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PubMed This is a summary of 15 peer-reviewed journal articles Updated
Ophthalmology

Clinical Tests, Imaging & Lab Reports

At a Glance

For Choroideremia, standard eye charts cannot accurately track disease progression. Doctors rely on structural imaging like FAF and OCT to measure retinal health. Mandatory genetic testing is also required to confirm your diagnosis and determine your eligibility for gene therapy clinical trials.

When you visit an eye specialist for Choroideremia (CHM), they will perform several tests. It is important to understand that the standard “eye chart” test (reading the letters) is often the least useful tool for tracking how the disease is actually changing. To truly understand your progression, you must look at your genetic and imaging data.

Why the “Eye Chart” is Not Enough

Best-Corrected Visual Acuity (BCVA) measures your ability to see fine detail at the very center of your vision [1]. Because CHM typically leaves the center of your eye (the fovea) intact until the very late stages, you might have 20/20 vision on a chart while simultaneously losing a significant amount of your peripheral retina [2][3].

For this reason, doctors use structural imaging—tests that take a “top-down” or “cross-section” look at your eye’s layers—to see the true state of your health [4][5].

The Gold Standard: FAF and OCT

Two specific imaging tests are essential for anyone with CHM:

  1. Fundus Autofluorescence (FAF): This test uses a special light to make the Retinal Pigment Epithelium (RPE) glow.
    • What it tracks: The doctor looks for the residual RPE area—the “island” of healthy cells remaining [6].
    • Why it matters: This area typically shrinks in a predictable “decay” pattern over years, making it the most reliable way to track your progression [6][7].
  2. Optical Coherence Tomography (OCT): This is like an ultrasound for the eye, showing the individual layers of the retina.
    • What it tracks: Doctors focus on the Ellipsoid Zone (EZ), which represents the health of your light-sensing cells (photoreceptors) [8][4].
    • Emerging Biomarkers: Doctors are now looking for hyperreflective foci (HF)—tiny, bright spots on the OCT that may indicate cellular stress or inflammation [9][10].

Your Genetic Report Checklist

Genetic testing is no longer optional; it is mandatory for a definitive diagnosis and is a fundamental requirement for enrollment in gene therapy clinical trials [11][12]. When you look at your lab report, ensure the following information is present:

  • Gene Name: It must explicitly state the CHM gene [13].
  • Mutation Nomenclature: Look for a string of letters and numbers like c.123C>T or p.Arg41* (this is called HGVS nomenclature) [11].
  • Mutation Type: This tells you how the gene is broken. Common types include:
    • Nonsense: A “stop sign” appears too early, stopping the protein from being made [14].
    • Frameshift: The genetic code is shifted, causing all subsequent instructions to be read incorrectly [15].
    • Splice-site: The “editing” of the gene is incorrect [14].
    • Deletion: A whole chunk of the gene is missing [15].
  • Classification: The mutation should be labeled as Pathogenic or Likely Pathogenic [11].
    • Note on VUS: If your report says VUS (Variant of Uncertain Significance), do not panic. This just means the lab needs more data—often by testing family members—to classify it properly. A genetic counselor can guide you through this process.

Tracking Your Data Over Time

Because CHM is a slow-moving condition, the goal of these tests is to establish a “baseline.” By comparing your residual RPE area (measured in mm²) from year to year, you and your doctor can determine your specific rate of progression and decide if you are a good candidate for upcoming treatments or trials [4][6].

Common questions in this guide

Why is the standard eye chart not enough to track my Choroideremia?
The standard eye chart measures central vision, which is often preserved until the late stages of Choroideremia. Because the disease usually starts by damaging the peripheral retina, doctors must use specialized imaging to accurately see and track these changes.
What does FAF imaging track in Choroideremia?
Fundus Autofluorescence (FAF) imaging tracks your residual RPE area, which is the remaining healthy tissue in your retina. Monitoring how this "island" of healthy cells shrinks over the years is the most reliable way to track your disease progression.
Why do I need an OCT scan for my eyes?
OCT stands for Optical Coherence Tomography, which acts like an ultrasound for your eye. It allows doctors to see the individual layers of your retina, evaluate the health of your light-sensing cells, and look for tiny spots that may indicate cellular stress or inflammation.
Why is genetic testing required for Choroideremia?
Genetic testing is mandatory to confirm a definitive Choroideremia diagnosis. Identifying your exact genetic mutation is also a fundamental requirement for enrolling in gene therapy clinical trials.
What does a VUS result mean on my genetic report?
VUS stands for Variant of Uncertain Significance. This simply means the laboratory needs more data to classify the mutation properly. Often, this involves testing family members to help determine if that specific genetic change is causing your symptoms.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What is the exact square millimeter (mm²) measurement of my 'residual RPE area' on my latest FAF scan?
  2. 2.How does the area of my 'ellipsoid zone' (EZ) on OCT compare to my last visit?
  3. 3.Does my genetic report use HGVS nomenclature (e.g., c.123C>T), and is it classified as 'Pathogenic'?
  4. 4.Are you seeing 'hyperreflective foci' (HF) on my scans, and what do they indicate about my current inflammation or progression?
  5. 5.Is my mutation a 'nonsense' mutation, a 'frameshift', or a different type?

