Intraocular Lens Power Calculation After Laser Thermal Keratoplasty: A Systematic Review of Clinical Outcomes and Predictive Accuracy

Purpose: To evaluate the accuracy of different intraocular lens (IOL) power calculation formulas and methodologies in patients with a history of Laser Thermal Keratoplasty (LTK) undergoing cataract surgery.

Methods: Systematic literature review of global evidence (1998–2025). A systematic search was conducted in PubMed, Scopus, and the Cochrane Library. Studies reporting refractive outcomes, mean prediction error (MPE), and the efficacy of various formulas (Clinical History Method, Haigis-L, Shammas-PL, and Barrett True-K) in post-LTK eyes were included. Of the 874 articles, 99 was studies screening, 35 relevant articles were synthesized to identify the most reliable predictive strategies.

Results: Historically, the Clinical History Method was the gold standard; however, its current applicability is limited by the lack of pre-refractive records. Standard third-generation formulas (SRK/T, Holladay 1) consistently resulted in a hyperopic surprise, with an MPE ranging from +1.00 to +1.50 D. Modern "No-History" formulas, particularly Barrett True-K and Shammas-PL, along with Total Corneal Refractive Power (TCRP) measurements from Scheimpflug imaging, showed significantly higher accuracy. Due to the regression nature of LTK, corneal stability remains a critical factor in long-term refractive predictability.

Conclusions: To avoid hyperopic surprises in post-LTK patients, surgeons should utilize modern formulas that account for the altered anterior-posterior corneal ratio. Targeting a slightly myopic refractive goal (−0.50 to −0.75 D) and using the ASCRS online calculator are recommended as the safest clinical practices.