Association of myopia and astigmatism with postoperative ocular high order aberration after small incision lenticule extraction.

OBJECTIVE: To investigate the correlation between higher-order aberrations (HOA) after small incision lenticule extraction (SMILE) and the severity of myopia and astigmatism, along with the relevant factors. These findings will provide valuable insights for decreasing the occurrence of HOA after SMILE and enhancing visual quality. METHODS: A total of 75 patients (150 eyes) with myopia and astigmatism who underwent SMILE were categorized into four groups based on the severity of myopia and astigmatism: Myopia Group 1 (Group M1, spherical diopter ranged from -1.00 D to -4.00 D), Myopia Group 2 (Group M2, spherical diopter ranged from -4.10 D to -10.00 D), Astigmatism Group 1 (Group A1, cylindrical diopter ranged from 0 D to -1.00 D), and Astigmatism Group 2 (Group A2, cylindrical diopter ranged from -1.10 D to -3.00 D). A comprehensive assessment was performed to examine the association between HOA and various relevant factors, including a detailed analysis of the subgroups. RESULTS: Group M1 had significantly lower levels of total eye coma aberration (CA), corneal total HOA (tHOA), internal tHOA, and vertical CA ( Z 3 - 1 ) after SMILE than Group M2 (P < 0.05). Similarly, Group A1 had significantly lower levels of total eye tHOA, CA, trefoil aberration (TA), corneal tHOA, TA, and vertical TA ( Z 3 - 3 ) after SMILE than Group A2 (P < 0.05). Pearson correlation analysis indicated a statistically significant positive relationship between the severity of myopia/astigmatism and most HOA (P < 0.05). Subgroup evaluations demonstrated a notable increase in postoperative HOA associated with myopia and astigmatism in Groups M2 and A2 compared with the control group. Lenticule thickness, postoperative central corneal thickness (CCT), postoperative uncorrected distance visual acuity (UDVA), and postoperative corneal Km and Cyl were strongly correlated with most HOA. Age, eyes, and postoperative intraocular pressure (IOP) were only associated with specific HOA. CONCLUSION: HOA positively correlated with the severity of myopia and astigmatism after SMILE. However, this relationship was not linear. HOA after SMILE was influenced by various factors, and additional specialized investigations are required to establish its clinical importance.

SmartSight Correction of Compound Myopic Astigmatism Treatments With Preoperative Astigmatism > 1.00 Diopter Using the SCHWIND ATOS: A Retrospective Case Series.

PURPOSE: To evaluate moderate to high astigmatism corrections on the outcomes of SmartSight lenticule extraction for myopic astigmatism with a new femtosecond laser system. METHODS: Two hundred ninety-two eyes consecutively treated for myopic astigmatism with astigmatism magnitude greater than 1.00 diopter (D) were evaluated at the 6-month follow-up visit. The mean age of the patients was 29 ± 6 years with a mean spherical equivalent of -5.06 ± 2.20 diopters (D) and a mean magnitude of refractive astigmatism of 1.74 ± 0.61 D. RESULTS: At 6 months, astigmatism was 0.10 ± 0.20 D. Uncorrected and corrected distance visual acuities (UDVA and CDVA, respectively) were both 0.0 ± 0.1 logMAR. Differences between postoperative UDVA and preoperative CDVA and the change in CDVA were both +0.4 ± 0.7 lines better than preoperatively (P < .0003). CONCLUSIONS: Lenticule extraction treatment using Smart-Sight is safe and efficacious at 6 months. Findings suggest that moderate to high astigmatism improves after SmartSight lenticule extraction in the treatment of myopic astigmatism. [J Refract Surg. 2024;40(5):e328-e335.].

Fitting-Shape-based Strategy for Topography-guided LASIK: A Prospective Study.

