First Author: M.Biarnés SPAIN
Co Author(s): D. Merino L. Ferraro M. Garcia P. Loza J. Mones
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To validate a newly developed adaptive optics scanning laser ophthalmoscope (AOSLO) instrument in patients with degenerative diseases in the context of the LITE (“Development of advanced laser imaging techniques for the anterior and posterior eye”) study.
Institut de la Màcula and Institut de Ciències Fotòniques (Barcelona, Spain).
After an initial small pilot study in healthy subjects to test the AOSLO performance in a clinical setting, we conducted a prospective, observational study of patients with Stargardt’s disease (STG) or retinitis pigmentosa (RP). Patients were visited at baseline, 3, 6 and 12 months. Functional (best-corrected visual acuity -BCVA- and microperimetry) and structural state-of-the-art (fundus photography, fundus autofluorescence (FAF), spectral domain optical coherence tomography (SDOCT) and fluorescein angiography) exams were conducted. AOSLO imaging was also performed at each visit. Quantitative measures (cone spacing) were derived only if the photoreceptor mosaic could be unambiguously detected in regions of interest (ROI), and correlation between state-of-the-art imaging and AOSLO was performed.
We screened 22 patients, and 16 were finally included (5 healthy, 6 with STG and 5 with RP). Patients with degenerative diseases had a median of 47 years old (range, 35 to 64), there were 45.5% (5/11) females and 81.8% (9/11) were right eyes. A patient with RP withdrawn from the study. Median baseline BCVA was 78 letters (range, 54 to 91) and median macular sensitivity on microperimetry was 16.8 dB (range, 3.5 to 27.8). AOSLO imaged photoreceptors in healthy individuals and cone spacing was determined for up to 12º eccentricity. In a patient with RP there was a 40% increased cone spacing in and outside the ring of increased FAF as compared to the same ROI in healthy individuals. On the other hand, irregular photoreceptor mosaics were obtained even in normal-appearing areas according to FAF and/or SDOCT, suggesting that loss of photoreceptor structure as seen on AOSLO precedes clinically identifiable damage to outer retina using current state-of-the-art instruments. In several areas, individual photoreceptors could not be identified.
The AOSLO prototype provided high-quality images of the retina in patients with STG and RP. AOSLO may be more sensitive to detect early structural damage than current imaging methods. In some areas the photoreceptor mosaic could not be unambiguously identified. Interpretation of findings in these areas requires clinical judgement, correlation with current state-of-the-art imaging methods and great care. The results may be useful to gain insights into disease progression and pathogenesis.