There is no question that the introduction of anti-VEGF agents has dramatically changed the landscape of how surgeons approach retinal diseases. New drugs continue to move through the investigative pipeline with clinical studies of emerging classes of agents beginning to show significant promise.
However, when it comes to diabetic eye disease with manifestations such as diabetic macular edema and diabetic retinopathy — particularly the proliferative retinopathy type — laser continues to have a place in our tool kit. Anti-VEGF and corticosteroid injections are effective in a range of DME presentations, and proliferative diabetic retinopathy can require a combination of both drugs and laser to achieve optimal outcomes and disease quiescence. The former plays a sort of temporizing role and laser treatment for the longer-term effect. When retinopathy is quite severe, combination therapy acts to resolve disease much faster than a single laser session or drug injection.
History and background
The first investigation that provided a treatment paradigm using laser in DME was the Early Treatment Diabetic Retinopathy Study. The trial found that panretinal photocoagulation (PRP) reduced the incidence of severe vision loss from proliferative retinopathy by 50%, and macular grid and/or focal photocoagulation reduced the incidence of moderate vision loss from clinically significant macular edema by 50%.
The Diabetic Retinopathy Clinical Research Network found that over a 2-year period, focal/grid laser photocoagulation was more effective and was associated with fewer adverse effects than 1- or 4-mg doses of triamcinolone for most patients with DME. Focal laser treatment is applied to leaking microaneurysms, whereas grid pattern photocoagulation is normally used for diffuse leakage. It is crucial to avoid the foveal avascular zone.
laser, on the other hand, delivers similar therapeutic benefits with no visible damage; therefore, it allows for re-treatments closer to the fovea. In general, subthreshold treatment strategies incorporate a higher density of laser spots (and much lower power) than conventional focal and grid macular laser treatments.
The three main types of subthreshold laser are MicroPulse (Iridex), selective retinal therapy and Endpoint Management (Topcon Pascal). Specific indications for subthreshold treatment are being explored, including DME, and efficacy has been suggested in central serous retinopathy, macular edema from retinal vein occlusion and drusen.
As treatment strategies are developed, a major focus is on ways to extend the time between treatments. For example, a significant difference in lifestyle and livelihood occurs when a patient who had been receiving intravitreal injection therapy monthly is able to be extended to a 6- or 8-week interval. Surgeons should not lose sight of the fact that this population is of working age, and they are busy taking care of families and maintaining packed schedules. Patients with diabetes also see other doctors and can have many physician appointments to juggle. Anything that clinicians can do to minimize the treatment regimen’s impact on patients’ lives is meaningful.
Subthreshold laser can allow surgeons to get an added benefit in DME patients who are not responding to anti-VEGF or steroid injections. By creating a treatment protocol that includes a schedule of injections plus laser can save patients from unnecessary risks associated with repeated injections and extend the time between office visits.
As surgeons, we always need to individualize treatment based on what is in the patient’s best interest overall — considering their age and lifestyle — in addition to their disease presentation. Furthermore, with the advent of genetic research and biomarker identification, we will be able to further customize therapy for the patients’ genetic profile in the not-so-distant future. For now, using a combination of treatment options to attack DME is the best approach to provide optimal visual outcomes for our patients.
Diabetic Retinopathy Clinical Research Network. Ophthalmology. 2008;doi.org/10.1016/j.ophtha.2008.06.015.
Distefano LN, et al. J Ophthalmol. 2017;doi:10.1155/2017/2407037.
Early Treatment Diabetic Retinopathy Study research group. Arch Ophthalmol. 1985;doi:10.1001/archopht.1985.01050120030015.
Disclosure: Mali reports he is a consultant, speaker and stock shareholder for Alimera Sciences, a consultant for and recipient of research funding from Allergan, a consultant and speaker for Genentech, a consultant, speaker and stock shareholder for and recipient of research funding from Regeneron, a consultant and speaker for and recipient of research funding from Notal Vision, a consultant and speaker for Sun Pharmaceutical Industries, and a consultant and speaker for Macular Degeneration Association.