Eye Terms Glossary
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ACRYLIC – is any of a group of glass-like thermoplastic resins made by polymerizing esters of acrylic acid; methacrylic; methyl methacrylic resin. It is the major component in present day plastic artificial eyes.

ADNEXA, OCULI – is the adjunct parts or appendages of the eye; e.g., the lacrimal apparatus, the eyelids, and other appendages of the eye.

ALGINATE – is a salt of alginate acid, which is extracted from marine kelp. Soluble alginates such as potassium, sodium, and magnesium can be changed into a gel by chemical reaction with calcium sulfate for use in taking impressions.

AMERICAN SOCIETY OF OCULARISTS – was founded in 1957 for the purpose of setting standards; education and research in the custom fitting and fabrication of ocular prosthetics and ocular prosthetic devices; presently offers the only formally structured educational program for the training of ocularists, as well as continuing education in ocular prosthetics required for recertification.

ANOPHTHALMOS – is the true absence of the eyeball.

BLINDNESS – in the United States, the usual definition is: central visual acuity of 20/200 or less in the better eye after correction, or visual acuity of more than 20/200 if there is a field defect in which the widest diameter of the visual field subtends an angle distance no greater than 20 degrees. Some states include up to 30 degrees.

CATARACT – is the partial or complete loss of transparency of the crystalline lens of the eye or its capsule; an opacity of the crystalline lens or its capsule.

CAVITY, ORBITAL – is the anophthalmic socket following enucleation or exenteration.

CONFORMER, CONVENTIONAL POSTOPERATIVE – is a temporary prosthesis, most commonly of clear acrylic, similar in shape to a conventional reform prosthesis; used following enucleation, evisceration, and socket reconstruction to preserve culs-de-sac. Some have central fenestrations to permit easy application of medications and escape of socket discharge.

CONJUNCTIVA – is the mucous membrane tissue extending from the eyelid margin to the corneal limbus, forming the posterior layer of the eyelids (palpebral conjunctiva) and the anterior layer of the eyeball.

CORNEA – is the transparent tissue constituting the anterior sixth of the outer wall of the eye; its radius of curvature is 7.7mm as contrasted to 13.5mm of the sclera. It consists of stratified squamous epithelium continuous with that of the conjunctiva, substantia propria, substantially regularly arranged collagen imbedded in muccopolysaccharide and an inner layer of endothelium.

DEPTH PERCEPTION – is the ability to recognize the differences in distance from the observer to different objects in space by use of stereo-scopic vision, overlay, parallax, perspective, etc.

ENUCLEATION – is the complete surgical removal of the eyeball, not including the adnexa.

EVISCERATION – is the surgical removal of the contents of the eyeball with retention of the sclera or cornea and sclera.

EXENTERATION, ORBITAL – is the surgical removal of all the orbital contents. Sometimes, this also includes removal of the eyelids.

EYE – is the organ of vision. In humans, it is a spheroid body approximately 1 inch in diameter, with the segment of a smaller sphere, the cornea, in front. It occurs in pairs, one in each of the bony orbits of the skull, and consists of an external coat of fibrous sclera and transparent cornea, a middle vascular coat, the uvea, composed of the iris, the ciliary body, and the choroids, and an internal nervous coat, the retina, which includes the sensory receptors for light. Within, it contains the anterior, the posterior, and the vitreous chambers, the aqueous humor, the vitreous body, the crystalline lens, the zonule of Zinn, and the intraocular portion of the optic nerve. Six extraocular muscles control its movements. Broader definitions sometimes include the conjunctiva, Tenon’s capsule, and associated appendages. 

GLAUCOMA – is an ocular condition in which there is a loss of visual function of the retina rods and cones, resulting from a sustained elevation of intraocular pressure. The consequences of the sustained pressure may be manifested in such signs and symptoms as excavation of the optic disc, hardness of the eyeball, reduced visual acuity, colored halos around lights, visual field defects, and headaches.

IMPLANT, ENUCLEATION – is a prosthetic device of glass, metal, plastic, human tissue, and other materials, which are surgically inserted at enucleation of the eye. Enucleation implants are designed to replace lost orbital volume and to provide a means for transmission of motility to the prosthesis. Most enucleation implants are spherical, or modified spherical, and vary in size from 14mm to 22mm. Implants may also be classed as integrated (buried and partially buried) where there is positive connection from muscle to implants to prosthesis; quasi-integrated where muscles are attached to implant and prosthesis is impression fitted to socket contour, or non-integrated when muscles are not attached to the implant.

IRIS – is the color of the eye. A disklike diaphragm of pigmented tissue lying behind the cornea and in front of the lens with a central opening (pupil) through which the amount of light entering the eye is controlled.

