Predicting Postoperative Astigmatism Using Scheimpflug Keratometry (Pentacam) and Automated Keratometry (IOLMaster)

Abstract

Purpose: To compare keratometry measurements obtained using an automated keratometer (AK, IOLMaster) and a Scheimpflug keratometer (Pentacam) in predicting residual astigmatism after cataract surgery.

Methods: Preoperative corneal astigmatism was calculated using preoperative refraction, an AK and a Scheimpflug keratometer (anterior corneal power [ACP] and true net power [TNP]) in 155 eyes of 107 Asian subjects. Phacoemulsification cataract removal and nontoric intraocular lens insertion (Akreos^®MI-60^™, Bausch & Lomb, Rochester, NY, USA) were performed through a 2.8 mm temporal clear corneal incision. Six months later, postoperative astigmatism (postA) was calculated using manifest refraction. Error angle (EA) and error magnitude (EM) of above keratometries (AK, ACP, and TNP) in prediction of postA was calculated. The correlation between preoperative astigmatism and postA was analyzed using power vectors (J₀ and J₄₅).

Results: AK resulted in the lowest EM and ACP resulted in the lowest EA. Preoperative astigmatism (preA) measured using AK, ACP, and TNP showed significant correlation with postA in both J₀ and J₄₅ components. (AK: rJ₀ = 0.554, rJ₄₅ = 0.559, ACP: rJ₀ = 0.346, rJ₄₅ = 0.281, TNP: rJ₀ = 0.409, rJ₄₅ = 0.231). Preoperative refractive astigmatism showed no significant correlation in any components.

Conclusions: PreA determined using AK showed superior performance in prediction of postA than ACP and TNP.

KEYWORDS::

• Astigmatism
• Cornea
• Keratometry
• Cataract surgery

Declaration of interest: This work was supported in part by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF 2010-0002532) (CYP); and an unrestricted core grant from Research to Prevent Blindness (RSC). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.