Chemistry of Ophthalmic Preparations: Proper Use, Formulation Errors and Recent Advances

Topical ophthalmic medications are among the most frequently used therapeutic modalities in the management of ocular diseases. However, the clinical effectiveness of topical ophthalmic formulations depends not only on their pharmacological properties but also on correct administration techniques and patient adherence. Owing to the physiological barriers of the eye and the rapid elimination of drugs, the bioavailability of topically administered ophthalmic agents is inherently limited, and improper application further exacerbates this limitation. Clinical studies have demonstrated that a substantial proportion of patients do not use topical ophthalmic formulations as recommended, leading to treatment failure, an increased risk of systemic adverse effects, and reduced patient compliance. In this review, the pharmacokinetic characteristics of topical ophthalmic formulations and the ocular barriers affecting drug delivery are discussed in detail. Principles of correct administration are comprehensively evaluated, and common application errors encountered in clinical practice are addressed. In addition, the potential adverse effects of preservatives commonly used in ophthalmic formulations, particularly benzalkonium chloride, on the ocular surface, as well as their impact on patient comfort and treatment adherence, are reviewed. The importance of patient education and regular clinical follow-up in achieving therapeutic success is emphasized. Furthermore, current and future strategies, including sustained-release drug delivery systems, drug loaded contact lenses, and digitally assisted applications, are discussed. In conclusion, proper use of topical ophthalmic formulations represents a fundamental determinant of the effectiveness of ophthalmic treatments. Improving clinical results and minimizing complications can be achieved by prioritizing thorough patient counseling, selecting non-preserved medications for suitable individuals, and adopting modernized administration technologies within medical routines.