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Sohaib Riyaz Rufai, Mervyn George Thomas, Ravi Purohit, Helena Lee, Frank A Proudlock, Irene Gottlob; Comparison of quantitative segmentation analysis and structural grading of foveal hypoplasia in infants for the prediction of future visual acuity: A longitudinal cohort study. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5788.
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Handheld spectral-domain optical coherence tomography (HH-OCT) can diagnose foveal hypoplasia in infantile nystagmus. Objective measurements of layers of the fovea and subjective structural grading of foveal hypoplasia may each predict future vision, but the strength and clinical value of these correlations remain to be defined. We performed the first longitudinal cohort study to compare these measures in infantile nystagmus.
We recruited patients with infantile nystagmus aged 6-36 months and captured foveal tomograms using HH-OCT. Tomograms were segmented as follows: photoreceptor length, outer segment length and Foveal Developmental Index (FDI – ratio of inner versus total retinal layers). Tomograms were graded for severity of foveal hypoplasia using a five-point grading system, adapted from the adult based system described by Thomas et al1, taking into account underdevelopment of key foveal structures including the foveal pit, outer segment and outer nuclear layer. A shallow foveal pit and disruption of the inner segment ellipsoid band are the features seen in atypical foveal hypoplasia. Patients were followed up until they were old enough to have logMAR vision testing. Data was analysed using linear mixed regression models.
We imaged 74 eyes from 39 patients (representing a powered cohort) with infantile nystagmus aged 6.3-33.4 (mean: 20.5, S.D. 8.8) months at the time of their first HH-OCT scan. This cohort included albinism (n=17), idiopathic infantile nystagmus (n=17) and achromatopsia (n=5). Mean follow-up was 40.8 months (range: 18.4-58.4; S.D. 11.7). Structural grading was the strongest predictor of visual acuity (r=0.85, F=109.3, P<0.0001) compared to photoreceptor length (r=0.73, F=12.1, P=0.001), outer segment length (r=0.70, F=69.1, P<0.0001) and FDI (r=0.57, F=4.1, P=0.05).
Conclusion: HH-OCT can predict future visual acuity in infants with foveal hypoplasia. Structural grading is a better predictor of future visual acuity than quantitative segmentation analysis. Quantitative segmentation analysis allows comparison within each structural grade.Reference:1. Thomas MG et al (2011). Ophthalmology. 118(8):1653-60
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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