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Take Caution of Normal Visual Acuity in Posterior Cortical Atrophy!

Tristan Jurkiewicz1,2, Maité Formaglio2, Sarah Verrecchia2

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Posterior cortical atrophy (PCA) patients show visual acuity declines on the ETDRS chart due to crowding and larger stimuli, unlike standard charts. This highlights the need for varied visual testing in ophthalmology.

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Alzheimer’s diseaseBenson syndromenear and far visionsimultanagnosiavisual crowding

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Area of Science:

  • Ophthalmology
  • Neuroscience
  • Cognitive Science

Background:

  • Higher-order visual symptoms in posterior cortical atrophy (PCA) are often overlooked in standard eye exams.
  • Traditional visual acuity charts like Snellen or Monoyer may not detect subtle visual deficits in PCA patients.

Purpose of the Study:

  • To compare visual acuity assessment using Monoyer and ETDRS charts at different distances (4m and 2m) in PCA patients versus typical Alzheimer's disease patients.
  • To investigate if visual crowding and stimulus size/distance affect visual acuity in PCA.

Main Methods:

  • Visual acuity was measured using Monoyer (single line) and ETDRS (all lines) charts at 4 meters.
  • Visual acuity was also assessed using the ETDRS chart at 2 meters.
  • Participants included patients with PCA (PCA-AD) and a control group with typical amnesic Alzheimer's disease (T-AD) without ophthalmologic issues.

Main Results:

  • The Monoyer chart failed to differentiate between PCA-AD and T-AD groups.
  • PCA-AD patients showed reduced visual acuity on the ETDRS chart at 4 meters compared to the Monoyer chart, indicating visual crowding.
  • PCA-AD patients exhibited further visual acuity reduction on the ETDRS chart at 2 meters compared to 4 meters, linked to stimulus size/distance effects.
  • This closer-distance acuity decrease correlated with higher-order visual symptoms (Q-ACP).

Conclusions:

  • Standard visual acuity tests may underestimate visual impairment in PCA.
  • The ETDRS chart reveals deficits related to visual crowding and stimulus size/distance in PCA patients.
  • Ophthalmologists should consider varied visual acuity testing conditions to accurately evaluate patients with suspected PCA.