Retinal Nerve Fiber Layer Changes after Intraocular Silicone Oil Tamponade in Rhegmatogenous Retinal Detachment

Rhegmatogenous retinal detachment (RRD) is a serious and emergency condition that may cause visual disturbance. Treatment includes pars plana vitrectomy with a tamponade such as intraocular gas or silicone oil (SO). In many countries, silicone oil is still favorable compared to intraocular gases as tamponade for reattachment of retinal detachment surgery. The application provides a higher anatomical success rate, especially in cases of proliferative vitreoretinopathy (PVR) that were previously considered untreatable. Objective assessment of the retinal nerve fiber layer (RNFL) using optical coherence tomography (OCT) in the eye with silicone oil tamponade is a challenge because of the limitations and difficulties in taking images. This study aims to assess the RNFL thickness changes in rhegmatogenous retinal detachment patients using SO tamponade and its subsequent removal conducted on a total of 35 post-operative RRD patients. Central macular and RNFL thickness, as well as best-corrected visual acuity (BCVA), were recorded at the time of tamponade and after the removal of the SO at 1, 4, and 8 weeks, respectively. The results showed that the changes in RNFL thickness significantly decreased in the group of ≤6 months, especially in the superior and temporal quadrants, and BCVA increased after SO removal (p < 0.05). Central macular thickness was significant (p < 0.001) at the end of the visit. Improved visual acuity is associated with decreased RNFL and central macular thickness after SO removal.

Centrifugally concentric ring-patterned drug-loaded polymeric coating as an intraocular lens surface modification for efficient prevention of posterior capsular opacification

Posterior capsular opacification (PCO) is the main postoperative complication after intraocular lens (IOL) implantation in cataract surgery, because of the proliferation of the residual lens epithelial cells (LECs) in the lens capsule. Drug-eluting IOLs, aimed to develop an in situ drug delivery device, are the promising concept in recent years. As IOLs are optical devices other than implants, the feasibility and applicability remain a challenge for drug-eluting coatings. In this investigation, a centrifugally concentric ring-patterned drug-loaded poly(lactide-co-glycolic acid) (PLGA) coating was designed and fabricated by the spin coating technique. The concentric ring-patterned morphologies and the drug loading and release properties were carefully investigated, and the spin coating parameters were optimized. A concentric annular coating with a thin center and thick periphery was obtained, which was particularly suitable for the surface modification of IOLs, as the visual pathway of the intraocular light transmission greatly requires good light transmittance of the IOLs. IOLs with the immunosuppressant cyclosporin A (CsA)-loaded coating (CsA @ PLGA) modification were then fabricated for PCO prevention. The in vitro LECs culture results showed that the CsA @ PLGA coating-modified IOLs significantly inhibited cell proliferation and induced cell death. Western blot analysis showed that the efficient cell inhibition behavior of CsA was due to the autophagy-mediated cell death pathway. The in vivo intraocular implantation results confirmed the desired PCO inhibition effect. Thus, the centrifugally concentric ring-patterned drug-loaded PLGA coating obtained by the spin coating technique provides a simple yet effective alternative of IOL modification for PCO prevention. STATEMENT OF SIGNIFICANCE: • Concentric ring-patterned polymer coating, specifically for drug-eluting IOL fabrication, was developed by the spin coating technique. • The immunosuppressant CsA inhibited LEC proliferation through the autophagy-mediated cell death pathway. • Concentric ring-patterned CsA-eluting IOLs exhibited reliable in vivo PCO prevention. • The drug-eluting IOLs fabricated by the simple and economical spin coating technique have a great potential in clinical translation.

Supercritical fluid technology for the development of innovative ophthalmic medical devices: Drug loaded intraocular lenses to mitigate posterior capsule opacification

Supercritical impregnation technology was applied to load acrylic intraocular lenses (IOLs) with methotrexate to produce a sustained drug delivery device to mitigate posterior capsule opacification. Drug release kinetics were studied in vitro and used to determine the drug loading. Loaded IOLs and control IOLs treated under the same operating conditions, but without drug, were implanted ex vivo in human donor capsular bags. The typical cell growth was observed and immunofluorescence staining of three common fibrosis markers, fibronectin, F-actin and α-smooth muscle actin was carried out. Transparent IOLs presenting a sustained release of methotrexate for more than 80 days were produced. Drug loading varying between 0.43 and 0.75 ± 0.03 µg_drug·mg^-1_IOL were obtained when varying the supercritical impregnation pressure (8 and 25 MPa) and duration (30 and 240 min) at 308 K. The use of ethanol (5 mol%) as a co-solvent did not influence the impregnation efficiency and was even unfavorable at certain conditions. Even if the implantation of methotrexate loaded IOLs did not lead to a statistically significant variation in the duration required for a full cell coverage of the posterior capsule in the human capsular bag model, it was shown to reduce fibrosis by inhibiting epithelial-mesenchymal transformation. The innovative application presented has the potential to gain clinical relevance.