The relation between visual acuity, fixation stability, and the size and location of foveal hard exudates after photocoagulation for diabetic maculopathy: a 1-year follow-up study.

PURPOSE: To study the relation between changes in visual acuity, fixation stability and the retinal area covered by hard exudates 3, 6 and 12 months after laser photocoagulation for diabetic maculopathy.
METHODS: Twenty-four eyes of 24 patients with diabetes mellitus were examined 3, 6 and 12 months after retinal photocoagulation for clinically significant macular oedema. Each examination included visual acuity testing (ETDRS charts), quantification of fixation stability using a scanning laser ophthalmoscope (Rodenstock 101) and fundus photography. The fundus photographs were digitised and the retinal area covered by hard exudates determined by image processing.
RESULTS: The retinal area covered by hard exudates decreased significantly during the first 6 months after treatment ( P=0.05, paired t-test), but increased again between 6 and 12 months after treatment. The visual acuity showed an increase, albeit non-significant, during the first 6 months after treatment followed by a decrease between 6 and 12 months after treatment. Quantification of fixation stability showed that four patients with central exudates fixated at the border of these lesions, and in two of these patients the disappearance of the exudates resulted in increased visual acuity and a change in fixation to the former exudate area.
CONCLUSIONS: The retinal area covered by hard exudates decreases during the first 6 months after central photocoagulation, but increases again between 6 and 12 months after the treatment. Hard exudates covering the foveal region contribute to disturbance of central vision.