In situ gelling systems are becoming one of the most popular and well-known, with many potential benefits from delivery systems, such as ease of use and ease of manufacture, improve adherence and patient comfort by minimizing the frequency of drug administration. In this review, we will describe the characterization and evaluation of the ophthalmic in situ gel preparation. Among them are physical evaluation (appearance and clarity, pH, isotonicity, gelation temperature, gelling capacity,

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... ty, and stability), chemical evaluation (determining drug content, drug release), microbiological evaluation (sterility, ocular irritability, ocular tolerability, antimicrobial activity, hemolysis activity, bovine corneal opacity and permeability (BCOP) test, preservative efficacy test (PET), microtetrazolium (MTT) reduction cytotoxicity test), and in vivo evaluation such as pharmacokinetic and pharmacodynamic evaluation. Characterizing the chemical, physical, microbiological, and miscellaneous properties of ophthalmic in situ gel formulations can meet the ideal requirements and help determine the best formulation of ophthalmic in situ gel to achieve higher bioavailability values, longer contact times, minimize side effects, not causing irritation or liquid tear production, and providing a maximum therapeutic effect. In situ gels offer the primary requirement of a successful controlled release product that is increasing patient compliance.