Outer retinal layer changes after dexamethasone implant for central retinal vein occlusion

Purpose: To analyze the outer retinal layer changes on spectral-domain optical coherence tomography after dexamethasone implant for the treatment of macular edema secondary to central retinal vein occlusions (CRVO). Methods: Thirty patients affected by macular edema related to CRVO (8 patients less than 50 years of age with nonischemic CRVO [<50-niCRVO], 12 patients more than 50 years with niCRVO [>50-niCRVO], and 10 patients with ischemic CRVO [iCRVO]) were included in a prospective study. After a comprehensive ophthalmologic examination, including best-corrected visual acuity, fluorescein angiography, and spectral-domain optical coherence tomography, each patient received a first implant. Further retreatments were performed on the basis of macular edema detection from the fourth month. Main outcome measure was the change in outer retinal layers at the 12-month examination. Results: The retinal layers of interest (external limiting membrane; ellipsoid zone; and retinal pigment epithelium) were classified as absent, disrupted, or present. The best baseline optical coherence tomography profile was found in <50-niCRVO group (absent external limiting membrane, ellipsoid zone, and retinal pigment epithelium layers in no patients; present and disrupted external limiting membrane in 25% and 75% of cases, respectively; disrupted ellipsoid zone and retinal pigment epithelium in 100% of cases), whereas the worst was detected in the iCRVO group (absent external limiting membrane, ellipsoid zone, and retinal pigment epithelium in 40%, 40%, and 10% of cases, respectively). A significant recovery of the retinal layers was observed in all CRVO subgroups; the greatest improvement was found in <50-niCRVO group. Median best-corrected visual acuity in the whole group improved from 0.85 to 0.45 (P = 0.0001). It is noteworthy that a significant best-corrected visual acuity gain was achieved only in eyes showing present or disrupted layers at baseline regardless of the CRVO subgroup examined, whereas eyes with absent layers at baseline were unable to attain any improvement. Conclusion: Dexamethasone implant can promote the resolution of macular edema in patients affected by any CRVO subform, but a beneficial functional outcome could be achieved by eyes showing no absence of outer retinal layers on spectral-domain optical coherence tomography at baseline.