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Mobile Medical Application for Cost-effective Strabismus Screening

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT03450980
Recruitment Status : Active, not recruiting
First Posted : March 1, 2018
Last Update Posted : February 19, 2020
National Eye Institute (NEI)
Information provided by (Responsible Party):
Kevin Houston, Massachusetts Eye and Ear Infirmary

Brief Summary:
Develop and evaluate a new smartphone based app to screen for and measure eye misalignment (strabismus). The investigators will validate the app against simulated strabismus of known magnitude and common clinical tests. They will evaluate the app as a screening tool in high risk populations, to determine the sensitivity and specificity. They hypothesize that the app can measure to within 2 units (prism diopters) of the ground truth, and that it will be correlated with gold standard tests.

Condition or disease Intervention/treatment Phase
Strabismus Other: EyeTurn App Not Applicable

Detailed Description:

The goal of the proposed project is the development and evaluation of a novel mobile medical application for the detection and monitoring of strabismus (eye misalignment). The image analysis technology necessary to measure strabismus using the corneal reflection technique (Photographic Hirschberg Test) has been available for many decades, however it has never been deployed using a smart phone. A smart phone platform will eliminate barriers of cost (since the hardware is maintained and updated by the smart phone industry), leading to rapid wide spread application and allowing the technology to finally reach its potential level of impact for children's eye care in the detection and management of strabismus. Strabismus causes visual confusion and double vision which ultimately results in the brain suppressing vision from the deviated eye. In children this results in under-development (amblyopia) with permanent vision loss in the deviated eye if not detected and treated at a young age. Strabismus in children is also associated with coordination problems such as postural instability and severe social disadvantages. Strabismus develops in an estimated 3-8% of children in the U.S. The prototype smart phone app (Referred to here as the Mobile Eye Alignment App - MEAA), uses photographic analysis of the corneal reflection (Purkinjie image) generated by the smart phone camera flash. The corneal reflection method uses the displacement of the reflection from the center of the pupil in the deviated eye to calculate the amount of eye misalignment. This measurement technique will be deployed for the proposed project using the hardware of the iPhone, a popular phone with an iOS operating system. Preliminary results suggest the app can measure differences in eye alignment of 1.6° (2.8 prism diopters). If successfully developed, the app has potential to be utilized to advance pediatric strabismus research by facilitating and reducing the cost of collecting enormous amounts of data from the general population and under-served or remote populations for epidemiological studies, and allowing researchers to capture eye alignment data much more frequently than is currently possible. Such a tool could better delineate the natural history of strabismus and perhaps help determine its causes. While devices are available which could make these measurements, the costs are prohibitively high (>$3,000 ea.) and will not reach the widespread availability of smart phones. Clinical goals for the app are to provide eye doctors with an objective measurement tool in the exam room, allow daily monitoring of treatment effects, and eventually to be used as a screening tool by school nurses, pediatricians, and parents. The barriers to market success of stand-alone devices is not the accuracy sensitivity or specificity of photographic analysis technique which has been reported with sensitivity from 53% to near 90% and specificity ranging from 76% to 94% for strabismus detection. Impact of strabismus screening for the young - Early detection for strabismus in young children, especially during the critical period up to 2 years of age, is important to ensure that treatment is administered as soon as possible. The success of amblyopia treatment depends on several factors, but principally on the age of onset and the age at which the treatment is initiated. Therapy for amblyopia is maximally effective if started before age 3 and can be initiated as early as 8 months, underscoring the critical need for early and widespread access to strabismus screening. Indeed, countries with long-standing early vision screening programs have reported significantly reduced rates of amblyopia. Access to strabismus screening is also important for older, school age children (age 7-17) suffering from amblyopia, for whom treatment can lead to significant improvements in visual acuity ranging from 20%-70% of patients, depending on their age bracket.

Aims Specific Aim 1: Develop and test key functionality of the strabismus app by comparing measurements with successive versions of the prototype app to known angles of eye deviation (non-strabismic volunteers will gaze at off axis targets of known eccentricity). Specific Aim 2: Evaluate the strabismus app accuracy and feasibility in a clinical environment.

