Influence of graft thickness and regularity on vision recovery after endothelial keratoplasty.

AIM: To assess the influence of graft thickness and regularity on visual recovery and postoperative wavefront aberrations after endothelial keratoplasty (EK). METHODS: 150 EKs performed in eyes with corneal endothelial disorders and no other ocular comorbidities, preoperative and postoperative assessment with spectral domain optical coherence tomography and postoperative assessment with whole eye wavefront aberrometry were retrospectively analysed. Eyes were classified into five groups: Descemet Membrane Endothelial Keratoplasty (DMEK), nanothin Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) (15-49 µm), ultrathin DSAEK (50-99 µm), thin DSAEK (100-149 µm) and conventional DSAEK (150-250 µm). RESULTS: The preoperative diagnosis was Fuchs dystrophy in 139 eyes (92.7%). The graft thickness measured after graft deswelling was in average 74 µm with a mean coefficient of variation of 17%. The average follow-up time was 32 months. The mean spectacle-corrected logarithm of minimum angle of resolution visual acuity improved from 0.76 (20/116) before surgery to 0.14 (20/27) at last follow-up visit. No significant differences in final visual acuity were found between the five groups. The time to reach 20/40 vision was significantly shorter in the DMEK and nanothin DSAEK groups compared with the remaining three DSAEK groups. No significant differences in postoperative aberrometry measurements were found between the five groups. Shorter time to reach 20/40 visual acuity was associated with better preoperative visual acuity and thinner graft. Higher final vision improvement was associated with poorer preoperative visual acuity. Higher postoperative high-order aberrations were associated with poorer preoperative visual acuity. CONCLUSION: The main advantage of DMEK and nanothin DSAEK over thicker DSAEKs was the rapidity of visual recovery. Final quality of vision was not influenced by graft thickness and regularity.

Corneal epithelial thickness mapping using Fourier-domain optical coherence tomography for detection of form fruste keratoconus.

PURPOSE: To determine whether optical coherence tomography (OCT) epithelial mapping can improve the detection of form fruste keratoconus. SETTING: French National Eye Hospital, Paris 6 Pierre & Marie Curie University, Paris, France. DESIGN: Retrospective comparative study. METHODS: Eyes with normal corneas, form fruste keratoconus, moderate keratoconus, or severe keratoconus were assessed using Fourier-domain OCT (RTVue 5.5), scanning-slit corneal topography (Orbscan IIz), and rotating Scheimpflug camera (Pentacam Comprehensive Eye Scanner). Several parameters provided by the software or derived from elevation maps, OCT pachymetric maps, and OCT epithelium parameters were evaluated and compared between the 4 groups. RESULTS: The study involved 145 eyes. There were no significant differences in the keratometry (K) value, inferior-superior value, keratoconus index, central K index, and topographic keratoconus classification indices between the form fruste keratoconus group and the control group (P > .05). Form fruste keratoconic corneas had less epithelial thickness in the thinnest corneal zone than normal corneas, and greater epithelial thickness in the thinnest corneal zone than keratoconic corneas (P < .005). The epithelial thickness in the thinnest corneal zone in form fruste corneas was located inferiorly (P < .005) and corresponded with the zone of minimum epithelial thickness and maximum posterior elevation (P < .005). The receiver operating characteristic curve analysis showed good overall predictive accuracy of the epithelial thickness in the thinnest corneal zone, with a 52 µm threshold value for discriminating form fruste keratoconic corneas from normal corneas. CONCLUSIONS: The epithelial thickness in the thinnest corneal zone and its location provided by the OCT epithelial mapping might be useful for the early diagnosis of form fruste keratoconus. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Fourier-domain optical coherence tomography imaging in keratoconus: a corneal structural classification.

