[Quantitative changes in tear film after refractive surgery: comparative study between PRK and LASIK]

Area of Science:

• Ophthalmology
• Corneal Surgery
• Ocular Surface Disease

Background:

• Refractive surgery, including photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK), is a common procedure for vision correction.
• Understanding the impact of these procedures on the ocular surface, particularly tear film dynamics, is crucial for patient management.

Purpose of the Study:

• To quantitatively compare tear film changes in patients undergoing PRK versus LASIK over a one-year period.
• To assess the temporal recovery of tear film function after refractive surgery.

Main Methods:

• A prospective, longitudinal, comparative study involving 48 patients (PRK) and 36 patients (LASIK).
• Tear film was evaluated using the Schirmer test (right eye) and the red phenol thread test (left eye) before and one year after surgery.
• Measurements were taken at baseline and at intervals up to one year post-operation.

Main Results:

• Both PRK and LASIK induced temporary reductions in Schirmer and red phenol thread test measurements between the first and third postoperative months.
• Tear film measurements returned to baseline (presurgical) values by the one-year postoperative mark for both surgical groups.
• No significant complications related to tear film changes were observed in the study cohort.

Conclusions:

• Refractive surgery procedures like PRK and LASIK cause transient, within-normal-limits alterations in tear film measurements.
• Tear film function demonstrates a full recovery to presurgical levels within one year post-procedure.
• These findings suggest that PRK and LASIK are safe regarding long-term tear film stability in otherwise healthy patients.