Can delayed scotomas (areas of partial alteration in the field of vision) improve with time?

Improvement of Delayed Scotomas Over Time

Yes, delayed scotomas can improve with time in some cases, particularly in patients with macular disease who develop eccentric fixation patterns to compensate for central vision loss. 1, 2

Mechanisms of Scotoma Improvement

Natural Adaptation

• Spontaneous improvement in visual acuity can occur in eyes with central scotomas, particularly in patients with bilateral geographic atrophy from age-related macular degeneration 2
• This improvement is often related to:
  • Development of a preferred retinal locus (PRL) - an eccentric area of retina used habitually for fixation when the fovea is damaged 1
  • Improved ability to find and hold fixation targets in areas of seeing retina 2
  • Adaptation of the oculomotor system to reference saccades to this new locus 3

Timeframe for Improvement

• The American Academy of Ophthalmology guidelines note that in patients with epiretinal membranes (ERMs), 26% of ERMs actually regress over a 5-year period 1
• Improvement in fixation can occur relatively quickly in experimental settings - research shows the oculomotor system can spontaneously and rapidly adopt a peripheral locus for fixation 3
• Once developed, this fixation locus can be retained over weeks even when the scotoma is no longer present 3

Factors Affecting Scotoma Improvement

Positive Factors

• Deterioration in the better-seeing eye may trigger improvement in the worse-seeing eye with scotoma 2
• Visible scotoma borders help the visual system adapt more quickly 3
• Development of multiple preferred retinal loci (PRLs) that can be used depending on the visual task 1

Limiting Factors

• Scotoma patterns that limit horizontal span for reading may restrict improvement in reading fluency 1
• Patients with foveal-sparing scotoma patterns (scotoma encircling the fovea) have limited potential for improvement 1
• Poor contrast sensitivity often accompanies scotomas and may limit functional improvement 1

Rehabilitation Options

Training Approaches

• Eccentric viewing training to optimize the patient's spontaneous preferred retinal locus 1
• Biofeedback training to develop a trained retinal locus (TRL) 1
• Saccadic compensation training has shown significant and stable improvement in visual search within 15-25 training sessions for patients with visual field disorders 4

Devices and Aids

• Magnification devices can assist with spot reading tasks even when they don't restore normal reading fluency 1
• Stand-mounted electronic magnification may improve reading speed 1
• Mouse-based video magnifiers can improve reading speed and duration 1

Important Caveats

• Prism spectacles for fixation relocation are NOT recommended based on high-quality evidence showing no significant benefit (Level 1+, Moderate Quality Evidence, Strong Recommendation) 1
• Even with magnification, reading with nonfoveal retinal fixation does not restore normal continuous print reading speed 1
• Patients should be encouraged to periodically test their central vision monocularly to detect changes over time 1
• The invisibility of scotomas makes them difficult for patients to perceive - they don't appear as black patches but rather as areas where content is missing yet not noticed 5

Clinical Monitoring

• Regular monocular Amsler grid testing is important for monitoring changes in scotomas 1
• Microperimetry can accurately detect both fixation patterns and scotomas, providing valuable information about a patient's adaptation 1
• Educating patients about signs and symptoms of progression is essential for timely intervention when needed 1

Remember that while improvement can occur, the degree varies significantly between individuals and depends on the underlying cause of the scotoma, its size and location, and the patient's ability to develop compensatory mechanisms.