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BackgroundWe aimed to investigate corneal densitometry and correlations with corneal morphological parameters in bilateral keratoconus (KCN) patients with unilateral Vogt's striae.MethodsOne hundred and-twelve patients (224 eyes) with bilateral KCN and unilateral Vogt's striae were enrolled in this cross-sectional contralateral eye study. Corneal densitometry and morphological parameters were measured using Pentacam HR.ResultsOur study revealed that corneal densitometry values of the anterior 0–2 mm and 2–6 mm, intermediate 0–2 mm and 2–6 mm, posterior 2–6 mm, and total cornea 2–6 mm in eyes with Vogt’s striae were significantly higher than those in eyes without Vogt's striae (P P P P P

To investigate the changes in posterior corneal elevations (PCEs) in the circular areas and local points after corneal collagen cross-linking (CXL) for the treatment of keratoconus.Method 1 divided the cornea into 0-2, 2-4, 4-6, and 6-8 mm regions centering on the apex. Method 2 obtained other 34 PCE values of local point that were identified on the nasal, supra-nasal, sub-nasal, superior, inferior, temporal, supra-temporal, and sub-temporal sides of the circle with diameters of 2, 4, 6, and 8 mm, and the apex and thinnest point.Method 1 showed a forward displacement of PCE at 1 month after CXL and then a backward displacement at 3 months. In Method 2, the points on the temporal side of 2 mm and 4 mm showed the same trend. The backward displacements of PCE on the temporal side of 2 mm at 6 months and on the temporal side of 4 mm at 12 months after CXL were both statistically different than those at 1 month after CXL (P 0.05). No significant forward displacement of PCE was found in all local points in different quadrants at 1 year after CXL.The PCEs in circular areas and characteristic points of different diameters in keratoconic eyes after CXL change with time. Local point assessment of the PCE is more clinically significant. In points selected in different quadrants of the cornea, the change in temporal points was more significant after CXL.

This study aimed to investigate the diagnostic value of corneal anterior, posterior, and total higher-order aberrations in keratoconic eyes.We enrolled 94 patients (152 eyes) with mild keratoconus (Group 1), 64 patients (101 eyes) with moderate keratoconus (Group 2), and 32 patients (52 eyes) with advanced keratoconus (Group 3) according to the Amsler-Krumeich classification system; 99 healthy controls (197 normal eyes) were likewise enrolled. Anterior, posterior, and total corneal higher-order aberrations were assessed using a rotating Scheimpflug camera. The 3rd-order and 4th-order root-mean-square values were calculated for higher-order aberrations, including coma, spherical, and trefoil aberrations. Differences between keratoconic and normal eyes were analyzed using Kruskal-Wallis tests. Receiver operating characteristic curves were evaluated for the keratoconus and control groups.The differences in coma 90, coma, trefoil, and spherical aberrations, as well as 3rd-order and 4th-order root-mean-square values, were statistically significant between the keratoconus and control groups for all anterior, posterior, and corneal aberrations. The absolute values of these higher-order aberrations were higher in the keratoconus groups than in the control group and increased with keratoconus severity in Groups 1-3. Coma and 3rd-order RMS values showed excellent sensitivity and specificity for discriminating between normal and keratoconus eyes for all anterior, posterior, and corneal aberrations.Coma aberrations and 3rd-order root-mean-square values may be valuable for diagnosing keratoconus. Combining these data with topography information may enable the effective and efficient detection of keratoconus in the future.

Purpose: To investigate the changes in posterior corneal elevations (PCEs) in the circular areas and local points after corneal collagen cross-linking (CXL) for the treatment of keratoconus.Methods: Method 1 divided the cornea into 0–2, 2–4, 4–6, and 6–8 mm regions centering on the apex. Method 2 obtained other 34 PCE values of local point that were identified on the nasal, supra-nasal, sub-nasal, superior, inferior, temporal, supra-temporal, and sub-temporal sides of the circle with diameters of 2, 4, 6, and 8 mm, and the apex and thinnest point.Results: Method 1 showed a forward displacement of PCE at 1 month after CXL and then a backward displacement at 3 months. In Method 2, the points on the temporal side of 2 mm and 4 mm showed the same trend. The backward displacements of PCE on the temporal side of 2 mm at 6 months and on the temporal side of 4 mm at 12 months after CXL were both statistically different than those at 1 month after CXL (P < 0.05). The PCE of the thinnest point was correlated with other corneal points, except the points on the nasal and sub-nasal sides of 4 mm.Conclusion: The PCEs in circular areas and characteristic points of different diameters in keratoconic eyes after CXL change with time. Local point assessment of the PCE is more clinically significant. In points selected in different quadrants of the cornea, the change in temporal points was more significant after CXL.

Background We aimed to compare the intraocular pressure (IOP) measurements by a dynamic Scheimpflug analyzer (Corvis ST), a non-contact tonometer, and an ocular response analyzer after hyperopic small-incision lenticule extraction (SMILE). Methods Thirteen patients who underwent hyperopic SMILE in one eye were enrolled prospectively. IOP and corneal biomechanical parameters were measured preoperatively and at 1 week, 1 month, and 3 months postoperatively with a non-contact tonometer (IOPNCT), Corvis ST (biomechanical corrected IOP [bIOP]), and ocular response analyzer (Goldmann-correlated intraocular pressure [IOPg] and cornea compensated IOP [IOPcc]). A linear mixed model was used to compare the IOPs and biomechanical values among methods at each time point. Results IOPNCT, IOPg, and IOPcc dropped significantly after surgery, with the amplitude being 3.15 ± 0.48 mmHg, 5.49 ± 0.94 mmHg, and 4.34 ± 0.97 mmHg, respectively, at the last follow-up visit. IOPNCT decreased by 0.11 ± 0.06 mmHg per μm of excised central corneal thickness. bIOP did not change significantly after surgery. Preoperatively, no difference was found among the four measurements (P > 0.05). Postoperatively, IOPNCT and bIOP were higher than IOPg and IOPcc. bIOP was independent of cornea thickness at last follow-up visit, whereas it correlated significantly with corneal biomechanics similar to the other three IOP values. Conclusion bIOP is a relative accurate measure of IOP after hyperopic SMILE.