Clinical context
Visual acuity alone is insufficient when judging corneal disease or surgery. Topography and tomography, surface regularity, biomechanics, endothelial cell density, quality of vision and stability all matter. After refractive procedures, epithelial healing, dry eye, haze, ectasia and the need for enhancement should be assessed separately.
What was studied
This multicenter retrospective study included one eye from each of 919 patients treated in Iraq between January 2023 and December 2025: 388 underwent SMILE, 344 FS-LASIK and 187 Trans-PRK. Outcomes were assessed at six months, one year and 18 months. Primary measures were spherical equivalent and the proportion within ±0.50 D of plano. Secondary measures included visual acuity, higher-order aberrations at six months, Ocular Surface Disease Index scores, loss of corrected-vision lines and enhancement procedures.
How the evidence was produced
A cohort study describes how outcomes are associated with an exposure or treatment in an observed clinical population. This design is useful for routine practice, uncommon events and longer follow-up, but it remains vulnerable to confounding by indication, baseline risk differences and missing data. An association should not automatically be interpreted as a causal effect.
How to interpret the result
In this cohort, SMILE was associated with refraction closest to emmetropia and greatest stability, FS-LASIK was intermediate, and residual myopia increased more after Trans-PRK. At six months, induced higher-order aberrations were lowest after SMILE and highest after Trans-PRK; OSDI followed the same order. These are associations. Procedure selection may have depended on corneal thickness and shape, myopia, surface status, equipment, nomograms and surgeon preference.
The result should be understood as an estimate for the population studied, not a promise of an individual outcome. Statistical and clinical significance, absolute and relative effects, and prespecified and exploratory analyses should be distinguished. When several endpoints or subgroups are reported, the prespecified primary endpoint for which the study was designed usually provides the most reliable inference.
Clinical applicability
The study may refine technique selection and informed discussion, but its conclusions depend on baseline corneal shape, stromal thickness, equipment, nomogram and surgeon experience. Applicability requires comparison of these factors and attention to variability, uncommon complications and follow-up duration rather than mean values alone.
Limitations
Treatment assignment was not randomized, so residual confounding can remain after multivariable regression. The study was limited to one country and three clinical pathways; results depend on the platforms and nomograms used. The smaller Trans-PRK group and differing indications complicate direct ranking. The full paper should be checked for baseline myopia, selection rules, visit completeness, handling of missing data, definitions of CDVA loss and enhancement, absolute OSDI and aberration values, and ectasia surveillance.
Beyond the limitations acknowledged by the authors, confidence is affected by sample size, follow-up duration, missing data, choice of comparator and relevance of the outcomes to routine care. Uncommon complications may remain undetected even in a well-conducted study. External validity is reduced when participants, equipment or investigator expertise differ substantially from everyday settings.
What to verify in the source
In the full paper, verify the protocol, eligibility criteria, baseline group characteristics, primary endpoint definition, confidence intervals, adverse events and losses to follow-up. Funding, conflicts of interest, trial registration and consistency between the published analysis and the original plan deserve separate attention. The DOI or source link below provides access to the primary publication for this check.