Background: To analyze objective and subjective visual quality differences between descemet membrane endothelial keratoplasty (DMEK) and ultra-thin descemet stripping automated endothelial keratoplasty (UT-DSAEK) with a paired contralateral-eye design. Methods: A cross-sectional, comparative, and observational case series study between DMEK and UT-DSAEK were presented. Visual acuity, refractive status and corneal quality assessment were compared between both endothelial keratoplasty techniques. The sample consisted of 20 eyes (10 patients) diagnosed with Fuchs endothelial corneal dystrophy. All measurements were performed preoperatively and at six months after surgery. Analyzed data included the measurement of objective scattering index, modulation transfer function, Strehl ratio, and optical quality assessment (OQAS) values. Contrast sensitivity, subjective patient satisfaction, visual acuity, tomography, pachymetry, endothelial cell count, and refraction status were also analyzed. Results: Objective and subjective visual quality variables had similar results among UT-DSAEK and DMEK procedures. Statistically significant differences favoring DMEK against UT-DSAEK were found in endothelial cell density (658.80 ± 139.33 and 1059.00 ± 421.84 cells/mm2, respectively), pachymetry (621.20 ± 33.74 and 529.70 ± 30.00 µm, respectively), and follow-up (45.50 ± 24.76 and 15.50 ± 8.43 months, respectively). Conclusions: UT-DSAEK and DMEK revealed no differences in terms of objective and subjective visual quality. However, DMEK showed a faster recovery during the follow-up, increased endothelial cell density, lower pachymetry, and a more anatomical posterior keratometry against UT-DSAEK in this case series paired-eye study.
To describe a new algorithm to measure corneal densitometry based on images obtained by swept source anterior segment ocular coherence tomography (SS-AS-OCT) and establish standard densitometry values in a group of normal eyes. METHODS: A total of 111 healthy participants (195 eyes) were enrolled in this study. Using a MATLAB designed algorithm, the cornea was segmented into three layers: anterior, posterior and mid-stroma, and it was divided into two concentric areas, 0-2 and 2-4 mm, resulting in nine areas for the analysis. The mean corneal densitometry values were calculated and expressed as grayscale units (GSU). RESULTS: The mean age was 57 years (range 22-87), with 100 (51.3%) right eyes and 95 (48.7%) left eyes. The total corneal densitometry was 86.9 ± 12.1 GSU. The mid-stroma layer had the highest densitometry values, 87.4 ± 12.1 GSU, and the anterior layer had the lowest values, 81.9 ± 14.2 GSU. Densitometry differences between the anterior layer and the mid-stroma layer (P < 0.001), as well as the anterior layer and the posterior layer (P < 0.05) were statistically significant. The 0-2 mm concentric area had higher mean densitometry values, 97.8 ± 12.7 GSU, and the differences were significant compared to the 2-4 mm concentric area (P < 0.001). No correlation was found between the corneal densitometry values and gender or age. CONCLUSIONS: The new MATLAB segmentation algorithm for the analysis of corneal SS-AS-OCT images is capable to objectively assess corneal densitometry. We provide standard and normal data for better clinical and research approach.
Purpose To assess agreement between corneal aberration measurements made through swept-source optical coherence tomography using a new anterior segment imaging device (Anterion) and a Scheimpflug imaging device (Pentacam HR) in healthy subjects. Methods Cross-sectional study. In 50 eyes of 50 healthy subjects, 14 aberration parameters (7 across the anterior corneal surface and 7 across the total surface) were measured in 4 mm and 6 mm optic zones using each device: oblique trefoil (Z3_-3), vertical coma (Z3_-1), horizontal coma (Z3_1), horizontal trefoil (Z3_3), spherical aberration (Z4_0), root mean square (RMS) lower order aberrations (LOA) and RMS higher order aberrations (HOA). Data for the two devices were compared through intraclass correlation coefficients (ICC), paired t tests, limits of agreement (LoA) and Bland Altman plots. Results Vertical coma was the only corneal aberration parameter that consistently showed excellent agreement (ICC > 0.8, mean difference −0.019, LoA −0.165 to 0.126). Good agreement (ICC = 0.75) between the devices was observed for RMS HOA, but this was slightly worse in the 6 mm optical zone (ICC = 0.667 for anterior RMS HOA). No over- or underestimation trend by one or other device was noted. Agreement was poor to moderate for the rest of the corneal parameters (ICC 0.2 to 0.7). Conclusion Despite good agreement overall for vertical coma and RMS HOA values, agreement for the remaining corneal aberration measurements was poor to moderate. As mean differences in our sample were overall small, in normal eyes these devices could be clinically judged as interchangeable.
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