[Status of center point thickness and correlation between anatomic and best corrected visual acuity changes after photocoagulation, in diabetic macular edema].

Background: Center point thickness in diabetic macular edema varies after photocoagulation according to its baseline status; it is unknown whether this variation reduces the correlation between anatomic and visual acuity changes.
Objective: to identify the contribution of baseline center point thickness to the correlation between anatomic and visual acuity after photocoagulation, in eyes with diabetic macular edema.
Methods: non-experimental, prospective, longitudinal, analytical study in diabetics with macular edema treated with photocoagulation, stratified by groups: visual acuity < 0.5 with (group 1) or without central thickening (group 2), and visual acuity = 0.5 with (group 3) or without central thickening (4). The correlations between changes of center point thickness, macular volume, and visual acuity were identified (Spearman).
Results: 79 eyes, 17 in group 1 (21.5%), 21 in group 2 (26.6%), 14 in group 3 (17.7%) and 27 in group 4 (34.2%). Center point thickness increased in groups 2 and 4, visual acuity decreased in group 3 and macular volume in all the groups. The correlations between center point thickness and best corrected visual acuity changes in group 3, and between macular volume and visual acuity in group 1 were negative. The correlations between anatomic variables and visual acuity were low in the sample (r= 0.14).
Conclusion: the increase of center point thickness in eyes without baseline central thickening produced opposite correlations between groups, which reduced the correlations in the samples. Stratification according to baseline center point thickness would make easier to evaluate other variables that modify the functional outcome after photocoagulation.