Purpose:
To investigate effect of age, gender, and time-of-day in standard automated perimetry reliability indices, among individuals with no perimetry experience.
Methods:
Three hundred forty-four subjects (glaucoma and glaucoma suspects) with no prior perimetry experience were submitted to standard automated perimetry (Humphrey-HFA-II 750i, using SITA strategy, central 24-2 program). Visual field reliability criteria (fixation losses ≤ 20%, and false negatives ≤ 33%, and false positives ≤ 33%, in either eye) was used as independent variable in a logistic regression to evaluate the effect of age, gender, global indices and time of testing. General polynomial regressions were used to evaluate the effect of each variable in the reliability indices. Tests were performed from 8:00 am to 6:00 pm (except from 12:00 am to 1:00 pm).
Results:
Mean age was 57.8 years (range, 15-87) and 37% of patients were male. Thirty-one subjects (9%) returned an unreliable test. Logistic regression showed a significant association between time of testing and the occurrence of an unreliable visual field. Subjects tested before 9:00 a.m. and after 4:00 pm had worse reliability indices (β=0.8060, p=0,03). Fixation losses (FL) were the most common reliability problem. A quadratic relation between FL in the right eye (OD) and time of testing was found to be statistically significant, indicating higher rates of FL in the beginning and the end of the day (p=0.03). We also found a positive association between FL and age in both eyes (OD: p=0.02; OS: p=0.01).
Conclusions:
In our population, perimetric novices demonstrated less reliable visual fields when tested in the beginning, or towards the end of the day. Older subjects had higher rates of fixation losses.
Keywords: perimetry • visual fields • clinical (human) or epidemiologic studies: systems/equipment/techniques