Ectasia after laser in situ keratomileusis

Area of Science:

• Ophthalmology
• Corneal Surgery
• Biomechanical Engineering

Background:

• Laser in situ keratomileusis (LASIK) is a common refractive surgery.
• Corneal ectasia is a rare but serious complication following LASIK.
• Existing literature lacks clear guidelines on pre- and post-operative corneal thickness thresholds for ectasia risk.

Purpose of the Study:

• To analyze cases of post-LASIK ectasia to identify risk factors.
• To investigate the relationship between corneal thickness and ectasia development.
• To determine if specific corneal thickness measurements can predict ectasia risk.

Main Methods:

• Review and analysis of 85 cases of post-LASIK ectasia.
• Exclusion of cases with pre-existing keratoconus or forme fruste keratoconus.
• Evaluation of available data on preoperative and postoperative corneal thickness, flap thickness, and surgical parameters.

Main Results:

• Many case reports lacked essential information for analysis.
• No specific residual or preoperative corneal thickness was identified as a definitive risk factor.
• A mechanically unstable postablation stromal thickness, likely individual to each eye, is the most plausible cause for ectasia in eyes without prior pathology.

Conclusions:

• Current literature cannot define a specific corneal thickness range that guarantees protection against post-LASIK ectasia.
• Further data including preoperative/postoperative thickness, flap dimensions, and laser parameters are needed to establish risk thresholds.
• Undetermined factors may also contribute to the development of post-LASIK ectasia.