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Information on eye movement disorders

Why we look so closely at your eyes

In order to perceive our environment we require not only image recognition and good visual acuity, but also the ability to execute a range of different eye movements with both eyes in a coordinated manner. Moving objects must be tracked, stationary objects must be viewed using quick eye movements, saccades, e.g., when reading, must be executed smoothly and much more. In the process, the eyes avoid image shifts by correcting to ensure that the image is in focus. This involves not only the eye muscles themselves and the nerves that control them, but also the control centres in the brainstem and cerebellum or in our cortex. Due to the connection between the eye muscles and the vestibular system, eye movement disorders can also occur with balance disorders or vertigo. A careful examination of eye movements thus ensures that these functions are also tested and that dysfunctions can be detected.

 

Subjective problems with eye movements

The most frequent subjective problems with eye movements are:

  • Blurred vision during eye movements or when the subject moves
  • Wobbling images (oscillopsia), all the time or in attacks
  • Double vision in certain gaze positions or all the time
  • Delayed gaze shifts
  • Considerable reading problems despite glasses with the correct prescription
  • Fixation problems
  • Difficulties identifying fast-moving objects, e.g. in road traffic

 

Examination methods

The cover test is used to examine the motility of the muscles in all gaze directions. When carrying out the cover test, the orthoptist looks for the slightest change in an existing strabismus angle in order to identify a weakness of the ocular muscles. The deviation is measured precisely using prismatic lenses and Harms’ tangent scale (comparative measurements can be performed to check findings or ocular torsion can be defined quantitatively). Additional examinations like testing the subjective visual vertical or fundus photography using scanning laser ophthalmoscopy permit clear identification of acquired strabismus of central origin (that means double vision, which is due to a dysfunction of the brainstem and the cerebellum).

The orthoptist also examines the accuracy and speed of saccades and smooth pursuit and looks for lapses in fixation or nystagmus (involuntary eye movements). If necessary, video-oculography is used to provide a precise recording of these involuntary eye movements.

 

Orthoptic treatment

If double vision, gaze palsies or ophthalmoplegia are present, orthoptic symptomatic treatment can be carried out:

In the acute phase, covering one lens of a pair of glasses (e.g. with a matt film) helps to restore orientation in daily life.

In the case of constant double vision, the strabismus angle is corrected by prismatic lenses in order to facilitate binocular vision.

In the case of movement disorders of the eye muscles which are due to nerve palsies

or dysfunctions of the control centers, movement exercises can also be carried out to support the treatment.

Treatment of nystagmus:

Drugs can help with certain types of acquired nystagmus. The orthoptist documents the change in the nystagmus. Sometimes treatment with prisms is possible.