The use of dexamethasone implant in eyes with macular edema secondary to retinal vein occlusion

Purpose: To evaluate the efficacy and safety of intravitreal dexamethasone implant (IDI) in patients with macular edema secondary to retinal vein occlusion (RVO) and to find out the factors that may effect the visual prognosis. Methods: The charts of 61 patients underwent IDI injection with at least a 6 months of follow up were reviewed retrospectively. Detailed ophthalmologic examination including best corrected visual acuity (BCVA), optical coherence tomography (OCT) and florescein angiography (FA) scans was performed preoperatively as well as at first, third and sixth months of postoperative follow-up. The effects of initial BCVA, intraretinal cyst diameter, presence of serous retinal detachment (SRD), photoreceptor inner segment outer segment (ISOS) layer integrity, retinal pigment epithelial (RPE) atrophy and the presence of epiretinal membrane (ERM) on visual prognosis were evaluated. Anatomic success was defined being ≤250 µm of central macular thickness (CMT) and functional success was defined as ≥3 lines of increase in BCVA for each eyes. Results: A total of 92 intravitreal dexamethasone implants were injected in 63 eyes of 61 patients (34 females, 27 males) with RVO. The mean age was 63.5±12.1 (38-91). Twenty-seven of eyes had central retinal vein occlusion (CRVO) and 36 had branch retinal vein occlusion (BRVO). Initial BCVA and CMT were 0.93±0.50 logMAR (0.30-2.00) and 628±26 µm (268-1726), whereas they were found as 0.65±0.44 logMAR (p<0.001) and 324±186 µm (p<0.001) in the first month, 0.67±0.45 logMAR (p<0.001) and 366±200 µm (p<0.001) in the third month, as well as 0.81±0.49 logMAR (p=0.004) and 530±233 µm (p<0.001) in the sixth month of follow-up. Functional success was achieved in 33.9% of the cases in both the first and third months, however it was found as 14.5 % in the sixth month of postoperative follow-up. Anatomic success was achieved in 59.7%, 48.4%, and 19.4% of the patients at the first, third and sixth months of the follow-up, respectively. The presence of SRD did not effect statistically significant both anatomic and functional success; however visual prognosis was worse in eyes in which an intraretinal cyst with a diameter of >600 µm was evident when compared to those with an intraretinal cyst of <300 µm and 300-600 µm in diameter in the third month (p=0.011, p=0.033 respectively). In 50% of the eyes with ISOS disintegrity, 66.7% of the eyes with RPE atrophy, and 75% of the eyes with ERM, no improvement in visual acuity was provided after dexamethasone implant application. However a significant increase in visual acuity was achieved after the treatment in eyes with a baseline BCVA of ≥1.0 logMAR (p<0.001), worse visual prognosis was present in such eyes when compared to those with a baseline BCVA of <1.0 logMAR (p<0.001). Intraocular pressure (IOP) rise ≥10 mmHg increase when compared to initial scores occured in 13.5% of the study eyes in the first month of postoperative follow-up, and the frequency of eyes with an IOP ˃30 mmHg measured at any of the postoperative visits was 6.5%. Visually significant cataract formation was present in 13.2% of the phakic eyes during the follow-up. Conclusions: Intravitreal dexamethasone implant was found effective and safe in patients with macular edema secondary to RVO; whereas it has a limited effect in eyes with a baseline visual acuity of ≥1.0 logMAR, intraretinal cyst of >600 µm in diameter, ISOS disintegrity, RPE atrophy and ERM.