Comparison of clinical outcomes of a corneal wavefront- and topography-guided platforms for laser in situ keratomileusis on virgin eyes: an expanded cohort study.

PURPOSE: To compare the clinical outcomes of myopiacorrected with corneal-wavefront-guided (CWG) laser in situ keratomileusis (LASIK) with AMARIS 1050S (SCHWIND eye-tech-solutions GmbH & Co. KG) and corneal-topography-guided (CTG) LASIK with WaveLight EX500 (Alcon Laboratories, Fort Worth, TX). METHODS: In this prospective, pseudo-randomized expanded cohort study, a total of 266 patients were subjected to binocular LASIK surgery, either with WaveLight EX500 (WaveLight group) or Amaris 1050S (AMARIS group) platforms. Data related to right eyes were selected for analysis. Corneal higher-order aberration (HOA) was selected as the primary endpoint; while visual acuity and refraction were the secondary endpoints. All the endpoints were assessed at 3 months postoperatively. RESULTS: There were 134 eyes in the AMARIS group and 132 eyes in the WaveLight group. After 3 months of postoperative follow-up, spherical and coma aberrations were significantly lower (P < 0.05) in the WaveLight group (spherical aberration: - 0.104 ± 0.199 µm; coma aberration: - 0.117 ± 0.202 µm) in comparison with the AMARIS group (spherical aberrations: 0.254 ± 0.146 µm; coma aberrations: 0.316 ± 0.297 µm). In the AMARIS group, 96.3% of the eyes achieved an uncorrected distance visual acuity (UDVA) of 20/20 while in the WaveLight group, 96.2% of the eyes achieved an UDVA of 20/20. Furthermore, the mean postoperative manifest refraction spherical equivalent (MRSE) was - 0.02 ± 0.28 in the AMARIS group and - 0.05 ± 0.21 in the WaveLight group (P = 0.34). CONCLUSIONS: Both WaveLight EX500 and Amaris 1050S LASIK showed excellent refractive and visual outcomes. In addition, the WaveLight group showed minimal spherical and coma aberrations when compared to the AMARIS group.

A new technique to implant intracorneal ring-segments from the perilimbal region: one-year prospective pilot study report.

BACKGROUND: Recently a new surgical technique for intracorneal ring-segments (ICRS) assisted by femtosecond laser (FSL) called ByLimB was developed, involving the creation of the incision from a paralimbic region. This study aims to evaluate the safety and efficacy of the ByLimb technique following one year of follow-up. METHODS: A prospective, single-center study was conducted at the Zaldivar Institute in Buenos Aires, Argentina. Keratoconus patients with indication for ICRS-FSL assisted procedure, operated with the ByLimb technique were included. By using the ByLimb technique, the ICRS are placed without affecting the tunnel's roof, and the end of the ICRS is always away from the incision area. Visual acuity, topographic astigmatism, and the occurrence of complications were evaluated. Safety index was the main outcome and efficacy indes was a complimentary outcome. RESULTS: A total of 17 eyes completed the 12-month follow-up period. The safety index was 1.10 (mean postoperative corrected distance visual acuity (CDVA) in decimal: 0.76/preoperative CDVA: 0.69), while the efficacy index was 0.89 (mean postoperative uncorrected distance visual acuity UDVA in decimal: 0.62/preoperative CDVA: 0.69). Mean preoperative astigmatism was 5.3 ± 2.3, decreasing twelve months after surgery at 2.1 ± 1.2 (p < 0.001). No eye loss lines of vision and no intraoperative complications were observed. During the first month after surgery, an improper positioning of the ICRS based on topographic assessment was detected in five cases. A second procedure was performed, which consisted of opening the incision and introducing a Sinsky hook, through which the ICRS was mobilized and placed in its correct position. No incisional alterations, signs of infection, anterior segment anomalies, or fundus alterations were observed. CONCLUSION: FSL-assisted ICRS implantation through the perilimbal region has demonstrated an adequate safety index one year post-surgery. Additionally, this technique has facilitated accurate realignment of ICRS during secondary surgical interventions within one-month post-surgery. While the current findings are promising, continued follow-up of these cases is warranted.

