RaScaL: A Pilot Study to Assess the Efficacy, Durability, and Safety of a Single Intervention with Ranibizumab plus Peripheral Laser for Diabetic Macular Edema Associated with Peripheral Nonperfusion on Ultrawide-Field Fluorescein Angiography

Macular laser photocoagulation in the management of diabetic macular edema: Still relevant in 2020?

Macular laser photocoagulation (MLP) is inferior to intravitreal vascular endothelial growth factor (VEGF) inhibitors in the treatment of center-involved diabetic macular edema (DME). Ultra-widefield fluorescein angiography-guided laser photocoagulation to presumed ischemic areas of the peripheral retina or MLP do not reduce the treatment burden nor improve the visual outcomes of eyes treated with anti-VEGF drugs. Destruction of retinal tissue is not necessary to induce a therapeutic response in DME. Modern lasers are capable of producing invisible laser "burns" that do not destroy the targeted tissue using micropulse subthreshold (ST) mode where the laser's duty cycle is modified or alternatively selective retinal therapy (SRT) where ultrashort pulses of continuous wave laser selectively target the RPE. The best results with micropulse ST laser are obtained in eyes with a central macular thickness ≤400 μm. Eyes need to be treated in a continuous manner with no spaces between burns in the edematous area. Micropulse ST-MLP downregulates inflammatory biomarkers produced by activated microglial cells and Müller cells. Micropulse ST-MLP may reduce the anti-VEGF injection burden in DME. In SRT, the diseased RPE is targeted and heated with the laser with the hope that the adjacent RPE migrates and proliferates into these areas to heal the diseased RPE. There is much less experience with SRT, but the results are promising and deserve further study.

The Evolving Treatment of Diabetic Retinopathy

Purpose

To review the current therapeutic options for the management of diabetic retinopathy (DR) and diabetic macular edema (DME) and examine the evidence for integration of laser and pharmacotherapy.

Methods

A review of the PubMed database was performed using the search terms diabetic retinopathy, diabetic macular edema, neovascularization, laser photocoagulation, intravitreal injection, vascular endothelial growth factor (VEGF), vitrectomy, pars plana vitreous surgery, antiangiogenic therapy. With additional cross-referencing, this yielded 835 publications of which 301 were selected based on content and relevance.

Results

Many recent studies have evaluated the pharmacological, laser and surgical therapeutic strategies for the treatment and prevention of DR and DME. Several newer diagnostic systems such as optical coherence tomography (OCT), microperimetry, and multifocal electroretinography (mfERG) are also assisting in further refinements in the staging and classification of DR and DME. Pharmacological therapies for both DR and DME include both systemic and ocular agents. Systemic agents that promote intensive glycemic control, control of dyslipidemia and antagonists of the renin-angiotensin system demonstrate beneficial effects for both DR and DME. Ocular therapies include anti-VEGF agents, corticosteroids and nonsteroidal anti-inflammatory drugs. Laser therapy, both as panretinal and focal or grid applications continue to be employed in management of DR and DME. Refinements in laser devices have yielded more tissue-sparing (subthreshold) modes in which many of the benefits of conventional continuous wave (CW) lasers can be obtained without the adverse side effects. Recent attempts to lessen the burden of anti-VEGF injections by integrating laser therapy have met with mixed results. Increasingly, vitreoretinal surgical techniques are employed for less advanced stages of DR and DME. The development and use of smaller gauge instrumentation and advanced anesthesia agents have been associated with a trend toward earlier surgical intervention for diabetic retinopathy. Several novel drug delivery strategies are currently being examined with the goal of decreasing the therapeutic burden of monthly intravitreal injections. These fall into one of the five categories: non-biodegradable polymeric drug delivery systems, biodegradable polymeric drug delivery systems, nanoparticle-based drug delivery systems, ocular injection devices and with sustained release refillable devices. At present, there remains no one single strategy for the management of the particular stages of DR and DME as there are many options that have not been rigorously tested through large, randomized, controlled clinical trials.

Conclusion

Pharmacotherapy, both ocular and systemic, will be the primary mode of intervention in the management of DR and DME in many cases when cost and treatment burden are less constrained. Conventional laser therapy has become a secondary intervention in these instances, but remains a first-line option when cost and treatment burden are more constrained. Results with subthreshold laser appear promising but will require more rigorous study to establish its role as adjunctive therapy. Evidence to support an optimal integration of the various treatment options is lacking. Central to the widespread adoption of any therapeutic regimen for DR and DME is substantiation of safety, efficacy, and cost-effectiveness by a body of sound clinical trials.

[Retinal laser treatment-avoiding mistakes]

Even in the era of intravitreal injection therapy (intravitreal operative injection of medication, IVOM) for the treatment of macular and retinal diseases, such as age-related macular degeneration (AMD), proliferative diabetic retinopathy (DR) and diabetic macular edema (DME) as well as proliferative stages and/or macular edema due to retinal vein occlusion (RVO), conventional retinal laser treatment is still of importance. It can be focally performed on an on-label basis for DME and macular edema due to branch RVO (BRVO) and its use as panretinal treatment for proliferative stages in retinal diseases as well as for the treatment of retinal holes is undisputed. The spectrum is extended by the treatment of less common diseases, such as retinal hemangioblastoma, macroaneurysms and subhyaloid macular hemorrhage. There is cause for concern that knowledge about the correct performance of retinal laser application might be shifted into the background due to an increase of IVOM treatment, which could lead to an increase in unnecessary errors. The aim of this manuscript is to increase awareness for the correct indications and execution of retinal laser treatment based on case examples of flawed or insufficient treatment.

