Predictability of Existing IOL Formulas After Cataract Surgery in Patients with a Previous History of Radial Keratotomy: A Retrospective Cohort Study and Literature Review

INTRODUCTION

This study aims to evaluate the accuracy of 12 different intraocular lens (IOL) power calculation formulas for post-radial keratotomy (RK) eyes. The investigation utilizes recent advances in topography/tomography devices and artificial intelligence (AI)-based calculators, comparing the results to those reported in current literature to assess the efficacy and predictability of IOL calculations for this patient group.

METHODS

In this retrospective study, 37 eyes from 24 individuals with a history of RK who underwent cataract surgery at Hoopes Vision Center were analyzed. Biometry and corneal topography measurements were taken preoperatively. Subjective refraction was obtained 6 months postoperatively. Twelve different IOL power calculations were used, including the American Society of Cataract and Refractive Surgery (ASCRS) post-RK online formula, and the Barrett True K, Double K modified-Holladay 1, Haigis-L, Panacea, Camellin-Calossi, Emmetropia Verifying Optical (EVO) 2.0, Kane, and Prediction Enhanced by Artificial Intelligence and output Linearization-Debellemanière, Gatinel, and Saad (PEARL-DGS) formulas. Outcome measures included median absolute error (MedAE), mean absolute error (MAE), arithmetic mean error (AME), and percentage of eyes achieving refractive prediction errors (RPE) within ± 0.50 D, ± 0.75 D, and ± 1 D for each formula. A search of the literature was also performed by two independent reviewers based on relevant formulas.

RESULTS

Overall, the best performing IOL power calculations were the Camellin-Calossi (MedAE = 0.515 D), the ASCRS average (MedAE = 0.535 D), and the EVO (MedAE = 0.545 D) and Kane (MedAE = 0.555 D) AI-based formulas. The EVO and Kane formulas along with the ASCRS calculation performed similarly, with 48.65% of eyes scoring within ± 0.50 D of the target range, while the Equivalent Keratometry Reading (EKR) 65 Holladay formula achieved the greatest percentage of eyes scoring within ± 0.25 D of the target range (35.14%). Additionally, the EVO 2.0 formula achieved 64.86% of eyes scoring within the ± 0.75 D RPE category, while the Kane formula achieved 75.68% of eyes scoring within the ± 1 D RPE category. There was no significant difference in MAE between the established and newer generation formulas (P > 0.05). The Panacea formula consistently underperformed when compared to the ASCRS average and other high-performing formulas (P < 0.05).

CONCLUSION

This study demonstrates the potential of AI-based IOL calculation formulas, such as EVO 2.0 and Kane, for improving the accuracy of IOL power calculation in post-RK eyes undergoing cataract surgery. Established calculations, such as the ASCRS and Barrett True K formula, remain effective options, while under-utilized formulas, like the EKR65 and Camellin-Calossi formulas, show promise, emphasizing the need for further research and larger studies to validate and enhance IOL power calculation for this patient group.

Merging PRK and Collagen Crosslinking: An Analysis of Literature and a Guide to Prevalent Protocols

PURPOSE

The purpose of this review was to summarize the different surgical approaches combining photorefractive keratectomy (PRK) and corneal crosslinking (CXL), present each protocol template in a simple format, and provide an overview of the primary outcomes and adverse events.

METHODS

A literature review was conducted as outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Eight different databases were searched. Papers were included if PRK was immediately followed by CXL.

RESULTS

Thirty-seven papers met the inclusion criteria of a total yield of 823. The latest research into simultaneous PRK and CXL has been shown to not only stabilize the cornea and prevent keratoconus progression but also improve the visual acuity of the patient. Improvements in uncorrected distance visual acuity and (spectacle) corrected distance visual acuity were found to be significant when considering all protocols. There were also significant reductions in K1, K2, mean K, Kmax, sphere, cylinder, and spherical equivalent. Random-effects analysis confirmed these trends. Corrected distance visual acuity was found to improve by an average of 0.18 ± 1.49 logMAR (Cohen's D [CD] 0.12; P <0.02). There was also a significant reduction of 2.57 ± 0.45 D (CD 5.74; P <0.001) in Kmax. Cylinder and spherical equivalent were also reduced by 1.36 ± 0.26 D (CD 5.25; P <0.001) and 2.61 ± 0.38 D (CD 6.73; P <0.001), respectively.

CONCLUSIONS

Combining the 2 procedures appears to be of net benefit, showing stabilization and improvement of ectatic disease, while also providing modest gains in visual acuity. Since customized PRK and CXL approaches appear superior, a combination of these would likely be best for patients.

Precision in IOL Calculation for Cataract Patients with Prior History of Combined RK and LASIK Histories

Purpose

This study aimed to evaluate the accuracy of 12 intraocular lens (IOL) power calculation formulae for eyes that have undergone both radial keratotomy (RK) and laser assisted in situ keratomileusis (LASIK) surgery to determine the efficacy of various IOL calculations for this unique patient group. Currently, research on this surgical topic is limited.

Methods

In this retrospective study, 11 eyes from 7 individuals with a history of RK and LASIK who underwent cataract surgery at Hoopes Vision were analyzed. Preoperative biometric and corneal topographic measurements were performed. Subjective refraction was obtained postoperatively. Twelve different intraocular lens (IOL) power calculations were used: Barrett True K No History, Barrett True K (prior LASIK, Prior RK history), Barrett Universal 2, Camellin-Calossi-Camellin (3C), Double K-Modified Holladay, Haigis-L, Galilei, OCT, PEARL-DGS, Potvin-Hill, Panacea, and Shammas.

Results

The rankings of mean arithmetic error (MAE), from least to greatest, were as follows: 3C (0.088), Haigis-L-L (-0.508), Shammas (-0.516), OCT Average (-0.538), Barrett True K (-0.557), OCT RK (-0.563), Galilei (-0.570), IOL Master (-0.571), OCT LASIK (-0.583), Barrett True K No History (-0.597), Pearl-DGS (-0.606), Potvin-Hill SF (-0.770), Potvin-Hill TNP (-0.778), Panacea (-0.876), and Barrett Universal 2 (-1.522). The 3C formula achieved the greatest percentage of eyes within ±0.25 D of target range (91%), while Haigis-L, Shammas, Galilei, Potvin Hill, Barrett True K, IOL Master, PEARL-DGS, and OCT formulae performed similarly, achieving 45% of eyes within ±0.75D of target refraction.

Conclusion

This study demonstrates the accuracy of the lesser known 3C formula in IOL calculation, particularly for patients who have undergone both RK and LASIK. Well-known formulae, such as Haigis-L, Shammas, and Galilei, which are used by the American Society of Cataract and Refractive Surgery (ASCRS), are viable options, although 3C formulae should be considered in this patient population. Furthermore, larger studies can confirm the best IOL power formulas for post-RK and LASIK cataract patients.

AvaGen Genetic Testing versus Ocular Screening Assessments Including the Keratoconus Severity Score (KSS) and Randleman Ectasia Risk Score System (ERSS) in Refractive Surgery Candidates

Purpose

To determine whether the AvaGen (AG) Genetic Eye Test provided additional information for screening for the presence of keratoconus (KC) and assessing KC risk in refractive surgery candidates, as compared to the Keratoconus Severity Score (KSS) and Randleman Ectasia Risk Score System (ERSS).

Methods

This retrospective study analyzed patients seeking refractive surgery at an eye clinic in the United States between January 2022 and July 2023. The inclusion criteria encompassed those with a family history of KC, positive KC indices, or both. Corneal evaluations and demographic information were recorded and analyzed. KSS and ERSS criteria were utilized to evaluate postoperative KC and ectasia risk, respectively. Patients were categorized on how the AG genetic test compared to KSS and ERSS criteria. Clinicians assessed topographic indices, criteria scoring, and AG testing to deliver a definitive surgical recommendation.

Results

Among the 19 patients evaluated for ectasia risk, AG testing showed lower KC risk than ocular screening in three patients (15.8%), equal risk in three patients (15.8%), and higher risk in 13 patients (68.4%). The mean AG scores were 45.7 ± 7.0, 49.0 ± 3.46, and 61 ± 13.0 for these respective categories. The most frequently identified KC risk genes were ADAMTS18, COL2A1, and COL4A1. The AG test modified the physician's recommendation for refractive surgery in nine cases (47.4%).

Conclusion

Despite the promising application of AG testing for assessing KC risk, further research and development are needed to enhance its applicability for screening refractive surgery candidates, in addition to standard ocular screening approaches.

