Various devices using optical amplification, infrared rays, photographs, and video can be used to measure pupil size. This kind of side effect is the cause of much discomfort among patients. Especially, when the pupil is exposed to dark illumination, the pupil becomes larger than the optic size of the intraocular lens, resulting in glaring and halo. Clinically, it is important to understand pupil changes exactly in dark versus bright illuminance. Pupil size increases when the illumination environment changes from bright to dark. Thus, various factors must be considered when measuring pupil size. Additionally, the ‘pupil fluctuation phenomenon’ means that pupil size can change even in a given light environment. Pupil size increases significantly from hyperopic astigmatism to myopic astigmatism, and a negative correlation with spherical aberration has been reported. In the case of glaucoma, pupil size varies according to the type of intraocular pressure (IOP) lowering eyedrops. Pupil size decreases significantly after cataract surgery versus before surgery, and it is significantly smaller than in those without diabetes mellitus before and after cataract surgery. Generally, pupil size changes with aging and it has been reported to decrease continuously until the 60s. The pupil is affected by the state of the sphincter muscle, according to the autonomic nerves distributed in the iris, and may vary from person to person depending on age and gender, even in the same lighting environment. In particular, it is important to accurately measure pupil size before performing cataract surgery or laser-related corneal refractive surgery, because pupil size can be an important cause of side effects, such as night light glaring and monocular double phase, which can occur after surgery. Pupil size is an important factor in predicting post-operative satisfaction. The pupil regulates the amount of light reaching the retina and minimizes chromatic aberration and spherical aberration to maximize visual perception. Other factors affecting pupil size can be used in a preoperative evaluation when considering cataract surgery or laser refractive surgery. Pupil size was significantly smaller in eyes with glaucoma. Humphrey static perimetry can be useful in measuring pupil size. In patients older than 50 years, pupil size was significantly larger in eyes with a history of cataract surgery. Pupil size decreased significantly as age ( p < 0.001) and central cornea thickness ( p = 0.007) increased, and increased significantly as logMAR BCVA ( p = 0.02) became worse and spherical equivalent ( p = 0.007) and RNFL thickness ( p = 0.042) increased. Pupil size was significantly smaller in glaucoma patients than in glaucoma suspects ( p < 0.001) or the normal group ( p < 0.001).

Comparisons of pupil size according to the presence of glaucoma were evaluated, as were correlations between pupil size and various factors, including age, logMAR best corrected visual acuity (BCVA), retinal nerve fiber layer (RNFL) thickness, spherical equivalent, intraocular pressure, axial length, central corneal thickness, white-to-white, and the kappa angle. Pupil size was measured with Humphrey static perimetry. In total, 825 eyes of 415 patients were evaluated retrospectively. We assessed the correlation between pupil size, measured by Humphrey static perimetry, and various affecting factors in patients with glaucoma.

Normal pupils size chart