A technique to compensate for irregularities (wavefront distortions) caused by imperfections (optical aberrations) in the ocular media, in particular the cornea and crystalline lens, when imaging the ocular fundus.
An automated system used to reveal the eye’s refractive characteristics from a source of light reflected off the retina.
Corneal topography system
An automated system used for producing a detailed map of the shape of the entire corneal surface. It is most useful in refractive surgery, after corneal transplant surgery, and in evaluating patients with keratoconus.
A handheld instrument used to examine the posterior segment, using the optics of the patient’s eye as a simple magnifier, and to assess the red reflex.
A device, worn on the head, that is used for the posterior segment examination in conjunction with auxiliary handheld diagnostic condensing lenses.
A tendency for the eye to accommodate when looking into instruments.
A device used to approximate the refracting power of the cornea by determining the curvature of the central outer corneal surface. It is typically used when fitting contact lenses and to diagnose disorders such as keratoconus.
A device that measures the power of spectacle or contact lenses.
Optical coherence tomography (OCT)
A system based on low-coherence interferometry, using interference of broadband or tunable coherent light, that provides a high-resolution cross-sectional image of the retina or cornea.
A method to infer the eye’s refractive error employed in autorefractors and aberrometers. A stationary source of light “floods” the eye. The light emerging from the eye is then isolated into multiple beams. The deflection or deviation of each individual light beam is then compared with its ideal reference position.
Scanning laser ophthalmoscope
A device that functions as both an ophthalmoscope and a fundus camera but requires significantly less light than those conventional flood illumination systems, thanks to the use of a rapidly scanning laser illuminating only a small spot of retina at a time.
Also called Scheimpflug camera, in which a camera rotates perpendicular with the source of illumination, such as slit beams of light incident on the cornea. This configuration corrects for the nonplanar shape of the cornea and, thus, results in “distortion-free” cross sections.
A method for detecting refractive errors using a double-pinhole aperture placed before the eye. Through such an aperture, an emmetropic eye forms a single point image of a distant point source on the retina; an ametropic eye forms a double image on the retina.
Commonly called the slit lamp. The slit-lamp biomicroscope permits magnified examination of the eye, using various kinds of illumination. It is primarily used to perform anterior segment examinations. Several attachments for the slit lamp extend its use beyond these examination techniques, such as auxiliary lenses for slit-lamp examination of the retina.
A device used to evaluate the corneal endothelium. Contact specular microscopy allows for higher magnifications than slit-lamp biomicroscopy, demonstrates cell morphology, and calculates endothelial cell density.
A device used to measure intraocular pressure. In Goldmann applanation tonometry specifically, performed with an attachment to the slit lamp, intraocular pressure is inferred from the amount of force required to flatten an area of 3.06 mm in diameter on the cornea.