Eye Conditions: What They Are and How They Affect Your Vision

Myopia (Nearsightedness)

Myopia is the most common refractive error worldwide, affecting approximately 30% of adults globally and growing rapidly due to increased near-work and reduced outdoor time. In myopia, the eyeball is too long or the cornea too steep, causing light to focus in front of the retina rather than on it. Near objects appear clear; distant objects are blurry.

LASIK candidacy: Myopia is the most successfully treated condition with LASIK. Prescriptions up to –12.00D can be treated, with optimal outcomes below –8.00D. Nearly all myopic patients who meet corneal thickness and stability requirements qualify.

Hyperopia (Farsightedness)

Hyperopia occurs when the eyeball is too short or the cornea too flat, causing light to focus behind the retina. Mild hyperopes may see reasonably well at all distances by accommodating (the lens straining to compensate), causing eye strain and headaches. Higher degrees cause blurry near and distance vision.

LASIK candidacy: Hyperopia is treatable with LASIK up to +6.00D, though results are less predictable at higher levels. Patients with high hyperopia (+4D and above) may be better served by ICL or RLE.

Astigmatism

Astigmatism results from an irregularly shaped cornea or lens — oval rather than spherical — causing light to focus at multiple points rather than one. Vision is blurry at all distances, often with distortion or ghosting of images. It commonly co-exists with myopia or hyperopia.

LASIK candidacy: Regular astigmatism up to 6.00D is treatable with LASIK. Irregular astigmatism (common in keratoconus) cannot be safely treated and may disqualify the patient. Topography-guided LASIK is particularly effective for patients with significant astigmatism.

Presbyopia

Presbyopia is the age-related stiffening of the eye's natural lens that begins around age 40, progressively reducing the ability to focus on near objects. It affects virtually everyone by age 50. Unlike other refractive errors, presbyopia is a lens problem, not a corneal one.

LASIK candidacy: Standard LASIK does not treat presbyopia. Monovision LASIK can reduce dependency on reading glasses by correcting one eye for near vision. Refractive Lens Exchange with a premium IOL is the most comprehensive solution for patients with significant presbyopia.

Dry Eye Syndrome

Dry eye syndrome occurs when the eyes don't produce enough tears or the tears evaporate too quickly. Symptoms include burning, stinging, redness, blurry vision, and paradoxical excessive tearing. It affects an estimated 16 million Americans.

LASIK candidacy: Dry eye is the most common reason for LASIK deferral. LASIK temporarily reduces corneal sensitivity and tear production. Mild dry eye can often be treated before surgery; moderate-to-severe dry eye may preclude LASIK altogether. SMILE carries a lower post-operative dry eye risk and may be an alternative.

Keratoconus

Keratoconus is a progressive condition in which the cornea thins and bulges into a cone shape, causing increasingly distorted and blurry vision that glasses struggle to correct. It typically develops in the teens and 20s and may progress through the 30s.

LASIK candidacy: Keratoconus is an absolute contraindication to LASIK, PRK, and SMILE. The surgery removes corneal tissue that the eye cannot spare, and could accelerate progression. Alternatives include corneal crosslinking (to halt progression), scleral contact lenses for visual correction, and ICL in stable cases. Forme fruste keratoconus (subclinical) also disqualifies for laser surgery.

Night Vision Problems

Night vision problems — halos, starbursts, and glare around lights — can result from large pupils, early cataracts, or higher-order aberrations. They may also occur temporarily after LASIK as a side effect, typically resolving within 3–6 months.

LASIK candidacy: Patients with large pupils in low light may have increased risk of night vision side effects after LASIK. Modern wavefront-guided and large-optical-zone treatments have significantly reduced this risk, but the pre-operative evaluation should include mesopic pupil measurement.

How Conditions Affect LASIK Candidacy

Condition	LASIK Status	Alternative
Myopia (up to -12D)	Excellent candidate	ICL for very high myopia
Hyperopia (up to +6D)	Good candidate	ICL or RLE for high hyperopia
Regular astigmatism	Good candidate	Toric ICL if not laser candidate
Presbyopia	Monovision LASIK option	RLE with multifocal IOL
Mild dry eye	May qualify after treatment	SMILE (lower dry eye risk)
Moderate/severe dry eye	Generally disqualified	ICL or manage medically
Keratoconus	Disqualified	Crosslinking, scleral lenses, ICL
Large pupils at night	Evaluate carefully	Wavefront-guided LASIK reduces risk

Understanding your specific condition and how it interacts with laser surgery is the starting point for any candidacy assessment. Review the LASIK candidacy guide and consult a qualified surgeon for a definitive evaluation.