The concept for transscleral delivery of selective laser trabeculoplasty (SLT) was developed by Prof. Michael Belkin, and the Belkin Laser company, now Belkin Vision, was established in 2013. The company’s goal is to provide accessible glaucoma care to a broad population, and the efficacy of the Belkin laser is being studied. Glaucoma Physician spoke with Prof. Belkin about the unique features of the company’s laser technology.
Q. What was the inspiration for developing the approach of the Belkin laser technology?
A. My dream has always been to provide an easy and accessible treatment for glaucoma patients. The idea came after writing an article demonstrating that all that is needed for laser therapy to have effect is for the energy to reach the target tissue, whereas the other characteristics of laser radiation, such as coherence and polarization, are irrelevant.1 It is known that the 532-nm wavelength used in conventional SLT penetrates tissues well, so theoretically, the laser energy just needs to reach the trabecular meshwork through the sclera rather than the SLT path through the cornea, which requires a gonioscope.
After initiating the proof-of-concept trial to prove that transscleral SLT is as safe and effective as conventional SLT, it became clear that it is just as effective as conventional SLT. We then developed the automated system and added image analysis to locate the limbus and an eye tracker to provide both safety and accuracy of the beam delivery to the predefined location. The result is an automated system with lasing complete in about 2 seconds.
Q. Tell us about what makes this laser unique in the glaucoma space.
A. If, as expected, we conclude GLAURIOUS — our multicenter, international, randomized controlled trial — as successfully as the proof-of-concept and first-in-human trials,1,2 we will have the fastest, easiest, and most intuitive treatment for glaucoma ever. The direct SLT (DSLT) will enable every ophthalmologist to effectively treat many more glaucoma patients and will obviate, for many patients, drug therapy compliance issues, as well as the side effects invariably associated with chronic eye-drop treatment, such as ocular surface disease.
Because the DSLT technology is easily amenable to remote use, and the system is easily transported, the physician need not be physically at the treatment site and can control the procedure from afar. This telemedicine capability will also alleviate at least some of the glaucoma treatment problems in ophthalmologically underserved areas of the world.
The LiGHT trial demonstrated that SLT is more effective in lowering intraocular pressure and preserving optic nerve integrity, as well as being more cost-effective than eye drops for initial therapy of open-angle glaucoma.3 Consequently, we expect DSLT to reduce glaucoma visual impairment and blindness.
Q. Can you describe some of the data that have come from studying the laser in glaucoma?
A. The limited clinical data so far1,2 indicate that DSLT is at least as effective as SLT. The proof-of-concept trial included 28 patients, randomized 1:1 to conventional SLT (with a goniolens) and transscleral SLT with the same instrument but without a goniolens. Six month follow-up results showed noninferiority. The first-in-human trial, which included 15 patients, was a single-arm trial that showed safety and efficacy of the automated device.
Q. In what settings can it be used and by whom?
A. Any ophthalmologist will be able to use our device, allowing for the treatment of many more patients. The device is a compact tabletop device, thus easily utilized in any location.
Q. How might incorporating this laser improve the glaucoma specialist’s practice?
A. Treatment takes just seconds, so imagine being able to treat at least double the number of patients that you normally would when using SLT. It will make treatment of glaucoma patients faster and more efficient, as simple and fast as prescribing eye drops. This applies to general ophthalmologists, as well as glaucoma specialists. In addition, the glaucoma specialist will be able either to treat a greater number of patients or have their colleagues use this simple DSLT technology, because there is no goniolens required, and this frees the physician up to perform more glaucoma and cataract surgeries in the meantime.
Q. What are the advantages to patients of using the Belkin laser over other SLT technology?
A. Our technology is fast, noninvasive, doesn’t involve contact with the eye, and is very gentle to the patient. There is no rotating goniolens on the eye and no blurry vision after using the coupling gel, so it is more comfortable for the patient. In times when distance is a benefit, Belkin laser treatment reduces contact with the patient.
Another advantage of our technology over conventional SLT is that it can most probably be used for treating angle-closure glaucoma (ACG). It was repeatedly proven that SLT is successful in reducing the pressure in this disease if sufficient parts of the anterior chamber angle can be visualized by gonioscopy. With DSLT, we do not have to see the angle at all because the application is external. The only way to treat ACG effectively in some patients is through cataract extraction, as peripheral iridectomy is insufficient, and there will never be enough cataract surgeons for the number of patients.
We will soon start a clinical trial, the Zhuiguang (Light Chaser) randomized controlled trial in Asia, to prove safety and effectiveness of DSLT in the Chinese population for open-angle glaucoma. We will then perform a similar ACG study there.
Q. Is it possible that there is risk of damage to limbal stem cells with the Belkin laser; if so, is there a way to mitigate this risk?
A. Indeed, DSLT laser is applied at the location of the epithelial limbal stem cells. The chances of damage are slight because the laser energy is below the safety limits. If laser application adversely affects the cells, it would be reflected by corneal epithelial damage that is identified in the clinical examination and by ocular surface disease symptoms. We monitored this in the GLAURIOUS study to 12 months.
It’s also important to note that other transscleral treatments, such as trans-scleral cyclophotocoagulation and trans-scleral laser therapy, which use orders of magnitude more energy than DSLT, are approved procedures. For patients who will be weaned off their glaucoma eye drops, DSLT will actually improve the condition of the ocular surface, which was damaged by the chronic use of these drops.
Q. What are the company’s plans for the rollout of the laser, in terms of where you plan to introduce it and seek approval?
A. We are actively working on CE and FDA approvals and hope to see our technology in the market soon. GP
References
- Geffen N, Ofir S, Belkin A, et al. Transscleral selective laser trabeculoplasty without a gonioscopy lens. J Glaucoma. 2017;26(3):201-207. doi:10.1097/IJG.0000000000000464
- Goldenfeld M, Belkin M, Dobkin-Bekman M, et al. Automated direct selective laser trabeculoplasty: first prospective clinical trial. Transl Vis Sci Technol. 2021;10(3):5. doi:10.1167/tvst.10.3.5
- Gazzard G, Konstantakopoulou E, Garway-Heath D, et al. Selective laser trabeculoplasty versus eye drops for first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trial [published correction appears in Lancet. 2019 Jul 6;394(10192):e1]. Lancet. 2019;393(10180):1505-1516. doi:10.1016/S0140-6736(18)32213-X
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