BLOG: Adjunctive medical therapy for glaucoma: The case against timolol
We are extremely fortunate to have a number of efficacious and relatively safe medical therapies to choose from when treating our patients with ocular hypertension and glaucoma.
In most cases, our initial “go-to” agent will be one of the prostaglandin analogues (latanoprost, bimatoprost, travoprost or tafluprost). These agents are highly effective, are dosed once daily and have a good safety profile. But glaucoma care is usually not that easy. The majority of treated individuals require more than one agent for IOP control. So, what next?
My next, or adjunctive, medical treatments of choice are usually either a topical carbonic anhydrase inhibitor (dorzolamide or brinzolamide) or a Rho kinase inhibitor (netarsudil). These agents are generally well tolerated, with essentially no risk for systemic adverse effects. Netarsudil has advantages of once-daily dosing and a mechanism of action that is in line with glaucoma pathophysiology. From an efficacy perspective, both classes have been shown to offer 24-hour IOP lowering.
What about timolol? Of course, timolol’s introduction in the late 1970s allowed ophthalmologists to control many glaucomas medically. At the time, many of these patients would have otherwise gone on to trabeculectomy surgery. Since timolol’s introduction, we have learned more about the agent’s drawbacks in terms of efficacy and safety. Several studies have shown that timolol’s efficacy is limited during the nocturnal time period. These findings may explain why patients with seemingly well-controlled daytime IOPs still experience glaucomatous progression — because of peak nocturnal IOPs that are higher due to waning efficacy of their beta-blockers. Furthermore, the daytime incremental efficacy of timolol is blunted in patients on oral beta-blocker therapy for systemic conditions. A host of potential systemic adverse effects — from disordered breathing to erectile dysfunction — also limit long-term usage of these agents. Finally, timolol may have negative effects on ocular perfusion pressure. These effects may have especially dire consequences for patients with low-tension glaucoma, who are suspected to have a more prominent vascular component to their disease process.
The above reasons make timolol a third- or fourth-line agent for patients in my practice. I am certain that with novel technologies such as contact lens sensors, we will learn more about the importance of 24-hour IOP control and the limitations of some of our topical medical agents in this regard.
Collapse