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
After PRK, epithelial status guides bandage-lens removal and follow-up. Yet a 'one-week' visit may occur on different days. This registry included 37,982 eyes of 18,991 patients undergoing same-session bilateral PRK from 2013 through June 2024 in a refractive-surgery network. Examinations occurred on postoperative days 5–9. Generalized estimating equations accounted for fellow-eye correlation, while visit day and optical zone were modeled categorically.
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
The main finding concerns measurement timing rather than a biological threshold: an earlier visit more often captures ongoing normal healing. Day 7 appears to be a more stable default assessment point in this network. Strong fellow-eye concordance suggests patient-level influences but identifies no mechanism. Lens removal and repeat visits must still consider defect size, symptoms, infection, drug toxicity and local protocol.
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
This retrospective registry did not randomly assign visit day. Earlier examination may reflect organizational or clinical factors, causing confounding. One network and bilateral same-session PRK may not represent unilateral surgery, other lasers, mitomycin regimens or bandage lenses. Defect size and later closure time were absent from the abstract. Verify the healing definition, reasons for visit timing, missing and repeat visits, surgeon and calendar-year handling, lens protocol, infections, pain and clinical consequences.
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.