Effects of cataract type and location on visual function: The Blue Mountains Eye Study

Abstract

Purpose To measure the effect of cataract type, severity and location on presenting, and best-corrected visual acuity, contrast sensitivity, and glare disability. Methods In all, 3654 (82.4% participation rate) eligible noninstitutionalised residents aged 49 years or older, living in two postcode areas of the Blue Mountains, Australia, received detailed eye examinations including visual acuity, contrast sensitivity, and glare disability testing. Data from right eyes were analysed using multiple regression modelling. Results The effect of age on visual acuity and contrast sensitivity only became evident in persons aged at least 60 years. Cataract severity was inversely related to visual acuity and contrast sensitivity. Late posterior subcapsular cataract caused the greatest reduction in visual acuity. Early grade cataract caused significant reduction in contrast sensitivity at intermediate and high spatial frequencies, but late grade cataract reduced contrast sensitivity across all spatial frequencies. There was insufficient study power to detect consistent significant effect of cataract on glare disability tests or cortical cataract location on visual function. Conclusions Age at least 60 years, cataract type, and cataract severity were principal determinants of visual acuity and contrast sensitivity in this study. Axial and superotemporally located cortical cataract had the greatest effect on visual function tests.

How should cataracts be measured?

“…Furthermore, the perceptions of risk will vary between patients and their decisionmaking will vary accordingly. In this issue Chua et al 15 have confirmed the widely held belief that cataract in the central area of the lens has a greater impact on vision. The information presented is a helpful addition to the decision-making process.…”

“…Exploring the subtleties of cataract assessment may help to define appropriate levels of service provision and avoid crude, expediency driven demand management devices. The data presented by Chua et al 15 offer a further step towards such a goal.…”

Effects of yellow filters on visual acuity, contrast sensitivity and reading under conditions of forward light scatter

“…People with age-related crystalline lens opacification often experience functional vision reduction, decreased contrast sensitivity (CS), and increased sensitivity to glare [1][2][3]. An increase in intraocular forward light scatter (FLS) has been proposed as the primary cause for visual dysfunction associated with lens opacification [4][5][6][7][8]), largely as a result of the difference in refractive indices between protein aggregates that make up the opacified material and that of the crystalline lens itself [5,9].…”

Contrast Sensitivity in Emmetropic Presbyopes with Small-Aperture Inlay Implantation: Normative Values and Postoperative Outcomes

“…This study further assigned a score of the lowest CS score minus 0.3 at each spatial frequency when a subject could not see any contrast patches to alleviate the impact of the floor effect and closely estimate the CS population means. This method was applied in similar sinusoidal grating contrast test such as CSV-1000 Contrast Testing Instrument [11,16]. Another method assigning half of the lowest logCS value to subjects with zero patches seen [12,18] uses the same principle even though deriving slightly different logCS scores.…”

“…Test results were represented in log10 unit of CS (logCS). A logCS score of 0.3 less than the lowest logCS score for a spatial frequency on the FACT chart was assigned when no patches were seen [11,16].…”