Smartphone Flicker Fusion Test for Vision Impairment

Overseen By Jan Full, BSN

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Randy Kardon

Disqualifiers: Scotoma, other ocular disorders

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 1

500 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests a new app called eyeFusion, designed to simplify the measurement of vision issues using a smartphone. The goal is to determine if the app can quickly and effectively assess flicker fusion, a type of vision measurement, in patients with optic disorders. Participants are divided into two groups: one with healthy individuals and another with people who have scotoma (a spot in the vision field that is absent or reduced). Individuals with known eye disorders other than scotoma are not eligible. This trial may suit those with scotoma or those without eye disorders who wish to help test the app. As an unphased trial, it offers participants the chance to contribute to innovative research that could transform vision assessment technology.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications.

What prior data suggests that this smartphone test is safe for vision impairment assessment?

Research shows that the eyeFusion app, used to check vision problems, is generally safe. In past studies, researchers monitored participants for safety, and no major issues emerged. Since this app measures vision using a smartphone, it doesn't involve surgery or drugs, typically resulting in fewer risks. The app simply assesses how eyes perceive flickering light, a straightforward and well-researched process. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the Smartphone Flicker Fusion Test for vision impairment because it could revolutionize how we diagnose visual disorders like scotoma. Unlike traditional methods, which often rely on bulky and expensive equipment, this test leverages the accessibility and convenience of smartphone technology to assess vision impairments. By using a smartphone, the test is not only more accessible but also potentially more cost-effective, making early detection and monitoring of vision issues easier for a wider range of individuals. This approach could significantly improve how quickly and efficiently vision impairments are detected and managed.

What evidence suggests that the eyeFusion app is effective for vision impairment?

Research has shown that the eyeFusion app, which assesses the ability to see flickering light, might help identify vision problems. In this trial, participants will divide into two groups: the "eyeFusion Control Subjects" group, consisting of healthy individuals with no known eye disorders, and the "eyeFusion Patients" group, consisting of individuals with scotoma. Studies have found that people with conditions like age-related macular degeneration score lower on this test, suggesting the app could help spot vision issues. The test has effectively distinguished between healthy and impaired vision in other situations. By measuring the ability to notice flickering, the app aims to quickly assess visual health. ^{1 2 3 5 6}

Who Is on the Research Team?

Randy Kardon, MD, PhD

Principal Investigator

University of Iowa

Are You a Good Fit for This Trial?

This trial is for people aged 18-80 with or without optic disorders. Healthy individuals with no known eye issues can join as controls, while those experiencing a blind spot (scotoma) are the patient group. Those with other ocular conditions cannot participate.

Inclusion Criteria

I have a blind spot in my vision.

I have no known eye disorders.

Exclusion Criteria

I have another eye condition.

I have a blind spot or another eye condition.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

Testing

Participants use the eyeFusion app to measure flicker fusion thresholds

Less than 2 minutes per session

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after testing

1 week

What Are the Treatments Tested in This Trial?

Interventions

• eyeFusion

Trial Overview

The study is testing an app called eyeFusion on smartphones to see if it's effective in measuring flicker fusion (the speed at which a flickering light appears steady) in patients with optic disorders.

How Is the Trial Designed?

Group I: eyeFusion Patients Experimental Treatment 1 Intervention

Scotoma subjects aged 18-80.

Group II: eyeFusion Control Subjects Active Control 1 Intervention

Healthy normal controls with no known eye disorders age 18-80.

Who Is Running the Clinical Trial?

Randy Kardon

Lead Sponsor

Trials

4

Recruited

1,100+

Published Research Related to This Trial

The study tested Augmented Reality Digital spectacles (AR DSpecs) on 21 patients with peripheral visual field losses, showing an average improvement of 18.81% in object detection while walking, indicating enhanced mobility.

The AR DSpecs improved eye tracking behaviors, leading to a more focused gaze on the central path and less scanning, which suggests that these spectacles can effectively aid patients in navigating their environment more safely.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Mobility improvement of patients with peripheral visual field losses using novel see-through digital spectacles. Sayed, AM., Shousha, MA., Baharul Islam, MD., et al.[2020]

The Accelerator 4-Alternative Forced-Choice Flicker Test prototype (A4FTp) demonstrated comparable diagnostic accuracy to established tests like Frequency Doubling Technology (FDT) and Optical Coherence Tomography (SD-OCT) for detecting chronic open angle glaucoma, with an area under the receiver operator characteristic curve (AUROC) of 0.82.

The A4FTp test is quick, averaging just over 2 minutes per eye, making it a time-efficient option for glaucoma detection compared to traditional methods, which could enhance its practical use in clinical settings.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Development and validation of a new glaucoma screening test using temporally modulated flicker. Fidalgo, BR., Jindal, A., Tyler, CW., et al.[2019]

Critical flicker/fusion (CFF) thresholds can effectively differentiate between patients with macular disease and those with media opacity, making it a useful potential vision test (PVT) for assessing retinal health.

