Comparing the fixational and functional preferred retinal location in a pointing task.

Area of Science:

• Ophthalmology
• Neuroscience
• Vision Science

Background:

• Central vision loss (CVL) necessitates compensatory eccentric viewing strategies.
• The preferred retinal locus (PRL) is clinically defined as the peripheral retinal area used for fixation.
• The utility of the fixational PRL in dynamic tasks like eye-hand coordination remains unclear.

Purpose of the Study:

• To investigate if the fixational PRL accurately represents the retinal area used during binocular eye-hand coordination in individuals with CVL.
• To compare fixational PRL characteristics with the retinal regions employed during dynamic pointing tasks.

Main Methods:

• Utilized scanning laser ophthalmoscopy to measure visual fields and fixational PRLs.
• Assessed monocular and binocular visual fields using an eye tracker on a computer monitor.
• Evaluated eye-hand coordination through monocular and binocular pointing tasks on a touchscreen, recording movement duration, eye movements, and accuracy.

Main Results:

• Participants with CVL demonstrated prolonged movement durations, increased eye movements, and reduced accuracy, particularly in monocular conditions.
• Compensatory behavioral changes did not consistently worsen when using retinal areas outside the fixational PRL.
• The fixational PRL's size and stability were insufficient to fully describe the pointing PRL used in the task.

Conclusions:

• The fixational PRL is not sufficient to define the entire area of peripheral retina utilized during dynamic eye-hand coordination tasks in patients with CVL.
• Individuals with CVL generally employ a larger retinal area for pointing than suggested by fixational PRL measurements alone.
• While fixational and pointing PRLs may overlap, the fixational PRL does not predict the full extent of the peripheral retina that can be effectively used for such tasks.