Abstract
Abstract: :
Purpose: Daily treatment with CJ–12,918, a 5–lipoxygenase inhibitor, leads to dose dependent lens opacities in the rat. The initial opacity consists of anterior subcapsular radial striations originating from the equatorial cortex and progresses to a complete cortical and nuclear opacity. The purpose of this study is to compare the use of Scheimpflug imaging with routine preclinical slit lamp biomicroscopic examinations for detecting and characterizing cataract formation in the albino rat using the CJ–12,918 cataract model. Methods: Female Sprague–Dawley rats were treated orally with 250 mgA/kg CJ–12,918 or vehicle control (0.5% methylcellulose) once daily for 19 days. Eyes were dilated with a 1% tropicamide solution. Scheimpflug and slit lamp examinations were conducted once pre–study and then on days 5, 8, 12, 15, and 19. Scheimpflug images (0o, 90o, and retroillumination) were acquired from each eye using the Nidek EAS–1000 anterior segment analysis system. Subsequent densitometric image analysis was performed using the EAS–1000 software. Retroillumination slit lamp images were captured using a Nikon FS–3V slit lamp. On day 19, eyes were collected for histopathological assessment. Results: Slight radial striations located in the anterior subcapsular equatorial cortex and progressing anteriorly were observed using the Nikon FS–3V slit lamp in 9/10 and 10/10 treated animals on days 12 and 15 respectively. By day 19, nuclear changes were discernible in 2/10 treated animals. Posterior cortical changes were observed in 1/10 treated animals. The retroillumination feature in the Scheimpflug system showed evidence of the radial striations in 6/10, 8/10, 10/10 treated animals on study days 12, 15, and 19, respectively. Scheimpflug imaging (0o or 90o) first showed quantitative evidence of anterior subcapsular density changes in 2/10 treated animals by day 15. By day 19, anterior subcapsular density changes and equatorial/posterior cortical changes were evident in 10/10 and 6/10 treated animals respectively. These observed radial striations were correlated to lenticular fiber swelling microscopically. Conclusions: The results of this study indicate that Scheimpflug imaging is not more sensitive than routine preclinical slit lamp examinations in detecting the CJ–12,918 opacity in the albino rat. The advantage of the Scheimpflug system for preclinical cataract assessment is the ability to quantitate longitudinal changes in lens transparency.
Keywords: cataract • imaging/image analysis: non–clinical • drug toxicity/drug effects