LASIK (Laser-Assisted In Situ Keratomileusis) is widely known for correcting distance vision problems like nearsightedness. However, it can also be adapted to treat the age-related decline in near focusing power, a condition known as presbyopia. This treatment uses specialized strategies to alter the eye’s optics, helping reduce a patient’s dependence on reading glasses.
Understanding Presbyopia: Why Reading Vision Fails
Presbyopia is distinct from common refractive errors like myopia or hyperopia that standard LASIK corrects. Traditional LASIK reshapes the cornea to adjust how light focuses onto the retina, treating vision issues caused by the cornea’s incorrect shape.
Presbyopia is caused by a progressive biological change inside the eye, typically starting around age 40 to 45. The natural lens, located behind the iris, gradually loses its flexibility. This loss of elasticity impairs the lens’s ability to change shape and accommodate, which is required to bring nearby objects into clear focus. Since standard LASIK only modifies the cornea, specialized techniques are necessary to address the reading vision problem.
Correcting Reading Vision Using Monovision
The most widely accepted laser solution for presbyopia is monovision, sometimes called blended vision. This technique determines the prescription targets for each eye during the procedure, intentionally setting one eye for clear distance vision and the other eye for clear near vision.
The dominant eye is typically corrected for clear distance vision, such as for driving. The non-dominant eye is intentionally left slightly nearsighted, allowing it to focus on objects at reading distance. The brain adapts to this visual imbalance, learning to automatically select the clearer image from the appropriate eye.
A critical step before monovision LASIK is a contact lens trial period to simulate the visual outcome. This trial determines if the patient’s brain can successfully adapt to the difference in focusing power. While often successful, this strategy can sometimes reduce depth perception, especially during activities like driving or sports. Some patients may also experience reduced vision quality in low-light conditions because neither eye is optimized for intermediate distances.
Emerging Multifocal and Advanced Procedures
Advanced laser techniques, often grouped as PresbyLASIK or multifocal LASIK, aim to address presbyopia by creating multiple focal points within a single eye. These methods reshape the cornea of both eyes to create concentric zones of different focusing powers, rather than assigning one function to each eye.
The laser sculpts the cornea’s surface to have areas for both near and distance vision. This creates an optical effect similar to a multifocal contact lens, focusing light from different distances simultaneously. The brain learns to interpret the clearest signal from the corresponding zone for the object being viewed.
The advantage of multifocal approaches is that both eyes are treated similarly, maintaining better binocular function and preserving depth perception more effectively than monovision. However, splitting light between multiple focal points means the resulting vision may not be as sharp at any single distance. This light splitting can also lead to visual side effects such as halos or glare around lights at night. Outcomes of these complex procedures can be more variable between patients than the established monovision strategy.
Key Considerations Before Choosing Surgery
Before committing to a laser procedure for presbyopia, a thorough eye examination is necessary to ensure the patient meets specific candidacy requirements. Factors like corneal thickness, overall eye health, and prescription stability are assessed. Candidates must have realistic expectations, understanding that the goal is typically reduced dependence on reading glasses, not total freedom from them.
Presbyopia is a progressive condition, meaning the natural lens will continue to age and lose flexibility even after the procedure. Initial positive results may diminish over many years, potentially requiring mild reading glasses for small print or prolonged near work later in life. Potential side effects, such as dry eyes, glare, and halos, are common in the initial recovery period and can occasionally persist. Patients who rely heavily on excellent depth perception, such as pilots, may be better suited to a more conservative approach due to the visual trade-offs involved.