Characterization of Abnormal Optic Nerve Head Morphology in Albinism Using Optical Coherence Tomography

Area of Science:

• Ophthalmology
• Medical Imaging
• Genetics

Background:

• Albinism is a group of inherited disorders characterized by a lack of pigment in the skin, hair, and eyes.
• Ocular maldevelopment is common in albinism, affecting various ocular structures.
• Optic nerve head (ONH) morphology in albinism has not been extensively studied using advanced imaging techniques.

Purpose of the Study:

• To characterize three-dimensional ONH morphology in people with albinism (PWA) using spectral-domain optical coherence tomography (SD-OCT).
• To investigate the relationship between ONH abnormalities and other retinal and clinical findings in PWA.

Main Methods:

• Three-dimensional SD-OCT imaging was performed on 56 PWA and 60 age- and sex-matched controls.
• Motion artifacts from nystagmus were corrected.
• ONH dimensions (disc, cup, rim) and peripapillary retinal nerve fiber layer (ppRNFL) thickness were quantified.

Main Results:

• PWA had horizontally elongated discs but similar disc areas compared to controls.
• Optic cup areas were significantly smaller in PWA, with many lacking a measurable cup, leading to smaller cup-to-disc ratios.
• ppRNFL was significantly thinner in PWA, particularly in the temporal quadrant, and correlated with central foveal ganglion cell thickness.
• ONH abnormalities, like cup-to-disc ratio, were associated with higher refractive errors in PWA.

Conclusions:

• Ocular maldevelopment in PWA extends to the ONH, not just the retina.
• Reduced ppRNFL thickness in PWA aligns with known reductions in ganglion cell numbers.
• Thicker ONH rim volumes in PWA may indicate incomplete ONH maturation.