to -16.98D). Cylinder was -1.46±1.15D (0.00 to -4.25D). One-year follow-up was available in 86% of the eyes and 3 months in 96%. Postoperative UDVA was 20/20 or better in 89% of the eyes, relative to 71% preoperatively. Postoperative SEQ refraction was ±0.50 D in 74% and ±1.00 D in 98% of the eyes. There was a gain of one line of CDVA in 43% of the eyes, 2 or more lines in 10% of the eyes, while there was a one line loss in 7% and no eyes lost 2 or more lines. The vector mean for the corneal SIA was 0.24 D Ax 100. Contrast sensitivity showed a statistically significant increase with a mean of 0.14 log units at 6, 12, and 18 cycles per degree (P<0.01). The mean change in ECC was -153±353 cells/mm2. Lens vault was 506±233 µm (114-924 µm). Footplate insertion was in zonular position in 48.3%, ciliary body in 49.2%, and sulcus in 2.5% of locations. CONCLUSION: ICL implantation resulted in high safety and efficacy but with an implantation vault range that ideally would be improved upon. VHF digital ultrasound of the lens footplate and posterior anatomical relations may provide essential information for evaluating postoperative vault outliers.

Intraoperative Swept-Source OCT-Based Corneal Topography for Measurement and Analysis of Stromal Surface After Epithelial Removal.

PURPOSE: To assess intraoperative stromal topography measurements using swept-source optical coherence tomography (OCT)-based topography/tomography after epithelial removal and to analyze the epithelial contribution to the corneal topography and optics. METHODS: This was a prospective series of 22 eyes of 19 patients referred to receive phototherapeutic keratotomy (PTK) for treatment of recurrent corneal erosion and a control group of 22 virgin eyes. Swept-source OCT corneal topography/tomography was obtained immediately before and immediately after mechanical deepithelialization before PTK. Epithelial thickness maps were obtained before the surgery using spectral-domain OCT in the control group and as a reference in the group with anterior basement membrane dystrophy. Topographic and optical characteristics, including the curvature, astigmatism, asphericity, and higher order aberrations of the cornea before and after deepithelialization were compared, and their differences correlated with the measurements derived from the epithelial thickness maps. RESULTS: Stromal topography measurements after deepithelialization were easily obtained and showed excellent repeatability. Assessment of corneal edema induced by deepithelialization revealed that it did not significantly affect the measured parameters. The stromal surface was steeper by 1.28 diopters, had higher with-the-rule astigmatism by 0.41 diopters, was more prolate, and had more higher order aberrations compared to the intact epithelialized corneal surface. These differences correlated well with the parameters derived from epithelial thickness maps. CONCLUSIONS: Measurement of stromal topography using swept-source OCT immediately after mechanical deepithelialization may be a viable method in therapeutic refractive surgery, where stromal topography-guided ablation is needed. A significant epithelial contribution to anterior corneal topography and optics was confirmed. [J Refract Surg. 2021;37(7):484-492.].

Postoperative Corneal Epithelial Remodeling After Intracorneal Ring Segment Procedures for Keratoconus: An Optical Coherence Tomography Study.

PURPOSE: To assess epithelial corneal remodeling by anterior segment optical coherence tomography (AS-OCT) after intracorneal ring segments (ICRS) implantation in keratoconic eyes. METHODS: This prospective observational study included patients with keratoconus receiving ICRS of different arc lengths according to their tomographic pattern. AS-OCT and corneal topography (Scheimpflug camera) were performed before and 1, 3, and 6 months after surgery. Corneal pachymetry mapping was performed and total corneal and epithelial thicknesses (3-mm central and 16 points on 6-mm zone) were measured over the pupil center using AS-OCT. Topographic parameters were also assessed. RESULTS: A total of 68 keratoconic eyes were analyzed (Amsler-Krumeich stages 1 to 4) in four groups of 17 eyes: 210° ICRS, 320° ICRS, double 160° ICRS, and single 160° ICRS. Corneal pachymetry mapping revealed that epithelial thickness increased significantly in the internal zones juxtaposed to the ICRS without smoothing during the postoperative period (P < .05). Mean maximum epithelial thickness increased from 67 ± 6 to 79 ± 7 µm for 210° ICRS, 66 ± 9 to 82 ± 4 µm for 320° ICRS, 63 ± 6 to 78 ± 7 µm for double 160° ICRS, and 62 ± 5 to 77 ± 5 µm for single 160° ICRS (P < .0001). Significant epithelial thickening at the apex of the cone was observed in all groups (P < .05). CONCLUSIONS: Significant epithelial thickening occurs after ICRS implantation adjacent to the ICRS to compensate for the ridge created with a thickening of epithelium over the cone due to regularization of the stromal surface. [J Refract Surg. 2021;37(6):404-413.].

Coma Influence on Manifest Astigmatism in Coma-Dominant Irregular Corneal Optics.

PURPOSE: To evaluate the influence of coma on manifest refractive cylinder (MRC) in eyes with coma-dominated corneal optics and suggest alternative guidelines for surgical planning of astigmatism correction in topography-guided ablation and toric intraocular lens (IOL) exchange surgery. METHODS: Twelve eyes with coma-dominant corneal optics and low lenticular astigmatism were selected. The astigmatism remaining after subtraction of total corneal astigmatism (TCA) and lenticular astigmatism from MRC, termed discrepant astigmatism, was calculated and correlated to corneal coma at the anterior surface. Refractive and topography data were then used to simulate topography-guided refractive surgery (topography-guided group) in 7 eyes and lenticular exchange surgery with toric intraocular lens (IOL) implantation (toric IOL group) in 5 eyes. The estimated postoperative MRC after correction of TCA or MRC for each group was compared. RESULTS: The axis and amplitude of discrepant astigmatism correlated strongly with the axis and amplitude of coma. In the topography-guided group, where topography-guided ablation eliminated corneal higher order aberrations (HOAs), TCA-based correction led to less estimated postoperative manifest astigmatism than MRC-based correction. In the toric IOL group, where removal of the crystalline lens did not affect corneal HOAs, MRC-based correction via toric IOL implantation led to less estimated postoperative astigmatism than TCA-based correction. CONCLUSIONS: Discrepant astigmatism in eyes with coma-dominant corneal optics correlates with coma. In such eyes, treating TCA, along with corneal HOAs, instead of MRC, seems appropriate in topography-guided treatments, whereas treating MRC may be a better choice in lenticular exchange surgery with toric IOL implantation, where corneal HOAs are not treated. [J Refract Surg. 2021;37(4):274-282.].