By Shreeya Nanda, Senior medwireNews Reporter
Swiss researchers report that patients with neovascular age-related macular degeneration (nAMD) experience increased incidence of outer retinal tubulation (ORT) over time, despite treatment with a vascular endothelial growth factor (VEGF) blocker.
Researcher Irmela Mantel (University of Lausanne) and colleagues explain that differentiating ORT from exudative intraretinal cysts is important, especially in patients given VEGF inhibitors in a variable dosing regimen, which is mainly guided by the presence of such cysts and subretinal fluid on optical coherence tomography (OCT).
They evaluated the medical records and spectral domain OCT (SD-OCT) scans of 480 nAMD patients (546 eyes) who were given ranibizumab monthly for 3 months followed by a pro re nata regimen based on monthly assessments. A scan was considered positive for ORT if it showed hyperreflective ovoid or round structures within the outer nuclear layer of the retina.
During a mean follow-up of 26.7 months, the overall incidence of ORT was 30%. But the incidence varied over time, with ORT detected in 2.5% of eyes at the first presentation of nAMD and in 9.8% of eyes at 6 months, rising further to 17.5%, 28.4%, 35.8% and 45.6% at 1, 2, 3 and 4 years, respectively.
For the study cohort as a whole, the average change from baseline of best-corrected visual acuity (BCVA) was 6.5 Early Treatment Diabetic Retinopathy Study letters at 1 year, 4.7 letters at 2 years, 9.5 letters at 3 years and 13.1 letters at 4 years.
But participants with ORT had smaller mean changes in BCVA from baseline than those without ORT, with a statistically significant difference between the groups at 1 (4.2 vs 7.6 letters) and 2 years (–0.1 vs 7.2 letters).
Mean BCVA was similarly lower in ORT-positive patients than in ORT-negative patients at all time points, with the difference at 1 (58.6 vs 68.4 letters) and 2 years (57.5 vs 69.2 letters) reaching statistical significance.
And when patients were stratified on the basis of baseline mean BCVA, those in the lower quartile were significantly more likely to develop ORT during follow-up than those in the higher quartiles.
Mantel et al conclude in Retina that “the identification of ORT precursor signs on SD-OCT might help clinicians to avoid unnecessary retreatment”.
They add: “The presence of ORT could also be considered a prognostic factor of functional outcomes in nAMD.”
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