Changes in Posterior Cornea and Posterior-To-Anterior Curvature Radii Ratio 1 year After LASIK, PRK, and SMILE Treatment of Myopia

PURPOSE

The purpose of this study was to compare changes in the posterior curvature and the posterior-anterior radii ratio of the cornea, 1 year postoperatively in laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE).

METHODS

This retrospective study was performed at a single surgical center. 199 eyes were included in the study from 119 patients with manifest refraction spherical equivalents from -7.61 to -2.54 D. 67 eyes underwent LASIK, 89 underwent PRK, and 43 underwent SMILE. Both preoperative and 1-year postoperative front and back sagittal keratometry were measured at 4- to 6-mm zones around the corneal vertex. Corneal asphericity (Q-value) was measured at an 8-mm zone around the corneal vertex.

RESULTS

The average change in the posterior-anterior radii ratio after LASIK, PRK, and SMILE did not differ between surgery groups at 4 mm (LASIK: -0.075, PRK: -0.073, SMILE: -0.072, P = 0.720), 5 mm (LASIK: -0.072, PRK: -0.068, SMILE: -0.068, P = 0.531), or 6 mm (LASIK: -0.075, PRK: -0.071, SMILE: -0.072, P = 0.456) zones. Anterior Q-value significantly positively increased after all 3 surgeries (P < 0.001). The posterior Q-value also significantly positively increased after LASIK (P < 0.001) and SMILE (P < 0.001), but not after PRK (P = 0.227). Both anterior and posterior keratometric power decreased significantly after LASIK, PRK, and SMILE for all diameters.

CONCLUSIONS

The change in the posterior-anterior radii ratio was not influenced by the type of refractive surgery performed, as indicated by statistically identical preoperative, postoperative, and delta values. In addition, the posterior cornea exhibited paracentral flattening after LASIK, SMILE, and PRK and increased oblateness after LASIK and SMILE.

Comparative Analysis of Corneal Higher-Order Aberrations after Laser-Assisted In Situ Keratomileusis, Photorefractive Keratectomy, and Small Incision Lenticule Extraction with Correlations to Change in Myopic Q-Value and Spherical Equivalent with and without Astigmatism

Background: This retrospective chart review compared the higher-order aberrations (HOAs) among photorefractive keratectomy (PRK), laser-assisted in situ keratomileusis (LASIK), and small incision lenticule extraction (SMILE) alongside changes in spherical equivalent (SEQ) and corneal shape (Q-value). Methods: Analyzing 371 myopic eyes, including 154 LASIK, 173 PRK, and 44 SMILE cases, Pentacam imaging was utilized pre-operatively and at one-year post-operative visits. Results: All procedures resulted in 100% of patients achieving an uncorrected distance visual acuity (UDVA) of 20/40 or better, with 87% of LASIK and PRK, and 91% of SMILE patients having 20/20 or better. Significant increases in HOAs were observed across all procedures (p < 0.05), correlating positively with SEQ and Q-value changes (LASIK (0.686, p < 0.05), followed by PRK (0.4503, p < 0.05), and SMILE (0.386, p < 0.05)). Vertical coma and spherical aberration (SA) were the primary factors for heightened aberration magnitude among the procedures (p < 0.05), with the largest contribution in SMILE, which is likely attributed to the centration at the corneal apex. Notably, PRK showed insignificant changes in vertical coma (-0.197 µm ± 0.0168 to -0.192 µm ± 0.0198, p = 0.78), with an increase in oblique trefoil (p < 0.05). Conclusions: These findings underscore differences in HOAs among PRK, LASIK, and SMILE, helping to guide clinicians.

Implication of Corneal Refractive Surgery in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked disorder due to a dystrophin mutation and is the leading cause of muscular dystrophy. DMD presents with characteristic systemic effects, including severe muscular atrophy, cardiomyopathy, and ocular manifestations. Performing corneal refractive surgeries in patients with DMD raises concerns regarding patient positioning, risk of cataracts, and other comorbid conditions. Published reports of photorefractive keratectomy, laser-assisted in situ keratomileuses, and small incision lenticule extraction are lacking in this population. Here, we discuss a patient being evaluated for a corneal refractive surgery. This article also discusses the current understanding of DMD, known ocular manifestations, and factors to consider when evaluating a patient for potential corrective vision laser surgery.

Management of Corneal Haze After Photorefractive Keratectomy

Photorefractive keratectomy (PRK) is a safe and popular corneal surgery performed worldwide. Nevertheless, there is potential risk of corneal haze development after surgery. Proper management of post PRK haze is important for good visual outcome. We performed a comprehensive review of the literature on the various risk factors and treatments for PRK haze, searching the PubMed, Google Scholar, SCOPUS, ScienceDirect, and Embase databases using relevant search terms. All articles in English from August 1989 through April 2023 were reviewed for this study, among which 102 articles were chosen to be included in the study. Depending on the characteristics of and examination findings on post PRK haze, different management options may be preferred. In the proposed framework, management of PRK haze should include a full workup that includes patient's subjective complaints and loss of vision as well as visual acuity, biomicroscopy, anterior segment optical coherence tomography, epithelial mapping, and Scheimpflug densitometry. Topical steroid treatment for haze should be stratified based on early- or late-onset haze. Mechanical debridement or superficial phototherapeutic keratectomy (PTK) may be used to treat superficial corneal haze. Deep PTK and/or PRK can be used to treat deep corneal haze. Mitomycin-C and topical steroids are prophylactic post-surgery agents to prevent recurrence of haze.

Exploring Nomograms for Implantable Collamer Lens Size Selection in Myopia: A Literature-based Compilation

Purpose

To provide a comprehensive guide of all implantable collamer lens (ICL) sizing nomograms and the respective preoperative diagnostic devices that are required. This guide would help clinicians in choosing the appropriate ICL size for myopic patients to optimize postoperative vault height.

Methods

A literature search of peer-reviewed journals describing methods and postoperative outcomes of ICL sizing was conducted. Research articles containing ICL nomograms or formulas were identified from this search. Preoperative variables necessary for these nomograms and the required diagnostic devices to measure these parameters such as topography, biometry, or ultrasound biomicroscopy (UBM) were noted. An additional search was conducted to identify artificial intelligence (AI) or machine learning (ML)-derived nomograms.

Results

Eighteen ICL sizing nomograms were identified through literature search. Five of these nomograms are available for use and require topography or biometry devices. Of these, four include the manufacturer's, optimized white-to-white (WTW), Kang, Kim, and Rocamora Nomograms. Eight of the 18 nomograms available for use require UBM. Eight of these include the Kojima, Nakamura, KS, ZZ, Dougherty, Parkhurst, Russo, and Reinstein Nomograms. Four of the 18 nomograms are ML-derived including Shen, Rocamora, Russo, and Kang Nomograms.

Conclusion

ICL nomograms are a vital tool in helping clinicians select the right ICL size for myopic patients to optimize postoperative vault reducing risk of postoperative complications. Based on available diagnostic devices such as topography, biometry, or UBM clinicians can integrate specific nomograms into practice.

Comparing Effective Optical Zones After Myopic Ablation Between LASIK, PRK, and SMILE With Correlation to Higher Order Aberrations

PURPOSE

To explore size, decentration, and eccentricity of effective optical zones (EOZs) in laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE) and correlate them to higher order aberrations (HOAs).

METHODS

This was a retrospective chart review of 188 eyes that underwent refractive surgery for compound myopia (61 LASIK, 84 PRK, 43 SMILE). EOZ measurements were determined using 1-year postoperative Pentacam (Oculus Optikgeräte GmbH) tangential difference maps. HOA data were measured using Pentacam wavefront aberration Zernike polynomials. Correlations between EOZs and HOAs were analyzed.

RESULTS

The EOZs of LASIK and PRK are smaller than SMILE at 19.54 ± 1.44, 19.39 ± 1.66, and 22.18 ± 2.61 mm2, respectively (P < .001). No difference existed in absolute decentration from corneal vertex (P = .078) or pupil center (P = .131), but horizontal and vertical components differed significantly (P < .001). Smaller EOZ areas were correlated with greater spherical aberration induction (rLASIK = -0.378, rPRK = -0.555, rSMILE = -0.501) and total HOA induction in all groups. Absolute decentration from corneal vertex positively correlated with total HOA (rLASIK = 0.396, rPRK = 0.463, rSMILE = 0.399) and directional vertical coma induction negatively correlated with vertical decentration from the corneal vertex (rLASIK = -0.776, rPRK = -0.665, rSMILE = -0.576) in all groups.