PURPOSE: To assess and compare the visual acuity and refractive outcomes of topography-guided laser in situ keratomileusis (LASIK) based on the fitting-shape-based refractive compensated and Phorcides software strategies. METHODS: Consecutive patients who underwent topography-guided LASIK were included in this study. Through double-masked simple randomization, patients were assigned to the Zhang & Zheng Auto-compensate Refraction (ZZ AR) group (the fitting-shape-based refractive compensated strategy using the ZZ AR calculator was used) or the Phorcides group (the topography analysis algorithm in Phorcides software [Phorcides LLC] was used). Only one eye per patient with binocular correction was randomly enrolled. The preoperative and postoperative visual acuities and refraction were analyzed at the 6-month follow-up visit. RESULTS: The ZZ AR and Phorcides groups comprised 156 and 147 eyes, respectively. At the 6-month postoperative follow-up visit, the median (range) absolute residual cylindrical refraction was 0.35 (1.01) and 0.47 (1.63) diopters (D) for the ZZ AR and Phorcides groups, respectively (P < .001). The percentages of patients with residual cylindrical power within 0.25 D were 29.49% and 13.61% for the ZZ AR and Phorcides groups, respectively (P = .001). Based on the percentages of patients with residual cylindrical powers within 0.50 and 1.00 D, the ZZ AR group showed better outcomes (P = .02 and .01). The percentage of patients with visual acuity better than 20/16 was significantly higher for the ZZ AR group than for the Phorcides group (P = .03). CONCLUSIONS: The fitting-shape-based refractive compensated strategy for topography-guided LASIK procedures can better optimize the visual acuity and astigmatic refraction than the Phorcides software strategy. [J Refract Surg. 2024;40(5):e336-e343.].

Comparative Study of Primary SMILE, SMILE Enhancement, and Femtosecond Laser-Assisted LASIK on Higher Order Aberrations and Corneal Densitometry.

PURPOSE: To compare differences in corneal densitometry (CD) and higher order aberrations (HOAs) in eyes that underwent small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for the treatment of myopia and myopic astigmatism at postoperative months 3, 6, and 12, and to evaluate their changes in a separate cohort of eyes after SMILE enhancement. METHODS: In this prospective, randomized, paired-eye clinical trial, consecutive eligible participants were randomized to undergo SMILE or FS-LASIK in either eye. Main outcome measures were CD and HOAs preoperatively and at 3, 6, and 12 months postoperatively. A separate cohort of consecutive patients who had SMILE and underwent enhancement were also included for comparison. RESULTS: For CD, no significant differences were found between SMILE and FS-LASIK up to month 12. For HOA measured by wavefront aberrometry, both SMILE and FS-LASIK had an increase in total root mean square (RMS) HOAs, spherical aberration (SA), and vertical coma up to month 12. SMILE had an additional increase in vertical quatrefoil, and FS-LASIK had an increase in horizontal coma at month 12. FS-LASIK had higher SA than SMILE, whereas SMILE had higher vertical quatrefoil than FS-LASIK at month 12. Central and posterior zone CD had significantly decreased after SMILE enhancement compared to after primary SMILE up to 2 years after enhancement. RMS HOAs, lower order aberrations, and SA were all increased after SMILE enhancement compared to after primary SMILE. CONCLUSIONS: SMILE induced lower SA but higher vertical quatrefoil than FS-LASIK at 1 year. Both SMILE and FS-LASIK had similar increases in RMS HOAs and vertical coma up to 1 year. There were no differences in CD between both groups. SMILE enhancement additionally had decreased central and posterior CD but greater RMS HOAs and SA compared to primary SMILE. [J Refract Surg. 2024;40(5):e291-e303.].

Uneven Corneal Epithelial Redistribution After Femtosecond Laser-Assisted Lenticule Intrastromal Keratoplasty in Correcting Moderate-to-High Hyperopia.

