Rhegmatogenous retinal detachment (RRD) is a vision-threatening condition with an estimated incidence of approximately 1 in 10,000 individuals annually. Pars plana vitrectomy (PPV) combined with intraocular tamponade agents such as expansile gas or silicone oil is a commonly used surgical treatment for retinal reattachment. Although anatomical success rates following PPV are high, postoperative retinal displacement has increasingly been recognized as a frequent phenomenon. Retinal displacement may lead to visual distortion, metamorphopsia, and patient dissatisfaction despite successful anatomical repair.

Fundus autofluorescence (FAF) imaging allows detection of retinal vessel printings (RVPs), which appear as hyperautofluorescent lines corresponding to the previous location of retinal vessels. These findings are considered markers of postoperative retinal displacement. Several studies have suggested that the type of intraocular tamponade may influence the occurrence of retinal displacement, with some reports demonstrating higher displacement rates in eyes treated with gas tamponade compared with silicone oil. However, findings remain inconsistent across studies, and limited data exist from South Asian populations.

This study aims to evaluate the influence of intraocular tamponade type on postoperative retinal displacement following PPV for primary rhegmatogenous retinal detachment in a Pakistani population.

This prospective randomized comparative study was conducted at the Section of Ophthalmology and Visual Sciences, Department of Surgery, Aga Khan University Hospital, Karachi, Pakistan. Patients diagnosed with primary rhegmatogenous retinal detachment who were scheduled to undergo pars plana vitrectomy were eligible for inclusion. Participants were randomized to receive either gas tamponade (sulfur hexafluoride [SF6] or perfluoropropane [C3F8]) or silicone oil tamponade at the end of surgery.

Step 1: Define the Arms

ARM 1: Gas Tamponade

ARM 2: Silicone Oil Tamponade

All surgical procedures were performed using a standardized 25-gauge pars plana vitrectomy technique by experienced vitreoretinal surgeons. Standard surgical steps included core vitrectomy, peripheral vitreous shaving with scleral indentation, drainage of subretinal fluid, retinopexy using laser or cryotherapy, and final internal tamponade according to randomized allocation.

Baseline demographic and clinical characteristics including age, gender, duration of symptoms, macular status, and presence of proliferative vitreoretinopathy were recorded preoperatively. Postoperative retinal displacement was assessed using fundus autofluorescence imaging at the 1-month follow-up visit. Retinal displacement was defined as the presence of hyperautofluorescent lines corresponding to retinal vessel printings on FAF images.

The primary outcome of the study is the incidence of postoperative retinal displacement at 1 month after surgery. Secondary analyses evaluate the relationship between retinal displacement and factors such as patient age and duration of retinal detachment prior to surgery.

Understanding the relationship between tamponade type and postoperative retinal displacement may help improve surgical planning and patient counseling regarding visual outcomes following retinal detachment repair.

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.

Inclusion Criteria:

• Diagnosis of primary rhegmatogenous retinal detachment (RRD).
• Planned management with pars plana vitrectomy (PPV).
• Age ≥ 18 years.
• Willingness and ability to provide written informed consent.

Exclusion Criteria:

• Prior vitreoretinal surgery in the study eye.
• Tractional or exudative retinal detachment.
• Media opacities (e.g., dense cataract, corneal opacity, vitreous hemorrhage) precluding fundus autofluorescence imaging.
• Any condition that, in the investigator's opinion, would preclude safe participation or compliance with study procedures.

Individual participant data (IPD) will not be shared outside the study team due to patient privacy concerns and institutional policies governing clinical data. All collected data will be used solely for the purposes of this study and related publications

No masking was performed. Both participants and treating surgeons were aware of the assigned tamponade. Outcome assessment was performed using fundus autofluorescence imaging without masking.