Snellen visual acuity versus pattern reversal visual-evoked response acuity in clinical applications

Area of Science:

• Ophthalmology
• Neuroscience
• Visual Science

Background:

• Best-corrected Snellen acuity (SA) is a standard measure of visual function.
• Pattern reversal visual-evoked response (PVER) offers an objective method to assess visual acuity.
• Comparing these methods is crucial for understanding visual system function and dysfunction.

Purpose of the Study:

• To compare best-corrected Snellen acuity (SA) with pattern reversal visual-evoked response (PVER) acuity.
• To evaluate the agreement between SA and different PVER acuity derivations (P0, P1, P2) in normal subjects and patients.
• To identify factors influencing the correlation between SA and PVER acuity.

Main Methods:

• Utilized a steady-state stimulus with five check sizes (160 to 10 min) in 1.0-octave steps.
• Derived PVER acuity from the linear function relating amplitude to log-adjusted check size, using intercepts of 0, 1, and 2 microV (P0, P1, P2).
• Compared SA and PVER acuities in 42 normal eyes and 457 patient eyes.

Main Results:

• In normal subjects, P0 showed the best agreement with SA (78.6% within +/- 2.0 octaves).
• In patients, P0 also showed the best agreement with SA (67.0% within +/- 2.0 octaves).
• A significant portion of patients (18.2%) with optic nerve disease showed large acuity differences (> -3.0 octaves) due to flattened PVER amplitude-check size curves.

Conclusions:

• The P0 derivation of PVER acuity demonstrates better correlation with Snellen acuity compared to P1 and P2.
• The PVER method is a valuable tool for visual acuity assessment, but its effectiveness can be reduced in cases of optic nerve disease.
• Further refinement of PVER analytical methods may be necessary for specific pathological conditions.