LASIK (Laser-Assisted In Situ Keratomileusis) corrects vision errors by using a laser to reshape the clear, dome-shaped front surface of the eye. A cataract is the gradual clouding of the eye’s natural lens, which sits just behind the iris. Generally, you cannot receive LASIK if you have a cataract because the cataract is a progressive obstruction within the eye. If the cataract is visually significant, LASIK will not resolve the internal clouding, making cataract surgery the definitive and preferred treatment pathway.
Distinguishing the Targets: Cornea vs. Lens
The reason these two conditions require separate approaches lies in the distinct parts of the eye they affect. LASIK targets the cornea, the outermost layer, to correct refractive errors like nearsightedness and astigmatism. This procedure permanently alters the corneal curvature to ensure light focuses precisely on the retina.
The cataract forms on the natural lens, located internally behind the cornea. A cataract causes the lens to become opaque, like a foggy window. Since LASIK only addresses the corneal shape, it cannot clear the existing cloudiness of the lens.
Attempting LASIK on an eye with a developing cataract is counterproductive because the cataract will continue to progress. As the lens becomes cloudier, it will negate the precise vision correction achieved by reshaping the cornea. The progressive nature of the cataract means the refractive benefit of LASIK would be temporary and the procedure would ultimately prove unnecessary.
Standard Protocol: When Cataracts Precede LASIK
When a person presents with both a refractive error and a visually significant cataract, the standard course of action is to prioritize the removal of the clouded lens. Cataract surgery is a highly successful procedure that removes the opaque natural lens and replaces it with a clear, artificial Intraocular Lens (IOL). This surgical approach simultaneously addresses the vision loss from the cataract and the pre-existing need for corrective lenses.
The IOL can often be selected to correct the patient’s refractive errors, such as myopia, hyperopia, and astigmatism, that LASIK would have targeted. The surgeon uses preoperative measurements to choose an IOL power designed to achieve a specific vision goal, frequently reducing or eliminating the need for glasses for distance vision.
For patients with early-stage cataracts or very high refractive errors, a procedure called Refractive Lens Exchange (RLE) may be considered. RLE uses the same surgical technique as cataract surgery but is performed on a clear or minimally clouded lens primarily to correct a significant refractive error. The new IOL is the permanent solution, correcting the internal focus of the eye and making any subsequent LASIK procedure largely redundant. Advanced IOLs, including toric and multifocal options, allow for comprehensive correction of vision during the single procedure.
Unique Challenges: Cataract Surgery After Previous LASIK
A distinct clinical scenario arises when a patient who had LASIK years earlier develops age-related cataracts. While the prior LASIK does not prevent cataract surgery, it introduces significant complexity to the surgical planning. LASIK permanently changes the cornea’s curvature, typically by flattening the central zone to correct nearsightedness.
Standard formulas used to calculate the required power of the IOL rely on the eye’s natural, unaltered corneal curvature measurements. In a post-LASIK eye, these standard measurements become inaccurate, often leading to miscalculations that result in a residual refractive error after surgery. The cornea’s new shape causes the traditional keratometry readings to overestimate the eye’s true refractive power.
To achieve an accurate outcome, surgeons must use specialized diagnostic tools, such as advanced corneal topography and optical biometry devices, to gather more precise data. They must also employ specialized calculation formulas that account for the altered corneal shape. Accessing the patient’s pre-LASIK refractive data and corneal measurements is helpful, as this historical information allows the surgeon to select the most appropriate calculation method and improve the predictability of the IOL power.