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Yuquan Wen, David Birch, QLT091001 Retinoid Study Group; SD-OCT May Predict Response to QLT091001 in Patients with LCA or RP associated with RPE65 or LRAT Mutations. Invest. Ophthalmol. Vis. Sci. 2013;54(15):683.
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SD-OCT measures were obtained from patients with LCA or RP associated with RPE65 or LRAT mutations as part of a prospective open-label study to evaluate the safety and efficacy of oral QLT091001, a synthetic retinoid replacement for 11-cis-retinal. Baseline SD-OCT parameters were compared to baseline visual function; baseline SD-OCT and changes were compared to the visual field response to QLT091001.
Comprehensive ophthalmic testing including SD-OCT (Spectralis HRA+OCT) was conducted in 14 patients with LCA and 17 patients with RP at 7 international sites. Oral QLT091001 was administered once daily for 7 days in all study patients. The patients were followed for up to 15 months. Average thickness of the outer segment (OS) layer (measured from the outer segment/retinal pigment epithelium border to the inner segment ellipsoid band) was calculated with a computer program aided by manual segmentation.
Eighteen of 28 eyes (64%) with LCA and 15/34 eyes (44%) with RP responded to QLT091001 (response is defined as expansions of Goldmann visual fields retinal areas by ≥20% at two consecutive study visits). Among these responders, the average baseline thickness of the OS layer (central 20°) was 14.22 microns (reduced by 56% from normal average [32 microns]) in the LCA cohort and 8.63 microns (reduced by 73% from normal) in the RP cohort. Non-responders had average baseline OS thickness of less than 5.72 microns in both cohorts (reduced by >82% from normal). The reductions of OS thickness in central 20° were significantly higher in non-responders than responders in the LCA cohort (p=0.003), but not significantly different in the RP cohort (p=0.27). The OS thickness in the central 20° measured at baseline did not change significantly during the follow-up visits.
Although the primary defect in LCA and RP due to RPE65 or LRAT mutations lies in the visual (retinoid) cycle, photoreceptor degeneration frequently occurs at an early age, even in the first decade of life. The present findings suggest that there is a close parallel between photoreceptor structure and function in these patients. SD-OCT may be useful for predicting the response to oral synthetic retinoid replacement.
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