Ranibizumab vs Laser in Diabetic Macular Edema

Kanish Mirchia, MBBS; Sophie J. Bakri, MD


August 06, 2014


A strength of this study is the inclusion of an extensive set of primary endpoints to evaluate all aspects of visual function. Although the changes observed in many of the study parameters were not statistically significant, the trend showed that ranibizumab led to equal if not greater improvements in visual function compared with laser photocoagulation, which is the current standard of treatment. The reported changes in visual acuity and adverse events were also consistent with previous large multicenter randomized controlled trials.

Another novel finding was the preservation of P50 wave on the pattern ERG in the ranibizumab group, suggesting that there is preservation of the macular cone receptors. This was also confirmed by the absence of macular ischemia or decline in global retinal function on multifocal ERG.

Limitations, including a small patient set, single-masking, and unmasking of visual-acuity assessors, influence the validity of the results. Another limitation of the study is that despite randomization, patients in the laser treatment group had a lower average BCVA at baseline (63.8 letters vs 70.4 letters) and a significantly longer duration of DME (32 months vs 21 months), both of which could indicate they had more advanced disease or irreversible damage from foveal atrophy; as a result, the benefit they could derive from treatment might be limited. Exclusion of thiazolidinedione status of patients in stratification is also a possible confounding factor.

The study is significant for clinical practice, because it suggests that the use of ranibizumab may lead to better recovery of visual acuity and preservation of retinal structure. Owing to the high prevalence of bilateral disease in DME, monthly injections carry a very high patient burden. As a result, the optimum dose (0.3 mg vs 0.5 mg) and optimum regimen of ranibizumab for DME need to be investigated. Evaluation of structural parameters with combined ranibizumab and laser treatment might be another viable option to reduce injection burden. In the absence of established guidelines for patient selection, injection-free interval, and retreatment criteria, physician judgment is crucial for the best quality-of-life outcome.

Laser remains the standard of care for patients with DME (not involving center or early DME) with preserved visual acuity (BCVA > 20/30), because these patient groups have not been examined in the LUCIDATE study or previous large randomized controlled trials. It is also unknown how to treat patients who do not respond to 3-6 months of anti-VEGF therapy (VEGF-receptor polymorphisms).

It is crucial for future studies to include these endpoints, with larger patient populations; longer durations; and better stratification of baseline values, including visual acuity > 20/30 and < 20/80. Longer-term structural and visual acuity data are also needed to determine durability of results with ranibizumab injections.



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