Comparison of Objective Visual Quality Following SMILE and SmartPulse Technology-Assisted TransPRK at a 1,050-Hz Ablation Frequency for Moderate-to-High Myopia.

PURPOSE: To compare the objective visual quality of moderate-to-high myopia corrected by small incision lenticule extraction (SMILE) and transepithelial photorefractive keratectomy (TransPRK) at a 1,050-Hz ablation frequency, assisted by Smart-Pulse technology (SCHWIND eye-tech-solutions). METHODS: This study involved 123 patients (123 eyes) with moderate-to-high myopia between July 2020 and January 2021. They were categorized into the SMILE group (67 patients, 67 eyes) and the TransPRK group (56 patients, 56 eyes). Follow-ups were conducted at 6 months postoperatively to record the logarithm of the minimum angle of resolution visual acuity, and the Strehl ratio and higher order aberrations were measured using the Sirius anterior segment analysis device (SCHWIND eye-tech-solutions) under a 6-mm pupil diameter at various postoperative intervals. RESULTS: At 1 week and 1 month postoperatively, the uncorrected distance visual acuity (UDVA) in the SMILE group was superior to that in the TransPRK group (P < .05 for both). At 1 week and 1 month postoperatively, the Strehl ratio value in the SMILE group was higher than that in the TransPRK group (P < .05 for both). At 1, 3, and 6 months postoperatively, coma was greater in the SMILE group than in the TransPRK group (P < .05 for all). Spherical aberrations were lower in the SMILE group than in the TransPRK group at 3 and 6 months postoperatively (P < .05). At 6 months postoperatively, UDVA was -0.09 ± 0.08 and -0.11 ± 0.05 logMAR in the SMILE and TransPRK groups, respectively, which exceeded their preoperative corrected distance visual acuity of -0.05 ± 0.04 and -0.09 ± 0.08 logMAR (all P < .001). Compared with preoperative values, the Strehl ratio, total higher order, coma, and spherical aberration differences were significantly increased postoperatively in both groups (all P < .001). CONCLUSIONS: Both surgical methods improved UDVA and each had its advantages. The visual quality of SMILE was superior at 1 week and 1 month postoperatively (Strehl ratio values were higher than those of the TransPRK group), and its spherical aberration was lower than that of the TransPRK group at 3 and 6 months; TransPRK with SmartPulse technology with a 1,050-Hz ablation frequency showed that coma was significantly lower than that of the SMILE group at 1, 3, and 6 months postoperatively. [J Refract Surg. 2024;40(7):e490-e498.].

Comparative Accuracy of Barrett Integrated Keratometry Toric Calculator With Predicted Versus Measured Posterior Corneal Astigmatism.

PURPOSE: To compare the prediction accuracy of the Barrett toric calculator using standard or integrated keratometry (IK) mode in combination with predicted or measured posterior corneal astigmatism (PCA) in a group of patients with cataract implanted with non-toric IOLs. METHODS: In this retrospective clinical cohort study, the medical records of patients with age-related cataract who underwent phacoemulsification with the implantation of an aspheric monofocal IOL were reviewed. Four methods, including standard keratometry with predicted PCA (PPCA), IK combined with predicted PCA (IK-PPCA), and IK combined with measured PCA derived from IOLMaster 700 (Carl Zeiss Meditec AG) or CASIA2 (Tomey) (IK-MMPCA or IK-CMPCA), were applied to the Barrett toric calculator to calculate the predicted residual astigmatism. The mean absolute prediction error (MAPE), centroid of the prediction error, and proportion of eyes within the prediction error of ±0.50, ±0.75, and ±1.00 diopters (D) were all ciphered out from the four methods, respectively. RESULTS: Data from 129 eyes of 129 patients were included in this study. The MAPE of the IK-PPCA method (0.57 ± 0.36 D) was significantly smaller than that of the PPCA (0.62 ± 0.38 D) and IK-CMPCA (0.63 ± 0.46 D) methods (P = .048 and .014, respectively). There were no significant differences in the centroid vectors of prediction errors and predictability rates among the four methods (all P > .05). CONCLUSIONS: In the current version of the Barrett toric calculator, the predictive accuracy of the IK mode incorporating PPCA was slightly superior to using the standard keratometry mode or incorporating MPCA. [J Refract Surg. 2024;40(7):e453-e459.].