LENS, CONCAVE – is a minifying lens. Lens having the power to diverge rays of light; also known as reducing, negative, mynopic, or minus lens, denoted by the sign “-“.

LENS, CONVEX – is a magnifying lens. Lens having the power to converge rays of light and to bring them to a focus; also known as converging, magnifying, hyperopic, or plus lens denoted by the sign “+”.

LENS, SCLERAL – is a flush fitting or minimal clearance partially opaque scleral cap fitted over the cornea and sclera of the eye. Optics are incorporated into the clear, acrylic pupillary area of the lens while the iris and sclera are matched to the fellow eye.

LIMBUS – is the transitional area created by the overlapping of the iris-cornea piece by opaque scleral acrylic in the laminated structure of a plastic artificial eye. The transition area, which exists when opaque sclera plastic gradually becomes thinner and more translucent, as at the edge of the cornea.

MELANOMA – is a tumor made up of melanin-pigmented cells.

MICROPHTHALMOS – is an abnormally small eyeball.

MONOCULAR – is pertaining to or affecting one eye.

MONOMER – is the liquid form of acrylic.

MUCUS – is the clear, sticky secretion of the mucus membrane, consisting of mucin, epithelial cells, leucocytes and various inorganic salts suspended in water.

NATIONAL EXAMINING BOARD OF OCULARISTS (NEBO) – is formed in 1980, a seven member Board consisting of ocularists, an ophthalmologist, a member of a related profession and a public member. The Board designs, writes and administrates certification and recertification examinations for the field of ocularistry. 

OCULARISTS, BOARD CERTIFIED (B.C.O.) – is one who has demonstrated competence in the fitting and fabrication of ocular prosthetics by having fulfilled all requirements for certification and recertification of the National Examining Board of Ocularists.

ORBITAL – is referring to cavities in the skull occupied by the eye and adnexa, surrounded by seven bones at the sides and near the eyelids at the front.

PERIPHERAL VISION – is the ability to perceive the presence, motion, or color, of objects outside the direct line of vision.

POLISHING – is the final process in the fabrication of a plastic prosthesis, in which surface scratches and imperfections are removed to produce a smooth, high gloss surface. This process is done using a small particle-polishing compound (liquid or dry) which is applied and worked on the surface of the plastic prosthesis, using a rag wheel buff rotating at varied speeds. Also, a procedure performed by the ocularist as part of required normal care and maintenance of the plastic prosthesis.

PROSTHESIS, CUSTOM OCULAR – is an ocular prosthesis that is fitted and fabricated to all of the specific requirements of an individual patient, utilizing accepted fitting and fabrication techniques and addressing all aspects of proper fitting, fabrication and the replication of iris and sclera in order to assure maximum comfort, cosmesis, and motility of the prosthesis, as well as development and/or maintenance of the socket.

PROSTHESIS, SCLERAL SHELL OCULAR – is a flush fitting, or minimum clearance, opaque acrylic scleral cover fitted over the phthisical or eviscerated globe. Iris, pupil, sclera tone and vascular details are matched to the fellow eye.

PUPIL – is the aperture in the iris, normally circular and contractile, through which the image-forming light enters the eye; the dark central spot of an ocellus.

RETINA – is the innermost coat of the eye, formed of sensitive nerve elements and connected with the optic nerve.

RETINOBLASTOMA – is a congenital malignant tumor, usually observed before the age of five.

RETINOPATHY, DIABETIC – is the spectrum of retinal changes accompanying longstanding diabetes mellitus. Background; early stage non-proliferative; proliferative, with growth of new abnormal blood and accompany fibrous tissue.

SCLERA – is the white part of the eye, a tough covering which, with the cornea, forms the major structural coat of the eye. It is covered by Tenon’s capsule, conjunctiva and epithelium.

SULCUS, RECESSED SUPERIOR – is the increased deepening of the furrow or depression of the upper eyelid, most frequently noted following enucleation.

TECHNIQUE, MODIFIED EMPIRICAL WITH IMPRESSION FITTING (EMPIRICAL WITH IMPRESSION OR IMPRESSION FITTING MODIFIED TECHNIQUE) – is a procedure for the custom fitting of a plastic ocular prosthesis in which an alginate impression is taken behind and around the fitting shape that has been modified, as needed, for comfort, cosmesis, motility, and socket development.

TECHNIQUE, MODIFIED IMPRESSION – is a procedure for the custom fitting of a plastic ocular prosthesis in which a full impression of the socket is taken using a fenestrated impression tray of a preselected size and shape. A wax model duplicated of the impression is then modified, as needed, for comfort, cosmesis, motility and socket development.