Strabismus

Strabismus

Strabismus (Squint Eyes)

Strabismus refers to a condition of misalignment of the eyes. The misalignment can be present on the horizontal; vertical or oblique level.

Causes

Infantile squint: these types develop typically from the third month of life
Secondary squint: This is a deviation which develops due to a disease affecting the vision in an eye. Accommodative squint: this type develops due to excessive hyperopia (far sightedness)

Evaluation

In the evaluation of strabismus all the factors that can cause the condition will be considered carefully by the ophthalmologist as each cause has different approaches and management.

Symptoms and presentation

Small children will usually present with the observation of the presence of a squint by the parents or the doctor. Older children and adults will possibly experience double vision when a squint develops.

Early management:

It is of extreme importance that strabismus must be examined and managed as early as possible. Firstly the cause must be determined. Secondly many types of strabismus can develop a lazy eye (amblyopia) in children. This problem is mostly reversible if detected early. If detected too late it becomes irreversible. Thirdly, the earlier the alignment and amblyopia can be corrected the better the long term visual outcome.

Types

The two most common types are:
  1. Inwards deviation ( Esotropia)
    Esotropia can be
    1. Infantile type which usually arises from about the third month of age. These eyes usually do not have a focus problem and have to be operated to correct the squint and preferably earlier than later.
    2. Accommodative type which usually manifests from about six months onwards. These eyes have a farsighted focus problem and have to be corrected with the appropriate spectacles. Surgery is uncommonly indicated in this type.
  2. Outwards deviation ( Exotropia)
    Exotropia tends to present a bit later in life. If it presents earlier it might have a different approach. Exotropia is usually of an intermittent nature ( sometimes straight and sometimes deviated) According to the measured deviations the appropriate management can be determined e.g. initial observation; eye exercises or muscle surgery

Each type of strabismus has its individual appropriate treatment. The aims are to obtain and maintain:
  1. Normal vision in both eyes. If amblyopia is present it will be managed with eye occlusion (patching) or penalization (dilating the pupil with eye drops.
  2. Correcting the alignment with glasses; prism glasses; surgery; botulinum toxin injection or exercises. These treatments are not applied randomly as one prefers, but are applied according to strict indications for a particular type of squint.
  3. Depth perception.