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RISHMA GOHIL, Oliver Comyn, Pearse Keane, Praveen Patel, James Bainbridge, Sobha Sivaprasad, Philip Hykin; Evaluation of choroidal thickness by enhanced depth imaging OCT in the LUCIDATE study: a randomised clinical trial to compare outcomes of ranibizumab with laser in diabetic macular oedema. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4919.
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The Enhanced Depth Imaging (EDI) technique of OCT allows visualisation of the choroid. Studies have shown that changes in choroidal thickness may accompany diabetic retinopathy and diabetic macular oedema (DMO). In this exploratory, post-hoc analysis from a clinical trial, we evaluated the effect of laser and ranibizumab therapy on choroidal thickness in DMO.
Randomised clinical trial. 36 subjects with centre-involving DMO, BCVA 55-79 ETDRS letters, moderate macular ischaemia only and no recent laser or anti-VEGF therapy were randomised 2:1 to receive ranibizumab injections (RBZ) or macular laser therapy. Subjects had Spectralis OCT EDI scans at baseline and at 12 week intervals to the primary endpoint at 48 weeks. Repeat scans were performed in “follow up” mode. Choroidal thickness was measured at 500 µm intervals across the macula from a high quality single horizontal line scan using measuring software incorporated within the HEYEX software, by a grader masked to treatment allocation. Results were evaluated for longitudinal change in either group and for between-group differences.
33 subjects completed 48 weeks follow up. The two groups were comparable in terms of age, grade of retinopathy, duration of DMO, HbA1C level and previous laser treatments. At baseline, subfoveal choroidal thickness was 278.5 ±70.7 µm and 297.0 ±62.7 µm in the ranibizumab and laser groups respectively. At 48 weeks, thickness was 278.7 ±75.2 µm (RBZ) and 308.2 ±81.8 µm (laser) (p=0.31). Mean choroidal thickness across the central 5mm of the macula was 243.5 ±58.8 µm at baseline and 245.5 ±58.3 µm at 48 weeks for ranibizumab; for laser it was 264.6 ±51.8 µm at baseline and 255.7 ±52.9 µm at 48 weeks (p=0.63). At baseline and 48 weeks, there was a weak correlation between subfoveal choroidal thickness and BCVA (baseline: r=0.31, p=0.082; 48 weeks r=0.29, p=0.096). Change in choroidal thickness did not correlate with change in retinal thickness (r=0.21, p=0.25).
This study found no change in choroidal thickness at 48 weeks with ranibizumab or laser therapy. Choroidal thickness did not correlate with retinal thickness but correlated weakly with visual acuity at baseline and 48 weeks. Further study is warranted to investigate the importance of choroidal thickness measurements in the evaluation of DMO.
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