The effect of refractive blur on the visual field using the ring perimeter

Area of Science:

• Ophthalmology
• Visual Science

Background:

• Visual field testing is crucial for diagnosing and monitoring various ocular conditions.
• Optical defocus can potentially impact visual field test results, but its specific effects require detailed investigation.

Purpose of the Study:

• To quantify the impact of optically induced blur on visual field sensitivity using high pass spatially filtered targets.
• To determine if pupil dilation alone affects visual field measurements.

Main Methods:

• Ten healthy subjects underwent visual field examinations.
• Examinations were performed with varying levels of optical overcorrection (0, +1.00, +2.00 diopters) in a cyclopleged state.
• Sensitivity thresholds were measured for central and peripheral visual fields.

Main Results:

• A significant loss of visual field sensitivity was observed with increasing optical blur (defocus).
• Mean thresholds increased from 4.79 dB (focused) to 7.16 dB (2.00 diopters blur), indicating reduced sensitivity (P < 0.001).
• Defocus effects on sensitivity were consistent across central and peripheral visual fields and were not influenced by pupil dilation alone.

Conclusions:

• Optically induced blur significantly impairs visual field sensitivity.
• A 2.37 dB decline in sensitivity due to defocus could lead to misinterpretation of results in clinical perimetry.
• Clinicians must account for optical defocus when interpreting visual field test outcomes.