Well.
‘Tis the season for LASIK + dry eye studies to be published, it seems.
The very interesting thing about “meta-analyses” (that’ the type of study this one is) is always how few studies make the cut. So few are good enough and included the right data to be able to add them together and crunch the numbers.
When you think about it, after 25 years of LASIK, which is by far the most popular elective eye surgery ever and which I think it’s fair to say permanently altered the landscape of ophthalmology, the fact that there are ONLY FOURTEEN studies with post LASIK dry eye data that made the cut for this meta-analysis - well, that’s staggering. I think the Journal of Refractive Surgery alone published more studies on LASIK every month than almost anything else for an awful lot of years, let alone what’s been published in all the other ophthalmology journals.
Only fourteen.
However, they were pretty clear about the results from those fourteen (see highlight below).
Dry eye after refractive surgery: A meta-analysis. Sambhi RS et al, Can J Ophthalmol. 2019 Aug 20.
OBJECTIVE:
To examine and compare the rates of dry eye after various refractive surgeries, including laser-assisted in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), femtosecond lamellar extraction (FLEx), and small incision lenticule extraction (SMILE).
STUDY DESIGN:
Systematic review and meta-analysis.
METHODS:
This systematic review and meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines. Databases searched included MEDLINE (Ovid), Embase, Cochrane Library, Cumulative Index of Nursing and Allied Health Literature, Web of Science, ProQuest Dissertations and Theses, and ClinicalTrials.gov. Meeting abstracts from European Society of Cataract and Refractive Surgeons, American Academy of Ophthalmology, Association for Research in Vision and Ophthalmology, and Canadian Ophthalmological Society were also examined. Articles underwent 3 stages of screening before data extraction and meta-analysis.
RESULTS:
In total, 3232 studies were found; 261 remained after title screening, 92 remained after abstract screening, and 14 studies progressed to data extraction. Meta-analysis indicated a significant reduction in tear break-up time (TBUT) with LASIK (standardized mean difference [SMD] = -0.3; confidence interval [CI]: -0.53 to -0.08) and FLEx (SMD = -1.09; CI: -1.44 to -0.74), and a nonsignificant reduction in TBUT with SMILE (SMD = -0.34; CI: -0.95 to 0.27) and PRK (SMD = -0.11; CI: -0.29 to 0.08). Meta-analysis also indicated a significant reduction in tear production with LASIK (SMD = -0.23; CI: -0.46 to -0.01), and a nonsignificant reduction in tear production with SMILE (SMD = 0.04; CI: -0.28 to 0.36), FLEX (SMD = -0.05; CI: -0.37 to 0.28), and PRK (SMD = -0.07; CI: -0.32 to 0.19).
CONCLUSIONS:
Overall, a significant reduction in postoperative tear production as well as TBUT time was seen with LASIK, and a nonsignificant reduction in postoperative tear production and TBUT was seen with SMILE, FLEx, and PRK. Ultimately, more high-quality randomized controlled trials are required to make concrete conclusions about dry eye parameters after refractive surgery.