Silicone Oil Utilized in Pars Plana Vitrectomy for Patients with Advanced Proliferative Diabetic Retinopathy: Physico-Chemical and Optical Properties.

Objective: Silicone oils have the role in maintaining the attachment of the retina in conditions where the risk of retinal re-detachment is high. However, silicone oils have the tendency to emulsify with subsequent complications. In this work, analyses have been performed to understand changes that occurred to the optical, and physical characteristics of the oil after removal from the vitreous cavity of patients underwent pars plana vitrectomy (PPV) for fibrovascular membranes/tractional retinal detachment (FVM/TRD). Methods: Four samples of silicone oil were allocated from patients who underwent PPV for FVM/TRD. The Fourier-transform infrared (FTIR) spectroscopy, micro-viscometry, and ultraviolet-visible spectrometer analyses were utilized to determine the changes in its chemical bondings, viscosity, absorbance, transmittance, buoyance, and specific gravity. Results: The mean age of the patients was 49.0 years. The mean duration of silicone oil implantation was 18.9 months. FTIR analysis showed significant breaking in the chemical bonding that was related to the lens status during the primary PPV, the presence of significant retinal hemorrhages, the duration of silicone oil implantation, and the degree of silicone oil filling. Similarly, viscosity and contact angle analyses revealed a reduction in the viscosity with similar factors to the FTIR analysis. Moreover, absorbance and transmittance were largely affected by the aggressiveness of FVM/TRD. Conclusion: This study revealed that certain factors such as the age of the patient, duration of silicone oil implantation, lens status, and the presence of retinal hemorrhages, the degree of silicone oil filling and aggressiveness of FVM/TRD may contribute to the emulsification process.

Vitreous Levels of Vascular Endothelial Growth Factor and Platelet-Derived Growth Factor in Patients with Proliferative Diabetic Retinopathy: A Clinical Correlation.

Background: The global epidemic status of diabetic retinopathy (DR) and its burden presents an ongoing challenge to health-care systems. It is of great interest to investigate potential prognostic biomarkers of DR. Such markers could aid in detecting early stages of DR, predicting DR progression and its response to therapeutics. Herein, we investigate the prognostic value of intravitreal concentrations of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) in a DR cohort. Materials and methods: Vitreous sample acquisition was conducted at King Abdullah University Hospital (KAUH) between December 2020 and June 2022. Samples were obtained from any patient scheduled to undergo a pars plana vitrectomy (PPV) for any indication. Included patients were categorized into a DR group or a corresponding non-diabetic (ND) control group. Demographics, clinicopathological variables, standardized laboratory tests results, and optical coherence tomography (OCT) data were obtained for each included individual. Intravitreal concentrations of VEGF and PDGF were assessed using commercial enzyme-linked immunosorbent assay (ELISA). Results: A total of 80 eyes from 80 patients (DR group: n = 42 and ND control group: n = 38) were included in the analysis. The vitreous VEGF levels were significantly higher in the DR group compared to the ND control group (DR group 5744.06 ± 761.5 pg/mL versus ND control group 817.94 ± 403.1 pg/mL, p = 0.0001). In addition, the vitreous PDGF levels were also significantly higher in the DR group than those in the ND control group (DR group 4031.51 ± 410.2 pg/mL versus ND control group 2691.46 ± 821.0 pg/mL, p = 0.001). Bassline differences between test groups and clinical factors impacting VEGF and PDGF concentrations were investigated as well. Multiple regression analysis indicated PDGF as the sole independent risk factor affecting best-corrected visual acuity (BCVA) at the last follow-up visit: the higher the PDGF vitreous levels, the worst the BCVA. Conclusions: Vitreous concentrations of VEGF and PDGF are correlated with DR severity and may exhibit a possible prognostic potential value in DR. Further clinical and experimental data are warranted to confirm the observed findings and to help incorporate them into daily practice.

Optical and Physical Properties of Silicone Oil Extracted from the Vitreous of Patients Who Underwent Vitrectomy for Retinal Detachment.

Purpose: Silicone oil (SO) is a crucial tool in vitreoretinal surgery. SO has the tendency to emulsify depending on certain factors. In this work, detailed analyses have been conducted to understand changes that occurred to the physical, optical, and chemical characteristics of the oil after removal from the vitreous cavity. Methods: Five samples of SO were collected from patients who underwent vitrectomy for rhegmatogenous retinal detachment. The fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible spectrometer, and contact angle analysis were utilized to determine the changes in its chemical bondings, transmittance, absorbance, viscosity, buoyance, and specific gravity. Results: FTIR analysis showed significant changes in the chemical bonding that might be related to the age of the patient, lens status, the presence of retinal hemorrhages, and the exposure to laser after implantation of SO. In addition, contact angle analysis revealed that the viscosity might be affected by duration of implantation and the age of the patient. Moreover, transmittance and absorbance were largely affected by the exposure to laser retinopexy after implantation. Conclusion: This study showed that certain factors such as the age of the patient, the exposure to laser, lens status, and the presence of retinal hemorrhages may contribute to the emulsification process.

Anterior Versus Retropupillary Iris-Claw Intraocular Lens: Indications, Visual Outcome and Postoperative Complications.

