Double vision, medically known as diplopia, is the perception of two images from a single object. This visual disturbance can significantly affect depth perception and balance, making daily activities difficult or hazardous. While Laser-Assisted In Situ Keratomileusis (LASIK) is a highly effective procedure for correcting common refractive errors, it is generally not a solution for pre-existing diplopia. The procedure is designed to fix clarity issues caused by the shape of the eye’s front surface, not the complex alignment or neurological issues that frequently cause double vision. For individuals with this condition, an evaluation of the underlying cause is necessary, as LASIK is often contraindicated for those with a history of diplopia.
How LASIK Addresses Vision Impairment
LASIK is a surgical technique aimed at improving visual acuity by precisely reshaping the cornea, the clear, dome-shaped front surface of the eye. The procedure specifically targets refractive errors, such as myopia, hyperopia, and astigmatism, which are imperfections in how the eye focuses light onto the retina.
The process involves creating a thin, hinged flap in the outermost layer of the cornea. Once this flap is gently lifted, an excimer laser is used to vaporize microscopic amounts of tissue from the underlying corneal stroma. This highly controlled ablation alters the cornea’s curvature, correcting the focal point of light entering the eye. The flap is then repositioned to act as a natural bandage, allowing for rapid healing.
By changing the corneal shape, LASIK adjusts the eye’s overall optical power, ensuring light rays converge sharply on the retina. This mechanism clears blurred vision caused by an incorrectly shaped cornea. Because the treatment focuses solely on the eye’s optics and not on muscular coordination or nerve function, its scope is limited to vision problems arising from corneal shape alone.
Differentiating Types of Double Vision
Double vision is classified as either monocular or binocular, distinguished by whether the symptom persists when one eye is covered. Understanding these two main categories is important for determining appropriate treatment and assessing LASIK’s role. Monocular diplopia continues even when the unaffected eye is closed, indicating the problem originates within the eye itself.
Common causes of monocular diplopia include corneal surface irregularities (like advanced astigmatism or dry eye syndrome) or cataracts. Cataracts can scatter light and create a ghost image. Since these issues affect the optical pathway of a single eye, correcting the underlying corneal or lens problem is required.
Binocular diplopia, conversely, disappears entirely when either eye is covered, meaning the issue arises from the eyes failing to work together as a synchronized pair. This type is often caused by misalignment of the extraocular muscles, a condition known as strabismus. Neurological disorders that affect the cranial nerves controlling eye movement, such as myasthenia gravis, stroke, or thyroid eye disease, are also frequent causes. Binocular diplopia requires treatment focused on eye alignment or the underlying systemic condition.
LASIK and the Risk of Induced Double Vision
While LASIK can occasionally resolve pre-existing monocular diplopia caused by corneal irregularities, it can also lead to new or worsened double vision. This is typically a recognized, though uncommon, complication of the procedure. The new visual disturbance is often temporary, resolving within weeks or months as the eye heals.
One common cause is an irregular corneal surface following laser ablation. If the treatment zone is not perfectly centered, the resulting decentered ablation can induce a prism effect, sometimes leading to vertical diplopia. Flap complications, such as microscopic wrinkles, can also scatter light, which the brain perceives as a double image.
Severe post-surgical dry eye is another factor, as an unstable tear film distorts the corneal surface, causing image ghosting. Furthermore, in individuals with a pre-existing, compensated weakness in eye muscle coordination, the change in optics following LASIK can destabilize the visual system. This decompensation can manifest as binocular double vision, even though the procedure did not directly affect the eye muscles.
Definitive Treatments for Double Vision
Since LASIK is a refractive correction procedure, definitive treatment for double vision must address the specific underlying cause, whether optical or alignment-related. For binocular diplopia resulting from mild eye muscle imbalance, prism lenses are a common non-surgical solution. These specialized lenses bend light, shifting the image seen by one eye so it aligns and fuses with the image from the other eye.
Prisms can be applied temporarily as a thin, stick-on Fresnel prism, or they can be permanently ground into the lens prescription once the double vision has stabilized. Vision therapy, involving a structured program of eye exercises, can also strengthen eye muscles and improve coordination in cases of convergence insufficiency. This therapy aims to train the eyes to work as a team.
For more pronounced or stable muscle misalignment, surgical intervention may be required. Eye muscle surgery involves adjusting the length or position of the extraocular muscles to physically realign the eyes. In cases of muscle paresis, botulinum toxin injections can temporarily weaken the stronger opposing muscle to stabilize the deviation before permanent surgery is considered. Addressing systemic conditions like diabetes or thyroid disease is also necessary, as treating the underlying medical issue often resolves the associated diplopia.