Laser eye surgery has helped millions of people worldwide achieve clear vision without glasses or contact lenses. Whether you are tired of fogged lenses, frustrated by the cost of contacts, or simply want the freedom of clear natural vision, laser vision correction may be an option — but not everyone is suitable. Understanding the suitability criteria before booking an assessment helps set realistic expectations and ensures that your appointment is clinically productive.
What Laser Eye Surgery Corrects
Laser eye surgery uses an excimer laser to permanently reshape the cornea and correct refractive errors — myopia (short-sightedness), hyperopia (long-sightedness), and astigmatism. The three main procedures are LASIK, PRK, and SMILE. All three aim to reduce or eliminate dependence on glasses and contact lenses; they differ in how the cornea is prepared before the laser is applied.
Laser eye surgery uses a highly precise excimer laser to permanently reshape the cornea — the clear front surface of the eye — to correct refractive errors including myopia (short-sightedness), hyperopia (long-sightedness), and astigmatism. The most widely performed procedures are LASIK, PRK, and SMILE. Each uses a similar underlying principle but differs in how the cornea is prepared before the laser is applied. All three procedures aim to reduce or eliminate dependence on glasses and contact lenses.
Key Suitability Criteria
To be a candidate for laser eye surgery, your prescription must be stable for at least 12 months, you must be aged 21 or older, your corneas must be of adequate thickness, you must have no corneal disease (particularly keratoconus), your dry eye should be absent or mild, and you must have realistic expectations. Suitability can only be confirmed after a thorough pre-operative assessment including corneal topography, pachymetry, and dry eye evaluation.
To be considered a candidate for laser eye surgery, you generally need to meet the following criteria. Your prescription must be stable — it should not have changed significantly in the past 12 months, as a changing prescription suggests the eye is still adapting. You should be at least 21 years of age, as prescriptions tend to stabilise in the early 20s. Your corneas must be of adequate thickness — laser surgery removes corneal tissue, so sufficient tissue must be available to safely achieve the correction while preserving structural integrity. You should have no corneal disease, particularly keratoconus, which is a firm contraindication to laser surgery. Dry eye should be mild or absent, as laser surgery can temporarily worsen tear film quality. Finally, you should have realistic expectations about what laser correction can and cannot achieve.
Who Is Not Suitable for Laser Surgery
Common reasons patients are found unsuitable for laser surgery include thin corneas, an irregular corneal shape consistent with keratoconus detected on topography, a prescription too high to be safely corrected by laser alone, significant pre-existing dry eye disease, and certain systemic conditions affecting wound healing. Patients who are pregnant or breastfeeding should defer assessment until prescription has stabilised after delivery.
Common reasons patients are found unsuitable for laser surgery include thin corneas that do not have sufficient tissue for safe treatment; irregular corneal shape consistent with keratoconus or other ectatic conditions detected on corneal topography; a prescription that is too high to be safely corrected by laser alone; significant pre-existing dry eye disease; and certain systemic conditions or medications that affect wound healing. Patients who are pregnant or breastfeeding should defer assessment until their prescription has stabilised after delivery, as hormonal changes can temporarily affect refractive measurements.
What if Laser Surgery Is Not Suitable?
If laser surgery is not suitable, two highly effective alternatives are available. A phakic intraocular lens (ICL) is implanted inside the eye without removing corneal tissue, making it an excellent option for patients with high myopia or thin corneas. Refractive lens exchange (RLE) replaces the natural lens with a premium artificial lens — the same procedure as cataract surgery — and is best suited to patients over 45 who also have presbyopia.
A finding that you are not suitable for laser surgery does not mean you are without options. Two highly effective alternatives are available. The first is a phakic intraocular lens — commonly known as an implantable collamer lens or ICL — in which a small corrective lens is implanted inside the eye in front of the natural lens. No corneal tissue is removed, making it an excellent option for patients with high myopia or thin corneas. The second is refractive lens exchange (RLE), in which the natural lens is replaced with a premium artificial lens — the same procedure as cataract surgery. RLE is best suited to patients over 45 who also have presbyopia and want to address the full range of their refractive error.
The Assessment Process at Northern Eye Consultants
Refractive surgery assessments at Northern Eye Consultants include corneal topography and tomography, corneal thickness measurement (pachymetry), dry eye evaluation, wavefront aberrometry, pupil size measurement, and a full dilated eye examination. Based on these findings, Dr MacIntyre will advise on which procedure — if any — is appropriate for your anatomy and lifestyle, and explain expected outcomes in detail. A referral from your GP or optometrist is required to attend for a consultation.
At Northern Eye Consultants, refractive surgery assessments are performed by Dr Ross MacIntyre, who holds subspecialty fellowship training in corneal and refractive surgery from the Wilmer Eye Institute at Johns Hopkins University. Your assessment will include detailed corneal topography and tomography, measurement of corneal thickness (pachymetry), dry eye evaluation, wavefront aberrometry, pupil size measurement, and a full dilated eye examination. Based on these findings, Dr MacIntyre will advise you on which procedure — if any — is appropriate for your individual anatomy and lifestyle, and explain the expected outcomes in detail. A referral from your GP or optometrist is required to attend for a consultation.
For detailed procedure guides and patient information from Dr MacIntyre, visit drmacintyre.com and corneaeyedoctor.com.