Repeatability of Automatic Measurements by an Anterior Segment Swept-Source OCT Biometer in Patients With Keratoconus.

PURPOSE: To evaluate the repeatability of automatic measurements of a new anterior segment optical coherence tomographer (ANTERION; Heidelberg Engineering) and their agreement with an anterior segment optical coherence tomography device combined with Placido disc corneal topography (MS-39; CSO) in patients affected by keratoconus. METHODS: Fifty-four consecutive patients were included. Three measurements were performed with the ANTERION and one with the MS-39. Repeatability was assessed by means of within-subject standard deviation, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). Agreement was investigated with the 95% limits of agreement. The paired t-test and Wilcoxon matched-pairs test were performed to compare the measurements of the different devices. RESULTS: Repeatability of ANTERION measurements was high, with an ICC greater than 0.98 for all parameters. Many parameters revealed a CoV of less than 1% and a CoV within 5% was obtained for astigmatism measurements. The ANTERION measured a significantly higher corneal power and the MS-39 more negative posterior keratometric values. These differences were mirrored by a moderate agreement for mean simulated keratometry and poor agreement for total corneal power and posterior keratometry. CONCLUSIONS: The ANTERION revealed high repeatability of automatic measurements and good agreement with the MS-39 for many parameters in patients affected by keratoconus, but for most parameters the two instruments cannot be considered interchangeable. [J Refract Surg. 2024;40(7):e445-e452.].

Outcomes of Corneal Compound Hyperopic Astigmatism With Presbyopia by Zeiss PRESBYOND Laser Blended Vision LASIK Using Default Custom Refractive Software Master Target Refractions for Reduced Anisometropia.

PURPOSE: To evaluate the effectiveness, safety, and stability of a modified PRESBYOND Laser Blended Vision protocol (Carl Zeiss Meditec AG) for correcting hyperopic astigmatism and presbyopia, using Custom Refractive Software Master (CRSM) targeting over a 6-month period. METHODS: A total of 636 eyes of 318 patients with a mean age of 51.05 ± 4.71 years (range: 40 to 60 years) met the inclusion and exclusion criteria. All patients completed a 6-month follow-up. CRSM software was used to generate ablation profiles for the MEL90 excimer laser (Carl Zeiss Meditec AG). The target refraction was emmetropic for the dominant eyes and between -0.75 and -1.12 diopters (D) for the near eyes. RESULTS: Visual and refractive results were studied separately by the dominant and non-dominant eyes. The mean attempt to correct for spherical equivalent refraction was +2.17 ± 1.16 D (range: -1.00 to +5.37 D). The mean attempted cylinder was -0.60 ± 0.75 D (range: -4.00 to 0.00 D). All eyes monocularly achieved uncorrected distance visual acuity (UDVA) of 20/25 or better after refractive treatment and 88% achieved 20/20. Binocularly all eyes achieved UDVA of 20/25 or better and 96.54% achieved 20/20. Ninety-eight percent of the patients maintained their corrected distance visual acuity before surgery and UDVA 6 months after surgery. CONCLUSIONS: This hyperopic micro-anisometropia protocol with PRESBYOND Laser Blended Vision was an effective, safe, and well-tolerated refractive treatment. It was an effective procedure with excellent results for UDVA and uncorrected near visual acuity and demonstrates that binocular summation exists. [ J Refract Surg. 2024;40(7):e480-e489.].

Diagnosis of forme fruste keratoconus with scheimpflug photography in Ghanaian patients.

