Central areolar choroidal dystrophy (CACD) is an inherited eye disease that slowly destroys the light-sensitive tissue at the center of the retina, eventually causing a well-defined patch of vision loss right in the middle of your visual field. It is caused by mutations in the PRPH2 gene, which provides instructions for a protein critical to the structure of photoreceptor cells. The condition typically becomes noticeable in a person’s thirties or forties, though it can appear earlier or later, and it progresses through recognizable stages over years to decades. Because the damage is confined to the macula, peripheral vision usually remains intact even as central vision deteriorates severely.
How the Name Came About
The condition was first described in 1884 by the ophthalmologist Edward Nettleship, who called it “central senile areolar choroidal atrophy.” Other early clinicians used terms like “central areolar choroidal sclerosis.” Over time, researchers realized two things that made those names misleading: the disorder is genetic rather than age-related, and the choroidal blood vessels do not show a true localized sclerosis. The name was updated to “central areolar choroidal dystrophy” to reflect its hereditary nature and the broader pattern of tissue degeneration involved.1JAMA Network. Central Areolar Choroidal Dystrophy “Areolar” refers to the roughly circular area of atrophy that develops in the macula, and “dystrophy” signals that the underlying cause is a genetic defect rather than aging or environmental damage.
The Four Stages of Progression
Clinicians grade CACD on a widely used four-stage system that tracks how the retinal pigment epithelium (RPE) and the underlying choroidal blood vessel layer break down over time.2PubMed. The development of central areolar choroidal dystrophy
- Stage 1: Subtle pigment changes appear just outside the center of the macula. Visual acuity at this point is often still normal or close to it, and many people have no symptoms.
- Stage 2: The pigment disruption spreads into a mottled ring encircling the fovea. Mild blurriness or difficulty with color discrimination, particularly along the blue axis, can begin here.
- Stage 3: Patches of geographic atrophy develop in the choroidal capillary layer around the fovea, but the very center is still spared. Vision loss becomes more noticeable because the ring of dead tissue encroaches on areas used for reading and face recognition.
- Stage 4: The atrophy extends into the fovea itself. Central vision drops sharply, sometimes to the level of counting fingers, though peripheral vision remains functional.
Progression through these stages is not on a fixed timetable. In one large family study, some members in their early thirties were still at stage 2 while a sibling just a few years older had already reached stage 3 with acuity as low as 0.05 in both eyes.3JAMA Ophthalmology. Clinical Findings in a Multigeneration Family With Autosomal Dominant Central Areolar Choroidal Dystrophy Associated With an Arg195Leu Mutation in the Peripherin/RDS Gene Older family members in the same study had vision ranging from counting fingers to 0.1, consistent with stage 4. The mean age at onset of noticeable visual loss across a broader cohort of nearly 100 mutation carriers was about 46 years, followed by gradual decline.4Ophthalmology. Centract Areolar Choroidal Dystrophy and Peripherin/RDS Mutations
The Genetics Behind CACD
CACD is inherited in an autosomal dominant pattern, meaning a single copy of a mutated gene from one parent is enough to cause the disease. The gene involved is PRPH2, which codes for a protein called peripherin-2. This protein sits in the outer segments of photoreceptor cells and helps maintain their disc-like structural shape. When peripherin-2 is malformed, photoreceptor outer segments become disorganized, and the cells gradually die.
Several different mutations in PRPH2 have been linked to CACD. The most commonly reported is p.Arg142Trp, which accounted for the vast majority of cases in a large Dutch study of 98 affected patients.4Ophthalmology. Centract Areolar Choroidal Dystrophy and Peripherin/RDS Mutations Other mutations like p.Arg195Leu and p.Arg172Gln have been identified in individual families. The specific mutation matters somewhat, but it does not reliably predict how severe the disease will be in any one person.
