Central visual field, visual acuity, and sudden visual loss after glaucoma surgery

Area of Science:

• Ophthalmology
• Optometry
• Vision Science

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Central visual field loss is a common manifestation of glaucoma.
• The relationship between visual acuity and visual field defects requires further elucidation.

Purpose of the Study:

• To investigate the correlation between Snellen visual acuity and central visual field loss in glaucoma.
• To quantify the impact of affected visual field quadrants on visual acuity.
• To identify factors influencing the accuracy of visual acuity measurements in glaucoma patients.

Main Methods:

• Examined 96 glaucomatous eyes from 79 patients using the Humphrey 10-degree test.
• Assessed visual field defect severity by the number of affected quadrants (≥10 decibel sensitivity loss at 1.4-degree eccentricity).
• Analyzed fixation stability and its impact on visual acuity measurements.

Main Results:

• Median visual acuity decreased gradually with increasing number of affected quadrants.
• A disproportionate loss of acuity was observed when both temporal quadrants were affected.
• Significant correlation found between visual acuity and foveal threshold.
• Difficulty with fixation, particularly prolonged fixation shifts, was a major source of error.
• Sudden visual loss occurred in 3% of eyes with advanced glaucoma; 1% lost acuity to 20/200 or worse.

Conclusions:

• Visual acuity is significantly correlated with the extent of central visual field loss in glaucoma.
• Temporal field defects have a more pronounced effect on visual acuity.
• Fixation instability is a critical factor affecting visual acuity assessment in glaucoma.
• Sudden visual loss in advanced glaucoma is infrequent but significant.