Lazy eye refers to the drifting or misalignment of an eye. This is usually the manifestation of amblyopia, where one eye is experiencing significant vision loss, and sometimes also strabismus (or "crossed eyes"), a general misalignment problem.
Let's walk through how amblyopia and lazy eye affect your vision and how it's typically corrected and treated.
Lazy eye / amblyopia: What's the difference?
There are two main conditions that result in what we see as a lazy eye:
Amblyopia is a developmental problem with the eye-brain connection: the brain has basically learned to ignore information from one eye. Amblyopia is not a problem with the eye itself, though it can both cause and be caused by such problems.
Strabismus, or "crossed eyes", is a misalignment of the eyes when the six muscles that surround and help focus the eyes are not working together properly. This can be both a cause and an effect of amblyopia.
How does a lazy eye affect my vision?
The most common symptoms of lazy eye are eye drifting and misalignment. But a lazy eye can cause serious vision problems:
- Rapid loss of visual acuity in the lazy eye when left uncorrected and increasingly unused
- Loss of binocular vision, leading to the inability to gauge depth.
- Increased risk of vision loss for the stronger eye, since vision problems that typically occur in both eyes will affect the stronger eye first.
What causes lazy eye?
Amblyopia occurs because the eye-brain connection is weak or undeveloped.
The most common cause of this is strabismus. When the eye muscles aren't able to align the eyes properly, especially during development, the brain receives a different image from each eye. The confusion is resolved by the brain's systematically ignoring one of the images. This leaves the eye unused and the corresponding brain area underdeveloped.
Another common cause is refractive error (near / farsightedness or astigmatism) that's greater in one eye. This also leads to mismatched input, then the precedence of one eye that causes the brain to ignore input from the other.
Anything that creates this sort of visual imbalance can also cause amblyopia. This includes childhood cataracts, clouded lenses, shape or size differences and other anatomic or structural abnormalities.
The earlier a lazy eye is checked out and treated, the better the chances of success. However, lazy eye treatment for adults is also effective, especially when motivation and commitment are strong. Studies show marked improvement in visual acuity of the weaker eye in older patients, though often with diminished rate, degree and extent of recovery.
There are two main steps to amblyopia treatment, the first part of lazy eye correction:
Step 1: Correcting vision problems
Eye conditions, such as cataracts, and refractive errors need to be corrected first and foremost. This is often as simple as prescribing glasses for near or farsightedness. Sometimes, in mild cases, correcting the vision of the weaker or lazy eye is enough for realignment.
Step 2: Retraining the eye-brain connection
In most cases, eye care practitioners block the stronger eye in order to train the brain to start recognising the image from the amblyopic or lazy eye. This can be done with a patch or with eye drops that temporarily blur vision.
Eye muscle surgery
Occasionally, even the correction of amblyopia doesn't correct strabismus issues that keep the eyes misaligned. In these cases, eye muscle surgery to strengthen or weaken certain muscles can help. A surgeon will either resect (or shorten) a muscle to strengthen it or recess a muscle (attaching it to a farther location) to weaken it.
In a small number of cases, mild misalignment due to convergence insufficiency (where the eyes have difficulty turning in to focus on close objects) can be corrected with eye muscle exercises. These eye exercises include pencil push-ups and computer vision therapy.
Remember, the earlier you treat a lazy eye, the higher the chances of success. Anytime you have problems with your eyes or vision, chat with your eye care practitioner or doctor as soon as possible.