Retinal vein occlusion
Investigations of the influence of baseline ischaemia
In patients with retinal vein occlusion (RVO), the presence or absence of central or peripheral ischemia at baseline may influence visual function at baseline and the course of best corrected visual acuity (BCVA) over time, suggest recent clinical trial findings.
The number of anti-VEGF injections or corticosteroid implants used for the treatment of branch RVO (BRVO) or central RVO (CRVO), however, may not be affected by these baseline ischaemia characteristics, according to Amelie Pielen MD.
“These initial investigations of the influence of baseline ischaemia were conducted as a secondary analysis using descriptive techniques. Now we are analysing the data for statistical significance,” said Dr Pielen, Department of Ophthalmology, Hannover Medical School, Hannover, Germany.
The COMRADE-B and COMRADE-C studies randomised 487 patients with visual impairment from macular oedema secondary to BRVO or CRVO to ranibizumab 0.5mg (Lucentis) or the dexamethasone 0.7mg implant (Ozurdex). Ranibizumab was given as a mandatory three monthly injections and then as needed. At 6 months, 175 patients enrolled in the COMRADE-Extension study comparing as needed ranibizumab and as needed dexamethasone implant treatment through month 12.
At baseline, investigators evaluated fluorescein angiography images for the presence of an enlarged central avascular area and for the presence and extent of peripheral retinal non-perfusion (PNP). Overall among the BRVO patients, about 25% had an enlarged central avascular area and about 35% had PNP. In the CRVO study, 10% of patients in the ranibizumab group and 22.7% of dexamethasone patients had an enlarged central avascular area while about 20% of patients in both treatment groups had PNP present.
Other comparisons between treatment groups in the two COMRADE studies showed them to be similar in their demographic characteristics except mean BCVA was lower in patients with an enlarged central avascular area versus in those without in both the BRVO (56.8 vs. 58.3 letters) and CRVO (68.9 vs. 81.8 letters) study groups. The same pattern was seen comparing eyes with and without PNP in both COMRADE studies.
Among ranibizumab-treated patients, BCVA gains from baseline to month 15 were similarly high independent of baseline central avascular area or PNP status (minimum mean gain 14.7 letters). Among CRVO patients, however, those with an enlarged central avascular area randomised to the corticosteroid implant lost vision over time (-6.4 letters).
In both the CRVO and BRVO cohorts and for both treatment groups, the mean number of treatments received was similar regardless of baseline ischaemic status. Across the subgroups with and without an enlarged central avascular area and among those with and without PNP, the mean number of ranibizumab injections was in the range of 7 to 8 while the average number of dexamethasone implants was about 1 to 1.5.