PURPOSE: To evaluate the characteristic of corrective epithelial thickness after femtosecond laser-assisted lenticule intrastromal keratoplasty (LIKE) to correct moderate-to-high hyperopia. METHODS: The prospective case series study of the LIKE procedure was performed to correct moderate-to-high hyperopia. The epithelial thickness map was generated by anterior segment optical coherence tomography (AS-OCT) in the corneal central 9-mm zone. Keratometry and corneal higher order aberrations were analyzed by Pentacam (Oculus Optikgeräte GmbH) preoperatively and postoperatively. RESULTS: In the 26 eyes of 13 participants who underwent the LIKE procedure for moderate-to-high hyperopia, the attempted spherical equivalence (SEQ) was +6.50 ± 1.09 diopters (D). Compared to the preoperative epithelial thickness maps, the postoperative epithelial thickness had become significantly thinner in the central 5-mm zone; the difference was 6 to 7 µm. The paracentral epithelium performed nonuniform remodeling; the thinnest epithelial thickness was located in the inferotemporal section, which has the greatest difference from the superonasal; the difference between these two was approximately 3 µm. Through correlation analysis, it was found that the sections with thinner epithelium were significantly related to corneal curvature and corneal vertical coma. CONCLUSIONS: The LIKE procedure can be used to correct moderate-to-high hyperopia. This study further indicated the epithelial remodeling characteristic after the LIKE procedure: the central and paracentral corneal epithelial thickness becomes thinner, and the epithelial thickness distributes non-uniformly, which may be the important factor of the postoperative curvature asymmetric distribution and induction of corneal vertical coma. [J Refract Surg. 2024;40(5):e321-e327.].

In Vivo Corneal Biomechanical Response to Three Different Laser Corneal Refractive Surgeries.

PURPOSE: To compare the effects of three common refractive surgeries on corneal biomechanics. METHODS: Two hundred seven patients who had refractive surgery were included in this study, of whom 65 received transepithelial photorefractive keratectomy (tPRK), 73 received femtosecond laser-assisted laser in situ keratomileusis (FSLASIK), and 69 received small incision lenticule extraction (SMILE). Each patient had biomechanical measurements using the Corvis ST (Oculus Optikgeräte GmbH) preoperatively and at 3 and 6 months postoperatively. The measurements included five parameters expected to be associated with corneal biomechanics: deformation amplitude ratio at 2 mm (DAR2), integrated inverse radius (IIR), stiffness parameter at first applanation (SP-A1), highest concavity time (HCT), and the updated stress-strain index (SSIv2). The variations in these parameters postoperatively among the three surgeries, and their relationship with corneal thickness (CCT) and intraocular pressure measured by the Dynamic Contour Tonometer (DCT-IOP) were analyzed. RESULTS: SP-A1 decreased significantly from preoperatively to 3 months postoperatively in all three groups, whereas DAR2 and IIR increased significantly, all indicating stiffness losses. Between 3 and 6 months postoperatively, the results were inconsistent, with DAR2 decreasing (indicating stiffness increases) and IIR increasing (denoting stiffness decreases) in the FS-LASIK and SMILE groups. The decrease in SSIv2 (the only measure of corneal material stiffness) postoperatively was comparatively less pronounced at both 3 and 6 months postoperatively. On the other hand, HCT remained generally stable after all three surgeries. Unlike DAR2, IIR, and SP-A1, the changes postoperatively in stiffness parameters HCT and SSIv2 were independent of the corresponding changes in both DCT-IOP and CCT. CONCLUSIONS: Among the stiffness parameters considered, SSIv2 was not correlated with CCT or DCT-IOP, and holds promise for representing the corneal material stiffness and how it remains largely unaffected by refractive surgeries. Overall, FS-LASIK had the most significant impact on corneal stiffness, followed by SMILE, and finally tPRK. [J Refract Surg. 2024;40(5):e344-e352.].

[Influence of corneal curvature and peripheral thickness on tonometry readings]. / Vliyanie krivizny i perifericheskoi tolshchiny rogovitsy na rezul'tat tonometrii.

