Silicone oil is the preferred tamponade following vitrectomy for retinal detachment surgeries associated with CMV retinitis. A wide range of retinal attachment rate varying from 8–95% has been reported in the literature for these cases with silicone oil tamponade [1, 9] With the advent of the HAART therapy for HIV patients, the life expectancy has increased over a period of time. Thus, an increased longevity necessitates SOR in many patients who have undergone primary vitreous surgery with silicone oil tamponade. As there is paucity of literature on the outcomes of such eyes following SOR, our study aimed to document the outcomes of these eyes. A similar study conducted by Morrison et al. [10] reported a 53% rate of redetachment after silicone oil removal at a median period of 4 months post-SOR. Nine eyes in their series had C3F8, SF6, or air injection at the end of surgery. They observed that simultaneous cataract surgery at the time of SOR and lower CD4 cell counts were associated with a greater risk of redetachment. Our study showed a redetachment rate of 18.2% (2/11; 95% CI, 0–41%). The mean CD4 cell count in their study was 173 cells/mm3, while that in our study was 365 cells/mm3. Also, none of our patients had cataract surgery combined with the SOR at the same sitting. The high CD4 cell count indicates a greater immune competence and possibly could be hypothesized to have contributed to better surgical outcome [11].
Our study has a few inherent limitations and observations. Being a retrospective study, the results need to be interpreted with caution. As the overall sample size is small (11 eyes) and the number of unfavorable events being still smaller (two redetachments), to derive any statistical inference from this study would be erroneous. The overall follow-up is short, both after the primary surgery and after silicone oil removal. This is possibly due to the majority of patients belonging to the lower socioeconomic strata as well as the high mortality associated with AIDS. Among the eyes that did not undergo SOR, 12 eyes had recurrent detachment. A high rate of loss of follow-up (62%) is a major limiting factor of the present study.
In summary, among the eyes that did not undergo SOR, 12 eyes had recurrent detachment. Overall, 14 out of 23 eyes (61%; CI, 40–79%) developed recurrent retinal detachment on follow-up. Our series also showed a retinal attachment rate of 82% following silicone oil removal at a mean follow-up of 7.5 months in eyes that underwent vitrectomy for CMV retinitis-related retinal detachment. This is an improvement on the rates that have been reported in the literature and could be attributed to the higher CD4 counts. Thus, though the overall redetachment rate post-vitrectomy with silicone oil is poor, in cases with attached retina over 6 months, there is a high attachment rate seen post-SOR. A larger prospective series with a longer follow-up is desirous to further validate these results.