Relation between macular morphology and visual function in patients with choroidal neovascularisation of age related macular degeneration

Abstract

Aim: To examine the relation between three measures of visual function (distance acuity, near acuity, and contrast sensitivity) and specific fluorescein angiographic characteristics of the macular lesion in patients with subfoveal choroidal neovascularisation (CNV) due to age related macular degeneration (AMD).

Methods: Visual evaluation and digital fundus fluorescein angiography were performed in 93 patients with subfoveal CNV. Standard morphometric techniques were used on two frames from the angiographic series closest to 30 seconds and 60 seconds respectively, to ascertain total lesion size (defined as the entire area of abnormal fluorescence), the size of the classic component, and the distance from the fovea to the closest point of healthy retina. Correlations were sought using Pearson's correlation coefficients. Stepwise regression was used to minimise multiple colinearity.

Results: When the study eye was the better eye of a patient's pair of eyes, the strongest correlation was between the size of the classic component and contrast sensitivity (r= 0.48, p <0.001) and was highly significant. When the study eye was the worse eye, significant correlations were observed between total lesion size and all three measures of visual function. The strongest correlation was observed between overall lesion size and contrast sensitivity (r = 0.52, p <0.001).

Conclusions: This study has shown that the status of the study eye (that is, better or worse eye of a pair of eyes) influences the impact of macular pathology in AMD on visual function. The distance of the fovea from healthy retina was found to be an important factor in predicting visual function.

Figure 1

(A) Fluorescein angiographic image showing a mixed choroidal neovascular membrane with classic and occult components. The components are outlined and the arrows indicate 6 o'clock position on optic disc and margin of the outlined classic component. (B) As in (A) with 2 mm grid superimposed to facilitate counting of intersections overlying the areas of interest.