LASIK (Laser-Assisted In Situ Keratomileusis) is a well-known procedure designed to correct common refractive errors like nearsightedness, farsightedness, and astigmatism. Millions of people have chosen LASIK to reduce their dependence on glasses or contact lenses for clear distance vision. A frequent concern for patients, particularly as they approach middle age, is how this permanent alteration to the eye might interact with or affect their ability to focus on objects up close. The procedure itself does not cause a change in near vision, but achieving perfect distance focus can certainly make age-related changes to near vision more noticeable.
Correcting Distance Vision: How LASIK Works
LASIK surgery operates by permanently reshaping the cornea, the transparent, dome-shaped tissue at the front of the eye. The cornea is responsible for a large portion of the eye’s total focusing power. When the corneal shape is irregular, such as being too steep in nearsightedness, light focuses incorrectly, resulting in blurred vision.
The surgeon creates a thin flap on the corneal surface and uses an excimer laser to vaporize microscopic amounts of underlying tissue. For nearsightedness, the laser flattens the cornea’s curvature, moving the eye’s focal point onto the retina. This sculpting changes the eye’s fixed optical power, establishing a new focus for clear viewing of distant objects. Standard LASIK procedures focus entirely on achieving optimal distance vision.
Why Near Vision Changes After Surgery
The main factor governing near vision is accommodation, which involves the eye’s internal lens changing shape to focus on close objects. This lens is separate from the cornea, the structure LASIK alters. Around age 40, the lens naturally begins to harden and lose flexibility, a condition known as presbyopia. Presbyopia limits the eye’s ability to accommodate, making close-up tasks like reading difficult.
LASIK does not cause presbyopia, but correcting nearsightedness can make its onset suddenly apparent. Nearsighted individuals have a natural “reading advantage” because their eye’s focal point is slightly short, allowing them to remove distance glasses and see clearly up close. When LASIK fully corrects this nearsightedness, it removes that advantage. The eye must then rely entirely on the diminished focusing power of the aging lens. This trade-off means a patient over 40 who gains perfect distance vision may simultaneously experience a loss of their previous, unassisted near vision.
Monovision: A Strategy for Blended Vision
For patients experiencing or approaching presbyopia, a surgical strategy called monovision is often employed to mitigate the loss of near focus. This approach intentionally corrects the dominant eye for optimal distance viewing. The non-dominant eye is deliberately left slightly nearsighted (myopic), allowing it to focus better on near or intermediate objects.
The brain naturally learns to suppress the slightly blurred image from the eye not being used, blending the two different focal points into a functional range of vision. This process is known as neuroadaptation, where the brain prioritizes the clearer input for the given distance. Because adapting to two different powers can be challenging, a trial period using monovision contact lenses is recommended before committing to the permanent surgical procedure. Blended vision is a variation of monovision where the power difference between the eyes is less severe, creating a smoother transition and a greater depth of field.
Patient Expectations and Post-Surgical Solutions
It is important for patients to maintain realistic expectations that LASIK corrects the cornea’s shape but cannot halt the natural aging of the internal lens. Even after a successful procedure, the eventual need for reading glasses is highly probable as presbyopia progresses. This is not a failure of the LASIK procedure, but the inevitable result of the lens becoming progressively stiffer over time.
For those who have not chosen monovision, or whose presbyopia has progressed beyond what monovision can manage, simple over-the-counter reading glasses remain a straightforward solution for close-up tasks. In cases where the initial refractive outcome is not optimal, a secondary enhancement procedure may be performed to refine the corneal shape further. LASIK provides excellent, long-lasting distance vision, but for many, it trades a dependence on distance correction for a later, age-related dependence on near correction.