Variability of subjective classifications of corneal topography maps from LASIK candidates.

PURPOSE: To evaluate the variability of subjective corneal topography map classification between different experienced examiners and the impact of changing from an absolute to a normative scale on the classifications. METHODS: Preoperative axial curvature maps using Scheimpflug imaging obtained with the Pentacam HR (Oculus Optikgeräte, Wetzlar, Germany) and clinical parameters were sent to 11 corneal topography specialists for subjective classification according to the Ectasia Risk Scoring System. The study population included two groups: 11 eyes that developed ectasia after LASIK and 14 eyes that had successful and stable LASIK outcomes. Each case was first reviewed using the absolute scale masked to the patient group. After 3 months, the same cases were represented using a normative scale and reviewed again by the same examiners for new classifications masked to the patient group. RESULTS: Using the absolute scale, 17 of 25 (68%) cases had variations on the classifications from 0 to 4 for the same eye across examiners, and the overall agreement with the mode was 60%. Using the normative scale, the classifications from 11 of 25 (44%) cases varied from 0 to 4 for the same eye across examiners, and the overall agreement with the mode was 61%. Eight examiners (73%) reported statistically higher scores (P < .05) when using the normative scale. Considering all 550 topographic analyses (25 cases, 11 examiners, and two scales), the same classification from the two scales was reported for 121 case pairs (44%). CONCLUSION: There was significant inter-observer variability in the subjective classifications using the same scale, and significant intra-observer variability between scales. Changing from an absolute to a normative scale increased the scores on the classifications by the same examiner, but significant inter-observer variability in the subjective interpretation of the maps still persisted.

Descemet's membrane endothelial keratoplasty: prospective study of 1-year visual outcomes, graft survival, and endothelial cell loss.

PURPOSE: To report 1-year outcomes of Descemet's membrane endothelial keratoplasty (DMEK) performed at 2 centers. DESIGN: Prospective, consecutive, interventional series. PARTICIPANTS: Patients with Fuchs' endothelial dystrophy, pseudophakic bullous keratoplasty, or failed previous graft (n = 136 eyes). INTERVENTION: The diseased central 7 mm of Descemet's membrane (DM) was stripped from the recipient cornea and replaced with healthy DM and endothelium stripped from donor corneas through a 2.8-mm corneal incision. Descemet's membrane endothelial keratoplasty was performed alone (n = 110) or combined with either phacoemulsification and intraocular lens implantation (n = 23) or pars plana vitrectomy (n = 3). MAIN OUTCOME MEASURES: Best spectacle-corrected visual acuity (BSCVA), manifest refraction, and endothelial cell density. RESULTS: Excluding eyes with pre-existing ocular comorbidities or those lost to follow-up, mean BSCVA at 1 year was 0.07 logarithm minimum angle of resolution (logMAR) units (20/24; range, 20/15-20/40; n = 81), improving from 0.51 logMAR (20/65; range, 20/20-counting fingers); 41% of the patients achieved a BSCVA of 20/20 or better, 80% could be corrected to 20/25 or better, and 98% achieved 20/30 or better vision. A refractive hyperopic shift of +0.24 ± 1.01 diopters (D; range, -1.50 to 2.25 D) was found at 1 year, but it was not statistically significant (P = 0.08). Also, there was no significant change in the preoperative astigmatism (P = 0.17). The endothelial cell loss at 1 year was 36 ± 20% (n = 94; range, 13%-88%), with most of the loss being observed during the first 3 months after surgery: 31 ± 18% (range, 3%-77%). The DMEK graft creation could not be successfully completed in 6 cases (4.2%). All these unsuccessful attempts were among the initial 40 cases. Intracameral air was used to fix graft detachments, which usually were partial and peripheral, in 62% of the cases. Eleven grafts (8%) demonstrated primary failure and 1 eye (0.7%) had secondary failure resulting from endothelial rejection. Episodes of immunologic rejection were documented in 7 eyes (5.1%) during the first year of follow-up. CONCLUSIONS: Descemet's membrane endothelial keratoplasty had better visual acuity results in the first year after surgery than typically reported for other endothelial keratoplasty techniques, such as Descemet's stripping automated endothelial keratoplasty, while having less refractive changes and similar endothelial cell counts but a higher rebubbling rate. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Novel pachymetric parameters based on corneal tomography for diagnosing keratoconus.

