Amsler Grid: A test card of equally spaced horizontal and vertical lines forming a grid that can be used at home, daily, to detect early ARMD (Age related macular degeneration).
Applanation Tonometry: The measurement of intraocular pressure , given in millimeters of mercury, in which the amount of force required to flatten an area of the cornea, by contact, is documented. This is a routine screening test forglaucoma.
Direct Ophthalmoscope: A handheld device used to visualize the fundus (retina) of the eye. It provides a magnified upright image of the retina.
Indirect Ophthalmoscope: Instrument consisting of a bright light source and a handheld magnifying lens used to visualize the posterior portion of the eye (thefundus). It creates an inverted image of the fundus projected in the front of the eye. This instrument has a wider field of view than the direct ophthalmoscope and the binocular model allows stereoscopic depth perception of the retina.
Lensmeter: An ophthalmic instrument used to measure the prescription in eyeglasses.
Ophthalmoscope: An illuminated instrument for visualizing the interior of the eye, particularly the fundus at the back of the eye. There are two types of ophthalmoscopes, the direct ophthalmoscope and the indirect ophthalmoscope.
Pachymeter: A diagnostic tool used for measuring corneal thickness usingultrasound. (sound waves). This is a very important tool for laser vision correctioncandidates. Pachymetry can also be measured using a pentacam diagnostic tool.
Pentacam: An advanced analysis system utilizing a slit illumination system and a Scheimpflug camera which rotates around the eye. This produces a set of three-dimensional measurement data which gives a precise geometric description of the anterior eye segment. This data in turn can be used to generate data on elevation, curvature, thickness and depth of the anterior chamber. Click here to learn more about Pentacam technology.
Perimetry: A method of charting the extent of a stationary eye’s visual field(peripheral vision) with test objects of various sizes and light intensities.
Phoropter: Refraction device which incorporates a series of spherical and cylindrical lenses and also includes prisms, occluders and pinholes. This device is used to determine an eye’s refractive error as well as a prescription for spectaclesand contact lenses.
Pinhole device: An opaque disc with one or more holes which blocks all but the centermost light rays from an object. It is used as a quick screening device to determine whether reduced vision is caused by refractive error. (Vision through the pinhole will improve if the decreased vision is caused by refractive error.)
Pupil Light: See Transilluminator
Pupillometer: An ophthalmic instrument used to measure the size (diameter) of the pupil.
Retinoscope: A hand held instrument which is used to determine an eye’srefractive error objectively (with no response required from the patient). Light from the retinoscope is projected into the eye and the movements of the light reflection are neutralized (eliminated) with corrective lenses.
Slit Lamp Biomicroscope: A table-top microscope that is used to examine the anterior portion (front portion) of the eye. This instrument cross-sections the eye so that the structures of the eye can be viewed in layer-by-layer detail. With the aid of a special handheld lens, it can also be used to examine the posterior portion (back portion or fundus) of the eye.
Snellen Chart: A test chart for assessing visual acuity. The chart contains rows of letters, numbers or symbols in standardized sizes with a designated distance at which each row should be legible to the normal eye. The standard testing distance is typically 20 feet.
Specular Endothelial Microscopy: A diagnostic test which allows the examiner to visualize both the pattern and density of endothelial cells through magnification via a technique that uses a slit lamp microscope in combination with light reflection from the endothelium.
Tonometry: See Applanation Tonometry
Topography: A measurement of the curvature of the cornea. A color map is created from a picture of the cornea that details the variations in the front surface curvature of the cornea.
Ultrasound: A method of diagnostic testing in which high frequency sound waves are transmitted into the eye from a hand-held probe. The sound waves are reflected by the ocular tissues. This method is used in pachymetry to measure the thickness of the cornea, in Ascan biometry to measure the length of the eye and in Bscan biometry to aid in the diagnosis of eye and orbital problems.
Visual Field: The full area of both central and peripheral vision that is visible to an eye that is fixating straight ahead. Also the name of a diagnostic instrument used to measure peripheral vision.
Wavefront: Wavefront technology creates a unique fingerprint of the visual aberrations of your eye. Wavefront sensors measure light rays reflected from the inside of your eye to detect refractive changes that previously were not capable of being diagnosed. It is used both as a diagnostic and therapeutic tool to enhance our abilities to measure your eyes with an accuracy that was previously unattainable. Click here to learn more about Wavefront Technology.