Target Audience: General Ophthalmologists
Source Article:American Journal of Ophthalmology Case Reports (2026)
Authors: Noriko Tsutsumi, Sonoko Sakata, Riyu Ikari, and Nobuyuki Ebihara
Introduction & Clinical Context
Tay-Sachs disease is a rare, progressive, autosomal recessive neurodegenerative disorder caused by a deficiency of the enzyme beta-hexosaminidase A. This enzyme deficiency leads to the abnormal accumulation of mathrm{GM_2} gangliosides in neuronal tissue, including the brain and the retina. While the classic cherry-red spot in the macula is a pathognomonic sign during early infancy, limited literature exists on the long-term structural and functional retinal changes as the disease progresses into late childhood. A recent case report details the long-term clinical evolution, optical coherence tomography (OCT) findings, and unique electroretinography (ERG) features of an infantile Tay-Sachs patient followed up to age 5 years and 8 months.
Pathophysiology of the Cherry-Red Spot
- Ganglion Cell Density: The characteristic cherry-red spot occurs due to lipid accumulation within the retinal ganglion cells (RGCs).
- Macular Appearance: Because RGC density is highest in the parafoveal region, lipid deposition creates a pale, opaque halo surrounding the fovea. The central fovea itself lacks RGCs, allowing the underlying red choroidal circulation to show through prominently.
Key Clinical Case Summary
Initial Presentation & Diagnosis
- Patient: A Japanese boy born at 38 weeks gestation with an uneventful neonatal period.
- Developmental Regression: Motor skill delays emerged at age 1 year and 1 month, followed by progressive loss of acquired skills.
- Systemic & Neurological Workup:
- Brain MRI demonstrated diffuse T_2 hyperintensity in the bilateral basal ganglia.
- Hyperacusis (marked hypersensitivity to auditory stimuli) was present.
- Initial differential included mitochondrial disorders (e.g., Leigh syndrome due to elevated lactate on MRS), but genetic testing was negative.
- Ophthalmologic Referral (Age 1 Year 6 Months):
- Patient was able to fixate on and follow objects.
- Optic discs appeared normal.
- Bilateral classic cherry-red spots were identified in the maculae.
- Biochemical Confirmation: Enzyme assay in skin fibroblasts showed a marked deficiency of beta-hexosaminidase A activity with normal total beta-hexosaminidase levels.
Disease Progression & Ophthalmologic Evolution
| Patient Age | Ophthalmic & Visual Findings | Clinical Significance |
|---|---|---|
| 1 Year 6 Months | Intact fixation/following; normal optic discs; distinct bilateral cherry-red spots. | Early stage with intact visual function and prominent parafoveal RGC lipid opacification. |
| 2 Years 1 Month | Complete loss of visual fixation and tracking. | Functional decline in the visual transmission pathway. |
| 4 Years 4 Months | Severe bilateral optic disc pallor/atrophy; noticeable fading/reduction of cherry-red spots. | RGC loss and inner retinal degeneration cause the opacified halo to diminish. |
| 4 Years 9 Months | Extinguished ERG responses in both eyes (flat maximal, rod, and cone traces under ISCEV standards). | Demonstrates advanced, full-thickness retinal involvement beyond RGC loss. |
| 5 Years 3 Months | Handheld OCT reveals diffuse retinal thinning/atrophy across all layers. | Hyporeflectivity in foveal/parafoveal inner layers and hyperreflectivity in peripheral inner layers. |
Key Takeaways for General Ophthalmologists
- A Fading Cherry-Red Spot Does Not Mean Improvement
- As Tay-Sachs disease advances, the cherry-red spot gradually fades.
- This reduction is caused by widespread death and atrophy of retinal ganglion cells rather than resolution of lipid storage.
- Sequential Loss of Visual Function
- Visual pathway degeneration (optic nerve to visual cortex) typically precedes outer retinal dysfunction.
- Central visual fixation is lost early, followed by severe optic atrophy.
- Novel Finding: Extinguished ERG in Late-Stage Disease
- Early literature reported normal or near-normal ERGs in younger Tay-Sachs patients.
- This report documents complete ERG extinction at age 4 years and 9 months.
- This suggests that while lipid accumulation initially targets RGCs, long-term disease leads to pan-retinal involvement affecting photoreceptors and outer retinal layers.
- Role of Multimodal Imaging in Neurodegenerative Storage Diseases
- Handheld OCT and non-invasive ERG testing provide critical objective markers for monitoring disease progression in pediatric neurodegenerative disorders.
