Localization of Fiber Folds in the Crystalline Lens and Influence on Visual Function

Abstract

Purpose: : The relationship between localization of fiber folds (FF) and cortical opacification (CO) in the crystalline lens was investigated. We examined the influence of FF on visual function.

Methods: : Subjects comprised 711 phakic eyes of 383 Japanese participants aged > 54 yrs (mean: 68.7 +– 7.0 yrs) of the Monzen Eye Study (2002 – 2004). Of these, two groups, FF+CO+ (27 eyes) and FF–CO+ (44 eyes), without opacification within a 3 mm diameter of the pupil center and a control, non–cataractous (79 eyes), were selected. Localization of FF and CO was determined by mapping incidences against angle of radial using retroillumination (EAS–1000 NIDEK) images. CO was categorized as wedge–shaped, oblique–shaped and both types together then graded according to the WHO cataract grading system. Contrast sensitivity was measured by CAT–2000 (NEITZ).

Results: : The prevalences of FF and CO were 28.7% and 41.1% respectively. 48.5% of wedge–shaped CO, 16.7% of oblique–shaped and 86.0% of both types together cases had FF. 4.5% of FF cases had no CO. 36.6% of CO cases had no FF. Both FF and CO were localized around the foot of the vertical axis of the pupil. At the position of 5 – 7 o’clock of the pupil the proportion of observed FF and CO were 58.2% and 61.8%, respectively. There was no significant difference between localization of FF and that of CO (Kruskal–Wallis H–test). There were no significant differences in contrast sensitivity between any of the three groups (ANCOVA correlation between 25% contrast sensitivity and age).

Conclusions: : Over 95% of FF cases had CO. Supporting the occurrence of CO along with FF is a breaking of lens fiber at the lens equator. Although under illumination of slit lamp microscopy FF were seen as parallel white lines similar to cortical opacification, FF had no influence on visual function.

Keywords: cataract • crystalline lens