AIM: This study aimed to differentiate moderate to high myopic astigmatism from forme fruste keratoconus using Pentacam parameters and develop a predictive model for early keratoconus detection. METHODS: We retrospectively analysed 196 eyes from 105 patients and compared Pentacam variables between myopic astigmatism (156 eyes) and forme fruste keratoconus (40 eyes) groups. Receiver operating characteristic curve analysis was used to determine the optimal cut-off values, and a logistic regression model was used to refine the diagnostic accuracy. RESULTS: Statistically significant differences were observed in most Pentacam variables between the groups (p < 0.05). Parameters such as the Index of Surface Variance (ISV), Keratoconus Index (KI), Belin/Ambrosio Deviation Display (BAD_D) and Back Elevation of the Thinnest Corneal Locale (B.Ele.Th) demonstrated promising discriminatory abilities, with BAD_D exhibiting the highest Area under the Curve. The logistic regression model achieved high sensitivity (92.5%), specificity (96.8%), accuracy (95.9%), and positive predictive value (88.1%). CONCLUSION: The simultaneous evaluation of BAD_D, ISV, B.Ele.Th, and KI aids in identifying forme fruste keratoconus cases. Optimal cut-off points demonstrate acceptable sensitivity and specificity, emphasizing their clinical utility pending further refinement and validation across diverse demographics.

Early elastic and viscoelastic corneal biomechanical changes after photorefractive keratectomy and small incision lenticule extraction.

PURPOSE: To compare early changes in the corneal biomechanical parameters after photorefractive keratectomy (PRK) and small incision lenticule extraction (SMILE) and their correlations with corneal shape parameters. METHODS: One hundred twenty four eyes received myopic PRK and SMILE for similar amounts of myopia. Corneal tomography with Pentacam HR, biomechanical parameters using Corvis ST, and Ocular Response Analyzer (ORA) were evaluated before and 2 weeks after surgery. The change in each parameter was compared between groups, while the difference in central corneal thickness and cornea-compensated intraocular pressure measured before and after surgery were considered as covariates. RESULTS: A significant reduction was seen in the corneal stiffness parameter at first applanation, and an increase in deformation amplitude ratio (DAR), and integrated inverse radius (IIR) in both groups after surgery (p < 0.001) Changes in DAR, and IIR were significantly greater in the SMILE than in the PRK group (p < 0.001) Corneal hysteresis (CH) and corneal resistance factor (CRF) decreased in both SMILE and PRK groups after surgery, (p < 0.001) with no statistically significant difference between groups (p > 0.05) Among new Corvis ST parameters, DAR showed a significant correlation with changes in Ambrosio relational thickness in both groups (p < 0.05). CONCLUSIONS: Both techniques caused significant changes in corneal biomechanics in the early postoperative period, with greater elastic changes in the SMILE group compared to the PRK group, likely due to lower tension in the SMILE cap and thinner residual stromal bed in SMILE. There were no differences in viscoelastic changes between them, so the lower CH may reflect the volume of tissue removed.

Analysis of surgically induced astigmatism of the anterior, posterior, and total cornea after implantable collamer lens implantation: a comparative study between temporal and superior clear corneal incisions.

BACKGROUND: To comparatively analyze the surgically induced astigmatism (SIA) of the anterior, posterior, and total corneas of eyes undertaking implantable collamer lens (ICL) implantation with temporal or superior corneal incisions. METHODS: One hundred and nine eyes of 109 patients who received ICL implantation were recruited: 40 eyes had temporal incisions and 69 eyes had superior incisions. Total corneal refractive power (TCRP); simulated keratometry of the anterior (Sim-KAnt) and posterior (Sim-KPost) corneal curvature; and astigmatism of the anterior (CAAnt), posterior (CAPost), and total (CATCRP) cornea were recorded through a Pentacam preoperatively and 3 months postoperatively. The SIA of the anterior, posterior, and total cornea were also compared between the two groups. RESULTS: There were no significant intergroup differences for TCRP, Sim-KAnt, Sim-KPost, CAAnt, CAPost, or CATCRP, preoperatively. However, values of CAAnt, CAPost, and CATCRP with temporal incision were significantly higher than those parameters with superior incision postoperatively. All of the SIA of the anterior, posterior, and total cornea were significantly lower for temporal incision than those with a superior incision (p < 0.001, p = 0.006 and p = 0.001 respectively). Meanwhile, the superior incisions created against-the-rule (ATR) astigmatism, and temporal incisions always induce with-the-rule (WTR) astigmatism in total cornea. CONCLUSIONS: A superior incision may be suitable for correcting WTR astigmatism, while a temporal incision for correcting ATR astigmatism when using a non-toric ICL. Meanwhile, temporal incision could be a better choice with little preoperative astigmatism or that preoperative astigmatism would be corrected with toric ICLs. TRIAL REGISTRATION: Registration number: ChiCTR2100051739. Prospectively registered: 01 October 2021.

