We ophthalmologists are all introduced to pinhole or small-aperture optics on the first day of our residency when we are taught how to measure visual acuity and refract a patient.
As a diagnostic tool, we learn that a pinhole visual acuity will give us important information about a patient’s potential visual acuity in a high luminance environment by neutralizing lower-order (myopia, hyperopia, astigmatism) and higher-order (irregular astigmatism, spherical aberration, coma, trefoil) optical aberrations. Two other valuable examinations are a well-done refraction and, when irregular