PURPOSE: To describe pachymetric progression indices (PPI) of the Pentacam HR (Oculus Optikgeräte GmbH) and the concept of relational thickness, and to test their accuracy for differentiating keratoconic and normal corneas compared with single-point thickness values. METHODS: One hundred thirteen individual eyes randomly selected from 113 normal patients and 44 eyes of 44 patients with keratoconus were studied using the Pentacam HR by acquiring central corneal thickness (CCT), thinnest point (TP), position of the TP and PPI at minimal (PPI Min) and maximal (PPI Max) meridians, and the average (PPI Ave) of all meridians. Relational thickness parameters were calculated as the ratios of TP and CCT and PPI values. Mann-Whitney U test assessed differences in groups for each variable. Receiver operating characteristic (ROC) curves were calculated for all variables and pairwise comparisons were performed. RESULTS: Statistically significant differences were noted between normal and keratoconic eyes for all parameters (P<.001), except for horizontal position of TP (P=.79). The best parameters, named Ambrósio's Relational Thickness (ART), were ART-Ave (TP/PPI Ave) and ART-Max (TP/PPI Max) with areas under the ROC curves of 0.987 and 0.983, respectively. The best cutoffs were 424 µm and 339 µm for ART-Ave and ART-Max, respectively. Pachymetric progression indices and ART had a greater area under the curve than TP and CCT (P<.001); TP (0.955) had a greater area under the curve than CCT (0.909; P=.002). CONCLUSIONS: Tomographic-derived pachymetric parameters were better able to differentiate normal and keratoconic corneas than single-point pachymetric measurements. Further studies are needed to evaluate the role of tomography in identifying early forms of ectasia as well as ectasia risk among LASIK candidates.

Corneal ectasia after LASIK despite low preoperative risk: tomographic and biomechanical findings in the unoperated, stable, fellow eye.

PURPOSE: To report a case of progressive corneal ectasia after LASIK with no detectable preoperative risk factors and to present three-dimensional corneal tomographic and biomechanical findings on the contralateral unoperated eye that would be considered low risk for ectasia and thereby a good LASIK candidate based on the Randleman Ectasia Risk Score System (ERSS). METHODS: A case report, literature review, and description of novel screening criteria based on Pentacam (Oculus Optikgeräte GmbH) corneal tomography are presented as well as Ocular Response Analyzer (ORA, Reichert Instruments) corneal biomechanical analysis. RESULTS: Progressive corneal ectasia after LASIK of the operated left eye was confirmed by corneal topography. Scheimpflug imaging identified a meniscus-shaped LASIK flap with a central thickness of 165 µm and residual stromal bed thickness of 280 µm. Randleman ERSS score was 2 for the ectatic eye before LASIK and 1 for the current status of the unoperated eye, which remained stable with normal topography and no change in refraction for >5 years. Low corneal hysteresis (8.6 mmHg) and corneal resistance factor (7.5 mmHg) were found in the unoperated, nonectatic eye, along with a suspicious waveform sign of a second rebounded peak after second applanation. Pentacam average pachymetric progression was 1.09 (normal is <1.15); the Belin-Ambrósio overall deviation index was 1.99 (normal is <1.9). CONCLUSIONS: Three-dimensional corneal tomographic and ORA biomechanical measurements provide additional information that may help identify individuals at high risk for naturally occurring or iatrogenic corneal ectasia.

Enhanced Tomographic Assessment to Detect Corneal Ectasia Based on Artificial Intelligence.

