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PubMed This is a summary of 10 peer-reviewed journal articles Updated
Ophthalmology

Getting it Right: Diagnosis and Distinguishing CACD from AMD

At a Glance

Central Areolar Choroidal Dystrophy (CACD) is often misdiagnosed as age-related macular degeneration (AMD). Doctors distinguish CACD by looking for highly symmetrical retinal changes, an absence of drusen, and an earlier age of onset. Genetic testing is required to confirm the diagnosis.

Getting an accurate diagnosis for Central Areolar Choroidal Dystrophy (CACD) can be a journey of its own. Because CACD is rare and shares features with more common conditions, doctors use a combination of advanced “multimodal” imaging and genetic testing to pinpoint exactly what is happening in your eyes.

How Doctors “See” CACD

Specialized imaging allows your eye care team to look beneath the surface of the retina to see the layers where CACD begins.

  • Optical Coherence Tomography (OCT): Think of this as an “ultrasound with light.” It provides a cross-section of your retina. In CACD, the doctor looks for attenuation (thinning) of the RPE layer and disruption of the light-sensing cells [1][2].
  • OCT-Angiography (OCT-A): This imaging shows the blood flow in the tiny vessels behind the retina. A hallmark sign of CACD, even in the very early stages, is choriocapillaris rarefaction—a thinning or loss of the tiny blood vessel network that feeds your retina [2][3].
  • Fundus Autofluorescence (FAF): This test uses special light to make certain structures in the eye “glow.” It helps doctors see the health of the RPE. In CACD, the doctor may see “speckled” patterns or dark, hypoautofluorescent spots that look like “punched out” areas where the tissue has thinned [1][4].

The Great Mimic: CACD vs. AMD

The biggest diagnostic challenge is that CACD can look very similar to Age-Related Macular Degeneration (AMD), especially the “dry” form known as Geographic Atrophy (GA) [5][2]. Misdiagnosis is common because both conditions lead to central vision loss and thinning of the retina. However, there are three key “tells” that point to CACD:

Feature CACD AMD
Drusen Usually absent. The area of loss looks “clean.” [5] Tiny yellow deposits (drusen) are almost always present. [5]
Symmetry Highly symmetrical. The left and right eyes often look like mirror images. [1] Often asymmetrical. One eye may be significantly more affected than the other. [1]
Age of Onset Often begins in the 30s, 40s, or 50s. [6] Typically begins after age 60. [7]

Why Genetic Testing is the “Gold Standard”

While imaging can provide strong clues, genetic testing is the only way to confirm a CACD diagnosis with 100% certainty [5]. By identifying a mutation in genes like PRPH2, GUCA1A, or CDHR1, your doctor can distinguish CACD from AMD or other similar-looking dystrophies [5][2].

Confirming the diagnosis through genetics is vital because:

  1. It guides your outlook: Knowing the specific gene helps your doctor predict how your vision might change over time [8].
  2. It informs your family: You will know exactly what the risks are for your children or siblings [9].
  3. It opens doors to research: Most clinical trials and future treatments require a confirmed genetic diagnosis to participate [10].

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Common questions in this guide

How can my eye doctor tell the difference between CACD and AMD?
Doctors look for three key differences: CACD typically lacks the yellow deposits called drusen, affects both eyes symmetrically, and often begins earlier in life (usually in the 30s to 50s) than age-related macular degeneration.
Why do I need genetic testing if my eye scans already show CACD?
While imaging provides strong clues, genetic testing is the only way to confirm a CACD diagnosis with absolute certainty. Finding the specific gene mutation helps predict how your vision might change, clarifies risks for your family, and qualifies you for potential clinical trials.
What does an OCT scan show if I have central areolar choroidal dystrophy?
Optical Coherence Tomography (OCT) is like an ultrasound using light that provides a detailed cross-section of your retina. In CACD, doctors use it to look for thinning in the retinal layers and disruption of your light-sensing cells.
What does choriocapillaris rarefaction mean on my eye scan report?
Choriocapillaris rarefaction is a thinning or loss of the tiny blood vessel network that feeds your retina. It is a hallmark sign of CACD that doctors can detect using a specialized imaging test called OCT-A.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Does my imaging show any drusen, and how does that help differentiate my condition from AMD?
  2. 2.Are the areas of atrophy in my eyes symmetrical?
  3. 3.What did my OCT-A scan show regarding the health of my choriocapillaris?
  4. 4.Can you explain the specific pattern of my fundus autofluorescence (FAF) and what it indicates about my RPE health?
  5. 5.Given my imaging results, which specific genetic tests would you recommend to confirm a CACD diagnosis?