Effect of Corneal Allogenic Intrastromal Ring Segment (CAIRS) Implantation Surgery in Patients With Keratoconus According to Prior Corneal Cross-linking Status.

PURPOSE: To compare the effects of corneal allogenic intrastromal ring segment (CAIRS) implantation on topographical measurements and visual outcomes of patients with keratoconus with and without corneal cross-linking (CXL) prior to the time of implantation. METHODS: Sixty-seven eyes with corneal allograft intrastromal ring segment implantation (KeraNatural; Lions VisionGift) due to advanced keratoconus were included in the study. Thirty-seven eyes had no CXL and 30 eyes had had CXL before being referred to the authors. The changes in spherical equivalent (SE), uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), steep keratometry (K1), flat keratometry (K2), mean keratometry (Kmean), maximum keratometry (Kmax), and thinnest pachymetry were retrospectively analyzed 6 months after the implantation. RESULTS: The median age was 29 years in the CXL group and 24.0 years in the non-CXL group (P > .05), respectively. All topographical and visual parameters before implantation were similar in both groups (P > .05 for all parameters). At 6 months, CDVA, K1, and Kmean showed higher improvement in the non-CXL group than the CXL group (P = .030, .018, and .039, respectively). CONCLUSIONS: CAIRS surgery has a flattening effect on both the corneas with and without CXL. The cornea with prior CXL treatment had less flattening effect due to the stiffening effect of prior CXL. [J Refract Surg. 2024;40(6):e392-e397.].

Risk Factors for Re-treatment After Keratorefractive Lenticule Extraction (KLEx) for Myopia and Myopic Astigmatism.

PURPOSE: To identify potential risk factors that increase the likelihood of re-treatment following keratorefractive lenticule extraction (KLEx) for myopia and myopic astigmatism. METHODS: This was a retrospective study of patients with myopia and myopic astigmatism who underwent KLEx using the VisuMax 500 laser (Carl Zeiss Meditec) between April 2015 and December 2020. Patients were assigned to one of two groups: the control group and the re-treatment group (if they had additional refractive surgery within 2 years of the primary treatment). The effect of different preoperative, intraoperative, and postoperative parameters on the re-treatment rate was analyzed. RESULTS: Overall 1,822 eyes of 938 patients were analyzed. In total, 2.96% of eyes (n = 54) underwent re-treatment. The re-treated patients were more likely to be women and have high myopia, high astigmatism, steep corneas, higher ocular residual astigmatism, and residual myopic and/or astigmatic refractive error. In contrast, no significant correlation was found between re-treatment rate and age, chord µ, type of astigmatism, and corneal thickness. CONCLUSIONS: Factors associated with higher rates of retreatment after KLEx included female gender, manifest refractive high myopia (> -5.00 diopters [D]), astigmatism (> 2.00 D), spherical equivalent (> 6.00 D), ocular residual astigmatism, steeper corneas, and postoperative residual myopic and astigmatic refractive errors. This study may help to preoperatively detect patients at risk for re-treatment, improve preoperative patient counseling, and optimize patient selection to reduce future re-treatment rates. [J Refract Surg. 2024;40(6):e362-e370.].

Total and simulated keratometry measurements using IOLMaster 700 and Pentacam AXL after small incision lenticule extraction.