CONCLUSIONS

SMILE results in a larger EOZ than LASIK and PRK, and absolute decentration remains comparable regardless of surgical reference center, despite horizontal/vertical differences. Surgical planning to ensure adequate EOZ size and centration may reduce induction of HOAs, including spherical aberrations and vertical coma. [J Refract Surg. 2023;39(11):741-750.].

Allogenic Lenticular Implantation for Correction of Refractive Error and Ectasia: Narrative Review

INTRODUCTION

Intrastromal lenticule implantation is a promising treatment option for corneal pathologies, from refractive error to ectasia. In this narrative review, we intend to feature up-to-date literature supporting the use of lenticular tissue, a compelling method that can be customized for a variety of applications, providing an additional source of donor tissue for treating corneal diseases.

METHODS

We searched databases PubMed, Mendeley, and Scopus last accessed 10 May 2023, for literature on stromal lenticules and narrowed based on relevance. Review articles, animal studies, ex vivo studies, and book chapters were excluded, while assessable and relevant articles published in English were included.

RESULTS

Storage methods from using fresh lenticules to dehydration have proven successful, with cryopreservation maintaining structure and cellular viability for up to 10 years. Successful use of lenticules for treatment of numerous pathologies including corneal ectasias, hyperopia, and presbyopia with additional insight into the treatment of corneal ulcers and perforations are highlighted in this narrative review.

CONCLUSION

Lenticular implantation is an innovative and advantageous treatment for various ocular pathologies, offering increased bioavailability, flexibility, and customization for patients. They can treat previously untreatable diseases and serve as a replacement for synthetic implants, with promising outcomes worldwide. Lenticular implantation has the potential to become a leading approach in ophthalmologic surgery. Further studies should aim to provide evidentiary support for a standardization of lenticule banking.

Incidence and Management of Epithelial-Related Complications After SMILE

Purpose

To investigate the incidence and management of only epithelial-related complications following small incision lenticule extraction (SMILE).

Patients and Methods

A retrospective, single-site study analyzed patients who underwent SMILE at Hoopes Vision Clinic in Draper, Utah, from June 2017 to February 2023. Demographic data and preoperative parameters were reviewed. Postoperatively, patients were assessed for visual acuity and complications at different time points. Statistical analyses were conducted between the control and complication groups.

Results

Four hundred and thirty-two eyes of 220 patients received SMILE. Postoperative epithelial-related complications were indicated in 68 (15.7%) eyes, including anterior basement membrane (ABM) changes (five [1.2%]) eyes), epithelial ingrowth (nine [2.1%] eyes), erosion (two [0.5%] eyes), rough epithelium (18 [4.2%] eyes), epithelial defect (12 [2.8%] eyes), diffuse lamellar keratitis (DLK) secondary to epitheliopathy (two [0.5%] eyes), microstriae secondary to epitheliopathy (four [0.9%] eyes), interface debris (21 [4.9%] eyes), and incisional fibrosis (one [0.2%] eye). There was a statistically significant difference in age, with older patients more likely to develop epitheliopathy postoperatively (P = 0.001). Additionally, patients with epithelial-related complications were more likely to receive photorefractive keratectomy (PRK) enhancement after SMILE than the control (P = 0.001). However, there was no statistical difference in uncorrected distance visual acuity (UDVA) better than 20/20 and corrected distance visual acuity (CDVA) between the complications group and the control at the last postoperative visit (P = 0.974 and 0.310, respectively). There was no statistically significant difference in the safety and efficacy indices between the complications and control group (P = 0.281 and 0.617, respectively).

Conclusion

In our study, epithelial-related complications were more prevalent in older patients and predisposed patients to require PRK enhancements after recovery from SMILE. Despite the incidence of epithelial-related complications, visual prognoses were favorable and achieved through various management strategies.

Comparing the Accuracy of the Kane, Barrett Universal II, Hill-Radial Basis Function, Emmetropia Verifying Optical, and Ladas Super Formula Intraocular Lens Power Calculation Formulas

Purpose

To assess the accuracy of five new-generation intraocular lens (IOL) power formulas: Barrett Universal II (BUII), Emmetropia Verifying Optical (EVO) Formula, Hill-Radial Basis Function (Hill-RBF), Kane Formula, and Ladas Super Formula (LSF).

Patients and Methods

This is a retrospective single-surgeon study from a refractive clinic and clinical research center in Draper, UT, USA. The primary outcome measures were mean absolute error (MAE) and median absolute error (MedAE). Secondary outcome measures were the standard deviation (SD) of each formula's refractive prediction errors (RPE) and the percentage of eyes within ±0.50D. Refractive predictions were compared to the postoperative spherical equivalent to determine the RPE for each formula. RPEs were optimized, and MAE, MedAE, SD of the AME, and percent of eyes achieving RPEs within the specified ranges of ±0.125 D, ±0.25 D, ±0.50 D, ±0.75 D, ±1.0 D were calculated. Subgroup analysis between different axial lengths was attempted but yielded insufficient statistical power to draw meaningful conclusions.

Results

A total of 103 eyes of 103 patients were included in our study after applying inclusion and exclusion criteria to 606 eyes from 2019 to 2021. Formulas ranked in ascending order by MAE were Kane, EVO, BUII, Hill-RBF, and LSF. The ascending rankings of MedAE were Kane, BUII, Hill-RBF, EVO, Ladas. Kane had a significantly lower MAE than Hill-RBF (p<0.001). EVO had the lowest SD of AMEs and the highest percentage of eyes within ±0.50 D. According to heteroscedastic testing, EVO also had a statistically significant lower SD than Hill-RBF.

Conclusion

Kane was the most accurate formula in terms of MAE and MedAE. EVO and BUII achieved marginally higher MAEs than Kane, suggesting these three formulas are comparable in performance. With the exception EVO and Hill-RBF, the heteroscedastic test yielded no significant differences in SD between the formulas. Although there were multiple statistically significant differences between the formulas in terms of MAE, MedAE, and SD, these differences may not be appreciable clinically. Lastly, there were no statistically significant differences in the percent of eyes with RPEs within ±0.50 D, suggesting similar clinical performance between formulas.

Influence of Preoperative Parameters on the Ratio of Keratometric Change per Diopter of Attempted Spherical Equivalent (∆K/∆SEQ) for Myopic Correction Within LASIK, PRK, and SMILE

Purpose

To compare 3 of the most common corneal refractive procedures; PRK, LASIK, and SMILE assessing ΔK/ΔSEQ ratio and its correlation with preoperative demographics including age, keratometry, pachymetry, cylinder value, and attempted myopic correction. The goal was to analyze the relative strength of each preoperative parameter in accounting for changes in ∆K/∆SEQ.

Patients and Methods

A total of 370 eyes from 102 male and 97 female patients (173 eyes PRK, 153 LASIK, and 44 SMILE) with ages ranging from 20 to 51 underwent refractive surgery for myopia between -0.25 and -7.71 D manifest refraction spherical equivalent (MRSE). All surgeries were performed at a single surgery center in Draper, Utah. The Pentacam was used for all optical measurements and data were gathered pre-operatively and then again 1-year post-operatively. Only patients who achieved emmetropia at a visual acuity of 20/25 or better were included.

Results

The mean ΔK/ΔSEQ ratio for LASIK (0.839 ± 0.020) was significantly greater than that of PRK (0.775 ± 0.022) and SMILE (0.709 ± 0.046). Age was found to negatively correlate with ΔK/ΔSEQ for both LASIK (r = -0.177) and SMILE (r = -0.451) procedures. Pre-op keratometry was found to negatively correlate with ΔK/ΔSEQ for LASIK (r = -0.202) but not for PRK or SMILE. Pre-op pachymetry was not correlated with ΔK/ΔSEQ for any of the procedures. Attempted myopic spherical equivalent (SEQ) correction was positively correlated with ΔK/ΔSEQ for LASIK (r = 0.236), PRK (r = 0.459), and SMILE (r = 0.304). Lastly, pre-op cylinder value was found to be correlated to ΔK/ΔSEQ in SMILE (r = -0.367), but not in LASIK or PRK.

