Ocular drug delivery is challenging due to the presence of anatomical and physiological barriers. These barriers can affect drug entry into the eye following multiple routes of administration (e.g., topical, systemic, and injectable). Topical administration in the form of eye drops is preferred for treating anterior segment diseases, as it is convenient and provides local delivery of drugs. Major concerns with topical delivery include poor drug absorption and low bioavailability. To improve the bioavailability of topically administered drugs, novel drug delivery systems are being investigated. Nanocarrier delivery systems demonstrate enhanced drug permeation and prolonged drug release. This review provides an overview of ocular barriers to anterior segment delivery, along with ways to overcome these barriers using nanocarrier systems. The disposition of nanocarriers following topical administration, their safety, toxicity and clinical trials involving nanocarrier systems are also discussed.

Dry eye disease (DED) is a tear film disorder resulting in hyperosmolarity of the tear film and inflammation of the ocular surface. DED is also referred to as keratoconjunctivitis sicca (KCS) and dry eye syndrome. DED represents a significant public health issue, particularly in older adults, and needs more research and attention. Despite the urgent need for safe and effective pharmacotherapies, there is currently only one approved medication, Restasis®, to tackle DED. In this review article, we present an overview of DED, classification, epidemiology, pathophysiology, diagnosis, and risk factors of DED. Special emphasis is placed on current treatment options for DED such as artificial tears, lipid-containing lubricants, liposomal spray, inserts, anti-inflammatory or immunosuppressant drops, antibiotics, dietary omega-3 essential fatty acids, autologous serum, intense-pulsed-light (IPL), punctual plugs, moisture-retaining eyeglasses, hydrophilic bandage contact lenses and secretagogues. The review also summarizes trends in DED treatment that are patented and are currently under investigation in clinical trials.

In conclusion, combination therapy with HPMC and CsA can be a potential once-a-day formulation for treating DED.

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