PURPOSE: This study investigates the influence of peripheral corneal thickness (PCT) and its curvature on tonometry readings. MATERIAL AND METHODS: The study included 49 patients (49 eyes) who were indicated for glaucoma surgery. Using bidirectional applanation tonometry, the following parameters were obtained: IOPcc, IOPg - intraocular pressure (IOP) corrected for corneal compensation, taken as the most reliable indicator; IOP converted to Goldmann measurement, taken as the result of applanation tonometry, ΔIOP (IOPcc-IOPg), CH and CRF (corneal hysteresis and corneal resistance factor). During corneal topography, the corneal thickness was studied in the center, PCT at 1.5; 2, 3, 4 and 5 mm from the center in four meridians, as well as ΔPCT (PCT 3 mm - PCT 1.5 mm), the curvature of the anterior and posterior surfaces of the cornea and the depth of the anterior chamber. Aberrometry was used to obtain refractometry data and the curvature of the anterior surface of the cornea. The influence of the studied parameters on ΔIOP was evaluated. RESULTS: ΔIOP correlated with CRF (r= -0.652), CH (r= -0.873), central corneal thickness (r= -0.293), PCT at all distances except 5 mm (r= -0.297; -0.287; -0.302; -0.303), with the strong and weak meridians of the anterior surface of the cornea (r=0.328; r=0.315), with the strong and weak meridians of the posterior surface, as well as the average curvature of the posterior surface (r=0.307; r=0.332; r=0.328). After step-by-step selection of the above parameters for creating a linear regression model for ΔIOP calculation, CH, CRF and PCT1.5mm remained in the model. The model describes ΔIOP with high accuracy (R2=0.974). CONCLUSION: Biomechanical parameters of the cornea are the leading factor of applanation tonometry error. Individual linear dimensions of the cornea (thickness, curvature) have a lesser effect.

Evaluation of the results of contact lens assisted corneal cross-linking treatment in keratoconus patients with thin corneas.

PURPOSE: We aimed to compare the efficacy and safety of accelerated contact lens-assisted cross-linking (CA-CXL) with Lotrafilcon B and Comfilcon A lenses in keratoconus (KC) patients with thin corneas. STUDY DESIGN: Retrospective, single-center study. MATERIALS AND METHODS: We retrospectively included 51 eyes of 39 KC patients with corneal thickness <400µm after epithelial scraping (Epi-off), who underwent accelerated CA-CXL treatment with Lotrafilcon B (n=20) and Comfilcon A (n=31). Uncorrected and corrected distance visual acuity (UDVA and CDVA), manifest refraction values, corneal topographic data and endothelial cell density were recorded at preoperative and postoperative 1st, 3rd and 6th month controls. RESULTS: CDVA in the Comfilcon A group was higher than CDVA before surgery at 6 months postoperatively (p<0.001). When the two lenses were compared, CDVA was found to be significantly higher in the Lotrafilcon B group in the preoperative, postoperative 1st month and 3rd month values, but there was no significant difference between the postoperative 6th month values (p=0.028, p=0.018, p=0.044, p=0.181, respectively). The maximum keratometry (Kmax) value at the 6th month after surgery in the Comfilcon A group was significantly lower than in the Lotrafilcon B group (p=0,009). There was no significant difference between the endothelial cell density values between the groups (p=0.623, p=0.609, p=0.794, p=0.458, respectively). There was no significant difference between the progression, regression, and stability rates of the two groups (p=0.714). CONCLUSIONS: Accelerated CA-CXL with Lotrafilcon B and Comfilcon A silicone hydrogel lenses is a safe and effective method to stop progression in patients with thin corneas.

Comparative evaluation of biomechanical changes and aberration profile following accelerated collagen cross-linking using hypo-osmolar and iso-osmolar riboflavin: A prospective study.

PURPOSE: To compare the changes encountered in corneal biomechanics and aberration profile following accelerated corneal collagen cross-linking (CXL) using hypo-osmolar and iso-osmolar riboflavin in corneal thicknesses of <400 and >400 microns, respectively. METHODS: This is a prospective, interventional, comparative study involving 100 eyes of 75 patients with progressive keratoconus. Eyes were divided into two groups based on corneal thickness: group 1 included eyes with a corneal thickness of <400 microns who underwent hypo-osmolar CXL, and group 2 included eyes with a corneal thickness of >400 microns who underwent iso-osmolar CXL. Corneal biomechanical and aberration profiles were evaluated and compared between groups. RESULTS: In group 1, all higher-order aberrations (HOA) except secondary astigmatism significantly decreased from baseline; however, in group 2, only coma and trefoil decreased. The corneal resistance factor and corneal hysteresis significantly improved in both groups, which was significantly greater in group 2 than in group 1. The change in inverse radius, deformation amplitude, and tomographic biomechanical index was significantly improved in group 2 as compared to group 1. CONCLUSION: Improvement in corrected distance visual acuity and decrease in HOA were significantly better in the hypo-osmolar CXL group; however, the improvement in biomechanical strength of the cornea was significantly better in the iso-osmolar group.