Questions For You

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References

References (15)
  1. 1

    Ranked Importance of Visual Function Outcome Measures in Choroideremia Clinical Trials.

    Josan AS, Taylor LJ, Xue K, et al.

    Investigative ophthalmology & visual science 2024; (65(13)):58 doi:10.1167/iovs.65.13.58.

    PMID: 39601638
  2. 2

    Natural History of the Central Structural Abnormalities in Choroideremia: A Prospective Cross-Sectional Study.

    Aleman TS, Han G, Serrano LW, et al.

    Ophthalmology 2017; (124(3)):359-373 doi:10.1016/j.ophtha.2016.10.022.

    PMID: 27986385
  3. 3

    Investigating the impact of asymmetric macular sensitivity on visual acuity chart reading in choroideremia.

    Baffour-Awuah KA, Taylor LJ, Josan AS, et al.

    Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists) 2024; (44(6)):1188-1201 doi:10.1111/opo.13356.

    PMID: 38989810
  4. 4

    A Prospective, Observational, Non-interventional Clinical Study of Participants With Choroideremia: The NIGHT Study.

    Maclaren RE, Lam BL, Fischer MD, et al.

    American journal of ophthalmology 2024; (263()):35-49 doi:10.1016/j.ajo.2024.01.022.

    PMID: 38311152
  5. 5

    Choroideremia: Toward Regulatory Approval of Retinal Gene Therapy.

    Yusuf IH, MacLaren RE

    Cold Spring Harbor perspectives in medicine 2023; doi:10.1101/cshperspect.a041279.

    PMID: 37277205
  6. 6

    Long-term Natural History of Atrophy in Eyes with Choroideremia-A Systematic Review and Meta-analysis of Individual-Level Data.

    Shen LL, Ahluwalia A, Sun M, et al.

    Ophthalmology. Retina 2020; (4(8)):840-852 doi:10.1016/j.oret.2020.03.003.

    PMID: 32362554
  7. 7

    An In Silica Model for RPE Loss Patterns in Choroideremia.

    Young BK, Shen LL, Del Priore LV

    Investigative ophthalmology & visual science 2021; (62(14)):10 doi:10.1167/iovs.62.14.10.

    PMID: 34779822
  8. 8

    Measurement and Reproducibility of Preserved Ellipsoid Zone Area and Preserved Retinal Pigment Epithelium Area in Eyes With Choroideremia.

    Hariri AH, Velaga SB, Girach A, et al.

    American journal of ophthalmology 2017; (179()):110-117 doi:10.1016/j.ajo.2017.05.002.

    PMID: 28499705
  9. 9

    Optical coherence tomography-derived biomarkers for disease severity in choroideremia and choroideremia carriers.

    Choi HS, Yoon CK, Park UC, et al.

    Canadian journal of ophthalmology. Journal canadien d'ophtalmologie 2026; (61(3)):722-730 doi:10.1016/j.jcjo.2025.11.014.

    PMID: 41386279
  10. 10

    HYPERREFLECTIVE FOCI AS A PATHOGENETIC BIOMARKER IN CHOROIDEREMIA.

    Romano F, Arrigo A, MacLaren RE, et al.

    Retina (Philadelphia, Pa.) 2020; (40(8)):1634-1640 doi:10.1097/IAE.0000000000002645.

    PMID: 31800458
  11. 11

    A hypomorphic variant of choroideremia is associated with a novel intronic mutation that leads to exon skipping.

    Waldock WJ, Taylor LJ, Sperring S, et al.

    Ophthalmic genetics 2024; (45(2)):210-217 doi:10.1080/13816810.2023.2270554.

    PMID: 38273808
  12. 12

    Progress in the development of novel therapies for choroideremia.

    Cehajic Kapetanovic J, Patrício MI, MacLaren RE

    Expert review of ophthalmology 2019; (14(6)):277-285 doi:10.1080/17469899.2019.1699406.

    PMID: 32002021
  13. 13

    Whole-exome sequencing reveals a novel CHM gene mutation in a family with choroideremia initially diagnosed as retinitis pigmentosa.

    Guo H, Li J, Gao F, et al.

    BMC ophthalmology 2015; (15()):85 doi:10.1186/s12886-015-0081-4.

    PMID: 26216097
  14. 14

    "Hypomorphic splice-site variants in the CHM gene: implications for patient selection and endpoint design in choroideremia gene therapy trials".

    Amjad A, Ali MR, Ali U, Mahato RK

    Annals of medicine and surgery (2012) 2026; (88(2)):2126-2127 doi:10.1097/MS9.0000000000004588.

    PMID: 41675726
  15. 15

    Whole exome sequencing of a family revealed a novel variant in the CHM gene, c.22delG p.(Glu8Serfs*4), which co-segregated with choroideremia.

    Dan H, Li T, Lei X, et al.

    Bioscience reports 2020; (40(5)) doi:10.1042/BSR20200067.

    PMID: 32364220

This page explains clinical testing, imaging, and genetic reports for Choroideremia for educational purposes only. Always consult your ophthalmologist or genetic counselor for interpreting your specific test results.

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