Conclusion

The ΔK/ΔSEQ ratio not only differs depending on the procedure being done but also by pre-operative factors such as age, keratometry, attempted correction, and cylinder value. Multiple linear regression analysis revealed that the attempted correction had the greatest effect on ∆K/∆SEQ out of all parameters in LASIK and PRK. For SMILE, age had the greatest predictive value of the change in ∆K/∆SEQ. While the exact effect of these parameters will vary by surgeon, all of these should be factored into a refractive surgeon's nomograms in order to achieve optimal visual outcomes for their patients.

A Literature Review of the Incidence, Management, and Prognosis of Corneal Epithelial-Related Complications After Laser-Assisted In Situ Keratomileusis (LASIK), Photorefractive Keratectomy (PRK), and Small Incision Lenticule Extraction (SMILE)

Our purpose is to provide a comprehensive investigation into the incidence, treatment modalities, and visual prognosis of epithelial-related complications in corneal refractive surgeries, including laser-assisted in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE). A systematic search of multiple databases was conducted by two independent examiners using various search terms related to epithelial-related complications and corneal refractive surgeries. A total of 91 research articles were included, encompassing a sample size of 66,751 eyes across the three types of surgeries. The average incidence of epithelial-related complications varied across the different types of corneal refractive surgeries. LASIK had an average incidence of 4.9% for epithelial defects, while PRK and SMILE had lower rates of 3.3% and 3.9%, respectively. Our findings indicate that SMILE has a lower incidence of epithelial defects compared to LASIK, potentially due to the less invasive nature of lenticule incision in SMILE. Visual prognosis after epithelial complications (EC) is generally favorable, with various supportive care and surgical interventions leading to significant improvements in postoperative visual acuity and full recovery. Understanding the incidence rates and management approaches for epithelial-related complications can guide clinicians in enhancing patient safety, refining surgical techniques, and optimizing postoperative outcomes in corneal refractive surgeries.

Assessment of Pupil Size and Angle Kappa in Refractive Surgery: A Population-Based Epidemiological Study in Predominantly American Caucasians

Purpose This retrospective study aims to establish normative values for pupil size, angle kappa, higher-order aberration, and astigmatism type in a largely Caucasian population in Utah, United States, utilizing the NIDEK OPD-Scan III system (Gamagori, Japan). Methods This study included 716 patients (1432 eyes) grouped based on spherical equivalence and age. Measurements were conducted under mesopic and photopic conditions. Statistical analysis involved Pearson's correlation and linear regression using the generalized estimating equation. NIDEK OPD-Scan III measured mesopic and photopic pupil size and angle kappa. The subjects were then grouped based on their spherical equivalence in diopters (D) and age in decades. The spherical equivalence groups were defined: >-6 D, -5.99 to -3 D, -2.99 to -0.25 D, -0.24 to 0.24 D, and >0.25 D (range 0.25-5.75 D). The higher-order aberration groups were based on the reason for the visit: laser-assisted in situ keratomileusis, photorefractive keratectomy, and small incision lenticule extraction as one group; cataract evaluation; and keratoconus. Astigmatism measurements were grouped into with-the-rule (WRT), against-the-rule (ATR), and oblique astigmatism, with further subgrouping into a young cohort (20-40 years) and an old cohort (>65 years).  Results Among 716 participants, 49.2% were men; the mean age was 42.1±15.5 (range 7-88 years). The average spherical equivalence for myopia eyes was -3.28±2.34 D, and 1.51±1.46 D for hyperopia eyes. The mean mesopic pupil size was 5.68 ± 1.09 mm; the photopic pupil size was 4.65±1.09 mm. Pearson's correlation coefficient for mesopic pupil size versus age was -0.551, and -0.42 for photopic pupil (p < 0.001); sphere vs mesopic pupil size was -0.200, and -0.173 for photopic pupil (p < 0.001). The regression analysis for mesopic pupil size versus age revealed a 0.39 mm decrease in average pupil size per decade increase in age, and 0.25 mm decrease per decade for photopic pupil. The regression analysis for mesopic pupil size versus sphere revealed a 0.22 mm decrease in average pupil size per 3D increase in sphere, and a 0.16 mm decrease 3 D increase in sphere for the photopic pupil. The mean mesopic angle kappa was 0.33 ± 0.15 mm; photopic angle kappa was 0.31±0.15 mm. Pearson's correlation coefficient for mesopic angle kappa vs spherical equivalence was 0.32, and 0.296 for photopic angle kappa (p <0.001 for both). Regression analysis for mesopic angle kappa vs spherical equivalence demonstrated a 0.051 mm increase in angle kappa per 3 D increase in spherical equivalence, and a 0.048 mm increase for photopic angle kappa (p < 0.001 for both). Among the higher-order aberration groups, the keratoconus group exhibited the highest levels. In terms of astigmatism type, WRT astigmatism was the most common in the young cohort, while ATR astigmatism was most prevalent in the older cohort. Conclusions The results of this study reveal significant associations between pupil size and increasing age, as well as between pupil size and increasingly positive refractive errors. These findings hold particular clinical relevance to older patients and individuals with hyperopia, as they undergo photoablative corneal refractive surgery or multifocal intraocular lens implantation. Understanding the established normative values for pupil size, angle kappa, higher-order aberration, and astigmatism type can aid clinicians in making more informed decisions and improving patient outcomes.

Prediction of Posterior-to-Anterior Corneal Curvature Radii Ratio in Myopic Patients after LASIK, SMILE, and PRK Using Multivariate Regression Analysis

The ratio of posterior-to-anterior curvature radii of the cornea (P/A ratio) is an important element in determining corneal refractive power. P/A ratio has been well studied in patients prior to undergoing refractive surgery, but its postoperative value remains less so. We aimed to examine the value of preoperative characteristics of refractive surgery patients in predicting the 1-year postoperative P/A ratio in LASIK, PRK, and SMILE using both linear and multivariate regression analyses. This was a retrospective study that included patients with manifest refraction spherical equivalents (MRSE) from -7.71D to -0.25D. In total, 164 eyes underwent LASIK, 183 underwent PRK, and 46 underwent SMILE. All patients had preoperative and 1-year postoperative front sagittal and back sagittal keratometry measurements at 4, 5, and 6 mm around the corneal vertex. Postoperative P/A after LASIK, PRK, and SMILE was found to be significantly correlated with MRSE and preoperative P/A. Stepwise variable selection in multivariate regression revealed that spherical equivalent was the most significant predictor of postoperative P/A. When coupled with other preoperative characteristics, including P/A, age, asphericity, and keratometry, the multivariate regressions were able to produce models with high predictive value in LASIK (adjusted R²: 0.957), PRK (adjusted R²: 0.934), and SMILE (adjusted R²: 0.894).

Comparing the Effectiveness of Smartphone Applications in the Measurement of Interpupillary Distance

Purpose To determine the accuracy of three smartphone applications in the measurement of interpupillary distance (IPD). Methods This study compared measurements from three smartphone applications to measurements obtained by a single trained examiner using a digital pupilometer in 44 subjects. The mean absolute error (MAE) of IPD prediction by each application was compared. Additionally, the frequency at which each application measured IPD within ± 0.05 mm, ± 0.10 mm, ± 0.25 mm, ± 0.50 mm, ± 0.75 mm, and ± 1.00 mm of the digital pupilometer measurement was determined. Results The Eye Measure (Dotty Digital, Sydney, New South Wales, Australia) and Warby Parker (Warby Parker, New York, New York) applications had significantly lower MAE of IPD measurements (0.511364 mm) compared to the PDCheck AR (EyeQue Corp., Newark, California) application (1.375 mm). The Warby Parker application most frequently obtained accurate IPD measurements within the following ranges: ± 0.05 mm, ± 0.10 mm, ± 0.25 mm, ± 0.50 mm, ± 0.75 mm, and ± 1.00 mm. Conclusion Of the three smartphone applications compared in this study, the Warby Parker application performed to the highest degree of accuracy and may serve as an adequate alternative when conventional IPD measurement methods are either unavailable or unable to be performed accurately.

