Laser corrects myopia by removing corneal tissue. The higher the prescription, the deeper the ablation required.
High myopia has been repeatedly associated with increased risk of postoperative corneal biomechanical compromise. ¹
Studies examining ectasia cases demonstrate that higher pre-operative refractive error and greater tissue removal correlate with instability. ²
The issue is not just correction magnitude, it is how much structural cornea remains afterwards.
If correcting your prescription requires excessive tissue removal, residual stromal bed thickness may fall below safe thresholds. Percent tissue altered (PTA) becomes critical. ³
Warning scenarios include:
- Myopia beyond standard laser ranges
- Combined high astigmatism
- Thin baseline corneal thickness
- Borderline tomographic indices
When structural safety margins narrow, we prioritise corneal endurance over refractive ambition.
High prescriptions do not always mean laser is impossible, but they require strict structural validation.
When limits are exceeded, the safest answer is restraint.
References
- Randleman JB, et al. Risk assessment for ectasia after corneal refractive surgery. Ophthalmology. 2008;115(1):37-50.
- Schallhorn SC, et al. Ectasia after refractive surgery. Int Ophthalmol Clin. 2003;43(3):89-100.
- Santhiago MR, et al. Percent tissue altered and ectasia risk. Am J Ophthalmol. 2014;158(1):87-95.
Related Topics
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- Why Thin Corneas Can Make Laser Eye Surgery Unsafe
- Percent Tissue Altered (PTA): The Biomechanical Threshold That Can Rule Out LASIK
- Why Normal Topography Isn’t Always Enough to Clear You for Laser Eye Surgery
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