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NCT Number: NCT06670989

Training to Modify Fixational Eye Movements for Optimizing Visual Performance in People With Central Vision Loss

People with central vision loss almost all have exaggerated fixational eye movements when compared with people with normal vision (e.g. larger amplitudes of microsaccades and ocular drifts). Central vision loss primarily results from eye diseases or disorders that affect the macular region of the retina, such as age-related macular degeneration (AMD) and Stargardt disease. The clinical wisdom is that exaggerated fixational eye movements are detrimental to vision. This forms the basis of the increasing number of clinical trials that use fixation stability (variability of eye positions during fixation) as an outcome measure to evaluate the effectiveness of interventions on age-related macular degeneration or other retinal diseases, despite the lack of causal evidence supporting or refuting a relationship between fixational eye movements and functional vision. If excessive fixational eye movements are indeed detrimental to vision for people with central vision loss, can we reduce the amount of their fixational eye movements, thus improve their fixation stability? And if so, does that lead to improved functional vision? The goal of this study is to examine the hypothesis that retinal image motion due to abnormal fixational eye movements can be modified through fixation training, with accompanied improvements in functional vision as a result.

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Key information

Conditions

Central Vision Loss From Macular Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Herbert Wertheim School of Optometry & Vision Science, University of California Berkeley

Berkeley, California, 94720, United States

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Participants with normal vision:

  • age 18 or above
  • best corrected visual acuity of at least 20/20 in each eye
  • cataracts, if present, must be minimal (grade 1 or below according to the Lens Opacity Classification System)
  • normal contrast sensitivity for their ages
  • stereoacuity at least 40 seconds of arc
  • no history or signs of any retinal diseases

Participants with macular disorders:

  • age 18 or above
  • macular disorder present in both eyes
  • presence of at least one scotoma within the central 5 degrees of the visual field and with best corrected visual acuity of at least 20/400 in the better-seeing eye
  • no foveal island of vision left (i.e. absolute scotoma must include the foveal area)
  • cataracts, if present, must be grade 2 or lower according to the Lens Opacity Classification System II

Exclusion criteria

Participants with normal vision:

  • younger than 18 years of age
  • best corrected visual acuity worse than 20/20 in each eye
  • cataracts worse than grade 1 according to the Lens Opacity Classification System II
  • abnormal contrast sensitivity for their ages
  • stereoacuity worse than 40 seconds of arc
  • history or signs of any retinal diseases

Participants with macular disorders:

  • younger than 18 years of age
  • macular disorder absent in at least one eye
  • no scotoma within the central 5 degrees of the visual field in the better-seeing eye
  • best corrected visual acuity of worse than 20/400 in the better-seeing eye
  • foveal island of vision
  • cataracts worse than grade 2 according to the Lens Opacity Classification System II

Treatment and study plan

Fixation training

Behavioral

Training (adapting) microsaccades during fixation

Primary outcomes

  1. Fixation stability

    Time frame: Data will be collected immediately before (within 1 hour) the first training session and immediately after (within 1 hour) the last training session. Data will be reported when analysis is completed for all participants (target date: by June 2025).

    Eye positions measured while participants looked at a stationary fixation target for 10 seconds, quantified as the area that captures 68% of eye positions (unit: deg^2).

Secondary outcomes

  1. Visual acuity

    Time frame: Data will be collected immediately before (within 1 hour) the first training session and immediately after (within 1 hour) the last training session. Data will be reported when analysis is completed for all participants (target date: by June 2025).

    Smallest letter that can be read on an acuity chart (Bailey-Lovie acuity chart). Unit of measurement will be in the logarithm of the minimum angle of resolution (logMAR).

  2. Contrast sensitivity

    Time frame: Data will be collected immediately before (within 1 hour) the first training session and immediately after (within 1 hour) the last training session. Data will be reported when analysis is completed for all participants (target date: by June 2025).

    The faintest (lowest contrast) letter that can be read using the Mars Contrast Sensitivity Test. Unit of measurement will be in the logarithm of the contrast sensitivity ("log units").

  3. Reading performance: Maximum reading speed

    Time frame: Data will be collected immediately before (within 1 hour) the first training session and immediately after (within 1 hour) the last training session. Data will be reported when analysis is completed for all participants (target date: by June 2025).

    Maximum reading speed (unit: words per minute) measured using the MNREAD Acuity Chart (MNREAD Acuity Chart is the name of the instrument that will be used).

  4. Reading performance: critical print size

    Time frame: Data will be collected immediately before (within 1 hour) the first training session and immediately after (within 1 hour) the last training session. Data will be reported when analysis is completed for all participants (target date: by June 2025).

    The smallest print size (unit: logMAR) on the MNREAD Acuity Chart that still allow participants to read at their maximum reading speed.

  5. Orientation judgement accuracy: low spatial-frequency

    Time frame: Data will be collected immediately before (within 1 hour) the first training session and immediately after (within 1 hour) the last training session. Data will be reported when analysis is completed for all participants (target date: by June 2025).

    Accuracy for judging the orientation (tilted to the left or right) of a low spatial-frequency grating. Unit of measurement will be in proportion-correct.

  6. Orientation judgement accuracy: high spatial-frequency

    Time frame: Data will be collected immediately before (within 1 hour) the first training session and immediately after (within 1 hour) the last training session. Data will be reported when analysis is completed for all participants (target date: by June 2025).

    Accuracy for judging the orientation (tilted to the left or right) of a high spatial-frequency grating. Unit of measurement will be in proportion-correct.

  7. Characteristics of fixational eye movements: microsaccade rate

    Time frame: Data will be collected immediately before (within 1 hour) the first training session and immediately after (within 1 hour) the last training session. Data will be reported when analysis is completed for all participants (target date: by June 2025).

    Fixational eye movements during the 10 seconds when participants are asked to fixate a target for fixation stability measurement (primary measurement) will be analyzed. The rate of microsaccades (fast eye movements during fixation) will be measured (unit: number per second).

  8. Characteristics of fixational eye movements: microsaccade amplitude

    Time frame: Data will be collected immediately before (within 1 hour) the first training session and immediately after (within 1 hour) the last training session. Data will be reported when analysis is completed for all participants (target date: by June 2025).

    Fixational eye movements during the 10 seconds when participants are asked to fixate a target for fixation stability measurement (primary measurement) will be analyzed. The amplitude of microsaccades (fast eye movements during fixation) will be measured (unit: degrees).

Sponsors and collaborators

Lead sponsor

National Eye Institute (NEI)

Nih

Registry information

Official study title

Training to Modify Fixational Eye Movements for Optimizing Visual Performance

Important dates

Study start
2022
Primary completion
2025
Study completion
2025
First posted
Nov 1, 2024
Registry last updated
Nov 1, 2024

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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