Assessing Visual Outcomes: A Comparative Study of US-FDA Premarket Approval Data for Multifocal and EDOF Lens Implants in Cataract Surgery

This study compares the efficacy, safety, and patient-reported outcomes of three intraocular implants (IOL): Tecnis Synergy IOL, AcrySof IQ PanOptix Trifocal, and Tecnis Symfony EDOF IOL. Participants achieving 20/20 or better uncorrected binocular visual acuity were as follows: Synergy-67% distance, 64% intermediate, and 47% near; PanOptix-73% distance, 73% intermediate, and 50% near; and Symfony-63% distance, 75% intermediate, and 22% near. Symfony demonstrated superior intermediate visual acuity compared to Synergy (p = 0.0182) for those achieving 20/25 or better. Both Synergy and PanOptix showed superiority over Symfony for near visual acuity (p < 0.0001). Halos were statistically more common in Synergy participants compared to PanOptix (p = 0.0013) and Symfony (p < 0.0001). Each trial lens outperformed its monofocal IOL in terms of independence from glasses or contacts, with Synergy and PanOptix showing statistical significance over Symfony. Comparing contrast sensitivities and defocus curves was challenging due to data variance and as such, standardization of United States Food and Drug Administration (US-FDA) data reporting is key for better comparison of outcomes among different IOL platforms.

Comparison of Corneal Power Difference Maps with Achieved Myopic Correction Using Scheimpflug Tomography After LASIK, PRK, and SMILE

Purpose

To compare corneal power difference maps (∆maps) obtained from the Pentacam in patients with 1 year follow-up after LASIK, PRK, and SMILE with further stratification to low, moderate, and high myopia.

Patients and methods

This retrospective study was comprised of patients who had preoperative and 1-year postoperative power maps that were obtained-front sagittal (SagF), refractive power (RP), true net power (TNP), and total corneal refractive power (TCRP)-for evaluation. Measurements were recorded and compared at the 4mm, 5mm and 6mm pupil and apex zones. Comparisons were made between each specific power ∆map and the surgically induced refractive change (SIRC). Further analysis of the ∆maps was performed based on degree of myopia (high, moderate, and low). Correlation and agreement were also assessed with regression and limits of agreement (LoA).

Results

There were 172 eyes in the LASIK group, 187 eyes in the PRK group, and 46 eyes in the SMILE group. In the LASIK group, TNP ∆map at 5mm pupil zone had the least absolute mean difference with SIRC (0.007 ± 0.42D). In the PRK group, TNP ∆map at 5mm apex zone was most accurate compared to SIRC (0.066 ± 0.45D). In the SMILE group, TCRP ∆map at 4mm apex zone had the closest absolute value when compared to SIRC (0.011 ± 0.50D). There was good correlation and agreement for all three surgery groups, LASIK: r = 0.975, LoA -0.83D to +0.83D, PRK: r = 0.96, LoA -0.83D and +0.95D, and SMILE: r = 0.922, LoA -0.97 D to +0.99D.

Conclusion

TNP ∆maps most accurately measured corneal power in the LASIK and PRK groups while TCRP ∆maps were most accurate in the SMILE group. The degree of myopia may change which ∆map is most accurate.

Artificial Intelligence in Ophthalmology: A Comparative Analysis of GPT-3.5, GPT-4, and Human Expertise in Answering StatPearls Questions

Importance Chat Generative Pre-Trained Transformer (ChatGPT) has shown promising performance in various fields, including medicine, business, and law, but its accuracy in specialty-specific medical questions, particularly in ophthalmology, is still uncertain. Purpose This study evaluates the performance of two ChatGPT models (GPT-3.5 and GPT-4) and human professionals in answering ophthalmology questions from the StatPearls question bank, assessing their outcomes, and providing insights into the integration of artificial intelligence (AI) technology in ophthalmology. Methods ChatGPT's performance was evaluated using 467 ophthalmology questions from the StatPearls question bank. These questions were stratified into 11 subcategories, four difficulty levels, and three generalized anatomical categories. The answer accuracy of GPT-3.5, GPT-4, and human participants was assessed. Statistical analysis was conducted via the Kolmogorov-Smirnov test for normality, one-way analysis of variance (ANOVA) for the statistical significance of GPT-3 versus GPT-4 versus human performance, and repeated unpaired two-sample t-tests to compare the means of two groups. Results GPT-4 outperformed both GPT-3.5 and human professionals on ophthalmology StatPearls questions, except in the "Lens and Cataract" category. The performance differences were statistically significant overall, with GPT-4 achieving higher accuracy (73.2%) compared to GPT-3.5 (55.5%, p-value < 0.001) and humans (58.3%, p-value < 0.001). There were variations in performance across difficulty levels (rated one to four), but GPT-4 consistently performed better than both GPT-3.5 and humans on level-two, -three, and -four questions. On questions of level-four difficulty, human performance significantly exceeded that of GPT-3.5 (p = 0.008). Conclusion The study's findings demonstrate GPT-4's significant performance improvements over GPT-3.5 and human professionals on StatPearls ophthalmology questions. Our results highlight the potential of advanced conversational AI systems to be utilized as important tools in the education and practice of medicine.

The Combined Utilization of Epithelial Thickness Mapping and Tomography in Keratorefractive Surgery Screening: One Imaging Modality is Not Sufficient

Increasing popularity and utility of epithelial thickness mapping (ETM) in keratorefractive surgery screening may begin to inappropriately devalue the use of tomography. An increasing body of research suggests that the interpretation of ETM based solely on the corneal resurfacing function may be insufficient to screen and select patients for refractive surgery. ETM and tomography are complementary and, when used together, may provide the safest and most optimal tools for keratorefractive surgery screening.

Reply to Cione et al. Comment on "Moshirfar et al. Accuracy of Six Intraocular Lens Power Calculations in Eyes with Axial Lengths Greater than 28.0 mm. J. Clin. Med. 2022, 11, 5947"

We thank Cioni et al. for their suggestions and comments [...].

Cutibacterium (Formerly Propionibacterium ) acnes Keratitis: A Review

ABSTRACT

Infectious keratitis is a devastating cause of vision loss worldwide. Cutibacterium acnes ( C. acnes ), a commensal bacterium of the skin and ocular surface, is an underrecognized but important cause of bacterial keratitis. This review presents the most comprehensive and up-to-date information for clinicians regarding the risk factors, incidence, diagnosis, management, and prognosis of C. acnes keratitis (CAK). Risk factors are similar to those of general bacterial keratitis and include contact lens use, past ocular surgery, and trauma. The incidence of CAK may be approximately 10%, ranging from 5% to 25% in growth-positive cultures. Accurate diagnosis requires anaerobic blood agar and a long incubation period (≥7 days). Typical clinical presentation includes small (<2 mm) ulcerations with deep stromal infiltrate causing an anterior chamber cell reaction. Small, peripheral lesions are usually resolved, and patients recover a high visual acuity. Severe infections causing VA of 20/200 or worse are common and often do not significantly improve even after treatment. Vancomycin is considered the most potent antibiotic against CAK, although other antibiotics such as moxifloxacin and ceftazidime are more commonly used as first-line treatment.

Comparing Visual Outcomes of Light Adjustable Intraocular Lenses in Patients With and Without Prior History of Corneal Refractive Surgery

PURPOSE

To assess visual outcomes of light adjustable intraocular lens (LAL; Calhoun Vision, Inc) implantation after cataract extraction in patients with a history of corneal refractive surgery.

METHODS

The records of patients who received LALs with and without a history of corneal refractive surgery were retrospectively reviewed. Data for 51 eyes (30 patients) with a history of corneal refractive surgery and 52 eyes (44 patients) without refractive surgery were analyzed. A total of 36 eyes of patients with and 43 eyes of patients without a history of corneal refractive surgery had 12-month follow-up data available. The primary outcomes evaluated were uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA).

RESULTS

At 12 months, 31% of eyes with a history of corneal refractive surgery had a UDVA of 20/20 or better and 97% of eyes were 20/40 or better. In contrast, 63% of patients with no history of corneal refractive surgery had 20/20 UDVA or better at 12 months and 100% were 20/40 or better. Of patients with a history of corneal refractive surgery, 55% and 83% of eyes at 12 months were within ±0.50 and ±1.00 diopters, respectively, of the target refraction compared to 89% and 96% of eyes without a history of corneal refractive surgery.

CONCLUSIONS

LALs are a promising platform for achieving excellent visual outcomes following cataract surgery. Patients with a prior history of corneal refractive surgery can achieve excellent visual outcomes with the LAL. However, this study found that patients with a history of corneal refractive surgery demonstrated less predictable visual acuity outcomes when compared to patients without a history of corneal refractive surgery. [J Refract Surg. 2023;39(5):311-318.].

