Preliminary study on developing ocular formulations for natural antioxidants to prevent long‐term complications associated with high myopia

Abstract

Aims/Purpose: The progression of retinal damage in high myopia (HM) has been associated with a reduction in its antioxidant capacity. α‐Lipoic acid (ALA), among other natural antioxidants, has gained important attention due to its impact on visual health1. The objective of this study is to develop ocular inserts containing ALA and to evaluate the potential ocular irritancy of ALA using the HET‐ CAM (hen's egg test‐chorioallantoic membrane) test.Methods: In the HET‐CAM test, five eggs were used under the following conditions: negative control (NaCl 0.9%), positive control (NaOH 0.1%), low concentration (0.01 M ALA), medium concentration (0.1 M) and high concentration (0.2 M). Bleeding, vascular lysis and coagulation were assessed for 300 s to calculate the Irritation Index (IS)2. For each ocular formulation, 5 mg of ALA was dissolved in phosphate‐buffered saline solution (PBS) with a pH 7.4. Different proportions of selected polymers (HPMC, PVP, HA and PG as an adjuvant) were homogenized and placed into a Petri dish, dried overnight and cut into 1 cm2 inserts.Results: The HET‐CAM measurement demonstrated the absence of haemorrhage, coagulation and lysis in the three tested concentrations of ALA. The IS score falls within the range of 0–0.9, classifying it as non‐irritant. In parallel, four ocular formulations containing 5 mg of ALA were prepared as follows: F1‐ PVP 10%; F2‐ PVP 2.5% and HPMC 1%; F3‐ PVP 2.5% and HA 1%; F4‐ PVP 1%, HA 1% and HPMC 1%. It was shown that F2 and F3 had preferred organoleptic characteristics.Conclusions: ALA was a non‐irritant and probably suitable for ocular administration as an antioxidant. Further research will be conducted to assess the efficacy of the ophthalmic inserts. However, preliminary findings suggest that these inserts hold promise as a potential formulation to delay the long‐term progression of high myopia.