Other factors that may affect perimetry results include patient refraction and pupil size. Uncorrected refractive errors cause blurring on the retina and decrease the visibility of stimuli. Thus, proper neutralization of refractive errors is essential for accurate perimetry. In addition, presbyopic patients must be given a refractive correction that focuses on the perimeter bowl. Care needs to be taken to center the patient close to the correcting lens to avoid a lens rim artifact where the rim blocks peripheral stimuli. A small pupil (< 2.5 mm) may produce artifacts on perimetry by reducing the amount of light entering the eye. However, such artifacts are now rare because the use of miotics (eg, pilocarpine) is now less common.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.