Prostaglandin Analogues for Ophthalmic Use: A Review of Comparative Clinical Effectiveness, Cost-Effectiveness, and Guidelines [Internet]

Glaucoma is an umbrella term that refers to eye diseases involving progressive degeneration of the optic nerve. This may lead to gradual irreversible vision loss and potential blindness if not detected or treated early. Although characterized traditionally by an elevated intraocular pressure (IOP), it is now known that glaucoma involves a characteristic atrophy of the optic nerve head, which may or may not be accompanied by elevated IOP. Nonetheless, an elevated IOP is the most important risk factor for glaucoma. IOP is dependent on secretion of aqueous humour by the ciliary body as well as drainage of aqueous humour from the eye. The normal IOP ranges between 10 mmHg and 20 mmHg with an average value of 15 mmHg. Ocular hypertension (OHT) is characterized by a higher than normal IOP level, in the absence of optic nerve damage or visual field loss. Open angle glaucoma (OAG), sometimes referred to as primary open angle glaucoma (POAG), is the most common form of glaucoma, accounting for more than 70% of glaucoma cases. This is caused by a higher concentration of fluid being produced within the eyes, or when the drainage system is not working properly, resulting in a buildup of pressure on the optic nerve, ultimately damaging the optic nerve. A less common type of glaucoma is closed-angle glaucoma or narrow angle glaucoma, which happens when the drainage angle in the eye (formed by the cornea and the iris) closes or becomes blocked.This usually occurs in old age, when the lens in the eye becomes larger, pushing the iris forward and narrowing the space between the iris and the cornea, thereby blocking the aqueous fluid from exiting through the drainage system, resulting in a buildup of fluid and an increase in eye pressure. Secondary glaucoma can occur as a result of other conditions (e.g., infection, inflammation, trauma, or pseudoexfoliation), medication usage (e.g., corticosteroids), or ocular surgery. Finally, in normal tension glaucoma (NTG), the optic nerve is damaged without a concomitant increase in eye pressure. The pathophysiology of NTG is still unclear.There is limited epidemiological data available for glaucoma in Canada. A recently published document by Health Quality Ontario reported more than 400,000 Canadians are affected with glaucoma, with the direct costs of vision loss from glaucoma estimated at $300 million annually. Similar findings were reported from the 2008-2009 Canadian Community Health Survey on Health Aging which estimated that 456,533 Canadians had a diagnosis of glaucoma.Treatments for glaucoma primarily involve lowering IOP levels to a normal range. The target IOP should be modified based on the patient’s age, quality of life (QoL) and risk factors for progression. Treatment strategies for patients with glaucoma include topical or systemic medications, laser therapy, and surgery, although the latter two are less common. Pharmacologic therapy is the most common method of lowering IOP and there are several types of agents available: prostaglandin analogues (PGAs, alternatively defined as prostamides), beta-blockers, carbonic anhydrase inhibitors, alpha adrenergic agonists, and direct-acting cholinergic agonists. Of these, the most common first-line therapy is with PGAs due to favourable effectiveness, once-daily administration, and tolerability compared with the other agents.,, Currently available PGAs include latanoprostene bunod (0.024%), latanoprost (LAT, 0.005%), travoprost (TRA, 0.004%), bimatoprost (BIM, available in two doses, 0.03% and 0.01%), and tafluprost (TAF). Patients who do not meet their target IOP may receive an additional agent, often timolol (TIM, 0.5%), a beta-blocker.In 2015, CADTH prepared a Rapid Response Summary with Critical Appraisal on the clinical effectiveness and cost-effectiveness of BIM compared with other PGAs for ophthalmic use. The objective of the current report is to evaluate the evidence published as of 2015 on the clinical effectiveness and cost-effectiveness of BIM versus other PGAs for ophthalmic use. Additionally, evidence-based guidelines regarding the use of BIM for elevated intraocular pressure will be reviewed.