The anisometropia refers to that visual condition in which there is graduation or different refractive error in each eye. For example, one eye may be nearsighted, and the other hyperopic, or both may be nearsighted, but the graduation of one eye relative to the other is very large. When the variation is slight, the brain tries to compensate for it.
However, if the difference in dioptre is high, four or more, the binocular vision may be altered since each retina captures a different image. One of the problems usually associated with anisometropia is lazy eye or amblyopia
Types of anisometropia
The patient can present the following visual combinations:
- Simple anisometropia
When one of the eyes is emmetropic, that is, without dioptres and therefore with normal vision, but the other eye is myopic or hyperopic.
- Composite anisometropia
This condition refers to when the refractive defect is the same in both eyes, but the difference in graduation is significant between one and the other.
- Mixed anisometropia
Each eye has a different refractive defect. This can be when one eye is myopic and the other hyperopic.
Another combination could be, for example, when one eye has farsightedness and another astigmatism.
Causes Of Anisometropia And Other Related Pathologies
The origin of this condition can be congenital and appear from children or present in adulthood after trauma or retinal detachment surgery, for example.
- Anisocoria
This eye condition is defined as the size and shape of the images once projected onto the retina of each eye. The brain cannot fuse them into a single image, and binocular vision is compromised. As a consequence, the patient usually experiences double vision (diplopia), headache, distortion of spatial vision, and photophobia, mainly.
- Squint
Anisometropia can also arise when the eyes are out of alignment and point in different directions (up, out, or down) by sending two different images to the brain.
- Amblyopia or lazy eye
It is usually the most frequent cause of anisometropia if it is not detected early in childhood, causing a progressive loss of visual capacity. If this occurs and needs treatment for this pathology, it will also be necessary to correct the patient’s amblyopia. Some of these defects can be cured if detected on time in order to avoid much complications and thermage (เท อ ร์ มา จ which is the term in Thai)