Role of peripheral pan-retinal photocoagulation in diabetic macular edema treated with intravitreal ziv-aflibercept

Purpose

The aim of this study was to investigate the possibility of decreasing the number of intravitreal anti-VEGF by peripheral pan-retinal photocoagulation (PPRP) in managing diabetic macular edema (DME) in a subcategory of patients who cannot comply to strict anti-VEGF follow-up protocols.

Materials and methods

This is a pilot prospective study. Consecutive patients with naïve DME were offered the choice of treatment and extend intravitreal ziv-aflibercept if they showed willingness for good compliance or PPRP with modified pro re nata intravitreal injections.

Results

Six eyes of 3 patients had PPRP versus 4 eyes of 4 patients had injections only. The number of anti-VEGF injections was markedly decreased when PPRP was administered from a mean number of injections of 16.8 (range 13–21; mean follow-up 24.3 months) to a mean number of 4.5 (range 0–8; mean follow-up 33.7 months). Mean initial central macular thickness (CMT) was 462.0 mm in the injection only group vs 457.3 mm in the PPRP group. Mean final CMT was 462.0 in the injection only group vs 350.0 in the PPRP group. Baseline and final mean logMAR (Snellen equivalent) best-corrected visual acuity was initially and finally 0.84 (20/137) and 0.60 (20/80) in the injection only group and 0.70 (20/100) and 0.69 (20/98) in the PPRP group, respectively. The monthly cost for the PPRP group was one-third of the monthly cost for the injection only group.

Conclusion

PPRP allowed for a decrease in the number of intravitreal anti-VEGF injections in selected DME patients (sick, difficult to ambulate, financial burden, and fear of injections).

Randomised trial of wide-field guided PRP for diabetic macular oedema treated with ranibizumab

BACKGROUND

Diabetic macular oedema (DMO) is effectively treated with ranibizumab but multiple injections are required. Where there is also peripheral ischaemia, it has been promoted that targeted panretinal photocoagulation (PRP) may reduce the number of injections.

METHOD

Patients with optical coherence tomography confirmed DMO and Ultra-widefield Fundus Fluorescein Angiography confirmed peripheral retinal ischaemia were randomised to PRP plus ranibizumab or ranibizumab monotherapy. After three injections, repeat injections were given until the visual acuity was stable and the macula was dry. Re-treatment was given if there was a drop of visual acuity and/or a recurrence of intra-retinal fluid. The primary outcome was the number of repeat injections required after the first 6 months up until 1 year.

RESULTS

There were 49 patients, 25 in the ranibizumab only group and 24 in the ranibizumab + PRP group recruited at seven UK sites. The average number of injections in the ranibizumab-only arm was 6.84 over 1 year and 2.52 between months 6 and 12. The average number of injections in the combined arm was 6.67, with the number of injections in the second 6 months 1.92. For the primary outcome, comparing the number of 6- to 12-month injections, the result was not statistically significant (p = 0.33).

CONCLUSION

The addition of targeted PRP to areas of non-perfusion in a patient with DMO does not reduce the number of injections required in the first year. It seems most likely that local VEGF at the macula is the main cause of DMO.

Anti-VEGF treatment and peripheral retinal nonperfusion in patients with central retinal vein occlusion

Purpose

To evaluate the association between the size of peripheral retinal nonperfusion and the number of intravitreal ranibizumab injections in patients with treatment-naïve central retinal vein occlusion (CRVO).

Methods

Fifty-four patients with treatment-naïve CRVO and macular edema were included. Each patient underwent a full ophthalmologic examination including optical coherence tomography imaging and ultrawide-field fluorescein angiography. Monthly intravitreal ranibizumab injections were applied according to the recommendations of the German Ophthalmologic Society. Two ophthalmologists quantified the areas of peripheral retinal nonperfusion (group 1= less than five disc areas, group 2= more than five disc areas). Correlation analyses between the size of nonperfusion with best-corrected visual acuity, central subfield thickness, and the number of intravitreal injections were performed.

Results

Best-corrected visual acuity improved significantly after intravitreal injections (P<0.001, both groups). Final central subfield thickness after treatment did not significantly differ between both groups (P=0.92, P=0.96, respectively). Mean number of injections in group 1 and group 2 was 4.12±2.73 and 9.32±3.84, respectively (P<0.001). There was a significant positive correlation between areas of nonperfusion and the number of injections in each group. (R=0.97, P<0.001; R=0.94, P<0.001, respectively).

Conclusion

Peripheral retinal nonperfusion in patients with CRVO correlates significantly with the number of needed intravitreal ranibizumab injections. Ultrawide-field fluorescein angiography is a useful tool for detection of peripheral retinal ischemia, which may have direct implications in the diagnosis, follow-up, and treatment of these patients.