[Lack of correlation between retinal variables before treatment and poor functional response after focal photocoagulation in diabetic macular oedema].

Background: Although photocoagulation reduces the incidence of moderate visual loss in eyes with focal diabetic macular oedema, some eyes may lose some vision after treatment. The proportion of eyes with poor functional response after photocoagulation, and whether any retinal variable is associated with this, is unknown.

Objective: To determine the proportion of eyes with diabetic macular oedema that have a poor functional response after focal photocoagulation, and their associated features.

Material And Methods: A non-experimental, longitudinal, comparative and retrospective study was conducted. The proportion and 95% confidence intervals (CI) of diabetics with macular oedema that had a poor functional response after focal photocoagulation (any visual loss after 6 weeks) were identified. The means of retinal variables before treatment were compared between eyes with and without a poor functional response using the Student t test for independent means.

Results: The study included 115 eyes of patients aged 59.3 (SD 9.24) years. Visual acuity was greater than or equal to 0.5 in 63 eyes (54.8%). A total of 33 eyes had a poor functional response after photocoagulation (28.7%, 95% CI: 13.3 to 44.1). The comparison between retinal variables and visual acuity before treatment did not show any differences between eyes with or without a poor functional response and eyes.

Conclusion: Retinal thickening and visual acuity improved or did not change in 71.3% of eyes with diabetic macular oedema with a single photocoagulation procedure. Retinal variables that are usually evaluated were unable to identify the remaining 28.7%, which could lose vision after that treatment, and would require additional interventions.