Dr Wong et al state that the number of cases with less than 2 months of tamponade is disproportionally low. The reason for the unequal distribution is that we consider 3 months as the minimum period of tamponade. This potentially introduces confounding, as the reason for early silicone oil removal could be related to worse outcome. Thus, although we revealed a statistically significant influence of tamponade duration, further study is needed to determine a causal relation, preferably using a controlled design, comparing equally sized groups. We thank Dr Wong et al for pointing out an error in the manuscript. The number of cases with tamponade of less than 2 months was not 10, as stated in the paper, but was 14. Of these 14 cases, 6 redetached, which amounts to 43% as depicted in the paper correctly.
Dr Wong et al describe a perceived discrepancy between the exclusion of cases with clinically apparent macular pucker and the performance of membrane peeling. The peelings performed were for membranes located outside the macula, for instance, along the retinectomy edges. The indication for peeling of these membranes was not standardized, and was mainly dependent on intraoperative assessment of the presence of traction after staining by membrane blue. The underlying idea was that prophylactic removal of dormant retinal traction could improve the outcome.
Our study was a retrospective, uncontrolled case series. The objective was to describe the transition from a two-port to a three-port technique. The reason for our transition was our hypothesis that the ability to perform an internal search could identify more retinal breaks, and that membrane removal could release dormant peripheral traction. Despite these theoretical advantages of the three-port technique, our results could not show any influence on outcome. Because of the retrospective, uncontrolled design of our study, there is plenty of room for confounding. But unless better equipped studies can show better results from a more expensive technique, we still feel that adherence to the traditional technique of oil removal is preferable.
Wong R, Lee E, Shunmugam M . Comment on ‘Silicone oil removal after rhegmatogenous retinal detachment: comparing techniques’. Eye 2012; 26: 1276.
Tan HS, Dell’Omo R, Mura M . Silicone oil removal after rhegmatogenous retinal detachment: comparing techniques. Eye 2012; 26: 444–447.
The authors declare no conflict of interest.