Tomographic findings of foveal hard exudates in diabetic macular edema.

PURPOSE: To report the intraretinal location of foveal hard exudates after vitrectomy to treat diabetic macular edema and to evaluate the visual outcome.
METHODS: In a prospective study, the tomographic features of 11 eyes (8 patients) with diabetic macular edema were evaluated with optical coherence tomography after vitrectomy. The intraretinal location of hard exudates at the fovea (anatomic foveola) and the relationship with visual acuity were investigated.
RESULTS: With optical coherence tomography, hard exudates were observed as highly reflective spots in the cross-sectional images. In six of 11 eyes (54.5%), the hard exudates were in the inner portion of the neurosensory retina; the final best-corrected visual acuity averaged 20/70 in the six eyes. In the remaining five eyes (45.5%), hard exudates were deposited not only in the neurosensory retina but also in the subretinal space. In optical coherence tomographic images, subretinal hard exudates were observed as highly reflective plaques, which were slightly elevated over the retinal pigment epithelium. The five eyes developed a serous retinal detachment at the fovea before or after vitrectomy. Subretinal hard exudates bridged the detached neurosensory retina and the retinal pigment epithelium in two eyes. The average final visual acuity level in the five eyes was 20/300. The visual outcome was significantly worse in five eyes with subretinal hard exudates than in six eyes with an intraretinal one (P <.05, Wilcoxon rank sum tests).
CONCLUSIONS: If serous retinal detachment develops before or after vitrectomy for diabetic macular edema, hard exudates tend to accumulate not only in the neurosensory retina but also in the subretinal space. The visual prognosis is worse in cases of subretinal exudation.