Analysis of keratometric measurements in accordance with axial length in an aged population

Abstract

To investigate keratometric measurements according to axial length in an aged population. Patients requiring cataract surgery with keratometric measurements from four different ophthalmic devices (autorefractor/keratometer, Scheimpflug imaging, corneal topography/ray-tracing aberrometry, and partial coherence interferometry) between January 2016 and March 2021 were reviewed retrospectively. Cases for which four ophthalmic devices were deployed in the same order a day were included in this investigation. The corneal curvature of the flattest and steepest meridian, mean corneal curvature, corneal astigmatism, steepest axis location, and axial length were evaluated. In total, 250 eyes (137 patients) were included in the analysis. A negative correlation was found between mean corneal curvature and axial length, with correlation coefficients of 0.587, 0.592, 0.588, 0.591, 0.588, and 0.562 for autorefractor/keratometer, Scheimpflug imaging, corneal topography/ray-tracing aberrometry, partial coherence interferometry, total corneal refractive power of Scheimpflug imaging, and simulated keratometry of corneal topography/ray-tracing aberrometry measurements, respectively. No statistically significant differences were found for corneal astigmatism according to axial length. In axial length group of less than 26.0 mm, negative correlation was found between axial length and mean frontal corneal curvature while no correlation was found between axial length and corneal astigmatism. All four ophthalmic devices showed good inter-device reliability for mean corneal curvature but not corneal astigmatism.

Combined Femtosecond Laser-Assisted Keratotomy and Cataract Surgery for Enhancing Refractive Outcomes. An Indonesian Case Study

“…An emmetropic state can be achieved through a steep cornea coupled with a relatively short axial length or a flat cornea combined with a relatively long axial length, indicating the presence of coordinated eye growth and an active emmetropization process. 20 These findings suggest a correlation between eye growth and an active emmetropization process. No significant differences were found in axial length between groups, which reduced the variability of refractive power and the impact on astigmatism calculation.…”

“…Astigmatism corrections aimed to be less than 0.5D have been mentioned to give satisfactory visual acuity. 20,21 Based on our data, patients who achieved the intended postoperative astigmatism target experienced various axis shifts in the right or left eye. The same pattern was also found in postoperative astigmatism that did not achieve the intended target.…”

Associations between corneal curvature and other anterior segment biometrics in young myopic adults

“…Corneal refractive power can be measured as corneal curvature (CC) which is commonly shown as simulated keratometry (SimK). In general and aged populations, it was shown that corneal refractive power was correlated to axial length (AL) 10 , 11 and some of the anterior segment biometrics, such as central corneal thickness (CCT) and anterior chamber depth (ACD) 10 .…”

Comparison of two swept-source optical coherence tomography devices, a Scheimpflug camera system and a ray-tracing aberrometer in the measurement of corneal power in patients with cataract

“…As different devices measure keratometry and the PK, TK and TNP values differently, to our knowledge, there is no standard technique for measuring keratometry. Since corneal curvature influences the degree of refraction and high corneal astigmatism may cause a range of visual problems, evaluations of both corneal curvature and corneal astigmatism are essential for cataract surgery [ 8 ]. In clinical practice, surgeons must understand whether these devices can be used interchangeably when measuring corneal parameters.…”