INTRODUCTION: In cases of inadequate capsular support for intraocular lens (IOL) implantation, iris-claw IOL is a practical option. Iris-claw IOL can be implanted anteriorly or retropupillary. In this study, we compare the outcome of implantation of iris-claw IOL between anterior and retropupillary locations. METHODS: We retrospectively examined the characteristics and outcomes of patients who underwent iris-claw "Artisan®" intraocular lens implantation (IOL) during the period of January 2014 to July 2020. The study population included all patients who underwent iris-claw IOL implantation, whether as a primary or secondary implantation, regardless of the causative indication. The study population was categorized by location of implantation and indication. The outcome was compared by visual acuity and postoperative complications. RESULTS: In this study, 171 eyes of 151 patients were included. Iris-claw IOL was implanted anteriorly in 110 (64.3%) eyes. The most common indication for iris-claw IOL was complicated cataract surgery, followed by ectopia lentis and by trauma. Patients with retropupillary position achieved better visual outcome whatever the causative indication. Anterior iris-claw IOL patients had more high intraocular pressure readings and macular edema. CONCLUSIONS: This study revealed that retropupillary iris-claw IOL may achieve better visual outcome without significant postoperative complications. Further prospective studies and trials on larger sample sizes are needed.

Unilateral Ocular Siderosis Bulbi Due to Missed Metallic Intraocular Foreign Body Masquerading as Anisocoria of Neurological Origin: A Case Report.

BACKGROUND Ocular siderosis is an uncommon cause of vision loss due to a retained ferrous intraocular foreign bodies (IOFB) that cause iron deposition in ocular tissues. The most common manifestations are cataract formation, diffuse pigmentary changes of the retinal pigment epithelium, iris heterochromia, dilated pupils, secondary glaucoma, iritis, and cystoid macular edema. CASE REPORT We report a case of 38-year-old man who presented with a left dilated pupil and visual field defect. Neurological examination results were normal. Brain magnetic resonance imaging revealed a gross artifact at the site of the left globe. The visual field test showed a peripheral arcuate nasal visual field defect in the left eye. Ophthalmic examination revealed peripheral pigmentary changes and a black elongated and elevated lesion located very anterior and inferior-temporal and attached to the retina with fibrous tissue. A computed tomography scan revealed a 1×1-mm-round hyperdense IOFB in the left vitreous cavity. The diagnosis of siderosis bulbi secondary to a missed IOFB was established. The patient underwent a pars plana vitrectomy for removal of the IOFB. Two weeks later, rhegmatogenous retinal detachment developed, and repair with silicon oil injection was done. One year after the last operation, the best corrected visual acuity in the left eye was 6/120, with normal intraocular pressure and an attached posterior pole. CONCLUSIONS This case highlights the importance of investigating for a retained IOFB in cases of unilateral retinitis pigmentosa changes.

International multi-center study of iatrogenic retinal tears in pars plana vitrectomy.

AIM: To study and compare the effect of different surgical settings on the development of iatrogenic retinal tears (IRT) in conventional (20-gauge) and microincisional vitrectomy. METHODS: An international retrospective comparative study of 394 patients who had simple vitrectomy at three tertiary centers. Surgeries were performed by four retina surgeons using different viewing systems. Two groups of eyes were compared: microincisional vitrectomy (327 eyes) and conventional (67 eyes) vitrectomy. An iatrogenic tear was defined as the occurrence of one or more peripheral retinal tears during surgery or at any visit in the first 6wk postoperatively. RESULTS: Mean age was 67±12y and 55% were female. Iatrogenic tears occurred in 11/394 (2.8%) of eyes. The rate of tears was similar among different surgeons and viewing systems (P=0.93 and P=0.76, respectively). Surgical indication, preexisting pseudophakia/aphakia, induction of posterior vitreous detachment (PVD) during surgery, and the use triamcinolone acetonide didn't significantly affect the rate of tears (P>0.1 for all factors). A higher rate of tears was found in the conventional group compared to the microincisional group (respectively, 7.5%, 1.8%, P=0.02). CONCLUSION: The rate of IRT in vitrectomy is not significantly affected by surgical indication, preexisting PVD or pseudophakia, or use of triamcinolone or different viewing systems but is significantly higher in conventional vitrectomy. Microincisional platforms improve the safety of vitrectomy regardless of the viewing system used.

Clinical Efficacy of Simulated Vitreoretinal Surgery to Prepare Surgeons for the Upcoming Intervention in the Operating Room.

PURPOSE: To evaluate the efficacy of the virtual reality training simulator Eyesi to prepare surgeons for performing pars plana vitrectomies and its potential to predict the surgeons' performance. METHODS: In a preparation phase, four participating vitreoretinal surgeons performed repeated simulator training with predefined tasks. If a surgeon was assigned to perform a vitrectomy for the management of complex retinal detachment after a surgical break of at least 60 hours it was randomly decided whether a warmup training on the simulator was required (n = 9) or not (n = 12). Performance at the simulator was measured using the built-in scoring metrics. The surgical performance was determined by two blinded observers who analyzed the video-recorded interventions. One of them repeated the analysis to check for intra-observer consistency. The surgical performance of the interventions with and without simulator training was compared. In addition, for the surgeries with simulator training, the simulator performance was compared to the performance in the operating room. RESULTS: Comparing each surgeon's performance with and without warmup trainingshowed a significant effect of warmup training onto the final outcome in the operating room. For the surgeries that were preceeded by the warmup procedure, the performance at the simulator was compared with the operating room performance. We found that there is a significant relation. The governing factor of low scores in the simulator were iatrogenic retinal holes, bleedings and lens damage. Surgeons who caused minor damage in the simulation also performed well in the operating room. CONCLUSIONS: Despite the large variation of conditions, the effect of a warmup training as well as a relation between the performance at the simulator and in the operating room was found with statistical significance. Simulator training is able to serve as a warmup to increase the average performance.