Associations Between Clinical Parameters and Optical-Physicochemical Properties of Silicone Oil Extracted after Pars Plana Vitrectomy: An <i>In Vitro</i> Analysis of 35 Eyes

<b><i>Purpose:</i></b> Silicone oil has several uses and indications in the ophthalmical field. This study aims to determine how the clinical, surgical, and patient factors influence the optical, physical, and chemical properties of silicone oil extracted from vitrectomized eyes and how these changes predispose to emulsification.<b><i>Methods:</i></b> A prospective laboratory-based analysis was adopted. A total of 35 silicone oil samples were obtained from 35 patients who underwent pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment (RRD; 18 eyes) or non-RRD indications (17 eyes). Ultraviolet-visible-infrared (UV-Vis-IR) spectrometry, micro-viscometry, Fourier-transform infrared (FTIR) spectroscopy, and proton nuclear magnetic resonance (¹H-NMR) spectroscopy were performed. Demographic and clinical parameters, including patient age, sex, tamponade duration, PPV indication, lens status, associated cataract surgery, argon laser exposure, and postoperative glaucoma, were obtained and correlated.<b><i>Results:</i></b> Compared with control silicone oil (5,000 cSt viscosity, 77.5% visible-light transmittance), extracted samples exhibited a lower mean viscosity (4,670.3 cSt) and reduced visible-light transmittance (71.8%). Non-RRD eyes showed lower transmittance but higher viscosity (4,857.5 vs. 4,493.5 cSt; <i>P</i> < 0.05) than RRD eyes. Argon laser exposure significantly reduced transmittance (<i>P</i> < 0.05) without affecting viscosity. FTIR indicated more chemical bond cleavage in non-RRD eyes.<b><i>Conclusions:</i></b> Non-RRD eyes exhibited reduced transmittance, increased viscosity, and chemical bond disruption, which may indicate increased emulsification. Furthermore, argon laser exposure appeared to exacerbate optical clarity loss. Strategic timing of silicone oil removal and careful surgical planning may help mitigate emulsification. Further studies are required to explore more secrets of silicone oil physics.