Optical Coherence Tomography in Knobloch Syndrome
Avrey Thau, BS; Mai Tsukikawa, MD; Nutsuchar Wangtiraumnuay, MD; Jenina Capasso, MS, LCGC; Elizabeth Affel, MS, OCT-C, CDOS, ROUB; Waleed Abed Alnabi, MD; Murtaza Adam, MD; Alex V. Levin, MD, MHSc
Wills Eye Hospital
Philadelphia, Pennsylvania, USA
Introduction: Knobloch syndrome is a rare genetic disorder classically defined by a triad of occipital defect, high myopia, and vitreoretinal degeneration with high risk for retinal detachment. Our study aims to characterize the morphological changes of the retina in patients with Knobloch syndrome using optical coherence tomography (OCT).
Methods: This retrospective case series reports findings on patients with a clinical and/or DNA diagnosis of Knobloch syndrome who received OCT testing during their clinical care. Diagnosis was made on the basis of high myopia, characteristic fundus appearance, and presence of occipital scalp or skull abnormalities with or without featureless iris and/or ectopia lentis.
Results: Over a five-year period, we studied 8 eyes from 5 patients (mean age 8.7 years, range 3 months to 39 years). Two eyes were excluded due to chronic retinal detachment. OCT findings included epiretinal membrane and peripapillary vitreoretinal traction with retinoschisis, an absent or rudimentary foveal pit in all but 2 eyes of 1 patient, poor retinal lamination, RPE atrophy, and photoreceptor depletion. Four eyes demonstrated myopic choroidal thinning, while 3 eyes disclosed enlarged choroidal vessels similar to pachychoroid.
Discussion: Our findings of epiretinal membrane, vitreoretinal traction, retinoschisis and pachychoroid have not been previously reported. The epiretinal membrane and vitreoretinal traction may explain the high incidence of retinal detachment in this syndrome.
Conclusion: We present novel OCT findings in Knobloch syndrome which may have diagnostic and treatment implications.
References: 1. AlBakri A, Ghazi NG, Khan AO. Biometry, optical coherence tomography, and further clinical observations in Knobloch syndrome. Ophthalmic Genetics. 2017;38(2):138-142.