Questions For You

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References

References (10)
  1. 1

    PRPH2-Associated Macular Dystrophy in 4 Family Members with a Novel Mutation.

    Choi H, Cloutier A, Lally D

    Ophthalmic genetics 2022; (43(2)):235-239 doi:10.1080/13816810.2021.2015790.

    PMID: 34906036
  2. 2

    MULTIMODAL RETINAL IMAGING REVEALS NEW PATHOGENIC INSIGHTS IN CENTRAL AREOLAR CHOROIDAL DYSTROPHY: A CASE SERIES.

    Romano F, Cozzi E, Boon CJF, et al.

    Retinal cases & brief reports 2024; (18(1)):32-38 doi:10.1097/ICB.0000000000001325.

    PMID: 36731070
  3. 3

    Phenotypic Differences in a PRPH2 Mutation in Members of the Same Family Assessed with OCT and OCTA.

    Albertos-Arranz H, Sánchez-Sáez X, Martínez-Gil N, et al.

    Diagnostics (Basel, Switzerland) 2021; (11(5)) doi:10.3390/diagnostics11050777.

    PMID: 33925984
  4. 4

    EARLY FINDINGS FROM A NATURAL HISTORY STUDY OF PATIENTS WITH THE PATHOGENIC p.Gly208Asp PRPH2 VARIANT ASSOCIATED WITH RETINAL DYSTROPHY.

    AlAshwal SM, Kako R, Kalaw FGP, et al.

    Retina (Philadelphia, Pa.) 2026; (46(3)):521-532 doi:10.1097/IAE.0000000000004712.

    PMID: 41212986
  5. 5

    Genetic screening for macular dystrophies in patients clinically diagnosed with dry age-related macular degeneration.

    Kersten E, Geerlings MJ, Pauper M, et al.

    Clinical genetics 2018; (94(6)):569-574 doi:10.1111/cge.13447.

    PMID: 30215852
  6. 6

    LONG-TERM FOLLOW-UP OF PRPH2 -ASSOCIATED RETINAL DYSTROPHY.

    Zhao Z, Miere A, Le HM, Souied EH

    Retinal cases & brief reports 2024; (18(2)):236-241 doi:10.1097/ICB.0000000000001351.

    PMID: 36053859
  7. 7

    New Insights on the Regulatory Gene Network Disturbed in Central Areolar Choroidal Dystrophy-Beyond Classical Gene Candidates.

    Kazmierczak de Camargo JP, Prezia GNB, Shiokawa N, et al.

    Frontiers in genetics 2022; (13()):886461 doi:10.3389/fgene.2022.886461.

    PMID: 35656327
  8. 8

    Clinical and Imaging Characteristics of PRPH2 Retinopathies in a Longitudinal Cohort and Diagnostic Implications.

    Seddon JM, De D, Grunenkovaite L, Ferrara D

    Investigative ophthalmology & visual science 2024; (65(14)):31 doi:10.1167/iovs.65.14.31.

    PMID: 39693084
  9. 9

    A Specific Macula-Predominant Retinal Phenotype Is Associated With the CDHR1 Variant c.783G>A, a Silent Mutation Leading to In-Frame Exon Skipping.

    Charbel Issa P, Gliem M, Yusuf IH, et al.

    Investigative ophthalmology & visual science 2019; (60(10)):3388-3397 doi:10.1167/iovs.18-26415.

    PMID: 31387115
  10. 10

    Progression Rate of Macular Retinal Pigment Epithelium Atrophy in Geographic Atrophy and Selected Inherited Retinal Dystrophies. A Systematic Review and Meta-Analysis.

    Bassil FL, Colijn JM, Thiadens AAHJ, Biarnés M

    American journal of ophthalmology 2025; (269()):30-48 doi:10.1016/j.ajo.2024.07.035.

    PMID: 39153684

This page is for informational purposes only and does not replace professional medical advice. Always consult your ophthalmologist or a genetic counselor to discuss your specific imaging results and diagnosis.

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