PURPOSE: Calculating the intraocular lens (IOL) in patients after corneal refractive surgery presents a challenge. Because an overestimation of corneal power in cases undergone this surgery leading to a subsequent under-correction of IOL power. However, recent advancements in technology have eliable measurement of total corneal power. The aim of this research was to assess the agreement in simulated keratometry (SimK) and total keratometry (TK) values between IOLMaster 700 and Pentacam AXL. METHODS: The study involved 99 patients (99 eyes) undergone small incision lenticule extraction (SMILE) surgery. Each patient underwent scans using IOL Master 700 and Pentacam AXL. The following parameters were recorded: SimK1, SimK2, Total K1 (TK1), and Total K2 (TK2) for IOLMaster 700; and SimK1, SimK2, True Net Power (TNP) K1, TNPK2, Total Corneal Refractive Power (TCRP) K1, and TCRP K2 for Pentacam AXL. Agreement between the two devices was evaluated using Bland-Altman plot, while paired t-test was utilized to compare any differences in the same parameter by both instruments. RESULTS: The results revealed a strong correlation between the two devices.Noticeable comparability was identified for all SimK variables. However, there were noticeable differences in TK measurements as well as TK1-TNPK1, TK2-TNP K2, TK1-TCRP K1, and TK2-TCRP K2 parameters when comparing the two devices. The IOLMaster 700 consistently measured steeper values than the Pentacam AXL, with significant and clinically relevant differences of 1.34, 1.37, 0.87, and 0.95 diopters, respectively. CONCLUSION: While there was a noticeable correlation between the IOLMaster 700 and Pentacam AXL in SimK measurements, a marked difference was noted in TK values. The two devices cannot be used interchangeably when quantifying TK values.

Risk Factors for Corneal Monochromatic Aberrations and Implications for Multifocal and Extended Depth-of-Focus Intraocular Lens Implantation.

PURPOSE: To discuss factors influencing corneal aberrations that might influence the optical quality after intraocular lens (IOL) implantation. METHODS: PubMed and Scopus were the main resources used to search the medical literature. An extensive search was performed to identify relevant articles concerning factors influencing the level of corneal aberrations as of August 27, 2023. The following keywords were used in various combinations: corneal, aberrations, defocus, astigmatism, spherical aberration, coma, trefoil, quadrafoil, intraocular lens, and IOL. RESULTS: Conclusive evidence is lacking regarding the correlation between age and changes in corneal aberrations. Patients with astigmatism have greater corneal higher-order aberrations than those with minimal astigmatism, particularly concerning trefoil and coma. Increased levels of corneal higher-order aberrations are noted following contact lens wear, in patients with dry eye disease, and with pterygium. Increased higher-order aberrations have been reported following corneal refractive surgery and for 3 months following trabeculectomy; regarding intraocular lens surgery, the results remain controversial. CONCLUSIONS: Several factors influence the level of corneal higher-order aberrations. Multifocal and extended depth-of-focus IOLs can share similarities in their optical properties, and the main difference arises in their design and performance with respect to spherical aberration. Preoperative evaluation is critical for proper IOL choice, particularly in corneas with risk of high levels of aberrations. [J Refract Surg. 2024;40(6):e420-e434.].

Epithelial thickness map-adjusted transepithelial photorefractive keratectomy for treatment of myopic astigmatism: 12-month results.

PURPOSE: To evaluate the refractive results of Transepithelial Photorefractive Keratectomy (t-PRK) with the Technolas Teneo2 Excimer laser platform. METHODS: In this retrospective comparative interventional case series, a total of 199 patients with myopia ranging from - 1 to - 7 diopters were enrolled and separated into three groups based on their target refraction of zero (group 1), - 0.25 (group 2), and - 0.5 diopters (group 3), respectively. The main outcome measure was post-operative cycloplegic refraction. Trans-PRK was performed using the Technolas Teneo2 Excimer laser. To prevent any remaining epithelium during stromal ablation, we adopted the thickest epithelial point in the 7 mm central map as the reference for Phototherapeutic keratectomy (PTK) depth. Patients were examined three and twelve months after the procedure, and the results were analyzed. RESULTS: At the 12-month follow-up, uncorrected distance visual acuity was 20/20 in all patients. However, there was a significant difference in cycloplegic spherical equivalent refraction between the three groups. The 12-month post-operative spherical equivalent refraction was 0.90 ± 0.33 D, 0.79 ± 0.26 D, and 0.60 ± 0.19 D in groups 1, 2, and 3, respectively (P < 0.001; Kruskal-Wallis test). The rates of spherical equivalent refraction of more than 0.75 D were 58.3%, 39.1%, and 9.1% in the 0 D, - 0.25 D, and -0.50 D groups, respectively (P < 0.001; Chi-squared test). CONCLUSIONS: The t-PRK with Technolas Teneo2 Excimer laser and epithelial thickness map adjustment of PTK induce a significant amount of residual hyperopia (> 0.75 D) in a large proportion of eyes with a target refraction of 0 or - 0.25, which is significantly reduced by using a target refraction of - 0.5.

