Macular edema and vitreous detachment.

To determine if vitreous changes play a role in macular edema, 197 eyes were selected, 113 with macular edema (68 diffuse and 45 cystoid) associated with different pathologies. We studied the vitreoretinal relationship in all cases. Photocoagulation was done in 21 eyes and vitreous examination before and after treatment. The difference between complete and incomplete posterior vitreous detachment (PVD) between the control and pathologic groups was statistically significant (P less than .0005). This shows that incomplete PVD is related to macular edema. The difference between complete and incomplete PVD and diffuse or cystoid macular edema was not statistically significant. It was significant between incomplete PVD without collapse and with contraction and diffuse and cystoid macular edema (P less than .0005). That is cystoid macular edema is associated with incomplete PVD with vitreous contraction. The vitreous usually collapses with laser treatment. Complete PVD before treatment seems to be associated with a good prognosis after photocoagulation. Cases with incomplete PVD and cystoid macular edema show worsening of the visual field after laser treatment.