Why you should consider laser therapy in young diabetic patients

Editor’s Note: Welcome to “Eye Catching: Let's Chat,” a blog series featuring contributions from members of the ophthalmic community. These blogs are an opportunity for ophthalmic bloggers to engage with readers with about a topic that is top of mind, whether it is practice management, experiences with patients, the industry, medicine in general, or healthcare reform. The series continues with this blog by Ragui Sedeek, MD, who is in practice at Elite Eye Care, Santa Maria, CA. The views expressed in these blogs are those of their respective contributors and do not represent the views of Ophthalmology Times or UBM Medica.

I recently moved my practice to San Luis Obispo County (SLO) in Central California. Founded in the 1850s and one of California’s 27 original counties, SLO is located along the Pacific Coast, about 200 miles north of Los Angeles and 235 miles south of San Francisco. The inland region is sparsely populated with vast areas of agricultural and government lands situated between small, unincorporated towns. Agriculture and tourism are among the key industries.

This is a heavily Hispanic, farming population, and many of my patients presenting with retinal disease have poorly controlled diabetes. The bulk of these individuals are in their 30s and 40s and many have “transient” or no medical insurance. Compounded by the fact that most diabetic disease occurs bilaterally, it quickly became evident to me that I needed to find an alternative to depending solely on anti-vascular endothelial growth factor (VEGF) injections in this group.

Although the agents work well, they require a significant long-term commitment to therapy on the part of the patient. In diabetic eye disease, a longer initial loading set of injections is needed when starting treatment compared with what has been shown in studies of age-related macular degeneration.

In addition to anti-VEGF agents, I often add a steroid injection, triamcinolone acetate (Kenalog, Bristol Myers Squibb), to target and shut down the massively mixed pool of inflammatory mediators and cytokines in diabetic eyes.

A steroid injection helps to reset the eye’s chemical milieu and makes it more responsive to anti-VEGF agents. In this young phakic population, however, a long-term steroidal implant is not acceptable due to the associated increased risk of cataract and glaucoma development.

I have found that a 2-mg dose of triamcinolone acetate along with the initial anti-VEGF treatment helps the latter work better and prolongs its effect. I try not to repeat the steroid injection more than once every 6 months to reduce the potentially serious side effects.

Adding laser therapy
In the intravitreal injection era, we are underutilizing laser therapy. Newer grid laser technology, as opposed to traditional focal laser photocoagulation, creates a non-damaging tissue reaction that provides a targeted treatment to the retinal pigment epithelium (RPE). I favor semi-automatic pattern scanning laser photocoagulation (PASCAL, Topcon) with Endpoint Management (EpM) subthreshold laser therapy for the treatment of diabetic macular edema (DME).

This technology differs from the traditional Early Treatment Diabetic Retinopathy Study (ETDRS) photocoagulative treatment to the perifoveal tissue that created unwanted collateral heat damage. EpM is rather a photostimulation to the RPE without ever reaching photocoagulation damaging temperature.

The laser’s use of high-density patterns enhances its clinical efficacy, allows for treatment through the fovea, and is repeatable. Although the visual improvement might not show up on the eye chart, subjectively, patients say their vision is slightly clearer within a couple of days of laser therapy.

I prefer to use EpM therapy for nonfoveal DME, and I use it in conjunction with monthly anti-VEGF injections for foveal involving DME.  I feel that some surgeons have become robotically dependent on data from optical coherence tomography (OCT) alone.

Although OCT images have great reproducibility to monitor response toward decreasing central macular thickness, one must be OCT savvy when using the technology to direct therapy in diabetic patients. Not all areas that appear thickened on OCT are truly edema.

Other factors cause thickness on OCT images including posterior hyaloid interface pathologies such as vitreomacular traction and epiretinal membranes. Moreover, gray-colored, filled cysts and palisades can be seen on OCT with amorphous retinal layers.

In my opinion, this is caused by some ischemic loss of Muller and glial cells. I believe using fluorescein angiography (FA) in conjunction with OCT is crucial to properly differentiate between truly leaking vascular disease and ischemic or mechanical thickening and better gauge treatment.

Protocol for young diabetic patients
In patients with center-involved DME, I perform a baseline FA and OCT and administer a loading dose of six injections with an anti-VEGF agent. At this stage, I evaluate their response with repeat FA and OCT. If it is not trending in the right direction, I add a steroidal agent, which typically are associated with a positive trend in decreased CMT and leakage on FA.

Once I see a trend, I seek to extend the treatment interval for my patients. I apply EpM laser treatment, and continue with a treat-and-extend strategy for anti-VEGF injections. Pars plana vitrectomy can be considered when there is a clear component of vitreomacular traction or macular puckering that compromises the full effect of anti-VEGF treatment

Conclusion
Combining anti-VEGF with steroid injections, EpM laser, and pars plana vitrectomy can decrease the overall long-term treatment burden on diabetic patients receiving anti-VEGF injections. Laser therapy is safer, faster, more comfortable, and is not associated with the same kind of risks as intravitreal treatment. It may allow patients to prolong the time intervals in between visits.

In the setting of a young, working-class diabetic population with poorly controlled diabetes and bilateral retinal disease within the setting of a lack of stable medical insurance, creative strategies to prolong treatment intervals or to graduate patients from the chronic need for anti-VEGF are crucial. Adding laser therapy to the treatment algorithm is a valuable option. 

 Ragui Sedeek, MD, is in practice at Elite Eye Care, Santa Maria, CA.  He can be reached at Dr.Sedeek@shepardeye.co

Disclosures:

This information is Dr. Sedeek’s opinion and experience and not that of Topcon.