Stargardt Macular Dystrophy: Changes in Fixation When Asked to Look Straight Ahead

Area of Science:

• Ophthalmology
• Retinal Diseases
• Visual Neuroscience

Background:

• Stargardt disease macular dystrophy (STGD) is a leading cause of inherited macular degeneration.
• Individuals with STGD often develop eccentric fixation, using peripheral retina for visual tasks.
• Understanding fixation behavior is crucial for assessing visual function and guiding therapeutic interventions.

Purpose of the Study:

• To investigate whether individuals with STGD alter their fixation location in response to specific instructions.
• To determine the extent and pattern of fixation changes in STGD patients compared to normally sighted individuals.

Main Methods:

• A case-control study involving 37 participants with STGD and 13 normally sighted controls.
• Fixation was measured using an Optos scanning laser ophthalmoscopy/OCT microperimeter under two conditions: 'look at the cross' (LC) and 'look straight ahead' (LS).
• Collected data included visual acuity, contrast sensitivity, and disease duration.

Main Results:

• Most STGD participants exhibited changes in fixation locus when instructed to look straight ahead.
• A significant proportion (51 eyes) showed fixation closer to the fovea under the LS condition, while some (13 eyes) maintained their fixation locus.
• No significant differences were found between groups based on age, visual acuity, contrast sensitivity, or age at disease onset.

Conclusions:

• Most STGD patients do not fully re-reference their fixation from eccentric points to the fovea, even with instructions.
• Fixation behavior in STGD can be dynamic and influenced by specific instructions, necessitating careful monitoring.
• Consistent instructions and fixation monitoring are essential for accurate visual function assessment in STGD research and clinical trials.