A Sharply Defined Pattern of Central Retinal Thinning
Picture the choroid as the soil nourishing the retina from beneath, threaded with the blood vessels that keep photoreceptor cells alive. Central areolar choroidal dystrophy is best imagined as one sharply defined patch of that soil eroding directly beneath the macula, while the surrounding ground stays entirely firm and untouched. That crisp, well-demarcated boundary — rather than a gradually fading edge — is one of the condition's most recognisable features on examination.
Kenyan patients typically present with this condition in their thirties or forties, often after a routine eye check turned up a clearly outlined pale patch that a local ophthalmologist correctly flagged as atypical for ordinary age-related change at that age.
The hallmark presentation is a slow, gradual blurring of central vision unfolding over years rather than months, with a well-defined blind spot forming directly in the centre of vision as the atrophic patch slowly expands. Reading and recognising faces become progressively more difficult, while peripheral vision remains essentially untouched throughout the entire course. Night vision, notably, tends to stay intact — a detail that separates this condition from rod-driven dystrophies such as retinitis pigmentosa, where night vision is typically affected early on.
Mutations in the PRPH2 gene are the most commonly identified cause, disrupting a protein essential to the structure of photoreceptor outer segments. The choriocapillaris, retinal pigment epithelium, and the photoreceptors directly above them degenerate together within a sharply confined central zone, rather than diffusely across the whole retina. Inheritance typically follows an autosomal dominant pattern.
A fundus examination reveals a clearly demarcated atrophic patch centred on the macula, and fundus autofluorescence is particularly useful for tracing exactly where the atrophy border sits. OCT assesses how much photoreceptor tissue survives at the margins of the patch, while electroretinography is typically near-normal — a finding that itself helps distinguish this condition from broader, more generalised retinal dystrophies. Genetic testing for PRPH2 rounds out the diagnostic picture.
Care focuses on tracking how quickly the atrophic patch is expanding, since that pace varies meaningfully from patient to patient and shapes how urgently intervention is considered. Regenerative stem cell therapy is evaluated for eligible patients as a way of supporting the still-viable tissue surrounding the atrophic zone, alongside low-vision planning built around the specific size and shape of the central blind spot as it develops over time.
Not at all — normal night vision is actually expected and consistent with this exact diagnosis, since the damage stays confined to the central macula rather than affecting the rod cells responsible for seeing in the dark. It's one of the details that actually helps confirm this specific condition rather than a broader retinal dystrophy.
The pace varies considerably from person to person, which is precisely why we track it with sequential imaging over time rather than relying on a single snapshot. Some patients see very gradual change over many years, while others progress somewhat faster.
The appearance can look similar — a well-defined atrophic patch — but this condition is inherited and tends to begin decades earlier than the geographic atrophy typically seen in older age-related disease. Genetic testing and the age at which it began are what distinguish the two.
In most cases, no — the damage in this condition stays confined to the central macular area rather than spreading outward, so peripheral vision and general mobility are typically preserved even as central vision continues to change over time.