The Impact of Antiviral Resistance on Herpetic Keratitis

ABSTRACT

Herpes simplex keratitis resistance to antiviral treatment presents a growing concern. The herpes simplex virus has many different mechanisms of resistance to antiviral treatment, which have been well described. Resistance to acyclovir occurs because of mutations in the viral thymidylate kinase and DNA polymerase that decrease this enzyme's affinity for its substrate. This article discusses factors that explain the prevalence of this resistance, the ability for recurrences in immunocompromised populations, current treatments for acyclovir-resistant herpes simplex keratitis, and novel therapies for this growing concern.

Refractive Changes After Nd:YAG Capsulotomy in Pseudophakic Eyes

Purpose

To analyze refractive changes after neodymium: yttrium-aluminum-garnet (Nd:YAG) posterior capsulotomy in pseudophakic eyes.

Patients and Methods

Patients who underwent Nd:YAG capsulotomy after cataract surgery from January 2013 to April 2022 were included in this retrospective study. Sphere, cylinder, spherical equivalent (SE), axis, and corrected distance visual acuity (CDVA) were compared pre- and postoperatively in 683 eyes of 548 patients at one month (n = 605 eyes) and one year (n = 211 eyes). Patients with both one-month and one-year follow-ups (n = 133) were also compared. Eyes were stratified into single-piece (n = 330), three-piece (n = 30), and light adjustable lenses (LALs) (n = 16). Pre- and postoperative measurements were analyzed within each group.

Results

Cylinder was significantly decreased at one-month (difference: 0.042±0.448 D, p = 0.006) and one-year (difference: 0.101±0.455 D, p = 0.003) compared to preoperative measurements. No significant change in sphere or axis was observed at follow-up visits (p > 0.05). CDVA significantly improved at both time points (p < 0.05). No significant change in any parameters between the one-month and one-year groups was observed (p > 0.05). There was significant improvement in CDVA in the single and three-piece lens groups (p < 0.0001 and p = 0.026, respectively), with no change in the LAL group (p > 0.05).

Conclusion

There were no changes in sphere, axis, or spherical equivalent after Nd:YAG capsulotomy. However, cylindrical error and CDVA were significantly better after the procedure. Lens type did not impact refractive parameters postoperatively.

Ocular Side Effects of Bisphosphonates: A Review of Literature

In rare cases, bisphosphonates are well established to cause ocular inflammation, presenting as uveitis, episcleritis, scleritis, orbital inflammation, and/or conjunctivitis. Some reports of bisphosphonate-associated neuro-ophthalmic complications also exist. We identified 101 reports in the literature relating to bisphosphonate-associated ocular complications. In a great majority of cases, symptoms resolve after discontinuation of the drug and anti-inflammatory treatment. Many cases recur if rechallenged with the same bisphosphonate. First-generation nonamino bisphosphonates, including clodronate and etidronate, are not associated with ocular inflammation. Only 2nd- and 3rd-generation amino bisphosphonates, including pamidronate, alendronate, risedronate, ibandronate, and zoledronate are associated with these complications. The mechanism of bisphosphonate-induced ocular inflammation may be related to activation of γ/δ T cells or M1 macrophages. Intravenous forms, such as pamidronate and zoledronate, tend to have higher rates and faster onset of ocular inflammation, generally presenting within days of infusion. In oral bisphosphonates, such as alendronate and risedronate, these complications present with more sporadic timing. Rates of complications are also higher when bisphosphonates are used for malignancy, as doses tend to be higher compared with doses for osteoporosis.

Bilateral Lipid Keratopathy in the Setting of Brimonidine Tartrate Use

Lipid keratopathy (LK) is a rare disease involving lipid deposition in the cornea resulting in corneal opacification. Primary LK can arise sporadically while secondary LK is seen in patients with a history of ocular trauma, medication exposure, infection, inflammation, or disorders resulting in derangements of lipid metabolism. Secondary LK is more common and occurs due to neovascularization. Use of precipitating medications should be considered in LK workup, particularly for patients in whom other etiologies have been ruled out. Brimonidine, an ocular hypotensive medication, can be associated with LK. We present a case of bilateral secondary LK in a patient with a history of prolonged brimonidine use, without additional contributing factors.

Comparative Visual Outcome Analysis of a Diffractive Multifocal Intraocular Lens and a New Diffractive Multifocal Lens with Extended Depth of Focus

This study compares the visual and refractive performance of the TECNIS Synergy (DFR00V-DFW150-225-300-375) multifocal intraocular lens (IOL) and the AcrySof IQ PanOptix (TFAT00-30-40-50-60) multifocal IOL. Patients who underwent phacoemulsification and cataract extraction and received either a multifocal Synergy or PanOptix IOL were included. Monocular uncorrected distance (UDVA), intermediate (UIVA), near (UNVA), and corrected distance (CDVA) visual acuities were assessed at three and six months postoperatively. Secondary outcome measures of photic phenomena were also assessed. A total of 140 patients (224 eyes) were included in this study, with 69 patients (105 eyes) in the Synergy group and 71 patients (119 eyes) in the PanOptix group. There were no statistically significant differences in UIVA or CDVA measurements across all time points. When assessing UDVA, at three months postoperatively, there were more eyes in the PanOptix group with vision better than 20/40 (p = 0.04). At three and six months postoperatively, the average UNVA was superior in the Synergy group (p = 0.01, 0.002). While the Synergy group reported more night vision disturbances at one and three months (p = 0.01, 0.03), the PanOptix group had more night vision disturbances at six months (p = 0.02). Although not statistically significant, the AcrySof IQ PanOptix multifocal IOL demonstrated better UDVA and UIVA sooner postoperatively than the TECNIS Synergy multifocal IOL. The Synergy IOL provided statistically better UNVA compared to the PanOptix IOL at three and six months postoperatively. Synergy patients reported more early photic phenomena than PanOptix patients, which later diminished.

Corneal Refractive Surgery Considerations in Patients with Cystic Fibrosis and Cystic Fibrosis Transmembrane Conductance Regulator-Related Disorders

This article discusses common ocular manifestations of cystic fibrosis (CF) and cystic fibrosis transmembrane conductance regulator-related disorders (CFTR-RD). A structured approach for assessing and treating patients with CF/CFTR-RD seeking corneal refractive surgery is proposed, as well as a novel surgical risk scoring system. We also report two patients with various manifestations of CFTR dysfunction who presented for refractive surgery and the outcomes of the procedures. Surgeons seeking to perform refractive surgery on patients with CF/CFTR-RD should be aware of mild to severe clinical manifestations of CFTR dysfunction. Specific systemic and ocular manifestations of CF include chronic obstructive pulmonary disease (COPD), bronchiectasis, recurrent pulmonary infections, CF-related diabetes and liver disease, pancreatic insufficiency, conjunctival xerosis, night blindness, meibomian gland dysfunction (MGD), and blepharitis. Corneal manifestations include dry eye disease (DED), punctate keratitis (PK), filamentary keratitis (FK), xerophthalmia, and decreased endothelial cell density and central corneal thickness. Utilization of the appropriate review of systems (ROS) and screening tests will assist in determining if the patient is a suitable candidate for refractive surgery, as CF/CFTR-RD can impact the health of the cornea. Collaboration with other medical professionals who care for these patients is encouraged to ensure that their CF/CFTR-RD symptoms are best controlled via systemic and other treatment options. This will assist in reducing the severity of their ocular manifestations before and after surgery.

One-Year Visual Outcomes and Corneal Higher-Order Aberration Assessment of Small-Incision Lenticule Extraction for the Treatment of Myopia and Myopic Astigmatism

We present a retrospective, single-center report of one-year visual outcomes for Small Incision Lenticule Extraction (SMILE) to treat myopia and myopic astigmatism, as well as to compare outcomes with other published literature, including results from the United States Food and Drug Administration (US FDA). A total of 405 eyes with a mean preoperative spherical equivalent of -5.54 diopters (D) underwent SMILE between April 2017 and April 2022. The outcomes measured included visual acuity, manifest refraction, vector analysis, and wavefront aberrometry at various time points, specifically pre-operative and twelve months post-operatively. Results were compared to other similar published studies of SMILE outcomes between 2012 and 2021. A total of 308 and 213 eyes were evaluated at three and twelve months, respectively. At twelve months, 79% of eyes achieved UDVA ≥ 20/20, and 99% had ≥20/40, with no patients losing ≥2 lines of vision. For accuracy, 84% of eyes were within 0.5 D of target SEQ, and 97% were within 1 D. Total corneal higher order aberrations (HOA) increased from 0.33 to 0.61 um. Significant change was found in vertical coma and spherical aberration at twelve months. SMILE remains a safe and effective treatment for myopia and myopic astigmatism. Clinical outcomes are likely to improve with increased surgeon experience and refinement of technology and nomograms.

