Strabismus and astigmatism are distinct conditions affecting vision. Strabismus, often called “crossed eyes,” is a condition where the eyes are not aligned and do not point in the same direction. One eye might look straight ahead while the other turns inward, outward, upward, or downward. This misalignment stems from issues with the muscles that control eye movement or the brain centers that direct them.
Astigmatism is a refractive error caused by an imperfection in the curvature of the eye’s cornea or lens. Instead of being uniformly round, the surface is shaped more like an American football, causing light to focus unevenly on the retina. This results in vision that can be blurry or distorted at all distances.
The Link Between Strabismus and Astigmatism
While strabismus and astigmatism are separate issues, they can be related. Significant uncorrected astigmatism, particularly if worse in one eye, can contribute to the development of strabismus. The brain receives a blurry image from the eye with severe astigmatism. To avoid this poor-quality information and prevent double vision, the brain may suppress input from that eye.
This suppression weakens the eye’s connection with the brain. Over time, the lack of use can cause the eye to drift and become misaligned, resulting in strabismus. Correcting significant refractive errors in children is important because it ensures the brain receives clear images from both eyes, encouraging them to work together.
It is also possible for the two conditions to exist without one directly causing the other. A person can have a genetic predisposition for both, leading them to develop independently. Research indicates a notable correlation between the presence of astigmatism and different forms of strabismus, suggesting a complex relationship.
Recognizing the Signs and Symptoms
The most apparent sign of strabismus is a visible misalignment of the eyes. You might notice that the eyes do not move together in a coordinated way. A person with strabismus may frequently squint, close one eye in bright sunlight, or tilt their head to align the images from the two eyes.
The primary symptoms of astigmatism are blurry or distorted vision. This can lead to eye strain and headaches, especially after tasks requiring visual focus like reading. Another common complaint is difficulty with night vision, where lights may appear to have halos or streaks. Squinting is a symptom present in both conditions, as it is an attempt to make vision clearer, highlighting the need for a professional evaluation.
Diagnosis and Corrective Options
An eye doctor performs several tests to diagnose strabismus and astigmatism. A visual acuity test measures the sharpness of vision, while a refraction test determines the presence of refractive errors like astigmatism. To diagnose strabismus, a specialist will conduct alignment and focusing tests, such as a cover test, to observe how the uncovered eye moves.
Correcting Astigmatism
The primary methods for correcting astigmatism are eyeglasses and contact lenses. The lenses have a cylindrical correction to compensate for the irregular curvature of the cornea or lens, allowing light to focus properly on the retina. For contact lens wearers, toric lenses are prescribed. For adults seeking a permanent solution, refractive surgeries like LASIK can reshape the cornea.
Treating Strabismus
If strabismus is linked to an uncorrected refractive error, prescribing eyeglasses is often the first step. Other treatments include:
- Placing a patch over the stronger eye to force the weaker, misaligned eye to work harder and develop better vision, a condition known as amblyopia.
- Vision therapy, which involves a series of eye exercises designed to improve eye coordination and focus.
- Prism lenses, which are incorporated into eyeglasses to bend light and help align the images from both eyes.
- Surgery on the eye muscles to adjust their tension and realign the eyes when other methods are not sufficient.