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Corrective lens. A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye.
Abbe number. In optics and lens design, the Abbe number, also known as the V-number or constringence of a transparent material, is an approximate measure of the material's dispersion (change of refractive index versus wavelength), with high values of V indicating low dispersion. It is named after Ernst Abbe (1840–1905), the German physicist ...
Reactive arthritis. Rheumatoid arthritis. Ehlers-Danlos Syndrome. Sarcoidosis. Scleroderma. Systemic lupus erythematosus. Temporal arteritis. Relapsing polychondritis. Granulomatosis with polyangiitis 50-60% have ophthalmologic manifestations, which can be a presenting feature in a minority of patients.
List of medical symptoms Medical symptoms refer to the manifestations or indications of a disease or condition, perceived and complained about by the patient. [ 1 ] [ 2 ] Patients observe these symptoms and seek medical advice from healthcare professionals.
When an object is located close to the eye, the rays of light from this object no longer approach the eye parallel to each other. Consequently, the eye must increase its refractive power to bring those rays of light together on the retina. This is called accommodation, and is accomplished by the eye thickening the lens. [11]
Spherical aberration. A perfect lens (top) focuses all incoming rays to a point on the Optical axis. In spherical aberration (Bottom) peripheral rays are focused more tightly than central rays. There are numerous higher-order aberrations, of which only spherical aberration, coma and trefoil are of clinical interest.
White dot syndromes. White dot syndromes are inflammatory diseases characterized by the presence of white dots on the fundus, the interior surface of the eye. [ 1] The majority of individuals affected with white dot syndromes are younger than fifty years of age. Some symptoms include blurred vision and visual field loss. [ 2]
Aphakia. Aphakia is the absence of the lens of the eye, due to surgical removal, such as in cataract surgery, a perforating wound or ulcer, or congenital anomaly. It causes a loss of ability to maintain focus ( accommodation ), high degree of farsightedness ( hyperopia ), [ 1] and a deep anterior chamber. Complications include detachment of the ...