In a study of 72 patients, CFF values were significantly lower in those with macular disease compared to those with media opacity or pseudophakia, indicating that CFF testing is not affected by media opacity but is sensitive to retinal disease.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Development of a critical flicker/fusion frequency test for potential vision testing in media opacities. Vianya-Estopà, M., Douthwaite, WA., Pesudovs, K., et al.[2004]

Two tablet-based tests for assessing real-world visual function—face discrimination and visual search—were evaluated in a study with 50 young, normally-sighted adults, showing stable performance estimates after about 20 trials.

Both tests were quick and easy to administer, with high completion rates and understanding among participants, suggesting they could be useful in clinical settings, although further research is needed for older adults and those with visual impairments.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Refinement and preliminary evaluation of two tablet-based tests of real-world visual function. Jones, PR., Tigchelaar, I., Demaria, G., et al.[2021]

Critical flicker-fusion frequency (CFF) was found to be significantly lower in patients with both non-exsudative and exsudative age-related macular degeneration (AMD), indicating a decline in visual processing speed associated with the disease.

CFF measurements could not differentiate between AMD patients and healthy individuals with similar visual acuity, suggesting that CFF is not a reliable diagnostic tool for AMD.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Critical flicker-fusion frequency in age-related macular degeneration. Maier, M., Groneberg, T., Specht, H., et al.[2021]

The study found that critical flicker fusion frequencies (CFF) are significantly reduced in patients with neuropathies compared to those with maculopathies, indicating that CFF can be a useful measure of temporal resolution in different eye conditions.

In amblyopic eyes, CFF is often equal to or better than the dominant eye, regardless of visual acuity, suggesting that CFF testing can help evaluate unexplained visual acuity reductions and highlight a dissociation between visual acuity and temporal resolution in amblyopia.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Critical (foveal) flicker fusion frequency (CFF) is helpful in differential diagnosis of organic lesions from orthoptic amblyopias]. Wildberger, H., Junghardt, A., Neetens, A., et al.[2009]

The critical flicker fusion frequency (CFF) test is a sensitive tool for detecting visual function changes in cataract patients, effectively distinguishing between simple cataracts and those with additional fundus diseases.

CFF can predict postoperative visual acuity more accurately than traditional tests, especially in cases with dense cataracts, making it a valuable tool for assessing visual prognosis in these patients.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The theory of critical flicker fusion frequency and its application in cataracts. Xu, G., Fu, J., Qi, H., et al.[2023]

Smartphones are becoming essential tools in clinical practice, especially in ophthalmology, where numerous apps can assist with tasks like measuring visual acuity and managing conditions such as amblyopia and glaucoma.

Despite the wide availability of these ophthalmology-related apps, there is a lack of clear evidence supporting their effectiveness, along with concerns about their development, regulation, and data security.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Smartphone use in ophthalmology: What is their place in clinical practice? Hogarty, DT., Hogarty, JP., Hewitt, AW.[2021]

The flicker sensitivity assessment technique developed for measuring straylight has been tested on approximately 400 subjects, demonstrating adequate precision and reliability for evaluating retinal integrity and the ability to perform the test.

Normal values for temporal contrast sensitivity (logTCS) were established around 2, with the test remaining unaffected by significant optical deterioration, indicating its robustness in assessing visual function across a wide age range (6 to 85 years).

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Psychophysics, reliability, and norm values for temporal contrast sensitivity implemented on the two alternative forced choice C-Quant device. van den Berg, TJ., Franssen, L., Kruijt, B., et al.[2019]

Citations

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withpower.com

withpower.com/trial/phase-scotoma-2017-e4425

Smartphone Flicker Fusion Test for Vision Impairment

Critical flicker-fusion frequency (CFF) was found to be significantly lower in patients with both non-exsudative and exsudative age-related macular degeneration ...

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clinicaltrials.gov/study/NCT03475147

Smartphone Flicker Fusion Test for Patients With Optic ...

This study will assess the validity of the test construct in measuring flicker fusion thresholds, and serve as a foundation for further ...

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pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC10141404/

Assessing Critical Flicker Fusion Frequency - PubMed Central

This narrative review aims to explore confounding factors that may affect the accuracy of cFFF threshold measurements, particularly in open-field studies.

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jcdr.net

jcdr.net/articles/PDF/21132/77605_CE[Ra1]_F(SL)_QC(PS_IS)_PF1(AG_OM)_PFA(IS)_PB(AG_IS)_PN(IS).pdf

Effect of Smartphone usage on Visual Fatigue Assessed by ...

Critical Flicker Fusion Frequency (CFFF) is a well-established physiological marker for assessing visual fatigue, where a decline in CFFF values ...

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researchgate.net

researchgate.net/publication/6528986_A_Critical_Flicker_Fusion_CFF_test_of_potential_vision_Post_print

A Critical Flicker Fusion (CFF) test of potential vision [Post ...

The CFF phenomenon effectively discriminated between subjects with and without retinal/neural disease and accurately predicted visual outcome ...

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link.springer.com

link.springer.com/article/10.1007/s00421-025-05935-7

Critical flicker fusion frequency: confounders and caveats

Critical flicker fusion frequency (cFFF) measures visual perception, with higher values indicating better performance.