Braille code – what is and history

What is Braille code system Braille – a tactile (touch-based) system of written language that features patterns of raised dots to represent letters of the alphabet, common words and contractions, mathematical symbols, and punctuation. Named after its developer, Louis Braille (1809–1852), braille allows people who are blind to read and, with adaptive typewriters and computer technology, to […]

Read More

Slit Lamp Examination

What is Slit Lamp Examination and definition Slit Lamp Examination is the examination of the outer EYE using a bright light focused into an elongated slit in combination with a biomicroscope. The examination takes place in a darkened room, with the person sitting on one side of the slit lamp and the ophthalmologist on the other side. The ophthalmologist […]

Read More

Cataract Extraction and Lens Replacement surgery

Cataract Extraction and Lens Replacement surgery definition Cataract Extraction and Lens Replacement surgery is an OPERATION to remove the LENS from the EYE after a CATARACT (cloudy occlusion in the lens) forms and replace it with a prosthetic intraocular lens (IOL). Ophthalmologists can extract a cataract at any stage of its development. The vast majority of people who undergo cataract extraction fully […]

Read More

Snellen Chart – eye test

What is Snellen Chart Snellen Chart is the familiar eye chart, featuring lines of letters and numbers that progressively decrease in size, to assess VISUAL ACUITY. Dutch ophthalmologist Herman Snellen (1834–1908) developed the chart in the 1860s. The top letter is typically E. A person with normal vision can read a one-inch letter from 20 feet away, designated […]

Read More

Corneal Transplantation – replacement of a diseased cornea

Corneal Transplantation definition Corneal Transplantation – the replacement of a diseased CORNEA with a healthy donor cornea. In the United States, ophthalmologists perform more than 45,000 corneal transplantations each year; up to 90 percent of people who receive transplanted corneas experience restored vision; success depends on the reason for the transplant. Ophthalmologists may recommend corneal transplantation to treat: […]

Read More

Tonometry test – definition

Tonometry test Definition Tonometry is a test that measures INTRAOCULAR PRESSURE (the pressure within the EYE). The primary reason for tonometry is to screen for GLAUCOMA, a condition for which elevated intraocular pressure is a characteristic symptom. Increased intraocular pressure is also common with ORBITAL CELLULITIS and GRAVES’S OPHTHALMOPATHY. Tonometry is a standard component of the OPHTHALMIC EXAMINATION. There are several methods of […]

Read More

Corrective Lenses – eyeglasses or contact lenses

Corrective Lenses definition and function Corrective Lenses – eyeglasses or contact lenses that alter the focal point of the lightwaves entering the EYE to correct REFRACTIVE ERRORS of vision, including HYPEROPIA (farsightedness), MYOPIA (nearsightedness), ASTIGMATISM(blurred or distorted vision), and PRESBYOPIA (age-related hyperopia). The eye’s natural focusing structures, the CORNEA and the LENS, gather lightwaves and refract (bend) them toward their centers. The cornea refracts the lightwaves first. […]

Read More

Vision Health – definition, protection, screening

Vision Health Definition Vision Health – personal care for the eyes to protect the eyes and preserve vision. The two most important elements of vision health are EYE protection and regular ophthalmic examinations. Vision Health and Protective Eyewear Most injuries to the eyes are preventable by wearing appropriate protective eyewear, which ranges from sunglasses to protect the eyes […]

Read More

Visual Acuity – definition

What is Visual Acuity and definition Visual Acuity – the ability to see objects clearly and sharply. Visual acuity assesses central vision and represents the function of the CORNEA, iris (pupil size), LENS, and RETINA. The SNELLEN CHART, which presents lines of letters of diminishing size, is the standard measure of visual acuity. Environmental factors that influence visual […]

Read More