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Johannes Birtel, Philipp Herrmann, Sander F. Garrelfs, Simon Dulz, Yevgeniya Atiskova, Roselie M. Diederen, Martin Gliem, Florian Brinkert, Frank G Holz, Camiel Boon, Bernd Hoppe, Peter Charbel Issa; Ocular phenotype and associations with systemic findings in patients with primary hyperoxaluria type I. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5424.
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© ARVO (1962-2015); The Authors (2016-present)
Primary hyperoxaluria type 1 (PH1) is a rare autosomal-recessively inherited disorder of the glyoxylate metabolism. It leads to an overproduction of oxalate, renal failure and is associated with oxalate deposits in renal and non-renal tissues. The typical disease course is the non-infantile form with end-stage renal disease (ESRD) by 20–30 years of age or even later in life, but the disease can also manifest as infantile oxalosis with ESRD within the first weeks of life resulting in a significantly reduced survival rate. Previously, significant retinal oxalate deposits have been described in PH1. However, the variable ocular phenotype, its severity, and associations with systemic findings are not fully understood to date. Ophthalmologic screening could be used to identify individuals with early-onset systemic deposits who may be more likely to require an aggressive therapeutic strategy.
In this cross-sectional descriptive study 64 PH1 patients, including 10 infantile oxalosis patients, from three tertiary referral centers were included. Subjects underwent ophthalmic examination including best corrected visual acuity (BCVA) testing and retinal imaging. Medical history and nephrology examination of all patients were obtained.
All patients with infantile oxalosis (20 eyes) revealed severe retinal alterations and oxalate deposits, including macular crystals and hyperpigmentations (n=7, 35%), subretinal fibrosis (n=13, 65%) with (n=7, 54%) or without (n=6; 46%) associated chronic retinal edema. In 7 eyes (35%) BCVA was significantly reduced (<20/50 Snellen equivalent). In contrast, all non-infantile PH1 patients (108 eyes) revealed normal BCVA (median 20/20). Six of the non-infantile patients (11%, all in ESRD) showed mild retinal changes which were interpreted as crystallized oxalate; two of these did not exceed the calcium oxalate plasma saturation threshold at the time of examination.
Severe ocular alterations occur in infantile oxalosis patients while mild or no ocular alterations are typical for non-infantile PH1 patients. Plasma oxalate levels and kidney function (exception infantile oxalosis) are not directly associated with retinal pathology. In light of clinical trials longitudinal studies will be needed to determine factors influencing the onset and natural history of crystallization.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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