Patterns of morphologic alteration correlate with vision in diabetic macular oedema: a cross-sectional evaluation of patients using the SAVE II protocol.

PURPOSE: We sought to describe and evaluate patients with clinically significant diabetic macular oedema (CSME) according to the improved SAVE II protocol and correlate findings with visual acuity and systemic parameters in the outpatient clinic for DR (diabetic retinopathy) management. METHODS: This was a cross-sectional case series study of patients with CSME, regardless of prior treatment. Visual acuity testing was performed according to the Early Treatment of Diabetic Retinopathy Study (ETDRS) protocol. Optical coherence tomography (OCT) and fluorescence angiography (FA) were performed. All imaging data were evaluated according to an improved version of the SAVE grading protocol for CSME (SAVE II). The main outcome measures were SAVE II oedema types and best-corrected visual acuity. Additional parameters of a blood sample (fasting glucose, haemoglobin A1c, serum creatinine, triglycerides, cholesterol, low-density lipoproteins, and high-density lipoproteins) were taken. RESULTS: In total, 66 eyes of 66 patients were included. The mean age of the patients was 64.9 ± 8.2 years. Two eyes were classified as SAVE oedema type 1, 19 eyes as SAVE oedema type 2, 28 eyes as SAVE oedema type 3, and 28 eyes as SAVE oedema type 4, respectively. Central retinal thickness and laboratory parameters were not significantly different between the groups. There was a statistically significant difference in ETDRS visual acuity between the SAVE groups 2 and 4 (p < 0.001) with lower vision in group 4. There was no statistically significant difference between oedema types 2 and 3 (p = 0.065) and oedema types 3 and 4 (p = 0.13). CONCLUSION: There was a significant correlation between the four defined oedema types and visual acuity. Morphologic findings did not correlate with any of the evaluated blood parameters.

Corneal Epithelial Remodeling Induced by Small Incision Lenticule Extraction (SMILE).

PURPOSE: To assess the reactive changes of the corneal epithelial thickness (ET) profile induced by small incision lenticule extraction (SMILE) for treatment of myopia. METHODS: This prospective observational study included 46 eyes of 23 patients that were scheduled for myopic SMILE. High-resolution spectral-domain optical coherence tomography (SD-OCT) and a custom image segmentation algorithm were applied to measure corneal ET at multiple time points within the central 5-mm zone. Postoperative ET alterations were correlated with treatment parameters and refractive outcomes. RESULTS: Mean age was 33 ± 6 years and mean spherical equivalent of surgical refractive correction was -4.78 ± 1.75 diopters. The average ET (averaged over the central 5-mm zone) increased from 52.3 ± 3.6 µm preoperatively to 57.7 ± 5.1 µm 6 months postoperatively (P < 0.01). Average ET was 101.9% of the preoperative thickness at 24 hours postoperatively, 103.2% at 1 week, 106.7% at 6 weeks, 109.3% at 3 months, and 110.4% at 6 months postoperatively. The epithelial thickening response could be modeled by an exponential recovery function and stabilized after 3 months. The extent of epithelial hyperplasia was highly dependent on the magnitude of the induced refractive correction (P = 0.002). CONCLUSIONS: In this initial study of corneal ET remodeling after myopic SMILE, significant epithelial thickening was detected as a function of the extent of surgical refractive correction. Moreover, the epithelial remodeling response to the corneal refractive change appeared to decrease with higher age. In our hands, the observed epithelial changes did not appear to affect the refractive outcome of SMILE. (ClinicalTrials.gov number, NCT02614625).

Semiautomated SD-OCT Measurements of Corneal Sublayer Thickness in Normal and Post-SMILE Eyes.

PURPOSE: To test the reliability of a novel algorithm for measuring corneal epithelial thickness (ET) and stromal thickness of normal eyes and post-small incision lenticule extraction (SMILE) corneas with spectral-domain optical coherence tomography. METHODS: In this prospective observational study, a customized semiautomated software algorithm was developed and applied to measure corneal ET and stromal thickness along the horizontal corneal meridian. Measurements were performed by 2 examiners in a randomized fashion on a sample of 40 eyes with previous SMILE for treatment of myopia and a control group composed of 40 normal eyes. The intrauser repeatability and interuser reproducibility were analyzed by calculating typical indices including the coefficient of variation and intraclass correlation coefficient. Corneal sublayer thickness profiles were compared between normal and post-SMILE eyes. RESULTS: In both groups, coefficients of variation were 3.2% or lower and intraclass correlation coefficients were 0.929 or higher indicating excellent reliability of the measurement method. Central ET was on an average 6 µm greater in post-SMILE corneas (58.8 ± 5.4 µm) compared with normal eyes (52.8 ± 4.0 µm), with P < 0.01. Also, there was greater interindividual variability in ET in post-SMILE corneas and their horizontal epithelial profile seemed to show a lenticular appearance. CONCLUSIONS: Highly favorable indices of measurement reliability were achieved for this novel method of measuring corneal sublayer pachymetry not only in normal eyes but also in eyes with previous SMILE. The corneal ET profile was significantly altered in post-SMILE eyes compared with normal corneas.