Topographical reproducibility of small scotoma using computerised dynamic fixation target

Area of Science:

• Ophthalmology
• Neuroscience
• Medical Technology

Background:

• Accurate mapping of the physiological blind spot is crucial for diagnosing visual field defects.
• Existing methods for blind spot mapping may lack precision or repeatability.

Purpose of the Study:

• To introduce and evaluate a novel computer-assisted dynamic fixation technique for mapping the physiological blind spot.
• To assess the repeatability and accuracy of this new technique in healthy subjects.

Main Methods:

• A computer-assisted dynamic fixation technique was developed, utilizing eye movements tracked by a joystick to maintain fixation on a meandering target.
• Suprathreshold static light offset stimuli were presented on a monitor to map the blind spot.
• The technique was tested on 10 healthy eyes, with each eye examined twice to assess repeatability.

Main Results:

• The physiological blind spot was measured with an average size of 5.7 degrees horizontally and 6.4 degrees vertically.
• The dynamic fixation method combined with light offset stimuli achieved an average topographical reproducibility rate of 73% for scotoma mapping.
• Variability in blind spot dimensions was low, averaging 1.4 degrees vertically and 0.6 degrees horizontally across repeated tests.

Conclusions:

• The computer-assisted dynamic fixation technique offers a repeatable and accurate method for mapping the physiological blind spot.
• This novel approach has potential applications in clinical ophthalmology for visual field assessment.
• The technique's ability to precisely map scotomas contributes to advancements in visual field testing technology.