High-resolution in vivo imaging in achromatopsia

Area of Science:

• Ophthalmology
• Medical Imaging
• Genetics

Background:

• Achromatopsia is a rare inherited retinal disorder characterized by reduced visual acuity, photophobia, and color vision deficiency.
• Understanding the structural retinal changes in achromatopsia is crucial for diagnosis and management.

Purpose of the Study:

• To characterize retinal changes in achromatopsia using ultrahigh-resolution optical coherence tomography (UHR OCT).
• To compare human achromatopsia findings with its animal models.

Main Methods:

• A comparative case series involving 13 patients with achromatopsia and 20 controls.
• Ultrahigh-resolution OCT (3-μm axial resolution) was used to obtain 3D scans of the fovea.
• Image analysis focused on reflectance profiles, foveal depth, outer nuclear layer (ONL) thickness, and retinal thickness (RT).

Main Results:

• A hyporeflective zone (HRZ) was observed in 7/13 patients, showing age-dependent and asymmetric nasal-temporal progression.
• Disruption of the inner segment/outer segment (IS/OS) junction and cone outer segment tip (COST) reflectivity was noted in all patients.
• Significant ONL thinning, reduced foveal depth, and retinal thickness were observed in achromats compared to controls, with age-dependent effects.

Conclusions:

• UHR OCT effectively detects various retinal signs in achromatopsia, including IS/OS junction and COST disruption, HRZ, and ONL thinning, indicative of cone photoreceptor degeneration.
• The age-dependent nature of HRZ and ONL thinning suggests achromatopsia is a progressive disorder.
• Foveal maldevelopment, a fetal defect, is also linked to cone photoreceptor degeneration in achromatopsia.