Tomography-Guided Iol Calculation After Intracorneal Ring Segments In Advanced Keratoconus: Achieving Sub-0.25 D Refractive Error
Published 2026 - 44th Congress of the ESCRS
Reference: POCAT593 | Type: Poster | DOI: 10.82333/qytd-4t84
Authors: Mrs Gabriela Egea Alvaro Egea Alvaro do Nascimento* 1 , Mrs Anary Isis Rossi Martins Moreira 1 , Mr Luciano Rabello Netto Cirillo 1 , Mr Marcelo Mastromonico Lui 1
1Oftalmologia,Hospital de Olhos - C.R.O,Guarulhos,Brazil
Purpose
To report the refractive outcome of phacoemulsification in a patient with advanced keratoconus previously treated with intracorneal ring segments (ICRS), emphasizing quarterly tomographic stability prior to cataract surgery and the accuracy of intraocular lens (IOL) power calculation with comparative formula analysis.
Setting
Interventional case report conducted at a specialized cornea and cataract center, with serial Scheimpflug tomography (Pentacam) performed every three months prior to cataract surgery.
Methods
Prospective interventional case report conducted at a specialized cornea and cataract center. A 58-year-old male with advanced keratoconus in the left eye (Kmax 55.7 D; pachymetry 423 µm; CDVA 20/40) underwent implantation of two intracorneal ring segments (160°/200 µm). Scheimpflug tomography was performed every three months for 11 months, confirming keratometric stability (<0.50 D variation). After stabilization, standard phacoemulsification with in-the-bag implantation of a +8.5 D monofocal IOL was performed. IOL power was calculated using tomographic keratometry (Km 47.1 D) and axial length (25.94 mm), with prediction analysis using Barrett, Haigis, Holladay 1 and SRK/T formulas.
Results
ICRS implantation reduced spherical equivalent from −12.12 D to −4.75 D (61%) and refractive astigmatism from 4.25 D to 2.50 D. Serial tomography demonstrated corneal stability prior to phacoemulsification. The emmetropic target IOL power was +8.27 D (Barrett), +8.31 D (Haigis), +8.25 D (Holladay 1), and +9.02 D (SRK/T). After implantation of a +8.5 D IOL, postoperative refraction was +0.00 −0.50 ×15 (spherical equivalent −0.25 D), with CDVA 20/40. Barrett and Holladay formulas showed the highest agreement with the achieved outcome (≈0.10 D deviation).
Conclusions
This case demonstrates that advanced keratoconus is not a barrier to refractive precision in cataract surgery when corneal regularization and documented tomographic stability are achieved prior to biometry. Tomography-guided IOL calculation enabled sub-0.25 D accuracy, with modern formulas showing high predictive performance. A structured sequential approach (ICRS, stabilization, then phacoemulsification) may redefine refractive expectations in ectatic corneas.