Repeatability assessment of anterior segment measurements in myopic patients using an anterior segment OCT with placido corneal topography and agreement with a swept-source OCT.

BACKGROUND: The precision of anterior segment biometric measurements in eyes has become increasingly important in refractive surgery. The purpose of this study is to assess the repeatability of the automatic measurements provided by a new spectral-domain optical coherence tomograph (SD-OCT)/Placido topographer (MS-39, CSO) and its agreement with a swept-source OCT (SS-OCT) biometer (CASIA SS-1000, Tomey) in patients with myopia. METHODS: The right eye of 235 subjects was scanned 3 times with both devices. The evaluated parameters included central corneal radius of the steep meridian, central corneal radius of the flat meridian, mean central corneal radius, thinnest corneal thickness, central corneal thickness, anterior chamber depth, corneal volume and diameter. The intraobserver repeatability of the MS-39 measurements was calculated using intraclass correlation coefficient (ICC), within subject standard deviation, coefficient of repeatability, coefficient of variation and repeated-measures analysis of variance of the 3 repeated measurements. The agreement between the two devices was evaluated by 95% limits of agreement (LoA). RESULTS: The majority of the parameters acquired from MS-39 showed high repeatability. The repeatability of corneal diameter was slightly lower than the other measurements, although the ICC remained high. Agreement with the CASIA SS-1000 was good, indicated by the Bland-Altman plots with narrow 95% LoA values for all parameters assessed. CONCLUSIONS: The high repeatability of automatic measurements by the new device supports its clinical application in eyes with myopia, and the good agreement between the two devices indicates they could be used interchangeably for the parameters evaluated.

Visual rehabilitation after LASIK complication: flap amputation, topo-guided surgery, and phacoemulsification.

We present a case of a patient complaining of monocular diplopia due to a decentered ablation after LASIK. The patient underwent a wavefront-guided retreatment, which resulted in an epithelial ingrowth complication. Additionally, the patient developed cataract, with cataract surgery requiring reliable biometric measurements. Therefore, we opted for corneal treatment and corneal surface regularization. Although we attempted to lift the flap and wash the interface initially, the procedure proved unsuccessful, thereby necessitating immediate flap amputation. Once the corneal surface was regularized in the seventh postoperative month, transepithelial photorefractive keratectomy was successfully performed to homogenize the ocular surface, thereby significantly improving the patient's corrected visual acuity and resolving monocular diplopia. The surface and corneal curvature stabilized by the fifth month after the procedure. Phacoemulsification was then performed along with the implantation of a toric monofocal lens, which was selected using an appropriate formula, resulting in an excellent uncorrected visual acuity.

Evaluation of the Agreement Between a New Pyramid Wavefront Sensor Aberrometer and Scheiner-Smirnov Aberrometers.

