What is a microtropia?
Microtropia is an unilateral strabismus of less than 5 degrees, usually with harmonious anomalous correspondence. Three forms may be distinguished: Primary constant, primary decompensating and consecutive microtropia.
What causes microtropia?
What causes microtropia? In most cases it is a congenital condition meaning it is present at birth. In some patients, microtropia may be present as a result of other treatment for a larger strabismus, i.e. glasses or surgery.
How do you test for microtropia?
Diagnosis of a microtropia was determined by the following criteria: (1) Cover test revealing only a latent deviation or no deviation, in patients with microtropia with identity, or a small manifest deviation in microtropes without identity, measuring <5°.
What causes eccentric fixation?
Eccentric or monocular fixation is a condition that exists only in amblyopic patients. It is most common in strabismic amblyopia and rare in anisometropic amblyopia. It occurs when the amblyopic eye actively attempts to fixate with an off-foveal point under monocular conditions (6).
What is Duane retraction syndrome?
Duane retraction syndrome (DRS) is a congenital eye movement anomaly characterized by variable horizontal duction deficits, with narrowing of the palpebral fissure and globe retraction on attempted adduction, occasionally accompanied by upshoot or down-shoot.
What is the abnormal retinal correspondence?
In abnormal retinal correspondence (ARC) — also known as anomalous retinal correspondence — there is an eye turn, known as strabismus. In this situation, the fovea of the turned eye is not looking at the object. This would usually cause double vision, which is very disabling.
What is eccentric fixation mean?
Eccentric fixation may be defined as a monocular phenomenon in which the eye utilises a portion of the retina other than the fovea for fixation. Eccentric fixation was once considered to be a rare complication of longstanding strabismus.
What is eccentric fixation?
We use the term eccentric fixation (ecc. fix.) when the amblyopic eye fixates with a retinal area which is not the fovea and when the retina of this eye is oriented around this area of fixation which gives the impression of “straight ahead.” The amblyopic eye does not redress and sticks to its ecc.
What gene causes Duane syndrome?
Mutations in the CHN1 gene are associated with familial isolated Duane syndrome.
What is Duane syndrome type 3?
Duane syndrome type 3: The ability to move the affected eye(s) both inward toward the nose (adduction) and outward toward the ear (abduction) is limited. The eye opening narrows and the eyeball retracts when the affected eye(s) attempts to look inward toward the nose (adduction).
How is abnormal retinal correspondence treated?
Treatment for Anomalous Retinal Correspondence It corrects certain eye alignment and other binocular vision problems. Vision therapy includes specific eye exercises paired with special lenses, prisms or eye patches to help improve poor visual skills and binocular vision problems.
What is microtropia in psychology?
Background: Microtropia is a small-angle strabismus with a highly developed degree of binocular cooperation. It is a unilateral comitant horizontal deviation less than 5 prism diopters (PD) in the presence of anomalous retinal correspondence (ARC), amblyopia, some motor fusion, and reduced stereoacuity.
What is micromicrotropia and how is it characterized?
Microtropia has been the subject of debate since Lang 6 coined the term to describe a small angled strabismus with anomalous retinal correspondence (ARC), normal fusional amplitudes, and reduced stereopsis.
What is reduced stereopsis in microtropia?
Reduced stereopsis is an invariable finding in microtropia. In a previous series of 29 patients with primary microtropia, 54% had stereopsis of 400″ of arc or less, while 42% demonstrated between 100 and 400″ of arc using non-random dot tests.
Can microtropia defy detection and improve visual potential in children?
Over the follow-up period, visual acuity improved but the alignment did not. Conclusion: Microtropia can defy detection, resulting in a reduced chance of achieving near-normal visual potential in children.
