lArticle

~ I

Constantine J. Forkiotis, OD, FCOVD, F AAOCharacteristics of

Spectacle LensesHow Patients Respond to Lenses

Lenses are one of the most powerful tools in altering light energyunder controlled conditions. A lens placed in front of the individual's eyesalters the light energy entering the eyes and the visual mechanism. Thelens aids in altering physiological conditions, permitting changes in per-ception of the world as well as the general overall physiology of theindividual. The result of the action of the lens is to affect every cell in thebrain, thereby creating changes expressed in the visual-motor and grossmotor levels of efficiency for that individual. Lenses therefore may offercompensatory values, remedial values and affects, and vision therapyvalues. Key Words: aftereffects, afterimages, cylinder, minus power, pluspower, prism, rehabilitation, therapy.

of the prescription (eyeglass power), thegreater the peripheral distortions suffered bythe eye and the central nervous system. It is amathematical and mechanical impossibility tohave perfection in both the central and periph-eral portions of the compensating spectaclelens. The stronger the lens, the greater thedistortion in the ability to judge size, distance,and all perceptions of personal time-space val-ues.

Spectacle lenses do not correct any defects.The lens affords a compensation that is alwaysinadequate for physiological deviation or def-icit. Individuals who are either nearsighted(myopia) or farsighted (hyperopia) are justas nearsighted or farsighted physiologicallywhether or not they are wearing lenses. Thebasic physiological performance remains thesame and now includes additional distortionscreated by the spectacle lens. Eventually, thevisual style and resultant philosophy and per-

Every lens has a prismatic value. Becauseof the prism effect, objects viewed through anylens are displaced to an apparent (different)location in space. Any lens positioned in frontof an eye to compensate for visual acuity def-icit causes increased deficits in the perceptualstatus of an individual. A piano (zero prescrip-tion strength) spectacle lens in front of an eyewith good visual acuity will slow the speed oflight, reduce brightness levels into the visualmechanism, alter size perception, and act as aweak tint.

Necessary ultraviolet light into the eyeand the brain is restricted by the use of a lens,with adverse affects. The greater the strength

Correspondence regarding this article should beaddressed to Constantine J. Forkiotis, on, 437Tunxis Hill Road, PO Box 741, Fairfield, CT06432-0741.

224 Journal of Optometric Vision Development