Evaluation of choroidal vascular index in patients undergoing surgical treatment for retinal detachment

Purpose: The aim of this study was to evaluate the subfoveal choroidal vascular structure and function in patients who underwent pars plana vitrectomy (PPV) for retinal detachment by calculating the subfoveal choroidal vascular index (SFCVI) value, to determine the relationship between SFCVI value and other parameters such as tamponade type, visual acuity, subfoveal choroidal thickness and to investigate the prognostic significance of SFCVI changes in postoperative examinations for visual acuity. Materials and Methods: Retrospective file data of patients who underwent PPV surgery with a diagnosis of retinal detachment at the Retina unit of the Ophthalmology Department of Karadeniz Technical University Faculty of Medicine between May 2022 and May 2024 were scanned. A total of 60 eyes were included in the study, 30 of whom had surgery as the case group and the eyes that did not have surgery as the control group. The cases were additionally divided into silicone group and C3F8 group according to the tamponade used. Spectral domain optical coherence tomography (SD-OCT) examinations including the center of the fovea were performed on the included patients at the first, third and sixth months after surgery. The patients' best corrected visual acuity (BCVA), intraocular pressure (IOP), subfoveal choroidal thickness (SFCT) calculated from SD-OCT images and subfoveal choroidal vascular index (SFCVI) data were analyzed. Results: The mean age of the patients was 61.0±12.2 years, 18 of whom were male (60%) and 12 of whom were female (40%). The mean axial length (AL) of the RD eyes was 23.9±1.0 millimeters and all had retinal tears. 1000 cst silicone oil (60%) was used as tamponade in 18 of the eyes that underwent surgery and perfluoropropane (C3F8) gas (40%) was used in 12 of them. The mean time from silicone oil tamponade to silicone oil removal was 65.7±30.4 days. A significant increase was observed in BCVA after surgery compared to preoperative values (p<0.001). The first month IOP value was significantly higher in the silicone group compared to the control group (p: 0.023), but no significant difference was found in the third and sixth month IOP values (p: 0.840, p: 0.898, respectively). In the case group, the first and third month SFCVI values were significantly lower than the control group (p: 0.018, p: 0.013, respectively), while no significant difference was observed in the sixth month SFCVI value (p: 0.491). In the C3F8 group, the first month SFCVI values were significantly lower than the silicone group (p: 0.026), but no significant difference was observed for the third and sixth month SFCVI values (p: 0.063, p: 0.385, respectively). The first and third month SFCVI values of the C3F8 group were significantly lower than the control group (p: 0.003, p: 0.023, respectively), but no significant difference was observed for the sixth month SFCVI value (p: 0.182). When the silicone group and the control group were compared, no significant difference was observed between the first, third and sixth month SFCVI values (p: 0.372, p: 0.170, p: 0.711, respectively). No significant change was observed in the SFCVI values within the study groups at the six-month follow-up (p>0.05). No significant correlation was observed between the SFCVI changes in the postoperative follow-up and BCVA, IOP and SFCVI values of the eyes that underwent PPV surgery (p>0.05). Conclusion: Subfoveal choroidal vascular flow in eyes that underwent pars plana vitrectomy surgery due to rhegmatogenous retinal detachment and in eyes that used C3F8 gas as tamponade decreases in the early postoperative period and returns to normal levels in the late postoperative periods. In patients who use silicone tamponade, the subfoveal choroidal vascular flow level can continue at a similar level without any significant change after surgery. In the early postoperative period after PPV surgery, subfoveal choroidal vascular flow is lower in patients who use C3F8 tamponade than in patients who use silicone tamponade. Studies with larger samples are needed to evaluate the relationship between SFCVI changes and visual prognosis after PPV surgery. Key Words: Subfoveal choroidal vascular index, pars plana vitrectomy, intraocular tamponade, visual acuity