Researchers in Ontario examined and compared the postoperative rates of dry eye after four refractive surgeries: laser-assisted in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), femtosecond lamellar extraction (FLEx) and small-incision lenticule extraction (SMILE). The study not only found a greater reduction in tear break-up time (TBUT) but also a maximum reduction in tear production with LASIK cases compared with the other modalities.

The meta-analysis consisted of data from 14 studies. Findings indicated significant TBUT reduction in LASIK and FLEx and a non-significant reduction in PRK and SMILE. However, results also found a significant reduction in tear production in LASIK, suggesting an increased incidence of dry eye. The other three surgeries displayed a non-significant reduction in tear production.

The researchers suggest that damage done to the corneal nerves may explain the increased rates of dry eye associated with LASIK.

The analysis had several limitations, however. The authors suspect that minor variability among the surgeons of each procedure could have affected the dry eye incidence. Additionally, the researchers note that there was only one study evaluating FLEx and two studies evaluating PRK and that SMILE is a relatively new refractive surgery procedure compared with the other techniques. They believe more quality randomized controlled trials for all procedures are required to make strong conclusions.

The study notes that improved understanding of the prevalence of dry eye after refractive surgery can help physicians better predict and manage patient outcomes, potentially alleviating the negative quality-of-life and socioeconomic impacts of post-refractive surgery dry eye.

Sambhi RDS, Sambhi GDS, Mather R, Malvankar-Mehta MS. Dry eye after refractive surgery: a meta-analysis. Can J Ophthalmol. August 20, 2019. [Epub ahead of print].