Why Severity Varies So Much, Even Within Families
One of the most striking features of CACD is how differently it can manifest even among relatives who carry the exact same mutation. Two siblings with the identical PRPH2 change can end up at different disease stages at the same age, or one may develop symptoms decades before the other. Researchers have documented cases where individuals carrying the same mutant allele present with very distinct clinical pictures, and the phenotype can shift as a patient ages, sometimes transitioning from one clinical classification to another.5PubMed Central. PRPH2-Related Retinal Diseases: Broadening the Clinical Spectrum and Describing a New Mutation
This variability extends beyond severity. In some families, the same PRPH2 mutation causes CACD in one member and a different retinal disease pattern in another.6PubMed. Phenotypic variability and long-term follow-up of patients with known and novel PRPH2/RDS gene mutations One case series documented a single splice-site mutation in PRPH2 that produced multiple different retinal phenotypes across seven members of one family, even though the mutation showed complete penetrance, meaning every carrier had some form of retinal disease.7PubMed Central. Intrafamilial Phenotypic Variability in PRPH2-Related Retinopathy The reasons for this unpredictability are not fully understood, but other genes, environmental factors, and possibly sex-linked biological differences all seem to play a role.
On the other end of the spectrum, some mutation carriers show no signs of disease at all. In the large Dutch cohort, up to about one in five carriers of the p.Arg142Trp mutation showed nonpenetrance, meaning they had the mutation but no detectable CACD, with some remaining unaffected into their sixties.4Ophthalmology. Centract Areolar Choroidal Dystrophy and Peripherin/RDS Mutations This is unusual for a dominant genetic disease and complicates genetic counseling. A negative eye exam in a middle-aged person from an affected family does not necessarily mean they did not inherit the mutation.
How CACD Is Diagnosed
Diagnosing CACD relies on a combination of clinical examination, retinal imaging, and sometimes electrical testing of retinal function. Because the early stages can look subtle on a standard dilated eye exam, advanced imaging has become increasingly important for catching the disease before significant vision loss occurs.
Fundus autofluorescence imaging, which maps the health of the RPE by measuring its natural fluorescence, is particularly useful. In CACD, a distinctive speckled autofluorescence pattern appears in the macula, reflecting patches of abnormal RPE metabolism. Near-infrared autofluorescence and optical coherence tomography angiography can detect RPE thinning and tiny areas of reduced blood flow in the choroidal capillary layer even at the earliest disease stages, sometimes before any symptoms are reported.8Retinal Cases and Brief Reports. Multimodal Retinal Imaging Reveals New Pathogenic Insights in Central Areolar Choroidal Dystrophy: A Case Series
Electrophysiology testing also provides useful information. A standard full-field electroretinogram, which measures the overall electrical response of the entire retina to light, typically comes back normal in CACD because the disease is confined to the macula and the rest of the retina functions fine. A multifocal electroretinogram, which maps responses from many small zones across the central retina, tells a different story: it reveals significant dysfunction in the perifoveal macula with relative preservation of the fovea itself, matching the ring-shaped atrophy pattern seen on imaging.9PubMed. Use of the multifocal electroretinogram in the evaluation of a patient with central areolar choroidal dystrophy This pattern helps distinguish CACD from conditions that affect the retina more broadly.
Telling CACD Apart from Age-Related Macular Degeneration
CACD and age-related macular degeneration (AMD) can look similar in their later stages, since both produce geographic atrophy of the macula. The confusion is compounded by the fact that CACD was originally described using the word “senile,” as if it were an aging disease. Getting the distinction right matters because the genetic implications, the expected course, and eventually the treatment options are very different.
Imaging provides the clearest separation. On autofluorescence imaging, the speckled macular pattern shows up in about 85% of CACD eyes but only around 6% of early AMD eyes. Conversely, sub-RPE deposits (drusen visible on cross-sectional scans) are far more common in AMD than in CACD, appearing in roughly 37% of AMD scans versus about 2% in CACD. Reticular drusen, a distinctive subtype of deposit, were present in over half of early AMD eyes and all of the geographic atrophy AMD eyes studied, but appeared in none of the CACD eyes.10PubMed. Central areolar choroidal dystrophy (CACD) and age-related macular degeneration (AMD): differentiating characteristics in multimodal imaging
CACD does not normally present with drusen. However, certain PRPH2 mutations, particularly the Arg142Trp variant, appear to predispose carriers to developing drusen alongside their dystrophy.11PubMed Central. Central areolar choroidal dystrophy with associated dominant drusen When drusen do appear in a CACD patient, the clinical picture can overlap substantially with AMD, making genetic testing the definitive way to sort things out. Age of onset is another clue: CACD symptoms typically begin decades before AMD would, though late-onset CACD cases in the fifties or sixties can fall into the age window where AMD is common.