PURPOSE: To assess agreement between a new aberrometer (Osiris-T; CSO) employing pyramid wavefront sensor technique and Scheiner-Smirnov aberrometer (OPD-Scan III; Nidek) on measuring ocular, corneal, and internal aberrations in healthy participants. METHODS: The measurements were conducted three times consecutively by an experienced examiner. The total root mean square (RMS) aberrations, higher order aberration RMS, coma Z3±1, trefoil Z3±3, spherical aberration Z40, and astigmatism II Z4±2 up to 7th order were exported in both 4-and 6-mm pupil zones. The parameters between the two devices were statistically compared using the paired t-test, and the differences assessed with Bland-Altman plots and 95% limits of agreement. RESULTS: This prospective study included 70 right eyes of 70 healthy participants with an average age of 25.94 ± 6.59 years (range: 18 to 47 years). The mean difference in the two devices ranged from 0.01 µm for astigmatism II Z4±2 to 0.63 µm for total RMS in 4 mm and from 0.01 to 1.41 µm in 6-mm pupil size. The Bland-Altman analysis of ocular, corneal, and internal aberrations indicated high agreement between the two devices and the maximum absolute values for 95% limits of agreement ranged from 0.03 to 1.06 µm for 4-mm pupil diameters and 0.12 to 1.13 µm for 6-mm pupil diameters. CONCLUSIONS: The newly developed pyramid wavefront sensor technique aberrometer demonstrated a high agreement with a Scheiner-Smirnov aberrometer when measuring ocular, corneal, and internal aberrations in healthy participants. Thus, the two aberrometers may be considered interchangeable for clinical applications. [J Refract Surg. 2024;40(4):e218-e228.].

Comparative Evaluation of Topographic Parameters Using Three Different Topographers in Keratoconic and Cross-linked Keratoconic Corneas.

PURPOSE: To compare the parameters of three different topographic devices (Pentacam HR, Oculus Optikgeräte GmbH; Sirius, Costruzione Strumenti Oftalmici; and Cassini, i-Optics) in grading the severity of keratoconus in cross-linked and non-cross-linked eyes. METHODS: This was a prospective comparative interventional study done in a tertiary eye care center, wherein 114 eyes of 68 patients with keratoconus were divided into two groups: 62 eyes that were observed and 52 eyes that were cross-linked. All eyes were evaluated on all three topographers at baseline, 3-month follow-up, and 6-month follow-up. RESULTS: The Sirius showed significantly lower values of mean flat keratometry in comparison to the Pentacam HR (limits of agreement [LoA]: 1.75 to 3.51%) and Cassini (LoA: 1.75 to 3.51%). The mean steep keratometry values were higher for the Cassini in comparison to the Pentacam HR (LoA: 4.39 to 7.02%) and Sirius (LoA: 3.51 to 6.14%). The mean steep keratometry values of the Sirius were significantly lower than those of the Pentacam HR and in both the cross-linked and observation groups (LoA: 3.51 to 6.14%). The mean keratometry values were significantly higher in the Cassini compared to the Pentacam HR (LoA: 3.51 to 8.77%) and significantly lower in the Sirius in comparison to the Pentacam HR (LoA: 3.51 to 6.14%). The mean difference in astigmatism was also statistically significant between the three tomographers in both groups, with the Cassini showing higher values (LoA: 3.51 to 5.26%) and the Sirius lower values than the Pentacam HR (LoA: 5.26 to 6.14%). CONCLUSIONS: The authors conclude the three devices cannot be used interchangeably. The Cassini showed better agreement and correlation with the Pentacam HR in the staging of keratoconus, whereas the Sirius tended to underdiagnose and under-stage the disease. [J Refract Surg. 2024;40(4):e260-e269.].

Higher order aberrations in keratoconus .

INTRODUCTION: Keratoconus is a progressive disorder of the cornea that causes thinning (Sedaghat et al. in Sci Rep 11(1):11971, 2021), ectasia, and irregular astigmatism, resulting in poor visual acuity that cannot be corrected with standard sphero-cylindrical spectacle lenses. One feature distinguishing keratoconic corneas is ocular aberrations, manifesting up to five or six times the amount of higher-order aberrations than a normal, healthy eye. These aberrations can cause visual disturbances even at the very early stages of the disease. METHODS: In the past, a diagnosis was derived from clinical symptoms, but technological advances have revealed multiple pre-clinical features, allowing for the differentiation between keratoconic and normal eyes at a much earlier stage. These include anterior and posterior corneal surface elevations, the corneal pachymetry profile, corneal epithelial patterns, wavefront aberration metrics, and corneal biomechanics (Sedaghat et al. in Sci Rep 11(1):11971, 2021).This review discusses the aberrations associated with keratoconus, how to measure them, and treatment methods to minimize their negative influence. CONCLUSIONS: Early diagnosis can lead to early treatment and may allow for arresting progression, thereby improving the long-term prognosis. With the acceleration of refractive surgery, it is important to identify patients with keratoconus, as they are usually contraindicated for refractive surgery.

