Intraocular pressure after excimer laser myopic refractive surgery

Area of Science:

• Ophthalmology
• Corneal Surgery
• Refractive Surgery

Background:

• Intraocular pressure (IOP) measurement is critical for diagnosing and managing glaucoma.
• Refractive surgeries like photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) alter corneal properties.
• The impact of these corneal changes on IOP measurements requires careful consideration.

Purpose of the Study:

• To investigate systematic changes in intraocular pressure (IOP) after PRK and LASIK.
• To compare IOP measurements between PRK and LASIK.
• To determine the relationship between refractive correction and IOP change.

Main Methods:

• Measured IOP using Goldmann applanation and non-contact tonometry in 54 patients post-PRK and 43 patients post-LASIK.
• Included patients with initial refractive errors ranging from -2.5 to -10.0 D.
• Utilized fellow unoperated eyes as controls and employed paired Student's t-test and ANOVA for analysis.

Main Results:

• A statistically significant decrease in IOP was observed in eyes treated with PRK and LASIK (p < 0.01).
• No significant IOP changes were noted in control eyes (p > 0.01).
• The magnitude of IOP reduction did not significantly correlate with the degree of refractive correction, though a trend was observed.

Conclusions:

• PRK and LASIK lead to a significant reduction in measured IOP, likely due to changes in corneal thickness, curvature, and tissue properties.
• The observed IOP reduction is approximately 0.5 mmHg per diopter of myopic correction.
• This IOP reduction must be considered when evaluating potential abnormalities in patients who have undergone refractive surgery.