This review aims to discuss the delicate balance between the physiological production of reactive oxygen species and the role of antioxidant nutraceutical molecules in managing radicals in the complex anatomical structure of the eye. Many molecules and enzymes with reducing and antioxidant potential are present in different parts of the eye. Some of these, such as glutathione, N-acetylcysteine, α-lipoic acid, coenzyme Q10, and enzymatic antioxidants, are endogenously produced by the body. Others, such as plant-derived polyphenols and carotenoids, vitamins B2, C, and E, zinc and selenium, and omega-3 polyunsaturated fatty acids, must be obtained through the diet and are considered essential nutrients. When the equilibrium between the production of reactive oxygen species and their scavenging is disrupted, radical generation overwhelms the endogenous antioxidant arsenal, leading to oxidative stress-related eye disorders and aging. Therefore, the roles of antioxidants contained in dietary supplements in preventing oxidative stress-based ocular dysfunctions are also discussed. However, the results of studies investigating the efficacy of antioxidant supplementation have been mixed or inconclusive, indicating a need for future research to highlight the potential of antioxidant molecules and to develop new preventive nutritional strategies.

Purpose: To validate the cytotoxicity test of perfluorocarbon liquids (PFCLs) for intraocular use according to the ISO 10993-5 standard. Methods: BALB/3T3, ARPE-19 cell lines, and 3-mm human retina ex vivo samples were cultured in 96-well plates. Contact areas of 22%, 59%, and 83% and 2.5-, 12-, and 24-hour contact times were tested in cell lines. Cell viability was quantified by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in ARPE-19 and neutral red uptake (NRU) viability assay for BALB/3T3. Apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay in ARPE-19 cells. 1-H perfluorooctane (1H PFO) and purified perfluorooctane (PFO) were used as cytotoxic and not cytotoxic controls, respectively. Cell viability was assessed by MTT assay in retina ex vivo samples. Results: Qualitative evaluation showed that cytotoxic control induced apoptosis, severe reactivity zones, and cytotoxicity according to ISO 10993-5 in all tested conditions. Quantitative evaluation of 1H PFO showed no cytotoxicity according to ISO 10993-5 on 22% areas, whereas cytotoxicity was detected on 59%, and 83% contact areas. The PFO was confirmed not to be cytotoxic in all tested conditions. Quantitative evaluation in retina ex vivo samples confirmed no cytotoxicity with PFO and cytotoxicity with 1H PFO. Conclusions: The direct contact cytotoxicity test according to ISO 10993-5 is a suitable method to detect the cytotoxicity of PFCLs and was validated using quantitative and qualitative approaches in ARPE-19 and BALB/3T3 cells covering 59% of the cell surface areas for 24 hours. Translational Relevance: Direct contact cytotoxicity test using specific conditions was validated, whereas different test conditions could not be validated.

The different anatomical compartments of the eye are highly subjected to reactive oxygen species (ROS) generation due to internal factors, such as metabolic high oxygen consumption, as well as environmental factors, including UV light. An antioxidant defense system is endowed in the eye tissues to regulate ROS quantity and activity. When this homeostatic system is overwhelmed, oxidative stress occurs, causing cellular damage, chronic inflammation, and tissue degeneration. It also plays a significant role in the development and progression of various ocular diseases. Understanding the mechanisms underlying oxidative stress in ocular conditions is thus crucial for the development of effective prevention and treatment strategies. To track marketed products based on antioxidant substances as active ingredients, the databases of the European Medicines Agency and the U.S. Food and Drug Administration were consulted. Only a limited number of items were identified, which were either used as therapeutic treatment or during ocular surgery, including antioxidants, synthetical derivatives, or pro-drugs designed to enhance tissue permeation and activity. This review aims to provide an overview of the primary ocular pathologies associated with oxidative stress and of the available pharmacological interventions centered around antioxidant molecules. Such insights are essential for advancing the development of effective prevention and novel treatment approaches.

Objective: To evaluate the clinical outcomes of cornea transplantation (penetrating keratoplasty, Descemet membrane endothelial keratoplasty, Descemet stripping automated endothelial keratoplasty, and deep anterior lamellar keratoplasty) using donor corneas stored in Eusol-C hypothermic storage medium compared to corneas stored in organ-culture. Methods: The clinical outcomes of 92 patients who underwent corneal transplantation with human donor corneas stored in Eusol-C medium at 2–8 °C were retrospectively evaluated. The control group consisted of 169 patients who received corneas organ-cultured at 31 °C. Donor age, sex, death-to-preservation time, and storage time were recorded. Endothelial cell (EC) density (ECD), EC mortality, and EC morphology scores were evaluated during storage in both groups. Complication rates, visual outcomes, and corneal transparency were monitored for up to six months. Results: The mean storage in Eusol-C time was 7.7 ± 2.5 days, while organ-culture time was 14.2 ± 4.0 days. In the Eusol-C group, ECD was 2398 ± 354 cells/mm², with an average EC morphology score of 3.4 ± 0.7/4. Approximately 28% of the corneas in the Eusol-C group had no EC mortality. In the organ-culture group, ECD was 2256 ± 328 cells/mm², with an average EC morphology score of 3.5 ± 0.5/4, and 42% were devoid of EC mortality. No complications, such as re-bubbling, were observed in both groups during surgery. Transparent corneas were achieved in 81.3% of the Eusol-C group the day after surgery. Mean corrected distance visual acuity (CDVA) at 3 and 6 months was 4.5 ± 4.0/10 and 5.4 ± 3.7/10 for the Eusol-C group and 5.0 ± 2.9/10 and 5.7 ± 2.8/10 for the organ-culture group, with no statistical differences observed between the groups. No graft failure was observed up to three months. Graft rejection occurred in the Eusol-C group and in the organ-culture group in, respectively, one and two cases at the six-month follow-up. Conclusions: Comparable surgical outcomes were achieved with donor corneas stored in both hypothermic Eusol-C and organ-culture media.

An ideal dye for intraocular use should effectively stain the target tissue while being easy to apply and remove. Additionally, it should not have any adverse effects resulting from prolonged contact with the retinal tissue. Recently, concerns have been raised about the safety of some vital dyes during surgical procedures as they may cross the internal limiting membrane and deposit on the retina. In this study, we aimed to investigate whether commercially available vital dyes, VIEW-ILM® and TWIN® (AL.CHI.MI.A. S.r.l., Ponte San Nicolò, Padova, Italy), have the potential to cross the internal limiting membrane during vitreoretinal surgery and deposit on the retina. Furthermore, we evaluated their safety in vitro and in vivo. A human-like pars plana vitrectomy was performed on porcine eyes ex vivo, with VIEW-ILM^® or TWIN^® used to stain the internal limiting membrane either with or without subsequent internal limiting membrane peeling. The two dyes were then extracted from retinal punches with or without internal limiting membrane, and quantified using high performance liquid chromatography. Safety was evaluated through in vitro cytotoxicity tests and in vivo skin sensitization and irritation tests according to ISO standards. High performance liquid chromatography analyses demonstrated that VIEW-ILM^® and TWIN^® effectively stained the internal limiting membrane without crossing the membrane. No residual dyes were found in the retinal layers after internal limiting membrane removal. Furthermore, both in vitro and in vivo safety tests confirmed the absence of cytotoxicity, skin sensitization, and irritation. The results of this study support the safety and efficacy of VIEW-ILM^® and TWIN^® for internal limiting membrane staining. The experimental protocol described in this study could be utilized to gain a comprehensive understanding of the characteristics of vital dyes.