Similar diabetic macular oedema outcomes with deferred vs prompt laser therapy

By Shreeya Nanda, Senior medwireNews Reporter

Visual acuity outcomes are comparable in diabetic macular oedema patients who receive laser treatment 24 weeks or more after initiation of ranibizumab injections and those for whom laser therapy is initiated concurrently, show the 5-year results of a US study.

“Although more than half of eyes in which laser treatment is deferred may avoid laser for at least 5 years, such eyes may require more injections to achieve these results when following this protocol”, observe Allison Ayala (Jaeb Center for Health Research, Tampa, Florida) and colleagues in Ophthalmology.

This study details the 5-year findings of a previously reported clinical trial in which patients with diabetic macular oedema were randomly assigned to receive intravitreal ranibizumab plus either deferred or prompt focal/grid laser treatment. Laser treatment in the deferred group was initiated a minimum of 24 weeks after the first ranibizumab injection, and then only if the diabetic macular oedema persisted.

At 5 years, the average change in visual acuity score from baseline was a comparable +9.8 letters for the 111 participants in the deferred laser treatment group and +7.2 letters for the 124 who received prompt laser treatment.

Vision loss was also similar in the deferred and prompt laser treatment groups, with 8% and 9% of participants, respectively, experiencing a loss of 10 letters or more.

The proportion of participants achieving a minimum 10- or 15-letter improvement in visual acuity from baseline favoured the deferred laser treatment arm, at 58% versus 46% and 38% versus 27%, respectively.

However, when patients were stratified by baseline visual acuity (≤65 vs ≥66 letters), the mean change in visual acuity from baseline was significantly higher in the deferred versus the prompt laser treatment arm only in the subgroup of patients with worse visual acuity at intake.

Patients in the deferred laser treatment group received a median of 17 ranibizumab injections over 5 years while those in the prompt laser treatment arm received a median of 13 injections. And in years 4 and 5 of the study, injections were not given to 45% and 52% of participants in the deferred laser treatment group, respectively, and 54% and 62% in the prompt laser treatment arm.

“[T]he differences in visual acuity outcomes between the prompt and deferred laser treatment groups may be real, in particular for eyes with worse baseline visual acuity, but must be tempered with the recognition that deferral of laser may require more injections over 5 years to achieve the results seen in this report and thus may entail greater costs”, conclude the researchers.

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