Reduced Electroretinogram Responses in Morphologically Normal Retina in Patients with Primary Hyperoxaluria Type 1

Area of Science:

• Ophthalmology
• Nephrology
• Genetics

Background:

• Primary hyperoxaluria type 1 (PH1) is a rare genetic disorder.
• It leads to excessive oxalate production and deposition, affecting multiple organs including the kidneys and eyes.
• Ocular manifestations in PH1 can impact vision and require thorough characterization.

Purpose of the Study:

• To describe ocular findings in patients with PH1.
• To correlate retinal anatomy with retinal function in PH1.
• To characterize retinal alterations across different stages of PH1 and varying renal impairment.

Main Methods:

• Cross-sectional study of 8 children (16 eyes) diagnosed with PH1.
• Ophthalmological assessment including slit-lamp biomicroscopy and indirect ophthalmoscopy.
• Retinal function assessed by electroretinography; retinal imaging via spectral-domain OCT and fundus autofluorescence.

Main Results:

• 25% of eyes had normal retinal structure and function.
• 50% showed functional impairment without structural abnormalities.
• 25% exhibited advanced retinal damage with significant morphological and functional impairment.
• No direct correlation found between renal disease severity and retinal phenotype severity.

Conclusions:

• PH1 patients exhibit diverse retinal phenotypes, sometimes with a mismatch between morphology and function.
• Retinal dysfunction in PH1 may involve mechanisms beyond oxalate crystal deposition.
• Further research is needed to understand the molecular basis of PH1 retinopathy.