Characteristics of peripheral refractive errors in eyes of patients with non-amblyopic myopic anisometropia.

BACKGROUND: This study aims to investigate relative peripheral refractive (RPR) characteristics in children with non-amblyopic myopic anisometropia and explore potential associations between relative peripheral refractive errors (RPRE) and myopia. METHODS: Relative peripheral refractive errors were assessed in 64 children diagnosed with non-amblyopic myopic anisometropia utilizing multispectral refraction topography (MRT). Two eyes of each patient were divided into into the more myopia eyes group (ME) and the fellow eyes group (FE). Evaluated parameters encompassed total defocus values (TRDV), defocus values at eccentricities spanning 0 to 15 degrees (RDV-15), 0 to 30 degrees (RDV-30), 0 to 45 degrees (RDV-45), as well as superior (RDV-S), inferior (RDV-I), temporal (RDV-T), and nasal (RDV-N) positions. RESULTS: The study revealed a noteworthy contrast in TRDV values between Group ME (0.52 ± 0.36) and Group FE (0.17 ± 0.41), with a substantial significance (P < 0.0001). While no significant RDV-15 difference emerged between Group ME (0.01 ± 0.05) and Group FE (-0.01 ± 0.07) (P > 0.05), a meaningful RDV-30 difference existed between Group ME (0.11 ± 0.14) and Group FE (0.03 ± 0.19) (P = 0.0017). A significant discrepancy in RDV-45 was also observed between Group ME (0.39 ± 0.29) and Group FE (0.13 ± 0.34) (P < 0.001). Notably, RDV-I and RDV-T positions demonstrated marked differences between Group ME and Group FE (P < 0.0001), whereas no significant disparity was noted in RDV-S and RDV-N positions (P > 0.05). CONCLUSION: Eyes exhibiting greater myopia manifested more hyperopic peripheral defocus in the context of anisometropia. MRT as a novel ophthalmic evaluation technique, holds promising potential for broader clinical applications in the future.

Comparison of the effectiveness of different corneal curvature measurement methods for IOL implantation in traumatic aphakic eyes with corneal injury.

BACKGROUND/AIM: To assess the refractive outcomes of secondary intraocular lenses (IOL) in patients with traumatic aphakic eyes with corneal penetrating injury and compare different corneal curvature measurement methods. METHODS: Patients with unilateral penetrating eye injuries underwent corneal wound repair and cataract extraction, followed by secondary IOL implantation. Corneal curvature measurements were taken on the contralateral healthy eye (Group A), from the affected eye before removing corneal sutures (Group B), or after suture removal (Group C). The refractive outcomes were compared among the three groups. RESULTS: The study included 261 eyes. The Mean Absolute Error (MAE) in Group C (0.99 ± 0.85 D) was significantly smaller than that in Group A (1.87 ± 1.71 D) and Group B (1.37 ± 1.20 D) (both P < 0.001). Moreover, the percentage of eyes with IOL prediction errors within ± 0.50 D in Group C (40%) was higher than that in group A (21.7%) (OR = 2.364, 95%CI: 1.272-4.392, P = 0.006) and group B (28.0%) (OR = 1.714, 95%CI: 0.948-3.099, P = 0.073), and the percentage of eyes with IOL prediction errors within ± 1.0 D in Group C (90.9%) was higher than that in group A (67.9%) (OR = 4.758, 95%CI: 2.131-10.626, P < 0.001) and group B (75.0%) (OR = 3.370, 95%CI: 1.483-7.660, P = 0.003) as well. CONCLUSIONS: In traumatic aphakic eyes with corneal sutures, IOL power calculation based on the corneal curvature of the injured eye after removing the corneal sutures yields the best refractive outcomes.

