Conditional Process Analysis For Flanged Intrascleral Haptic Fixation With Double-Needle Technique
Published 2023 - 41st Congress of the ESCRS
Reference: PO0418 | Type: Free paper | DOI: 10.82333/4rmz-a996
Authors: Ji Hyun Yoon* 1 , Woong-Joo Whang 1 , Young-Sik Yoo 2 , Kyung-Min Koh 3
1Ophthalmology ,The Catholic University of Korea, Yeouido St. Mary's Hospital,Seoul ,Korea, Republic Of, 2Ophthalmology ,The Catholic University of Korea, Uijeongbu St. Mary's Hospital,Uijeongbu,Korea, Republic Of, 3Ophthalmology ,Konyang University College of Medicine, Kim’s Eye Hospital,Seoul ,Korea, Republic Of
Purpose
To develop an intraocular lens (IOL) calculation formula specialized for Yamane intrascleral haptic fixation by incorporating conditional process analysis, and to compare its predictive accuracy to modern IOL calculation formulas without information on the anterior chamber depth.
Setting
This retrospective cross-sectional study included 62 eyes of 62 Korean patients who underwent intrascleral haptic fixation surgery at Yeouido St. Mary’s Hospital between December 2018 and March 2021.
Methods
The medical records of 62 eyes of 62 patients that received IOL scleral fixation using Yamane technique were reviewed. Partial coherence interferometry was used to obtain the axial length, keratometry and corneal radius. 3-D Scheimpflug corneal tomography was used to obtain the horizontal corneal diameter. The manifest refraction was measured preoperatively and postoperatively at 6 months after surgery. Correlation analysis of the biometric values was done, and a new formula for predicting the effective lens position was developed based on the theory of conditional process analysis. The prediction error calculated by the new formula was compared to that of the Barrett Universal II, EVO 2.0, and third-generation formulas.
Results
The preoperative axial length, keratometry and the corneal diameter were significantly correlated to one another. Based on the theory of conditional process analysis, we were able to obtain a new formula with these variables as mediators. As a result of the prediction error analysis, the newly developed formula showed the lowest standard deviation and median absolute error in eyes that received intrascleral haptic fixation surgery. The third-generation formulas, especially the Hoffer Q formula, demonstrated comparable results. The third-generation formulas with Wang-Koch axial length adjustment yielded less accurate results.
Conclusions
The refractive outcomes calculated with modern IOL formulas are influenced by the preoperative corneal diameter. The new formula developed from conditional process analysis may be an alternative or transitional method in IOL power calculation with intrascleral fixation.