Abstract
PurposeIn the event that any ocular parameter involved in the calculation of intraocular lens power could not be properly measured in one eye, it is important to know whether clinically relevant differences between both eyes can be expected. The aim of this work is to evaluate the symmetry of interocular biometric parameters.MethodsThis was a prospective, cross-sectional study involving 4090 subjects. Patients underwent consecutive swept-source optical biometry performed with an IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany). The biometric parameters that were evaluated were: axial length (AL), mean anterior curvature (Rm), anterior chamber depth (ACD), crystalline lens thickness (LT), central corneal thickness (CCT) and white-to-white (WTW). The Chang–Waring chord distance (CWC-D) and the Chang–Waring chord angle (CWC-A) were also evaluated.ResultsThere is an excellent correlation between both eyes for almost all the biometric parameters under study, with the exception of the CWC. Agreement for AL was better for eyes shorter than 24 mm. The linearity of the OD-vs-OS relationship can be correctly assumed for all parameters (Cusum test: p > 0.05 in all cases).ConclusionThere are no clinically significant interocular differences for the biometric parameters under study, although for all of them, except the LT, statistically significant differences did arise. In the case of AL, moderate differences can be expected in eyes larger than 24 mm.
Highlights
Numerous ocular symmetry assessment studies have been carried out, concluding that two eyes follow similar patterns regarding several ocular parameters [1,2,3,4,5]
There is an excellent correlation between both eyes for almost all the biometric parameters under study, with the exception of the Chang–Waring chord (CWC)
The results of the present study confirm that our 4090 patient population show excellent ocular symmetry in terms of Rm, anterior chamber depth (ACD), lens thickness (LT), central corneal thickness (CCT) and W–W, as well as moderate ocular symmetry for Chang–Waring chord distance (CWC-D), as assessed by means of the swept-source optical biometry system IOLMaster 700 (Carl Zeiss Meditec AG, Jena, Germany)
Summary
Numerous ocular symmetry assessment studies have been carried out, concluding that two eyes follow similar patterns regarding several ocular parameters [1,2,3,4,5]. We can say that structural symmetry is inherent to both eyes [2]. This ocular symmetry can aid the diagnosis of pathologies, but it could help to improve postoperative outcomes, among other scenarios. In LASIK refractive surgery or cataract surgery, several studies have concluded that postoperative refraction in the first eye can help predict refraction outcomes in the second eye [5,6,7,8]. The latest-generation formulas have included an increasing number of parameters— such as white-to-white (W–W) or corneal thickness— with the aim of fine-tuning postoperative outcomes, and the different eye biometers have evolved to newer swept-source optical coherence tomography (OCT) technology [9]
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