Living with CACD and Current Management
There is no treatment that stops or reverses the retinal degeneration in CACD. Management focuses on monitoring disease progression, maximizing the vision that remains, and planning for the practical consequences of central vision loss. Low vision rehabilitation, including magnifying devices, specialized lighting, and training in eccentric viewing techniques, can help affected people maintain reading ability and independence for longer than they might otherwise.12Journal of Optometry. Central areolar choroidal dystrophy with associated dominant drusen
Because peripheral vision is preserved, mobility is generally maintained even in advanced stages. People with stage 4 CACD can still navigate their environment, recognize large objects, and move around safely. The most significant functional losses center on tasks that require sharp central detail: reading standard print, recognizing faces at a distance, and driving. Early referral for occupational and visual rehabilitation services can make a substantial difference in quality of life, particularly for younger patients who may face decades of progressive central vision loss.
Genetic counseling is an important part of management for affected families. Because CACD is autosomal dominant, each child of an affected parent has a 50% chance of inheriting the mutation. The unpredictable severity and the possibility of nonpenetrance make these conversations nuanced. A person who inherits the mutation might progress slowly and retain useful central vision well into middle age, or they might experience rapid decline in their thirties. Genetic testing can identify carriers before symptoms appear, which allows for closer monitoring and early intervention with low vision supports as needed.
What Animal Research Is Revealing About Mechanisms and Sex Differences
Much of what we understand about the cellular chain of events in CACD comes from mouse models carrying mutations in the Prph2 gene. Recent work using these models has identified a sequence of pathological events: in young animals, the photoreceptor outer segments become structurally disorganized and the immune system begins to activate, including complement pathways. Middle age appears to be a critical turning point, where cell death accelerates and the barrier function of the RPE starts to break down, marking the shift from early dysfunction to overt degeneration.13Nature (Cell Death Discovery). Age- and sex-dependent retinal degeneration in peripherin-2 mutant mice, a model of central areolar choroidal dystrophy
Perhaps the most unexpected finding from this research involves sex differences. Female mice carrying the Prph2 mutation showed greater and more sustained inflammatory activation than males from the earliest disease stages, driven in part by complement system upregulation and specific inflammatory signaling pathways. Female mice also had greater functional decline and more photoreceptor loss overall.13Nature (Cell Death Discovery). Age- and sex-dependent retinal degeneration in peripherin-2 mutant mice, a model of central areolar choroidal dystrophy Whether this translates directly to human CACD is not yet clear. The clinical literature has not established a consistent sex difference in human disease severity, and the variability among human patients is enormous regardless of sex. Still, the finding raises the possibility that hormonal or immune factors influence the pace of degeneration and could eventually inform treatment strategies.
The Search for Future Therapies
Because CACD stems from a single-gene defect, it is a natural candidate for gene therapy. The idea is straightforward in principle: deliver a functional copy of PRPH2 to the retinal cells that need it before too many photoreceptors are lost. In practice, gene therapy for PRPH2 mutations faces several challenges. The protein needs to be produced in precise amounts and integrated into the delicate disc structures of the outer segments. Too much peripherin-2 can be as problematic as too little, since the protein’s structural role depends on precise ratios with its binding partner, ROM1.
No gene therapy for CACD has reached clinical trials as of mid-2025, but the broader field of retinal gene therapy has advanced rapidly. The approval of a gene therapy for a different inherited retinal dystrophy caused by RPE65 mutations demonstrated that the approach can work for photoreceptor diseases. Researchers are also exploring whether anti-inflammatory treatments might slow the immune-driven component of degeneration identified in animal models, and whether RPE cell replacement therapies could eventually restore function in areas of geographic atrophy. For now, these remain experimental, and the timeline for any CACD-specific therapy is uncertain.
One practical implication of the evolving treatment landscape is that early and accurate genetic diagnosis matters more than it used to. If a therapy becomes available for a specific PRPH2 mutation, patients who already know their genotype and have been monitored for disease stage will be best positioned to benefit. For families with a history of CACD, genetic testing and regular retinal imaging create a baseline that could prove valuable in ways that were not possible a generation ago.