PURPOSE: To improve the detection of corneal ectasia susceptibility using tomographic data. DESIGN: Multicenter case-control study. METHODS: Data from patients from 5 different clinics from South America, the United States, and Europe were evaluated. Artificial intelligence (AI) models were generated using Pentacam HR (Oculus, Wetzlar, Germany) parameters to discriminate the preoperative data of 3 groups: stable laser-assisted in situ keratomileusis (LASIK) cases (2980 patients with minimum follow-up of 7 years), ectasia susceptibility (71 eyes of 45 patients that developed post-LASIK ectasia [PLE]), and clinical keratoconus (KC; 182 patients). Model accuracy was independently tested in a different set of stable LASIK cases (298 patients with minimum follow-up of 4 years) and in 188 unoperated patients with very asymmetric ectasia (VAE); these patients presented normal topography (VAE-NT) in 1 eye and clinically diagnosed ectasia in the other (VAE-E). Accuracy was evaluated with ROC curves. RESULTS: The random forest (RF) provided highest accuracy among AI models in this sample with 100% sensitivity for clinical ectasia (KC+VAE-E; cutoff 0.52), being named Pentacam Random Forest Index (PRFI). Considering all cases, the PRFI had an area under the curve (AUC) of 0.992 (94.2% sensitivity, 98.8% specificity; cutoff 0.216), being statistically higher than the Belin/Ambrósio deviation (BAD-D; AUC = 0.960, 87.3% sensitivity, 97.5% specificity; P = .006, DeLong's test). The optimized cutoff of 0.125 provided sensitivity of 85.2% for VAE-NT and 80% for PLE, with 96.6% specificity. CONCLUSION: The PRFI enhances ectasia diagnosis. Further integrations with corneal biomechanical parameters and with the corneal impact from laser vision correction are needed for assessing ectasia risk.

Descemet's membrane automated endothelial keratoplasty (DMAEK): visual outcomes and visual quality.

BACKGROUND/AIMS: To determine whether the stromal rim that carries the bare endothelial graft in Descemet's membrane automated endothelial keratoplasty (DMAEK) has any effect on final visual outcome or visual quality. METHODS: Twenty-four DMAEK eyes and 22 Descemet's membrane endothelial keratoplasty (DMEK) eyes (with no stromal rim) were evaluated for corrected distance acuity, full-field Humphrey visual field (VF) 120-2 and pupil size. The inner and outer diameter of the DMAEK stromal ring was measured from slit lamp photos. Patients completed a questionnaire rating postoperative symptoms and visual complaints. Exclusion criteria were pre-existing glaucoma, retinal pathology or inability to return for postoperative examinations. RESULTS: Median Snellen acuities were comparable between DMAEK and DMEK groups: 20/25 and 20/20-3, respectively. The mean central opening of the DMAEK stromal ring was 5.6 × 5.5 (range 3.8-6.9) mm. The incidence of VF defects, visual complaints of glare, halos, light sensitivity and night driving difficulties was comparable between groups (all p > 0.1). A larger scotopic pupil size (< 5.5 mm) was not associated with increased incidence of VF defects in either group (p = 0.3). CONCLUSIONS: Surprisingly, compared with uniformly thin DMEK grafts, DMAEK grafts with a stromal rim had no increase in VF defects or visual complaints.

Endothelial keratoplasty: fellow eyes comparison of Descemet stripping automated endothelial keratoplasty and Descemet membrane endothelial keratoplasty.

PURPOSE: To evaluate patients' perspectives and outcomes of 2 different endothelial keratoplasty (EK) techniques performed in the fellow eyes of the same patients: Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). METHODS: In this fellow eye, comparative, retrospective case series, the records of 15 patients who underwent DSAEK in 1 eye and DMEK in the fellow eye and completed at least 1 year of follow-up after the second procedure were reviewed. Visual outcomes and endothelial cell density were assessed. Patient satisfaction was evaluated using a subjective questionnaire. RESULTS: At 12 months postoperatively, the mean best spectacle-corrected visual acuity (BSCVA) in the DMEK group was 0.07 logarithm of the minimum angle of resolution (20/24) and 0.20 logMAR (20/32) in the DSAEK group (P = 0.004). The majority of the patients (85%) perceived better visual quality in the DMEK eye. Furthermore, 62% preferred or would recommend DMEK to a friend or relative, whereas 15% preferred DSAEK and 23% reported no preference between the surgical procedures. The 1-year endothelial cell loss and the perceived discomfort level during the postoperative period were comparable for the 2 procedures. CONCLUSIONS: The majority of the patients preferred or would recommend the DMEK procedure. Faster visual recovery and better final visual acuity were the main benefits of the DMEK technique.