The influence of age-related cataract on blue-on-yellow perimetry.

PURPOSE

The influence of cataract on the blue-on-yellow visual field is unknown. The aim of the study was to compare the effect of age-related cataract on the normal blue-on-yellow (B-Y), yellow-on-yellow (Y-Y) and white-on-white (W-W) visual field.

METHODS

Forty normal subjects (age range, 60 to 81 years) randomly performed B-Y, Y-Y, and W-W perimetry using a modified Humphrey Field Analyser 640 (HFA) (Program 24-2). Twenty age-matched patients with cataract underwent the same testing paradigm. Cataract was classified using the LOCS II system. Ocular media absorption was measured with the HFA by determining the difference in scotopic sensitivity to 410-nm and 560-nm stimuli. Forward light scatter was measured by the direct compensation technique of van den Berg. Unweighted mean deviation (MD), short-term fluctuation, and corrected pattern standard derivation indices were calculated for each patient with cataract for each of the three stimulus combinations.

RESULTS

Cataract produced an adverse effect on the MD (i.e., a more negative MD) in all patients for each of the three stimulus combinations. The magnitude depended on the degree and type of cataract and was highly correlated with forward light scatter. The attenuation in sensitivity was greatest for the B-Y and W-W stimulus combinations; the B-Y field was preferentially affected by posterior subcapsular cataract and the W-W field by anterior cortical cataract.

CONCLUSIONS

Cataract predominantly causes a general reduction in B-Y sensitivity. Caution therefore needs to be exercised in the interpretation of the B-Y visual field in patients in whom glaucoma and cataract coexist.