Selective Laser Trabeculoplasty (SLT) has gained usage because practitioners have more awareness of ocular surface disorders. They also recognize it as a way to simplify drop regimens and resolve compliance issues with application of IOP lowering drops. Based on recent data in 2022, is it time for SLT to become the recommended initial treatment of glaucoma, not just an option for patients?
In other parts of the world, this has already become the case. The National Institute for Health and Care Excellence (NICE) of the UK recommends SLT be the first line of treatment. They have published a flowchart of management options for people with chronic open angle glaucoma that states: offer a generic prostaglandin analogue (PGA) only after SLT, if SLT is not suitable, if the person chooses not to have SLT, or if the person is waiting for SLT and needs an interim treatment.
Over three years of promising data from the LiGHT study1 has assisted in changing this concept on glaucoma management. However, this study focused mostly on mild glaucoma patients. Another study, "Selective laser trabeculoplasty versus 0·5% timolol eye drops for the treatment of glaucoma in Tanzania: a randomised controlled trial,"2 found SLT to be superior to timolol in severe glaucoma patients.
The purpose of the COAST trial, an ongoing study, is to understand if SLT performed at low energy is as effective as SLT performed at standard energy, and also to see if repeating SLT at low energy once a year will prevent or delay the need for daily eye drop medications better than waiting for SLT to wear off before repeating it.
Some believe delivering a low dose of laser energy on a regular basis, comparative to a vaccine booster shot, automatically before the IOP control wanes would be more beneficial. The goal of the COAST trial is to move one step closer to the possibility of a drop-free lifetime for our patients.
SLT applied directly to the surface of the eye, not through a gonial prism, is referred to as DSLT (Eagle). The goal is to develop a more efficient and patient-friendly laser therapy. Since no coupling agent or contact lens is needed, both eyes can be treated in one sitting without blurring the patient's vision.
This is currently not available in the US however there are two significant European trials: "European trial Automated Direct Selective Laser Trabeculoplasty: First Prospective Clinical Trial" and "Direct selective laser trabeculoplasty in open angle glaucoma study design: a multi-centre, randomized, controlled, investigator-masked trial (GLAUrious)."3 The GLAUrious trial advisory board plans to present information to FDA very soon.
ViaLase is an OCT-guided femtolaser trabeculostomy that is an alternative to traditional Schlemm's canal surgery is performed in a clinic setting rather than an operating room. Vialase is currently in clinical trials. The 2021 study found the perfusion pressure was decreased in the perfused anterior segments that underwent FLT with a mean decrease in the perfusion pressure of 22% from baseline.
Bimatoprost implant (DURYSTA) is injected directly into the anterior chamber where it delivers the medication for up to for months. It decreases risk of surface toxicity4 and compliance issues when compared to drop therapy. DURYSTA is only FDA-approved for one application at the moment because implants don't dissolve as quickly as desired and the possible don't want consequences to the epithelium are still unknown.
Negative pressure application
Negative pressure application via a multi-pressure dial involves the patient wearing airtight eye goggles which create a micro environment. These goggles are attached to a negative pressure pump which reduces pressure only in this micro environment, relative to the retrobulbar space, effectively lowering IOP. This nightly non-pharmalogical and non-surgical method can be likened to sleep apnea therapy.
The study data will be presented to the FDA shortly, and I am optimistic that it will be a nice option for some of our patients who are getting worse despite seemingly good pressure control. Think of it like nightly dialysis of the optic nerve. If we can lower pressure low enough that they get axoplasmic flow it might help with ganglion cell health.5
Incisional surgery is recommended when cataract surgery required and coincident glaucoma, progression of disease despite medicines and laser, poorly compliance and/or intolerance to medications. Three decades ago there were only three incisional surgery methods available for lowering IOP while now there is a plethora of surgical options including iStent, Hydrus and the newer Streamline surgical system.
There are many reasons to look forward to the future of glaucoma treatment. As newer methods aquire more clinical data and more procedures are approved by the FDA, practicioners will find it easier to tailor treatment to the needs of each patient. This will not only to improve their eye health but also their quality of life.
- Gazzard G, Konstantakopoulou E, Garway-Heath D, et al; LiGHT Trial Study Group. Selective laser trabeculoplasty versus eye drops for the first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trial [published online ahead of print March 8, 2019]. Lancet. doi: 10.1016/S0140-6736(18)32213-X.
- Philippin H, Matayan E, Knoll KM, et al. Selective laser trabeculoplasty versus 0·5% timolol eye drops for the treatment of glaucoma in Tanzania: a randomised controlled trial. The Lancet. Global Health. 2021 Nov;9(11):e1589-e1599. DOI: 10.1016/s2214-109x(21)00348-x. PMID: 34655547; PMCID: PMC8526362.
- Congdon N, Azuara-Blanco A, Solberg Y, et alDirect selective laser trabeculoplasty in open angle glaucoma study design: a multicentre, randomised, controlled, investigator-masked trial (GLAUrious)British Journal of Ophthalmology Published Online First: 25 August 2021. doi: 10.1136/bjophthalmol-2021-319379
- Medeiros FA, Walters TR, Kolko M, Coote M, Bejanian M, Goodkin ML, Guo Q, Zhang J, Robinson MR, Weinreb RN; ARTEMIS 1 Study Group. Phase 3, Randomized, 20-Month Study of Bimatoprost Implant in Open-Angle Glaucoma and Ocular Hypertension (ARTEMIS 1). Ophthalmology. 2020 Dec;127(12):1627-1641. doi: 10.1016/j.ophtha.2020.06.018. Epub 2020 Jun 13. PMID: 32544560.
- Russell J. Swan, Tanner J. Ferguson, Manjool Shah, Kelly W. Muir, Thomas W. Samuelson, Iqbal Ike K. Ahmed, Richard L. Lindstrom, Nathan M. Radcliffe, John P. Berdahl; Evaluation of the IOP-Lowering Effect of a Multi-Pressure Dial at Different Negative Pressure Settings. Trans. Vis. Sci. Tech. 2020;9(12):19. doi: https://doi.org/10.1167/tvst.9.12.19.