High-Fluence Epithelium-off Accelerated Pulsed Corneal Cross-linking (15 mW/cm2; 7.2 J/cm2) for Pediatric Keratoconus: A 3-Year Retrospective Analysis.

PURPOSE: To assess the safety and efficacy of treatment and secondarily determine the topographic changes, visual outcomes, and demarcation line depth after high-fluence pulsed light accelerated cross-linking (ACXL) in pediatric patients (younger than 18 years) with progressive keratoconus. METHODS: This retrospective analysis included 32 eyes (25 children, aged 11 to 18 years), with progressive keratoconus treated with high-energy epithelium-off pulsed light ACXL (7.2 J/cm2, 15 mW/cm2, 12 minutes, 2 seconds on/1 second off). Corrected distance visual acuity (CDVA), Scheimpflug tomography, and anterior optical coherence tomography measurements were recorded preoperatively and 1, 2, and 3 years postoperatively. RESULTS: A total of 32 eyes were included. Significant CDVA improvement, pachymetry, and maximum keratometry reduction were found at all follow-up visits. Mean keratometric values remained stable, and astigmatism showed a mild worsening (< 0.25 D) with statistical significance at 1 and 3 years. Total aberration showed discordant results and coma aberration had a slight improvement without statistical significance. The demarcation line depth was 265 ± 26 µm. Three patients developed mild haze without visual acuity loss. None of the patients underwent a second CXL procedure. CONCLUSIONS: In pediatric patients, high-fluence epithelium-off pulsed light ACXL appears to be a safe and effective procedure to halt the progression of keratoconus, slightly improving the CDVA and keratometric values. [J Refract Surg. 2024;40(3):e148-e155.].

Interchangeability in Automated Corneal Diameter Measurements Across Different Biometric Devices: A Systematic Review of Agreement Studies.

PURPOSE: To provide an up-to-date review of the agreement in automated white-to-white (WTW) measurement between the latest topographic and biometric devices. METHODS: In this systematic review, PubMed, Web of Science, and Scopus databases were searched for articles published between 2017 and 2023, focusing on WTW agreement studies on adult, virgin eyes, with or without cataract and no other ocular comorbidities. Studies evaluating WTW measurements performed with autokeratometers, manual calipers, or manual image analysis were excluded. When available, the following metrics for the agreement of WTW measurements between pairs of devices were included: mean difference ± standard deviation, 95% limits of agreement (LoA), LoA width, 95% confidence interval (95 CI%), and intraclass correlation coefficient (ICC). RESULTS: Forty-one studies, covering comparisons for 19 devices, were included. Altogether, 81 paired comparisons were performed for 4,595 eyes of 4,002 individuals. The mean difference in WTW measurements between devices ranged from 0.01 mm up to 0.96 mm, with varying CI. The 95% LoA width ranged from 0.31 to 2.45 mm (median: 0.65 mm). The majority of pairwise comparisons reported LoA wider than 0.5 mm, a clinically significant value for phakic intraocular lens sizing. CONCLUSIONS: Nearly all analyzed studies demonstrated the lack of interchangeability of the WTW parameter. The corneal diameter, assessed by means of grayscale en-face image analysis, tended to demonstrate the lowest agreement among devices compared to other measured biometric parameters. [J Refract Surg. 2024;40(3):e182-e194.].

Interface fluid syndrome caused by the corneal perforation injury after small incision lenticule extraction: a case report.