Motorcycle-Associated Ocular Injuries: A Narrative Review

Purpose

Motorcycle-related injuries involving the eye and orbit are not well characterized, with a paucity of prospective studies focusing specifically on motorcycle-associated eye injuries nor literature reviews having been conducted on the subject. To better understand the injury types and descriptive characteristics of patients experiencing motorcycle-associated eye injuries, we sought to conduct a narrative review.

Methods

The research team utilized the following databases: PubMed, EMBASE, and Web of Science to query for English articles from peer-reviewed journals that provided some patient data regarding eye injury due to motorcycle or moped accidents or usage.

Results

A total of 65 studies were included in our qualitative synthesis. Of these studies, 40 (61.5%) were case reports, 20 retrospective case series (30.8%), and five (7.69%) were observational prospective studies. Among the 25 retrospective and prospective studies, 12 (48.0%) of these studies primarily focused on motorcycle-associated injuries. These 65 studies described a wide variety of motorcycle-associated eye injuries, including but not limited to orbital fractures and associated sequelae, foreign bodies, vitreoretinal trauma, neuro-ophthalmic trauma, corneal injuries, open globe injuries, lacerations, and globe avulsions.

Conclusion

The current state of the literature indicates that knowledge regarding the ocular manifestations of motorcycle accidents is limited to mostly case reports and few retrospective cohort studies focused specifically on motorcycle-associated eye injuries. However, it is evident that the types of motorcycle-associated eye injuries are legion and predominantly seen in adult males, potentially leading to severe injuries and loss of vision and blindness.

Explantation of KAMRA Corneal Inlay: 10-Year Occurrence and Visual Outcome Analysis

PURPOSE

To evaluate 10 years of KAMRA corneal inlay explantation and associated visual outcomes.

PATIENTS AND METHODS

Single-site retrospective chart review of 22 cases of AcuFocus KAMRA Inlay (ACI7000PDT) explantation (range 1 week-1 year). Uncorrected distance visual acuity (UDVA), uncorrected near visual acuity (UNVA), corrected distance visual acuity (CDVA), and manifest refraction at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year post-explantation were reviewed.

RESULTS

The explantation rate was 8.2% across 10 years. All patients underwent KAMRA explantation due to dissatisfaction with their vision including blurry near vision, impaired night vision, decreased vision in dim lighting, streaks or halos, haze, and double vision. Mean UDVA pre-implant was -0.01±0.13 logMAR (logarithm of the minimal angle of resolution), 0.30±0.22 logMAR pre-explant, and 0.16±0.15 logMAR post-explant (n=20). Mean UNVA pre-implant was 0.37±0.09 logMAR, 0.38±0.13 logMAR pre-explant, and 0.42±0.21 logMAR post-explant (n=20). Mean CDVA pre-implant was -0.01±0.04 logMAR and 0.05±0.11 logMAR post-explant (n=17). Mean CDVA pre-explant was 0.04±0.07 logMAR and 0.04±0.11 logMAR post-explant (n=19). Significant differences were observed between pre-implant and post-explant UDVA (p=0.009), and between pre-explant and post-explant UDVA (p=0.02). All patients (100%) had 20/20 or better CDVA pre-implant but decreased to 73.7% post-explant. Sixty percent (12/20) of the patients lost UDVA Snellen acuity lines post-explant. MRSE was -0.31±0.29 D pre-implant and +0.26±0.77 D post-explant (p=0.007) with note of a hyperopic shift. The hyperopic shift in 31.6% (6/19) of patients did not resolve after explantation. Post-explant residual corneal haze occurred in 72.7% (16/22) of patients.

CONCLUSION

Although the KAMRA corneal inlay is a removable device, patients may experience residual corneal haze, hyperopic shift, and deficits in UDVA after explantation compared to pre-implantation UDVA.

Accuracy of Six Intraocular Lens Power Calculations in Eyes with Axial Lengths Greater than 28.0 mm

The purpose of this study was to compare the accuracy of several intraocular (IOL) lens power calculation formulas in long eyes. This was a single-site retrospective consecutive case series that reviewed patients with axial lengths (AL) > 28.0 mm who underwent phacoemulsification. The Wang−Koch (WK) adjustment and Cooke-modified axial length (CMAL) adjustment were applied to Holladay 1 and SRK/T. The median absolute error (MedAE) and the percentage of eyes with prediction errors ±0.25 diopters (D), ±0.50 D, ±0.75 D, and ±1.00 D were used to analyze the formula’s accuracy. This study comprised a total of 35 eyes from 25 patients. The Kane formula had the lowest MedAE of all the formulas, but all were comparable except Holladay 1, which had a significantly lower prediction accuracy with either AL adjustment. The SRK/T formula with the CMAL adjustment had the highest accuracy in predicting the formula outcome within ±0.50 D. The newer formulas (BU-II, EVO, Hill-RBF version 3.0, and Kane) were all equally predictable in long eyes. The SRK/T formula with the CMAL adjustment was comparable to these newer formulas with better outcomes than the WK adjustment. The Holladay 1 with either AL adjustment had the lowest predictive accuracy.

Corneal Transplant Rejections in Patients Receiving Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) are antibodies that target and block immune checkpoints. These biologics were initially approved by the United States Food and Drug Administration (US FDA) in 2011 for the management of melanoma. Since then, the use of ICI therapy has increased, with many new medications on the market that treat approximately 50 types of cancers. Patients receiving this therapy are at an increased risk for transplant rejection, including corneal rejection. Ophthalmologists must be aware of individuals receiving ICI therapy as it may be a relative contraindication for patients with a history of corneal transplantation. Patients on ICIs may also experience ocular side effects, including uveitis, dry eye, and inflammation, while on checkpoint inhibitor therapy. This commentary discusses the current understanding of immune checkpoint inhibitors, their mechanism of action, their ocular side effects, and their role in corneal transplant rejection.

Photorefractive Keratectomy Enhancement (PRK) After Small-Incision Lenticule Extraction (SMILE)

Purpose

To determine rates of enhancement and visual prognosis following photorefractive keratectomy (PRK) enhancement of small-incision lenticule extraction (SMILE).

Patients and Methods

This retrospective, single-site study reviewed all cases of primary SMILE at Hoopes Vision in Draper, Utah between March 14, 2017 and April 8, 2022 to identify any cases that required follow-up enhancement. Primary SMILE was performed using Visumax 500 kHz femtosecond laser (Carl Zeiss Meditec, Jena, Germany). All enhancements were performed with alcohol-assisted PRK, using a WaveLight EX500 excimer laser (Alcon Laboratories, Inc., Fort Worth, TX).

Results

Four hundred and five eyes underwent primary SMILE, of which 15 later underwent PRK enhancement (enhancement rate of 3.7%). No significant difference in pre-SMILE data was identified between the enhancement and non-enhancement groups. The average age of those who underwent PRK enhancement was 33.8±6.3 years old and ranged from 25 to 45. Following primary SMILE, 13 eyes (87%) had an uncorrected distance visual acuity (UDVA) of 20/40 or better, and none had a UDVA of 20/20 or better. After one year of post-enhancement follow-up, all eyes had a UDVA of 20/40 or better, and 13 eyes (87%) had a UDVA of 20/20 or better (Figure 1). All were within one diopter of target spherical equivalent (SEQ), 13 (87%) were within 0.50 D, and 10 (67%) were within 0.25 D. Of those with 12-month follow-up data, none had UDVA worse than corrected distance visual acuity (CDVA), and none had lost lines of CDVA. Efficacy and safety indices were 1.03 and 0.99, respectively.

Conclusion

Following SMILE, ophthalmologists may anticipate an enhancement rate of one to seven percent. In these cases, PRK is a safe and effective procedure for enhancement of SMILE.

Inflammatory Bowel Disease Guidelines for Corneal Refractive Surgery Evaluation

Inflammatory bowel disease (IBD) is a chronic systemic inflammatory condition that can potentially adversely affect surgical outcomes in patients receiving elective ophthalmic procedures. In this case series, 21 eyes of 11 patients with ulcerative colitis or Crohn’s disease underwent laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), or small incision lenticule extraction (SMILE). Their surgical outcomes were followed up for an average of 8.9 ± 4.6 months. All the patients in this study did well, with 100% of eyes corrected for distance vision achieving uncorrected distance visual acuity 20/20 by postoperative month three. Common symptoms noted during the postoperative period included dry eyes, irritation, foreign body sensation, and blurry vision, all of which improved in prevalence and severity over the follow-up period, and none of the patients experienced a flare-up of their disease. Despite the successful outcomes in these patients, the authors recognize the inherent risks of operating on patients with IBD. Currently, there are no consensus guidelines for clinicians to follow to ensure that they are adequately screening these patients for eligibility, so the authors are suggesting a relevant, focused review of systems, a brief IBD history-related questionnaire, and a preliminary surgical decision-making flowchart for use in surgical evaluation.

