No abstract

Direct analysis of the digitized images of the Placido mires projected on the cornea is a valid and effective tool for detection of corneal irregularities. Although based only on the data from the anterior surface of the cornea, the new indices performed well even when applied to the KC suspect eyes. They have the advantage of simplicity of calculation combined with high sensitivity in corneal irregularity detection and thus can be used as supplementary criteria for diagnosing and grading KC that can be added to the current keratometric classifications.

Purpose: To comprehensively evaluate visual function in eyes with geographic atrophy (GA) as compared to normal eyes. Patients and Methods: Sixty-three eyes from 63 patients ≥50 years old were recruited for this observational study; 31 were identified as normal macular health eyes and 32 with GA. Visual function was tested with best corrected visual acuity (BCVA), low luminance visual acuity (LLVA), low luminance deficit (LLD), reading speed, macular integrity microperimetry, fixation stability, and contrast sensitivity function (CSF). Anatomic function was evaluated with spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF). Quality of life and vision were assessed with the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25). Results: Visual function and quality of life are reduced in patients with GA. Moderate and strong correlations in the GA group were found between maximum reading speed (r = 0.787) (p˂0.01), CS spatial frequency 3 cpd (r = 0.441) (p˂0.05), CS spatial frequency 6 cpd (r = 0.524) (p˂0.01), fixation P1 (r = 0.379) (p˂0.05), macular sensitivity (r = 0.484) (p˂0.05) and atrophic area (r = −0.689) (p˂0.01), and the VFQ-25 composite score. Conclusion: The decreased visual function is reflected in a poor quality of life in patients with GA. Reading speed, contrast sensitivity, fixation, and macular sensitivity are strongly associated with vision-related quality of life. The results suggest the importance of the reading letter size in patients with GA. Microperimetry and reading speed are useful tools to better assess visual impairment in patients with GA.

Purpose: to assess anterior scleral thickness (AST) across diverse scleral meridians and to evaluate the relationship with corneal biomechanical response and several ocular parameters. Methods: This prospective non-randomized study comprised 50 eyes of 50 patients (mean age, 29.02 ± 9.48 years). Anterior scleral thickness was measured meridionally at three scleral locations (1, 2, and 3 mm posterior to the scleral spur) using swept-source optical coherence tomography. A multivariate model was created to associate AST with several ocular parameters. Principal component analysis (PCA) was used to reduce linearly the dimensionality of seven biomechanical input metrics to two significant components, C1 and C2. Two multivariate analyses were performed to associate C1 and C2 with AST and several ocular parameters. Results: AST was thickest in the inferior (581 ± 52 µm) and thinnest in the superior meridian (441 ± 42 µm) when compared to all meridians (p<0.001), and similar in the nasal (529 ± 53 µm) and temporal (511 ± 59 µm) meridians (p>0.05). The sclera exhibited the thinnest point 2 mm posterior to the scleral spur (p<0.001). The AST was significantly linked with axial length, central corneal thickness, and intraocular pressure (p<0.001). The PCA showed that C1 accounts for 53.84% whereas C2 for the 16.51% of the total variance in the original variables. The C1 model was significantly associated with AST along all meridians (p<0.001). The partial correlation was moderate in the nasal (r= -0.36, p<0.001) and inferior (r= -0.26, p=0.004) meridians whereas weak in the temporal (r= -0.14, p=0.05) and superior (r= -0.15, p=0.05) meridians. Conclusions: The relationship between the new biomechanical component and the AST provides the first evidence of the association of AST with the corneal response parameters which should be considered in corneal response interpretation. Tissue thickness varied significantly among meridians supporting the asymmetrical expansion of the ocular globe. The AST was associated with several ocular parameters.