Influence of Tamponade on Retinal Shift in Eyes Undergoing Vitrectomy for Rhegmatogenous Retinal Detachment: A Comparison of Gas Versus Silicone Oil in a Pakistani Population

Detailed Description Background Rhegmatogenous retinal detachment (RRD) is a vision-threatening condition in which a retinal break allows fluid to accumulate in the subretinal space, leading to separation of the neurosensory retina from the retinal pigment epithelium. Surgical repair aims to achieve retinal reattachment and preserve visual function. Pars plana vitrectomy (PPV) is a standard surgical technique for the management of RRD. The use of intraocular tamponade agents is essential to support retinal breaks postoperatively until retinopexy becomes effective. Commonly used tamponade agents include expansile gases and silicone oil, which differ in their physical properties, duration of action, and clinical indications. Postoperative retinal displacement has been increasingly recognized following anatomically successful retinal detachment repair. This phenomenon refers to a shift in retinal position after reattachment and may contribute to visual disturbances such as metamorphopsia and diplopia despite successful surgery. Retinal displacement can be detected using fundus autofluorescence (FAF) imaging, where hyperautofluorescent lines corresponding to previous retinal vessel locations (retinal vessel printings) may be observed. The influence of tamponade type on postoperative retinal displacement remains unclear. Additionally, there is limited data evaluating this relationship in South Asian populations. Study Rationale Understanding whether the choice of intraocular tamponade affects the occurrence of retinal displacement may help refine surgical decision-making and improve patient counseling regarding visual outcomes following PPV for RRD. Study Design and Setting This is a prospective, randomized, parallel-group clinical trial conducted at a tertiary care academic center. Eligible patients with primary rhegmatogenous retinal detachment undergoing pars plana vitrectomy are enrolled and randomized into two groups based on the type of intraocular tamponade used. Randomization and Allocation Participants are randomized in a 1:1 ratio to receive either gas tamponade or silicone oil tamponade. Randomization is performed using a pre-generated random number sequence by an independent individual not involved in recruitment or surgery. Allocation concealment is ensured using sequentially numbered, opaque, sealed envelopes opened intraoperatively after retinal reattachment and prior to tamponade insertion. Surgical Technique All procedures are performed by experienced vitreoretinal surgeons using a standardized approach. A 25-gauge three-port pars plana vitrectomy is performed, including core vitrectomy, induction of posterior vitreous detachment when required, peripheral vitreous shaving with scleral indentation, and drainage of subretinal fluid. Perfluorocarbon liquid may be used as needed. Retinal breaks are treated with cryotherapy and/or endolaser photocoagulation. Following retinal reattachment, the assigned intraocular tamponade (expansile gas or silicone oil) is administered. Perioperative management is standardized across both groups, with the tamponade agent being the primary variable. Outcome Assessment Postoperative evaluation includes fundus autofluorescence imaging using a standardized imaging system. Imaging is performed postoperatively, with the primary assessment based on images obtained at approximately one month, when adequate visualization is expected across both groups. Retinal displacement is identified by the presence of hyperautofluorescent lines corresponding to previous retinal vessel positions. Images are graded using predefined criteria and categorized as demonstrating displacement, no displacement, or unassessable due to poor quality. Unassessable images are excluded from the primary analysis. Data Collection and Analysis Baseline demographic and clinical characteristics are recorded prospectively. Statistical analysis is performed using standard software. Continuous variables are summarized using appropriate measures of central tendency and dispersion, while categorical variables are summarized as frequencies and percentages. Comparative analysis is conducted between groups to evaluate differences in the proportion of eyes demonstrating retinal displacement. Appropriate statistical tests are applied based on data type and distribution, with a significance threshold set at p \< 0.05.