Changes in the Anterior Lamina Cribrosa Morphology with Glaucoma Severity.

This study was designed to evaluate if primary open angle glaucoma (POAG) and its severity are associated with the shape of the lamina cribrosa (LC) as measured by a global shape index (LC-GSI), or other indices of LC curvature or depth. Optical coherence tomography (OCT) scans of the optic nerve head (OHN) were obtained from subjects with POAG (n = 99) and non-glaucomatous controls (n = 76). ONH structures were delineated, the anterior LC morphology reconstructed in 3D, and the LC-GSI calculated (more negative values denote greater posterior concavity). Anterior LC depth and 2D-curvature were also measured. Severity of glaucoma was defined by the extent of visual field loss, based on the Hodapp-Parrish-Anderson grading. Linear regression analyses compared LC characteristics between controls, mild-moderate, and advanced POAG groups. After adjusting for age, gender, ethnicity, intraocular pressure, axial length and corneal curvature, the LC-GSI was most negative in the advanced POAG group (mean [standard error] = -0.34 [0.05]), followed by the mild-moderate POAG group (-0.31 [0.02]) and then controls (-0.23 [0.02], PTrend = 0.01). There was also a significant trend of increasing LC depth and greater LC horizontal curvature with increasing severity of glaucoma (PTrend = 0.04 and 0.02, respectively). Therefore, with more severe glaucoma, the LC-GSI was increasingly more negative, and the anterior LC depth and curvature greater. These observations collectively correspond to greater cupping of the ONH at the level of the LC. As the LC-GSI describes the 3D anterior LC morphology, its potential usage may be complementary to existing ONH parameters measured on OCT.

Assessment of Circumferential Angle Closure with Swept-Source Optical Coherence Tomography: a Community Based Study.

PURPOSE: To evaluate the diagnostic performance of swept-source optical coherence tomography (SS-OCT, CASIA SS-1000; Tomey Corporation, Nagoya, Japan) for angle closure detection, in comparison with gonioscopy, in a community setting. DESIGN: Reliability analysis. METHODS: A total of 2027 phakic subjects aged ≥50 years, with no previous history of glaucoma, laser (including peripheral iridotomy), intraocular surgery, or ocular trauma, were consecutively recruited from a community polyclinic in Singapore. Gonioscopy was performed by a single trained ophthalmologist. SS-OCT angle scans, which obtain radial scans for the entire circumference of the angle, were analyzed by a single examiner, masked to the subject's clinical details. On SS-OCT images, angle closure was defined as contact between the iris and any part of the angle wall anterior to the scleral spur. Different cutoff values of the degree of circumferential angle closure (≥35%, ≥50%, and ≥75%) were taken for analysis to assess SS-OCT performance in detecting angle closure. RESULTS: A total of 1857 subjects (91.6%) were included in the final analysis after excluding poor-quality SS-OCT scans. Almost 90% of the subjects were Chinese, with a mean age of 61.8 ± 6.7 years, and more than half were women (63.5%). The overall AUC of SS-OCT manual grading against gonioscopy was 0.84 (95% confidence interval, 0.81-0.88). The prevalence of angle closure on SS-OCT was 26.1% for the ≥35% definition, with an area under the curve of 0.80 (0.77-0.84), sensitivity of 82.5% (75.3%-88.4%), and specificity of 78.5% (76.5%-80.4%). The first-order agreement coefficient statistics for the 2-quadrant gonioscopic definition of angle-closure with corresponding ≥35%, ≥50%, and ≥75% angle closure definitions for SS-OCT were good at 0.89 (0.83-0.93), 0.88 (0.842-0.93), and 0.88 (0.831-0.99), respectively. CONCLUSIONS: In this large community-based study, SS-OCT exhibited moderate performance for angle closure detection compared to gonioscopy as the reference standard.

Positional and rotational stability of the toric phakic intraocular lens under high +Gz environments.

BACKGROUND: Phakic intraocular lens (PIOL) implantation is a surgical option for correction of refractive errors. PIOLs can be use to correct myopia, hyperopia, and astigmatism. It is a surgical option available to patients in addition to methods such as laser cornea refractive surgery, e.g., laser assisted in-situ keratomileusis (LASIK) and photo-refractive keratectomy (PRK). Visian implantable collamer lens (ICL) are posterior chamber lenses which are surgically positioned in a phakic eye in the sulcus between the iris diaphragm and the natural crystalline lens. CASE REPORT: This case report describes the stability of Visian toric ICL in a candidate with bilateral implants under high +Gz force exposure in a human centrifuge trainer. The subject was sequentially exposed to three incremental +Gz profiles of +5 Gz, +7 Gz, and +9 Gz. Pre- and post-+Gz exposure, ophthalmic examination revealed no ICL displacement, implant touch or induced cataract, or change in refractive error. DISCUSSION: The rotational stability of the toric implants was also demonstrated by identical subjective refractions in both eyes taken pre- and post-+Gz, exposure. A search of the literature did not reveal any published articles on intraocular stability of ICL in the +Gz environment. This case report suggests that ICL may be considered an alternative to laser refractive surgery for patients subjected to a high +G, environment such as military aviators.