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Prism correction. Prism lenses (here unusually thick) are used for pre-operative prism adaptation. Eye care professionals use prism correction as a component of some eyeglass prescriptions. A lens which includes some amount of prism correction will displace the viewed image horizontally, vertically, or a combination of both directions.
The prism cover test (PCT) is an objective measurement and the gold standard in measuring strabismus, i.e. ocular misalignment, or a deviation of the eye. It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components. [1]
The most common strabismus finding is large angle exotropia which can be treated by maximal bilateral eye surgery, but due to the progressive nature of the disease, strabismus may recur. Those that have diplopia as a result of asymmetric ophthalmoplegia may be corrected with prisms or with surgery to create a better alignment of the eyes.
The Four Prism Dioptre Reflex Test (also known as the 4 PRT, or 4 Prism Dioptre Base-out Test) is an objective, non-dissociative test used to prove the alignment of both eyes (i.e. the presence of binocular single vision) by assessing motor fusion.
The type of double vision can be horizontal, vertical, torsional, or a combination. Treatment of the double vision depends on both the type of double vision and the ability of two eyes to work together, also called binocular function. [12]
Congenital fourth nerve palsy is a condition present at birth characterized by a vertical misalignment of the eyes due to a weakness or paralysis of the superior oblique muscle. Other names for fourth nerve palsy include superior oblique palsy and trochlear nerve palsy. [1] When looking to the right/left the nerve/muscle is not strong enough or ...
The following equipment is used to complete a Subjective Refraction: [citation needed] Jackson Cross Cylinder: a combination of two cylinders whose powers are numerically equal and of opposite sign (+/-) and whose axis are perpendicular to one another. [2] This is used to search for astigmatism.
Typical ocular signs involving CNIII include outwards and downwards drifting of eyes , difficulty in controlling inward and upward eye movements, drooping of eyelid and double vision. Pupil dilation ( mydriasis ) and reduction in pupillary light reflexes can also be observed as pupillomotor fibers are also affected by CNIII paralysis. [11]
Eyecare professionals (optometrists and ophthalmologists) are trained to determine the specific corrective lenses that will provide the clearest, most comfortable, and most efficient vision, avoiding double vision and maximizing binocularity. Over-the-counter correction
Chromatic correction of visible and near infrared wavelengths. Horizontal axis shows degree of aberration, 0 is no aberration. Lenses: 1: simple, 2: achromatic doublet, 3: apochromatic and 4: superachromat. In the earliest uses of lenses, chromatic aberration was reduced by increasing the focal length of the lens where possible.