BACKGROUND: To report a case of interface fluid syndrome (IFS) following traumatic corneal perforation repair after small incision lenticule extraction (SMILE). CASE PRESENTATION: A 23-year-old woman, with a past history of SMILE, was struck in the left eye with a barbecue prod and subsequently underwent corneal perforation repair at local hospital. Primary wound repaired with a single 10 - 0 nylon suture at the area of leakage. After the surgery, her best corrected visual acuity (BCVA) was 20/30. Four days later, she presented at our hospital with blurred vision, and interface fluid syndrome (IFS) was diagnosed. Intraoperative optical coherence tomography (iOCT) was used to guide the resuturing of the corneal perforation in the left eye, followed by anterior chamber gas injection. At the first postoperative month, the BCVA was 20/25. The corneal cap adhered closely to the stroma, the surface became smooth. CONCLUSIONS: This case illustrates that any corneal perforation following lamellar surgery, including SMILE, may lead to IFS. It is crucial to consider the depth of corneal perforation, and intraoperative optical coherence tomography (iOCT) plays a unique role in the repair procedure.

Outcomes of accelerated corneal cross-linking for pediatric and adult keratoconus: a comparative study.

PURPOSE: To compare the visual, refractive, and topographic outcomes of a high irradiance accelerated corneal crosslinking (ACXL) protocol after a 12-month follow-up between pediatric and adult patients with progressive keratoconus (KC). METHODS: Retrospective, comparative, cohort study. Patients with KC were divided into two groups: pediatric (≤ 18 years) and adult (> 18 years). All of them were managed with epi-OFF ACXL (30 mW/cm2, 8 min, pulsed 1:1 on and off = 7.2 J/cm2). Visual, refractive, and topographic values were measured preoperatively and at 1, 3, 6, and 12 months postoperative. KC progression, defined as a Kmax increase of ≥ 1D during follow-up, was recorded. RESULTS: Eighty-nine eyes (53 patients) were included for analysis; 45 (50.6%) eyes were from pediatric patients and 44 (49.4%) from adults. At one-year follow-up, pediatric patients experienced significantly higher rates of progression (22.2% vs. 4.5%, p = .014). Contrariwise, female gender (Beta = - 3.62, p = .018), a baseline uncorrected visual acuity of Snellen ≥ 20/60 (Beta = - 5.96, p = .007), and being ≥ 15 years at ACXL treatment (Beta = - 0.31, p = .021) were associated with non-progressive disease. A significant improvement in best-corrected visual acuity, Kmin, Km, and Kmax was recorded in both groups. Overall, 86.5% of eyes from both groups showed Kmax stabilization or improvement. CONCLUSIONS: Despite the similarity in visual, refractive, and topographic outcomes in both groups, younger age was associated with KC progression after ACXL at one year of follow-up.

The effect of transepithelial corneal collagen cross-linking treatment on optical quality of the cornea in keratoconus: 12-month clinical results.

PURPOSE: To evaluate the effect of transepithelial corneal collagen crosslinking (CXL) treatment on the optical performance of the cornea at 12-month follow-up after CXL in patients with progressive keratoconus. METHODS: One hundred and ten eyes of 67 patients were included. The following corneal optical aberrations over the 4-mm-diameter pupil were recorded via Sirius dual-scanning corneal tomography: total, anterior and posterior amount of corneal higher order aberrations [HOAs], vertical coma, horizontal coma, vertical trefoil, oblique trefoil, and spherical aberration, and Strehl ratio of point spread function (PSF). RESULTS: There were significant improvements in mean root mean square error values for corneal total HOA, total coma, anterior HOA, anterior coma, and vertical coma following CXL (P > 0.05, for all). No significant changes were found in the posterior aberometric parameters. PSF value did not change after CXL (P > 0.05). The corneal topographic measurements not revealed a change in the mean simulated keratometry-1, simulated keratometry-2, and maximum keratometry compared with the baseline measurements (P > 0.05, for all). At 12 months, there was a significant improvement in the uncorrected (UCVA) and best corrected (BCVA) visual acuity (P < 0.001, both). Most corneal aberrations correlated significantly with postoperative BCVA, but changes in HOAs were not statistically associated with improvements in visual acuity. CONCLUSIONS: Transepithelial CXL was effective in stabilizing the keratometric indices and improving the most corneal aberrations in keratoconic eyes 1 year after the procedure. While the healing effect on aberrations after CXL was in total and anterior parameters, no significant changes were observed in the posterior surface. In addition, it was observed that transepithelial CXL treatment did not cause a significant change in PSF distribution data.