Primary Vitrectomy With Silicone Oil or SF6 for Rhegmatogenous Retinal Detachment

Macular Perfusion and Sensitivity Following Silicone Oil Tamponade Versus SF6 Gas for Primary Rhegmatogenous Retinal Detachment

Rhegmatogenous retinal detachment (RRD) is the separation of the neurosensory retina from the retinal pigment epithelium caused by the presence of a break that leads to the passage of fluid from the vitreous cavity into the potential subretinal space. It is a sight threatening disease, affecting largely people 50 years or older, with an annual incidence varying between 6.3 and 17.9 people per 100,000 population, and is unfortunately increasing. Although other surgical options do exist for the repair of primary RRD, pars plana vitrectomy (PPV) has clear advantages and is certainly effective in the treatment of these patients. Several agents are used for intraocular tamponade following PPV for RRD. These agents are either silicone oil (SO) or gases like air, perfluoropropane (C3F8), sulfur hexafluoride (SF6), or perfluoroethane (C2F6). In addition to the complications uniquely peculiar to using SO, research has found out that a reduction in retinal sensitivity on microperimetry was greater in SO tamponade in comparison with gas, as well as poorer visual outcome, microvasculature damage and affection of retinal layers including ganglion cell complex (GCC) in the SO group. Even though many studies were done to compare between SO and intraocular gas tamponades with respect to many aspects, only one study compared the effects SO had on macular vasculature and anatomy in comparison with air and no study at all to date has compared the SO to SF6 gas in terms of retinal vascular changes, correlating them to thinning of GCC and macular sensitivity, which is precisely the main aim of the current study.

Rhegmatogenous retinal detachment (RRD) is the separation of the neurosensory retina from the retinal pigment epithelium (RPE) caused by the presence of a break that leads to the passage of fluid from the vitreous cavity into the potential subretinal space. It is a sight threatening disease, affecting largely people 50 years or older, with an annual incidence varying between 6.3 and 17.9 people per 100,000 population, and is unfortunately increasing. Although other surgical options do exist for the repair of primary RRD, viz. scleral buckling and pneumatic retinopexy, primary pars plana vitrectomy (PPV) has clear advantages and is certainly effective in the treatment of these patients, with a primary success rate of 85%, making it the leading management modality. Several agents are used for intraocular tamponade following PPV for RRD, in order to provide surface tension across the retinal breaks thus preventing the ingress once more of fluid into the subretinal space, giving time for the permanent seal provided by the retinopexy done whether photocoagulation or cryopexy. These agents are either silicone oil (SO) or gases like air, perfluoropropane (C3F8), sulfur hexafluoride (SF6), or perfluoroethane (C2F6). In addition to the complications uniquely peculiar to using SO, research has found out that a reduction in retinal sensitivity on microperimetry was greater in SO tamponade in comparison with gas, as well as poorer visual outcome, microvasculature damage and affection of retinal layers including ganglion cell complex (GCC) in the former group leading to the so-called Silicone Oil-Related Visual Loss (SORVL). Even though many studies were done to compare between SO and intraocular gas tamponades with respect to many aspects, only one study by Zhou et al in 2020 compared the effects SO endotamponade had on macular vasculature and anatomy in comparison with sterilized air tamponade and no study at all to date has compared the SO to SF6 gas in terms of retinal vascular changes, correlating them to thinning of GCC and macular sensitivity, which is precisely the main aim of the current study.

Surgeon will be masked to the tamponading agent (silicone oil or gas) till the end of the operation when either agent will be injected.

Primary pars plana vitrectomy will be performed and silicone oil will be used as the tamponading agent. For these patients, optical coherence tomography (OCT) and angiography (OCTA), along with microperimetry will be done 2 months after the primary surgery. Then they will be scheduled for silicone oil removal after 3 months from the time of primary surgery. Finally, the OCT, OCTA, and microperimetry will be repeated once more after 4 months from the vitrectomy (i.e. one month after the silicone oil removal).

Primary pars plana vitrectomy will be performed and sulfur hexafluoride (SF6) will be used as the tamponading agent. For these patients, optical coherence tomography (OCT) and angiography (OCTA), along with microperimetry will be done 2 months and 4 months after the primary surgery.

Silicone oil will be used at the end of primary vitrectomy. OCT, OCTA and microperimetry will be done 2 months later. Silicone oil will be removed at 3 months. Finally, the OCT, OCTA, and microperimetry will be repeated once more after 4 months from the vitrectomy.

Sulfur hexafluoride (SF6) will be used at the end of primary vitrectomy. OCT, OCTA, and microperimetry will be done 2 months and 4 months after surgery.

Comparison of foveal avascular zone area between the different treatment arms as a measure of macular perfusion.

Comparison of the thickness of ganglion cell complex in microns between the different treatment arms using optical coherence tomography (OCT)

Comparison of best corrected visual acuity between the different treatment arms using standard Snellen charts.

Comparison of single-operation anatomical success (retinal reattachment) rate between the different treatment arms

Inclusion Criteria: Primary rhegmatogenous retinal detachment Exclusion Criteria: Macula-on retinal detachment Change of decision of type of endotamponade used intraoperatively Giant retinal tear Proliferative vitreoretinopathy worse than grade B Recent lens surgery within the previous 3 months prior to presentation Prior vitreoretinal surgery Macular hole Signs of epiretinal membrane Diabetic retinopathy Macular degeneration or other macular disorders Inferior retinal breaks between 4 and 8 o'clock History of uveitis History of glaucoma

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