Efficacy and Safety of the Modified Cretan Protocol in Patients with Post-LASIK Ectasia

Objectives: To investigate the clinical efficacy and safety of the modified Cretan protocol in patients with post-laser in situ keratomileusis ectasia (PLE). Materials and Methods: In this retrospective study, 26 eyes of 16 patients with PLE were treated with the modified Cretan protocol (combined transepithelial phototherapeutic keratectomy and accelerated corneal collagen cross-linking). Visual, refractive, tomographic, and aberrometric outcomes and point spread function (PSF) were recorded preoperatively and at 6, 12, and 24 months after treatment. Results: Both uncorrected and best corrected visual acuity were stable at 24 months postoperatively compared to baseline (from 0.89±0.36 to 0.79±0.33 logarithm of the minimum angle of resolution [LogMAR] and 0.31±0.25 to 0.24±0.19 LogMAR, respectively, p>0.05 for all values). The mean K1, K2, Kmean, thinnest corneal thickness, and spherical aberration at baseline were 45.76±5.75 diopters (D), 48.62±6.17 D, 47.13±5.89 D, 433.16±56.86 µm, and -0.21±0.63 µm respectively. These values were reduced to 42.86±6.34 D, 45.92±6.74 D, 44.21±6.4 D, 391.07±54.76 µm, and -0.51±0.58 µm at 24 months postoperatively (p<0.001, p=0.002, p<0.001, p=0.001, and p=0.02, respectively). The mean spherical equivalent, manifest cylinder, Kmax, central corneal thickness, other corneal aberrations (root mean square, trefoil, coma, quatrefoil, astigmatism), and PSF remained stable (p>0.05 for all variables), while anterior and posterior elevation were significantly improved at 24 months postoperatively (p<0.001 and p=0.02, respectively). No surgical complications occurred during the 24-month follow-up. Conclusion: The modified Cretan protocol is a safe and effective treatment option for PLE patients that provides visual stabilization and significant improvement in topographic parameters during the 24-month follow-up. Further studies are needed to support our results.

Diagnostic value of corneal optical densitometry in keratoconus.

PURPOSE: To investigate the clinical significance of the correlation between optical densitometry and both biomechanical and morphological parameters in keratoconus (KC) and to verify the diagnostic value of optical densitometry in KC. METHOD: This cross-sectional study included 436 eyes of 295 patients with KC. Corneal optical densitometry, morphological parameters and biomechanical parameters were measured. Spearman's correlation analysis was employed to investigate the association between optical densitometry and both biomechanical and morphological parameters. RESULT: Optical densitometry of the anterior (0-2 mm and 2-6 mm), central (0-2 mm), posterior (2-6 mm) and total (2-6 mm) layers correlated positively with SPA1, while the posterior layer (0-2 mm) correlated negatively. Optical densitometry of the anterior layers 2-6 mm, 6-10 mm, and the central layer 6-10 mm negatively affected AL1, while the posterior layer 0-2 mm positively affected it. Optical densitometry of the anterior, central, and posterior layers 0-2 mm and 2-6 mm positively influenced the morphological parameters K1F, K2F, KmF and the absolute values of K1B, K2B, KmB. Optical densitometry of the center (0-2 mm) and posterior (2-6 mm) layers negatively influenced TCT. Optical densitometry of the anterior (0-2 mm and 2-6 mm), center (0-2 mm), posterior (2-6 mm) and total (2-6 mm) layers correlated positively with ACE and PCE, whereas the posterior layer (0-2 mm) correlated negatively. CONCLUSION: Optical densitometry was correlated with biomechanical and morphological parameters in keratoconus, suggesting its potential as a diagnostic indicator for assessing keratoconus progression and treatment efficacy.