The effect on the macular function of laser photocoagulation for diabetic macular edema.

The benefit of focal and grid-laser photocoagulation in reducing the risk of visual loss from diabetic macular edema has been established. In order to investigate the effect of this treatment on macular function, 30 diabetics with macular edema and 1.0 visual acuity were tested before and after laser treatment at intervals of 1 week, and 1 and 3 months, respectively. The test was carried out by means of nyctometry, contrast sensitivity, hue discrimination and critical flicker frequency of blue cones. All patients had abnormal results in macular tests before treatment. During the follow-up, visual acuity remained stable and the macular tests did not statistically modify, except for nyctometry, which deteriorated at the 1-week follow-up (P = 0.02) and then increased to the basal values, and contrast sensitivity [improved at the last control (P = 0.006)]. Clinical regression of macular edema was observed, but macular function tests never normalized. Patients with diabetic macular edema and good visual acuity should be monitored with many functional methods, and laser treatment should be performed before macular function deteriorates irreversibly.