Contact Lenses as Drug Delivery System for Glaucoma: A Review

Abstract

Glaucoma is an optical neuropathy associated to a progressive degeneration of retinal ganglion cells with visual field loss and is the main cause of irreversible blindness in the world. The treatment has the aim to reduce intraocular pressure. The first therapy option is to instill drugs on the ocular surface. The main limitation of this is the reduced time of the drug staying on the cornea. This means that high doses are required to ensure its therapeutic effect. A drug-loaded contact lens can diffuse into the post lens tear film in a constant and prolonged flow, resulting in an increased retention of the drug on the surface of the cornea for up to 30 min and thus providing a higher drug bioavailability, increasing the therapeutic efficacy, reducing the amount of administered drug, and thereby provoking fewer adverse events. Several different systems of drug delivery have been studied in recent decades; ranging from more simple methods of impregnating the lenses, such as soaking, to more complex ones, such as molecular imprinting have been proposed. Moreover, different drugs, from those already commercially available to new substances such as melatonin have been studied to improve the glaucoma treatment efficacy. This review describes the role of contact lenses as an innovative drug delivery system to treat glaucoma.

In Vivo Efficacy of Contact Lens Drug-Delivery Systems in Glaucoma Management. A Systematic Review

“…Recently, Peral et al detailed technical aspects of a CL drug-delivery system in glaucoma, highlighting the increased drug bioavailability [21]. Simultaneously, administering a lower drug dose, adverse events' frequency and severity were reduced [21].…”

“…Recently, Peral et al detailed technical aspects of a CL drug-delivery system in glaucoma, highlighting the increased drug bioavailability [21]. Simultaneously, administering a lower drug dose, adverse events' frequency and severity were reduced [21]. In particular, only 20% of the drug dose was required to produce a similar therapeutic effect with CL drug-delivery systems compared to the dose needed with eyedrops delivery systems [65].…”

“…A sustained drug-delivery system could overcome all the issues mentioned-adherence, pulsatile therapeutic effect, and low retention time. Therefore, over the last decade, the pharmaceutical industry has developed alternative drug-delivery systems [19,21]. These solutions can be classified as intraocular (e.g., implants, nanoparticles, and inserts) or topical (e.g., conjunctival inserts, contact lens (CL), gels, nanoparticles, mucoadhesive polymers, ointments, solutions, and suspensions) [19].…”

Soft Contact Lenses as Drug Delivery Systems: A Review

“…There are two main groups of contact lenses depending on the designed material: soft contact lenses–made of hydrogel or silicone hydrogel polymers, and rigid gas-permeable contact lenses (RGP) [ 28 ]. The soft materials for use as drug delivery systems are of more interest because of their hydrophilic properties, biocompatibility, and comfort of use [ 34 , 35 ].…”

“…The dynamic of this research is evidenced by the number of publications that appear in scientific journals. Table 1 summarises the review papers that have been published in recent years [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ].…”