From the Guidelines
LASIK surgery is generally contraindicated in people with thin corneas, as it can lead to insufficient residual stromal bed thickness and increase the risk of corneal ectasia, a serious complication that causes progressive corneal bulging and vision deterioration. According to the most recent study 1, patients with unstable refractions should be evaluated for evidence of corneal ectasia, and corneal topography and tomography should be reviewed for evidence of irregular astigmatism or abnormalities suggestive of keratoconus or other forms of corneal ectasia.
Some key points to consider when evaluating a patient for LASIK surgery include:
- Corneal thickness: Patients with corneal thickness below 500 microns are typically not good candidates for traditional LASIK, as this can leave insufficient residual stromal bed thickness (less than 250-300 microns) and increase the risk of corneal ectasia 1.
- Alternative procedures: For patients with thin corneas, alternative vision correction procedures may be more appropriate, such as PRK (Photorefractive Keratectomy), SMILE (Small Incision Lenticule Extraction), or implantable collamer lenses (ICLs) 1.
- Pre-operative evaluation: A comprehensive pre-operative evaluation including corneal topography and pachymetry (corneal thickness measurement) is essential to determine if a patient is a suitable candidate for LASIK or would benefit from an alternative procedure 1.
It's also important to note that corneal cross-linking (CXL) can reduce the risk of progressive ectasia in patients with keratoconus, and specialty contact lenses, including hybrid and scleral lenses, should be trialed for visual rehabilitation prior to keratoplasty 1. Ultimately, the decision to proceed with LASIK surgery should be made on a case-by-case basis, taking into account the individual patient's unique characteristics and needs, and prioritizing their morbidity, mortality, and quality of life outcomes.
From the Research
LASIK Surgery and Thin Corneas
- LASIK surgery is not absolutely contraindicated in people with thin corneas, but it requires careful consideration and evaluation of the individual's corneal thickness and other factors 2, 3.
- Studies have shown that refractive laser surgery, including LASIK, can be safe and effective in patients with thin corneas (less than 500 microns) 2.
- However, the American Academy of Ophthalmology and the Spanish Ophthalmology Society list extreme values of mean central keratometry and pachymetry as relative contraindications for laser corneal refractive surgery 4.
- Other studies have demonstrated the safety and efficacy of photorefractive keratectomy (PRK) combined with crosslinking in eyes with thinner pachymetry and tomographic abnormalities 5.
- In cases where corneal ectasia occurs after LASIK, combined topography-guided PRK and collagen cross-linking (the Athens Protocol) may be an effective treatment option 6.
Key Considerations
- Corneal thickness and pachymetry are important factors to consider when evaluating a patient for LASIK surgery 2, 3.
- The use of advanced imaging technologies, such as optical coherence tomography (OCT), can help assess corneal thickness and detect potential abnormalities 3.
- Patients with thin corneas or other relative contraindications may still be candidates for LASIK surgery, but require careful evaluation and consideration of the potential risks and benefits 4, 5.