Subtle grayish halo with temporal gap (best seen with indirect ophthalmoscopy). Adaptive optics scanning laser ophthalmoscopy (AOSLO) is a technique used to measure living retinal cells. The optical design of fundus cameras is based on the principle of monocular indirect ophthalmoscopy. Ophthalmoscopy and fundus photography have long been used to examine the retina. Veterinarians employ three general methods&colon; tonometry, gonioscopy, and ophthalmoscopy. Leukocoria can be detected by a routine eye exam (see Ophthalmoscopy). This may be done by ophthalmoscopy or fundus photography, and possibly slit lamp examination. Scanning laser ophthalmoscopy (SLO) is a method of examination of the eye. He taught himself direct ophthalmoscopy, a skill for which he would later become particularly noted. The fundus can be examined by ophthalmoscopy and/or fundus photography. The diagnosis is made by examination of the eye, using ophthalmoscopy. Both age-related drusen and optic disc drusen can be observed by ophthalmoscopy. Direct and indirect ophthalmoscopy is necessary to evaluate the retina and particularly the optic nerve. Ophthalmoscopy frequently reveals creamy yellow-to-orange colored subretinal infiltrates. Ophthalmoscopy is done as part of a routine physical or complete eye examination.