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Ophthalmology. In ophthalmology, horror fusionis is a condition in which the eyes have an unsteady deviation, with the extraocular muscles performing spasm-like movements that continuously shift the eyes away from the position in which they would be directed to the same point in space, giving rise to diplopia. Even when the double vision images ...
Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
Diagnosis of convergence insufficiency is made by an eye care professional skilled in binocular vision dysfunctions, such as an optometrist, opthomologist, or orthoptist to rule out any organic disease. Convergence insufficiency is characterized by one or more of the following diagnostic findings: patient symptoms, high exophoria at near ...
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. [1] It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components. [1]
Metamorphopsia is a symptom of several common retinal and macular diseases, therefore treating the underlying disorder can improve symptoms. For people who have conditions such as Epiretinal membrane (ERM), Macular Holes and Retinal Detachment, decreased metamorphopsia is associated with an increase in visual acuity.
Chronic progressive external ophthalmoplegia ( CPEO) is a type of eye disorder characterized by slowly progressive inability to move the eyes and eyebrows. [1] It is often the only feature of mitochondrial disease, in which case the term CPEO may be given as the diagnosis. In other people suffering from mitochondrial disease, CPEO occurs as ...
Aberrations of the eye. The eye, like any other optical system, suffers from a number of specific optical aberrations. The optical quality of the eye is limited by optical aberrations, diffraction and scatter. [1] Correction of spherocylindrical refractive errors has been possible for nearly two centuries following Airy's development of methods ...
Fixation disparity. Fixation disparity is a tendency of the eyes to drift in the direction of the heterophoria. While the heterophoria refers to a fusion-free vergence state, the fixation disparity refers to a small misalignment of the visual axes when both eyes are open in an observer with normal fusion and binocular vision. [1]