Free papers detail | 11th Asia Pacific Tele Ophthalmology Society Symposium

Title
Intraocular Lens Power Calculation in Highly Myopic Eyes with Axial Length ≥28 mm: Impact of two Corneal Keratometries and Anterior Segment Parameters

Authors
Yiwei Wu, Lingyun Chi, Huiyi Jin

Presenting
Yiwei Wu

PURPOSE:
To compare the accuracy of 12 intraocular lens (IOL) formulas in eyes with axial length (AL) ≥ 28 mm, and to identify the anterior segment parameters affecting prediction error (PE).

METHODS:
415 eyes undergoing phacoemulsification with IOL implantation were included in this retrospective observational study. PEs were calculated for 5 conventional formulas (Haigis, Hoffer Q, Holladay 1, Holladay 2 and SRK/T) with optimization and 7 new-generation formulas (Barrett Universal II [BUII], Cooke K6, EVO 2.0, Hoffer QST, Kane, Ladas Super Formula [LSF] and Pearl-DGS). Predicted postoperative spherical equivalent (SE) was calculated using keratometry (K) and total keratometry (TK) measured by IOLMaster 700. Q values, posterior mean keratometry, corneal volume, anterior chamber volume and angle, and back-to-front corneal radius ratio were measured by Pentacam. Stepwise linear regression identified parameters associated with PE.

METHODS:

415 eyes undergoing phacoemulsification with IOL implantation were included in this retrospective observational study. PEs were calculated for 5 conventional formulas (Haigis, Hoffer Q, Holladay 1, Holladay 2 and SRK/T) with optimization and 7 new-generation formulas (Barrett Universal II [BUII], Cooke K6, EVO 2.0, Hoffer QST, Kane, Ladas Super Formula [LSF] and Pearl-DGS). Predicted postoperative spherical equivalent (SE) was calculated using keratometry (K) and total keratometry (TK) measured by IOLMaster 700. Q values, posterior mean keratometry, corneal volume, anterior chamber volume and angle, and back-to-front corneal radius ratio were measured by Pentacam. Stepwise linear regression identified parameters associated with PE.

RESULTS:
Using the K method, BUII, EVO 2.0, Hoffer QST, Holladay 2, Kane and Pearl-DGS showed lowest median absolute PE and highest formula performance index. BUII, Cooke K6, EVO 2.0, Holladay 2 and Pearl-DGS performed stably across axial groups (p > 0.05). K achieved lower AE than TK for all formulas except Hoffer QST, Holladay 2 and Pearl-DGS(all p > 0.05), with Kane performing better using TK (p = 0.024). Lens thickness (LT) independently affected PE for Holladay 2 and all new-generation formulas, with greater LT associated with myopic shifts (p < 0.05).

RESULTS:

Using the K method, BUII, EVO 2.0, Hoffer QST, Holladay 2, Kane and Pearl-DGS showed lowest median absolute PE and highest formula performance index. BUII, Cooke K6, EVO 2.0, Holladay 2 and Pearl-DGS performed stably across axial groups (p > 0.05). K achieved lower AE than TK for all formulas except Hoffer QST, Holladay 2 and Pearl-DGS(all p > 0.05), with Kane performing better using TK (p = 0.024). Lens thickness (LT) independently affected PE for Holladay 2 and all new-generation formulas, with greater LT associated with myopic shifts (p < 0.05).

CONCLUSIONS:
EVO 2.0 provided the most accurate predictions with K method. Except for Kane, K outperformed TK. LT independently influences PE and should be considered in future IOL calculations.