SUMMARY
Purpose:
To evaluate the prevalence and risk factors associated with unreliable visual field examinations in glaucoma patients and glaucoma suspects who underwent their first visual field examination.
Methods:
The records of 262 patientes with glaucoma or glaucoma suspects who underwent their first visual field examination were analyzed using the Humphrey Visual Field Analyzer from January to December 1996. Visualfields were considered unreliable when fixation lasses were greater than 20%, false negative responses were higher than 33% or false positive responses were greater than 33%.
Results:
Forty-eight (18.3%) patients showed unreliable fields. Of these, 34 (64.5%) had high fixation loss rate and 17(29%) had excessive false negative responses. Low reliability was associated with age below or equal to 15 years (p = 0. 0005) or visual acuity less than 201200 (p = 0. 0002). False negative results were positively correlated with age older than 65 years (p = 0. 022 7), visual acuity less than 201200 (p = 0. 005), severe visual field defects (p = 0. 00001 7), and higher SF rate (p = O. 0091 ). Fixation loss was associated with age below or equal to 15 years (p = 0. 00008) and visual acuity less than 201200 (p = 0. 0012).
Conclusion:
The majority of unreliable visual field tests was due to either excessive fixation loss or excessive false negative responses. Young patients or patients with low visual acuity may need detailed explanation and continuous patient monitoring in order to reduce the fixation loss rate. Patients with extensive visual field damage secondary to glaucoma, who are older than 65 years and have visual acuity less than 20/200 are at greater risk of increased false negative responses.
Keywords:
Visual field; Reliability; Glaucoma; Automated perimetry