Primary Hypothesis: For strabismus ranging from 1 to 30 prism diopters (target range), the optimized version of the app will provide measurements which are not significantly different from the ground truth (simulated strabismus) or clinical tests of eye alignment.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 190 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Masking Description:

Aim 1) In the comparison of the app against the ground truth the study staff will be masked to the ground truth value.

Aim 2) In comparison of the app against the clinical gold standards, the study staff making the clinical gold standard measures (prism alternating cover test and Modified Thorington test) will be masked to the app measurement.

Analyses: Study staff and statistician performing the analysis will be masked to which group data is from the app and which is from the ground truth and gold standard tests.

Primary Purpose: Screening
Official Title: Mobile Medical Application for Cost-effective Strabismus Screening
Actual Study Start Date : February 1, 2018
Actual Primary Completion Date : December 30, 2019
Estimated Study Completion Date : December 30, 2022

Arm Intervention/treatment
EyeTurn App
All participants will have their eye alignment measured with both the experimental device (EyeTurn app) and the clinical gold standard tests or ground truth (simulated strabismus gaze angles).
Other: EyeTurn App
App software which analyzes the position of ocular surface reflections in a photograph to quantify eye misalignment (strabismus)

Primary Outcome Measures :
  1. Strabismus angle with the app compared to ground truth and gold standard tests [ Time Frame: 15 minutes ]
    Strabismus angle is typically reported in prism diopters (PD) where 1PD = 0.57degrees.

Secondary Outcome Measures :
  1. Perceived Value Survey [ Time Frame: 5 minutes after completion of the tele-strabismus consult ]
    A 10 point likert-type rating scale to quantify the perceived value (1 low value to 10 high value) of the app tele-strabismus consultation (a subaim in the clinical evaluation aim)

  2. Test-Retest repeatability of the app [ Time Frame: 3 app measurements taken over approximately 1 minute ]
    Strabismus angle

  3. Robustness [ Time Frame: 1 year ]
    calculation of the percentage of capture failures (capture failures/ total number of attempted image captures)

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 88 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

Ground Truth Aim Study (closed for recruitment):

  • Age 18 to 88
  • Normal or corrected to normal vision

Clinical Aim Study:

  • Ages 18 to 88
  • Strabismus
  • Able to keep looking at a visual target for 30-60 seconds
  • Able to report locations of visual targets during testing

Exclusion Criteria:

Ground Truth Aim Study:

  • Age less than 18 or greater than 88.

Clinical Study:

  • Age less than 18 or greater than 88
  • Inability to keep looking at a visual target for 30-60 seconds
  • Inability to report locations of visual targets during testing

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT03450980

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United States, Massachusetts
Ophthalmology of Clinical Research Office, Mass Eye and Ear
Boston, Massachusetts, United States, 021141
Sponsors and Collaborators
Massachusetts Eye and Ear Infirmary
National Eye Institute (NEI)
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Principal Investigator: Kevin E Houston, OD Massachusetts Eye and Ear
Publications of Results:
Other Publications:
Rowe, F.J., Clinical Orthoptics. 3rd ed. 2012: Wiley and Sons. 486.
Barnard, S. and E. Johnson, Detecting strabismus. Optician, 2013.

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Responsible Party: Kevin Houston, Principal Investigator, Massachusetts Eye and Ear Infirmary Identifier: NCT03450980    
Other Study ID Numbers: 15-061H
2R44EY025902-02 ( U.S. NIH Grant/Contract )
First Posted: March 1, 2018    Key Record Dates
Last Update Posted: February 19, 2020
Last Verified: February 2020
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
Keywords provided by Kevin Houston, Massachusetts Eye and Ear Infirmary:
Double Vision, Amblyopia
Additional relevant MeSH terms:
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Ocular Motility Disorders
Cranial Nerve Diseases
Nervous System Diseases
Eye Diseases