OBJECTIVE: To study corneal morphologic changes in a large keratoconic population and to establish a structural optical coherence tomography (OCT) classification. DESIGN: Cross-sectional, observational study. PARTICIPANTS: A total of 218 keratoconic eyes from 218 patients and 34 eyes from 34 normal subjects. METHODS: A Fourier-domain OCT system with 5-µm axial resolution was used. For each patient, 3 high-resolution scans were made across the keratoconus cone. All scans were analyzed by keratoconus specialists who were not given access to patients' clinical and topographic data, and who established an OCT classification. The reproducibility of the classification and its correlation with clinical and paraclinical characteristics of patients with keratoconus were evaluated. The OCT examinations were performed every 4 months to follow up structural corneal changes. MAIN OUTCOME MEASURES: Evaluation of the structural corneal changes occurring in keratoconus cases with various stages of severity based on OCT findings. RESULTS: Fourier-domain OCT classification containing 5 distinct keratoconus stages is proposed. Stage 1 demonstrates thinning of apparently normal epithelial and stromal layers at the conus. Stage 2 demonstrates hyperreflective anomalies occurring at the Bowman's layer level with epithelial thickening at the conus. Stage 3 demonstrates posterior displacement of the hyperreflective structures occurring at the Bowman's layer level with increased epithelial thickening and stromal thinning. Stage 4 demonstrates pan-stromal scar. Stage 5 demonstrates hydrops; 5a, acute onset: Descemet's membrane rupture and dilaceration of collagen lamellae with large fluid-filled intrastromal cysts; 5b, healing stage: pan-stromal scarring with a remaining aspect of Descemet's membrane rupture. The reproducibility of the classification was very high between the corneal specialist observers. Clinical and paraclinical characteristics of keratoconus, including visual acuity, corneal epithelium and stromal thickness changes, corneal topography, biomechanical corneal characteristics, and microstructural changes observed on confocal microscopy, were concordant with our OCT grading. CONCLUSIONS: Optical coherence tomography provides an accurate assessment of structural changes occurring in keratoconus eyes. These changes were correlated with clinical and paraclinical characteristics of patients. The established classification not only allows structural follow-up of patients with keratoconus but also provides insight into the pathogenesis of keratoconus and treatment strategies for future research.

Patients' subjective assessment of the duration of cataract surgery: a case series.

OBJECTIVES: Surgery duration is a source of preoperative anxiety for patients undergoing cataract surgery. To better inform patients, we evaluated the agreement between objective and patient-perceived surgery durations. DESIGN: Case series. SETTING: Public teaching university hospital (Paris, France). PARTICIPANTS: During the study period, 368 cataract surgery cases performed on 285 patients were included, 85 cases were excluded from the final analysis. All patients who had uneventful phacoemulsification were included. Cases with any significant intraoperative adverse event or cases requiring additional anaesthesia other than topical were excluded. Resident performed cases were also excluded. PRIMARY AND SECONDARY OUTCOMES: Procedures were timed (objective duration) and patients were asked, immediately afterwards, to assess the duration of their surgery (patient-assessed duration). The agreement between objective and patient-assessed durations as well as influencing factors was studied. RESULTS: Mean objective duration (13.9±5 min) and patient-assessed duration (15.3±6.9 min) were significantly correlated (Spearman's r=0.452, p<0.0001). Furthermore, Bland-Altman analysis and the intraclass correlation coefficient (0.341, 95% CI 0.23 to 0.44) were quite in agreement. On univariate analysis, senior-performed procedures were significantly shorter than those performed by juniors (13.4 vs 17.8 min, p=0.0001). Pain was recorded as 'no sensation' (31.5% of the cases), 'mild sensation' (41%), 'moderate pain' (23.3%), 'intense pain' (3.5%) and 'unbearable pain' (0.7%). Groups with high pain score had significantly longer procedures (p<0.001). Multivariate analysis revealed that the only independent factors associated with both the objective and patient-assessed durations of surgery were surgeon's experience and pain-score. CONCLUSIONS: In our study, patients' estimated and real duration of the surgery showed moderate agreement, suggesting that emotions associated with eye surgery under topical anaesthesia did not dramatically hinder the patients' perception of time. However, the benefit of preoperative counselling regarding the duration of surgery will need further evaluation.