Evaluating Where Laser Trabeculoplasty Fits into the Glaucoma Treatment Algorithm
Robert Noecker, MD, MBA
Glaucoma providers need to embrace a more positive outlook when treating glaucoma and think about optimizing therapy for a given patient rather than waiting to declare failure if the intraocular pressure (IOP) no longer is at target over a period of time. This outcome is expected as targets lower or disease worsens.
Newer laser trabeculoplasty technologies such as SLT (Selective Laser Trabeculoplasty) and MLT (Micropulse Laser Trabeculoplasty) are increasingly being used as therapeutic interventions for open angle glaucoma. The treatment algorithm has opened up due to the fact that modern laser trabeculoplasty techniques are as effective as older continuous wave technologies such as ALT (Argon Laser Trabeculoplasty) in lowering IOP.
It appears that all laser trabeculoplasty works via the same mechanism of action, that is injury is caused to trabecular endothelial cells which leads to cytokine release and monocyte recruitment into the area. The monocytes facilitate a sustained increase in facility of outflow that lowers IOP. Unlike ALT however, the newer technologies do not appear to cause permanent and ongoing structural damage to the trabecular meshwork, therefore the downside to using laser trabeculoplasty as early or first line therapy is minimized.
Laser trabeculoplasty tends to work best when used early in the treatment algorithm and in patients with higher IOPs. In the SLT/MED study, patients who were randomized to SLT as initial therapy versus medical therapy took fewer steps (i.e. changes in therapy) to reach predetermined target pressures compared to topical medication as initial therapy arm.1 Melamed demonstrated that SLT could reduce IOP on the order of 30% from baseline when used in a glaucoma population as initial therapy.2 Patients in that study had higher baseline IOPs than other studies in which SLT was used as adjunctive or replacement therapy.
SLT can be used in combination with glaucoma medications and as replacement therapy in some cases. Francis conducted a study of using SLT to reduce medication load and maintain IOP control in patients who were well controlled on therapy already.3 Through the use of laser trabeculoplasty, patients were able to keep their IOPs in the teens with less medication after treatment.
Laser trabeculoplasty can be repeated and can lower IOP in those patients who had good initial responses to the laser.4 In a study by Hong, patients who were treated with SLT once and experienced a positive drop in IOP were retreated with the same laser therapy.5 The authors found that subsequent treatment resulted in another drop in IOP and maintenance of patients at target IOPs. In the original registration trial for SLT, one of the treatment arms was the group of patients who had prior ALT which had lost effectiveness.6 It was shown that subsequent SLT was effective in lowering IOP in that population at a level similar to that seen in patients only treated with medications previously.
Many discussions about the use of laser trabeculoplasty have centered on the use of laser trabeculoplasty versus medications or other modes of glaucoma therapy. In the real world of treating glaucoma, the truth is that eye care providers need all of the treatments available and that a majority of glaucoma patients will need multiple therapies over time to control their disease – either medical, laser or surgical.
A period of two years of good IOP control with no or fewer medications is time well spent. Likewise, some time of good IOP control with a prostaglandin analogue before having to add a combination drug is also a positive outcome. Enhancements in therapy are normal and expected when caring for chronic diseases like glaucoma. Laser trabeculoplasty and medical therapy are both effective tools for glaucoma treatment and patients should be advised that they will likely need each mode of therapy over time to efficiently treat their disease.
1. Waisbourd M, Katz LJ. Selective laser trabeculoplasty as a first-line therapy: a review. Can J Ophthalmol. 2014 Dec;49(6):519-22.
2. Melamed S, Ben Simon GJ, Levkovitch-Verbin H. Selective laser trabeculoplasty as primary treatment for open-angle glaucoma: a prospective, nonrandomized pilot study. Arch Ophthalmol. 2003 Jul;121(7):957-60.
3. Francis BA, Ianchulev T, Schofield JK, Minckler DS. Selective laser trabeculoplasty as a replacement for medical therapy in open-angle glaucoma. Am J Ophthalmol. 2005 Sep;140(3):524-5.
4. Khouri AS, Lari HB, Berezina TL, Maltzman B, Fechtner RD. Long term efficacy of repeat selective laser trabeculoplasty. J Ophthalmic Vis Res. 2014 Oct-Dec;9(4):444-8.
5. Hong, BK, Winer JC, Martone JF, Wand M, Altman B, Shields B. Repeat selective laser trabeculoplasty. J Glaucoma. 2009 Mar; 18(3):180-183.
6. Latina MA, Sibayan SA, Shin DH, Noecker RJ, Marcellino G. Q-switched 532-nm Nd:YAG laser trabeculoplasty (selective laser trabeculoplasty): a multicenter, pilot, clinical study. Ophthalmology. 1998 Nov;105(11):2082-8; discussion 2089-90
Robert Noecker, MD, MBA is glaucoma and cataract surgeon at Ophthalmic Consultants of Connecticut in Fairfield, CT. Dr. Noecker is currently also Clinical Assistant Professor of Ophthalmology at Yale University School of Medicine and Clinical Professor of Surgery at the Frank Netter School of Medicine of Quinnipiac University.