medwireNews: The pretreatment central subfield thickness in the eyes of patients with diabetic macular edema (DME) is the strongest predictor of outcome after one year of treatment with ranibizumab, with a reduction linked to better visual acuity outcomes, report researchers.
A larger improvement in visual acuity after treatment in such patients was also associated with younger age, less severe diabetic retinopathy, and the absence of surface wrinkling retinopathy, they add.
The presence of hard exudates within 6 mm of the foveal center was also associated with a more favorable improvement in patients' optical coherence tomography scans, after adjusting analysis for baseline central subfield thickness measurements, say Haijing Qin (Jaeb Center for Health Research, Tampa, Florida, USA) and team.
"Identification of factors associated with relatively good or poor outcomes can help inform treating ophthalmologists and patients as to what they can expect, on average, when choosing intravitreal ranibizumab as a treatment for DME," write the researchers in the Archives of Ophthalmology.
The findings indicate that no clinical variables predict patients for whom treatment is harmful after 1 year, they report.
The study included 361 eyes randomly assigned to 0.5 mg ranibizumab plus either immediate laser treatment (n=180) or deferred treatment (≥24 weeks, n=181), whose visual acuity letter score was measured using the best-corrected Electronic Early Treatment Diabetic Retinopathy Study test.
Baseline (pretreatment) central subfield thickness was 406 µm, and eyes with greater thickness were more likely to achieve greater reductions in thickness over time, at a median decrease of 46% for eyes with baseline central subfield thickness of less than 300 µm, and 82% for eyes with baseline thickness of 500 µm or more.
At 1 year, younger patients benefitted more from ranibizumab than older patients, with a significant 2.2-letter improvement in visual acuity for every 10-year reduction in age, after adjustment for baseline visual acuity. Furthermore, eyes with moderate or severe nonproliferative diabetic retinopathy had a significant 4.0-letter or higher increase at one year compared with those with proliferative diabetic retinopathy, or prior panretinal photocoagulation.
Eyes with no evidence of surface wrinkling retinopathy also had a four-letter increase in visual acuity compared with their peers with questionable or definite wrinkling retinopathy.
"These analyses suggest that intravitreal ranibizumab could be considered for all patients with center-involved DME," conclude Qin et al.
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