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- ultrasound: A-Scan
- Type of ultrasound device that emits very high frequency waves that are reflected by the
ocular structures and converted into electrical impulses. Used for differentiating normal
and abnormal eye tissue or for measuring length of eyeball.
See Free Eye Tests.
- ultrasound: B-Scan
- Ultrasound procedure in which high frequency waves are reflected by eye tissues and
orbital structures and then converted into electrical pulses that are displaced as bright
spots on a black background. Provides a cross-sectional view of tissues used for
evaluating structures that cannot be seen directly.
See Free Eye Tests.
- ultrasound: eye
- Transmission into the eye of high frequency sound waves that are reflected by ocular
tissues and displayed on a screen so the internal structures can be visualized. Aids in
diagnosis of eye and orbital problems.
See Free Eye Tests.
- ultraviolet rays
- Invisible part of the light spectrum whose rays have wavelengths shorter than the violet
end of the visible spectrum and longer than X-rays. UVA and UVB light are harmful to
your eyes and skin.
See Free Eye Tests.
- UV protection
- Protection offered by sunglasses against UVA and UVB light that is harmful to the eyes.
Sunglasses should protect against 99 percent of these harmful rays. Particularly important
when around water or snow where failure to use protection can result in painful burn to
outer layer of eye and temporary blindness.
See Free Eye Tests.
- uveitis
- A disease, often misdiagnosed, that causes inflammation of the structures of the uveal
tract: iris, ciliary body or choroid. Inflammation may occur suddenly, be chronic, or be
recurrent. Symptoms include eye pain, sensitivity to light, blurred vision, tearing and
redness. Uveitis is often related to a systemic condition such as rheumatoid arthritis,
multiple sclerosis, sarcoidosis and ankylosing spondylitis. Usual treatment is
administration of eye drops to relieve symptoms and reduce inflammation.
See Free Eye Tests.
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