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R

Radial Keratotomy (RK)
Radial Keratotomy (RK) is a surgical procedure performed to improve cases of nearsightedness. The procedure involves making a series of precise radial incisions in the cornea of the eye, the number and location determined by the degree of nearsightedness in the patient. The incisions permit the sides of the cornea to protrude and as a result, flatten the center of the cornea, bringing the focal point of the eye closer to the retina. The result is a dramatic improvement of the patient’s distance vision.
Refraction
A deviation in the course of rays of light when passing from one transparent medium into another of different density; determination of refractive errors of the eye.
Refractive Error
Ametropia
Refractive Media
The transparent parts of the eye having refractive power.
Refractive Surgery

ree-FRAK-tiv SUR-jah-ree

See PRK, LASIK & RK.

Relucent
Reflecting light.
Retina

REH-tih-nah)

A thin tissue lining the innermost wall of the eye. Once light has passed through the iris, it hits the retina and is converted to electrical signals which are carried by the optic nerve to the brain. The outlying parts of the retina are responsible for peripheral vision while the center area, called the macula, is used for fine central vision and color vision.

REH-tih-nah)

A thin tissue lining the innermost wall of the eye. Once light has passed through the iris, it hits the retina and is converted to electrical signals which are carried by the optic nerve to the brain. The outlying parts of the retina are responsible for peripheral vision while the center area, called the macula, is used for fine central vision and color vision.

retina

retinal function

Retinal Detachment

When a portion of the retina comes loose from the back of the eye, the separation is called retinal detachment. Peripheral vision is usually lost first, and if the detachment continues, all vision in that eye may be completely lost.

retinal detachment

Example of vision with retinal detachment:

retinaldetch-ex

In a vitreous detachment, the vitreous pulls away from the retina, causing the patient to see flashes of light.

vitreousRetinalDetach

vitreousdetach-ex

Retinoblastoma

re-ti-no blah-sto'mah

A malignant tumor of the retina that appears in early life and may occur in one or both eyes. Usually observed before the age of 5, it is composed of embryonic cells and tends to invade the choroid and optic nerve. In some cases, it may extend beyond the confines of the eyeball and cause cataracts and glaucoma.

Retinoscope
A device for the objective determination of refractive error.
Retroillumination
To illuminate from behind by reflecting light from a deeper structure.
RK
Radial Keratotomy (RK) is a surgical procedure performed to improve cases of nearsightedness. The procedure involves making a series of precise radial incisions in the cornea of the eye, the number and location determined by the degree of nearsightedness in the patient. The incisions permit the sides of the cornea to protrude and as a result, flatten the center of the cornea, bringing the focal point of the eye closer to the retina. The result is a dramatic improvement of the patient’s distance vision.
The Eye Encyclopedia is a collection of eye care terminology created by practicing optometrists and ophthalmologists. The information provided is not intended to be a substitute for regular medical care or to diagnose or treat any medical condition, and should be used only as a supplemental source of information. Please consult your doctor if you have any questions or concerns about your eye health.