Laser-Assisted In Situ Keratomileusis (LASIK) Enhancement for Residual Refractive Error after Primary LASIK

Background: To evaluate the safety, efficacy, and predictability of laser-assisted in situ keratomileusis (LASIK) enhancement after primary LASIK and compare to Food and Drug Administration (FDA) criteria. Methods: Patients who underwent LASIK enhancement after primary LASIK between 2002 and 2019 were compared to those who underwent LASIK without retreatment. Patient demographics, preoperative characteristics, visual outcomes, and postoperative complications were compared between groups. Epithelial ingrowth (EI) development was stratified based on duration between primary and secondary procedures. Results: We compared 901 eyes with LASIK enhancement to 1127 eyes without retreatment. Age, sex, surgical eye, sphere, cylinder, and spherical equivalent (SE) were significantly different between groups (p < 0.05). At 12 months post-enhancement, 86% of the eyes had an uncorrected distance visual acuity of 20/20 or better and 93% of eyes were within ±0.50 D of the target. Development of EI (6.1%) demonstrated an odds ratio of 16.3 in the long-term compared to the short-term (95% CI: 5.9 to 45.18; p < 0.0001). Conclusions: Older age at primary LASIK, female sex, right eye, and larger sphere, cylinder and SE were risk factors for enhancement. Risk of EI significantly increased when duration between primary and enhancement procedures exceeded five years. LASIK enhancements produce favorable outcomes and meet FDA benchmarks for safety, efficacy, and predictability.

Review of Presbyopia Treatment with Corneal Inlays and New Developments

Presbyopia may represent the largest segment of refractive errors that is without an established and effective refractive surgery treatment. Corneal Inlays are materials (synthetic or allogenic) implanted in the stroma of patients’ corneas to improve presbyopia. These inlays, introduced into the United States in 2015 via the small-aperture corneal inlay (KAMRA^TM, SightLife Surgical/CorneaGen, Seattle, Washington, United States), were met with an initial wave of enthusiasm. Subsequent models like the shape-changing corneal inlay (RAINDROP^TM, Revision Optics, Lake Forest, California, United States) offered excellent results for patients, but longer-term research raised questions about patient safety. At the time of this article, no synthetic corneal inlays are available in the United States for the correction of presbyopia. Other options for presbyopia correction include allograft corneal inlays, trifocal synthetic corneal inlays, pharmacologic therapies, scleral incisions or additive techniques and PresbyLASIK. Presently, allograft inlays consist of corneal lenticules removed from patients undergoing Small Incision Lenticule Extraction (SMILE). We will review corneal inlays and other alternative procedures that may provide effective and predictable treatments for patients with presbyopia.

Ocular Features and Clinical Approach to Cataract and Corneal Refractive Surgery in Patients with Myotonic Dystrophy

Myotonic dystrophy is the most common inherited muscular dystrophy in adults and presents as two forms, type 1, and type 2. Ocular manifestations such as premature cataract formation, may be the first diagnostic sign or symptom of the disease, offering ophthalmologists a unique diagnostic role. Fuchs' endothelial corneal dystrophy, ptosis and ocular melanoma are other possible findings. Systemic features can help providers better understand the disease and any accommodations to be made in clinical or surgical settings. Some patients with this disease may request evaluation of certain cataract or corneal refractive procedures. This article focuses on pertinent information for clinicians to utilize when evaluating and treating patients with myotonic dystrophy and specific surgical perspectives to consider prior to any ocular interventions. Hydrophobic intraocular lenses are still recommended in these patients with careful observation of capsular phimosis and posterior capsular opacities.

Assessing Patients with Alpha-1 Antitrypsin Deficiency for Corneal Refractive Surgery: A Review and Clinical Experience

Alpha-1 Antitrypsin Deficiency (AATD) is an autosomal inheritable disorder that impairs the protease inhibitor alpha-1 antitrypsin. This disorder presents with various systemic effects, including liver cirrhosis, centrilobular emphysema, and ocular manifestations. Performing corneal refractive surgery in patients with AATD raises concerns regarding the increased rates of corneal erosions, corneal ulcerations, potential developing descemetoceles, and other ocular manifestations. Patient outcomes for laser-assisted in situ keratomileuses (LASIK), photorefractive keratectomy (PRK), small incision lenticule extraction (SMILE), and other ocular corrective surgeries are lacking in this population. This article provides experiences performing corneal refractive surgery, discusses the current understanding of AATD, including its ocular manifestations, and explores factors to consider when evaluating patients for corneal procedures. The aim of this paper is to address the manifestations of AATD prior to performing corrective vision surgery.

Corneal Refractive Surgery Considerations in Patients on Dupilumab

Dupilumab is a biologic approved by the United States Food and Drug Administration (US FDA) for the treatment of atopic dermatitis. While it is an effective medication for eczema, ocular side effects are common in patients receiving dupilumab therapy. Greater consideration is needed when evaluating these individuals for corneal refractive surgery. Dupilumab patients may suffer from atopy, a condition that also merits consideration in those desiring refractive surgery. Additional testing and careful consideration are needed, as these patients have an increased risk of dry eye syndrome, keratoconus, cataracts, diffuse lamellar keratitis, viral keratitis, and perioperative infection. This commentary discusses the current understanding of dupilumab ocular side effects and investigates factors to consider when evaluating these patients for corneal refractive surgery.

Atypical presentation of acanthamoeba keratitis resembling central toxic keratopathy

PURPOSE

To describe an atypical case of acanthamoeba keratitis with positive in vivo confocal microscopy in a non-contact lens user who presented with signs and symptoms suggestive of central toxic keratopathy.

OBSERVATIONS

The patient presented with bilateral, though sequential, decreased visual acuity with mild pain. Examination showed stromal haze with corneal flattening and thinning without epithelial defects. Optical coherence tonometry of the right eye revealed an inverse dome-shaped appearance of the opacity and in-vivo confocal imaging showed double-walled cysts consistent with acanthamoeba. Corneal haze, stromal loss, resolved and visual acuity improved over time.

CONCLUSION AND IMPORTANCE

Acanthamoeba is a rare cause of infectious keratitis that is most often associated with contact lens wear in developed countries. Typically, it presents with a unilateral decrease in visual acuity, photophobia, watering, and pain that is out of proportion to slit lamp examination findings. However, many atypical presentations have been reported in the literature. Consequently, it may be misdiagnosed, especially early in the course of the disease. This delay in diagnosis can lead to progressive ulceration and visual impairment. In addition, cyst formation can make eradication with anti-amoebic treatment especially difficult.Central toxic keratopathy is a non-inflammatory clinical syndrome of unknown etiology that is most often associated with excimer laser ablation, though other associated causes have been reported. It is characterized by a central or paracentral opacity with corneal stromal loss and resultant hyperopic shift. The opacification and stromal loss mostly resolve over the course of months with an improvement in visual acuity. This report may help physicians broaden their differential and correctly diagnose atypical presentations of amoebic infection.

Delayed Epithelial Healing with Corneal Edema and Haze After Photorefractive Keratectomy Using Intraoperative Mitomycin C

We report an unusual presentation of presumed mitomycin C toxicity with possible subsequent hypersensitization to other medication toxicities. A 50-year-old female presented three months after photorefractive keratectomy with intraoperative mitomycin C for the management of persistent epithelial defects, corneal haze, and edema. She was found to have used an expansive and rapidly changing medical regimen which may have caused additional toxicity. These medications included besifloxacin, bromfenac, and ketotifen. Additives such as benzalkonium chloride and DuraSite^® may have also contributed. Intraoperative mitomycin C can result in longstanding corneal haze, edema, and delayed epithelial healing in the setting of corneal refractive surgery. These may leave the cornea more susceptible to additional subsequent medication toxicities during the postoperative period. This report describes a case of mitomycin C exposure leading to a prolonged sensitivity to other medication toxicities, which has not been discussed elsewhere in the literature.