---
title: What prescription is too high for laser eye surgery?
description: "There is no single cut-off that suits everyone, but a prescription is too high for laser eye surgery when treating it would leave the cornea structurally unsafe or vision unpredictably poor. ## Safety limits and corneal structure High corrections remove…"
url: "https://bluefinvision.com/knowledge-base/topics/suitability/what-prescription-is-too-high-for-laser-eye-surgery/"
updated: "2025-12-23"
category: Suitability
---

# What prescription is too high for laser eye surgery?

There is no single cut-off that suits everyone, but a prescription is too high for laser eye surgery when treating it would leave the cornea structurally unsafe or vision unpredictably poor.

## Safety limits and corneal structure

High corrections remove more tissue, so planning tools focus on how much cornea would remain and how strong it will be.

- Predicted residual stromal thickness below accepted safety thresholds increases ectasia risk
- High percentage tissue altered (PTA) values are linked to post-LASIK ectasia
- Very steep or thin corneas may already be biomechanically vulnerable
- High myopia combined with significant astigmatism often reaches the limit sooner
- Abnormal topography or tomography can make even modest prescriptions unsafe

## Alternatives when limits are exceeded

When the planned ablation would be unsafe, surgeons usually recommend different approaches rather than "pushing" the cornea.

- Surface laser (PRK) or SMILE with more conservative targets
- Phakic intraocular lenses such as ICLs for very high prescriptions
- Refractive lens exchange in older patients with early lens changes
- Continuing with contact lenses or glasses if surgery offers no safe benefit
- Shared decision-making to balance visual goals with long-term corneal health