Periodic eye and vision examinations are an important part of preventive health care. Many eye and vision problems have no obvious signs or symptoms. As a result, individuals are often unaware that problems exist. Early diagnosis and treatment of eye and vision problems are important for maintaining good vision and eye health, and when possible, preventing vision loss.
Individuals who are especially encouraged to have periodic eye examinations include, but are not limited to: diabetic patients, hypertensive patients, patients with family history of glaucoma or macular degeneration, and patients on high risk medications such as hydroxychloroquine (Plaquenil), chloroquine, or history of long term use of corticosteroids.
A comprehensive adult eye and vision examination may include, but is not limited to, the following tests. Individual patient signs and symptoms, along with the professional judgment of the doctor, may significantly influence the testing done.
A patient history helps to determine any symptoms the individual is experiencing, when they began, the presence of any general heath problems, medications taken and occupational or environmental conditions that may be affecting vision. You will be asked about any eye or vision problems you may be having and about your overall health, as well as any previous eye or health conditions of you and your family members.
Reading charts are often used to measure visual acuity. Visual acuity measurements evaluate how clearly each eye is seeing. As part of the testing, you are asked to read letters on distance and near reading charts. The results of visual acuity testing are written as a fraction such as 20/40.
When testing distance vision, the top number in the fraction is the standard distance at which testing is done, twenty feet. The bottom number is the smallest letter size you were able to read. A person with 20/40 visual acuity would have to get within 20 feet of a letter that should be seen at 40 feet in order to see it clearly. Normal distance visual acuity is 20/20.
Preliminary testing may include evaluation of specific aspects of visual function and eye health such as depth perception, color vision, eye muscle movements, peripheral or side vision, and the way your pupils respond to light.
This test measures the curvature of the cornea, the clear outer surface of the eye, by focusing a circle of light on the cornea and measuring its reflection. This measurement is particularly critical in determining the proper fit for contact lenses.
A refraction is conducted to determine the appropriate lens power needed to compensate for any refractive error (nearsightedness, farsightedness, or astigmatism). Basically, a refraction is the determination of a patient’s glasses prescription.
This testing may be done without the use of eye drops to determine how the eyes respond under normal seeing conditions. In some cases, such as for patients who can’t respond verbally or when some of the eyes focusing power may be hidden, eye drops are used. The drops temporarily keep the eyes from changing focus while testing is done.
Assessment of accommodation, ocular motility and binocular vision determines how well the eyes focus, move and work together. In order to obtain a clear, single image of what is being viewed, the eyes must effectively change focus, move and work in unison. This testing will look for problems that keep your eyes from focusing effectively or make using both eyes together difficult.
Measurement of pressure within the eye (tonometry) is performed. Elevated pressure in the eye signals an increased risk for glaucoma. External examination of the eye includes evaluation of the cornea, eyelids, conjunctiva and surrounding eye tissue using bright light and magnification.
Evaluation of the lens, retina and posterior section of the eye may be done through a dilated pupil to provide a better view of the internal structures of the eye.