Interocular symmetry analysis of bilateral eyes

Abstract

The purpose of this study was to evaluate the interocular symmetry of several biometric parameters between both eyes. The symmetry between the right and left eye of 397 subjects in 14 biometric parameters, spherical equivalent of refractive error (SE), Jackson crossed cylinder power of refractive error astigmatism with axes at 90° and 180° (RJ₀) and at 45° and 135° (RJ₄₅), best-corrected visual acuity (BCVA), average corneal curvature (CC), Jackson crossed cylinder power of corneal astigmatism (CJ₀ and CJ₄₅), corneal asphericity coefficient (Q), intraocular pressure (IOP), central corneal thickness (CCT), axial length (AL), anterior chamber depth (ACD), lens thickness (LT) and vitreous chamber depth (VCD), was assessed by comparative data analysis. Aside from RJ₀ (p = 0.00), RJ₄₅ (p = 0.02) and Q (p = 0.00), the overall interocular differences of other biometric parameters between fellow eyes were not significant (p > 0.05). The interocular correlation and Bland-Altman plots showed a good agreement between fellow eyes in 14 biometric parameters. Correlations between interocular differences in SE and that in RJ₀ (p = 0.03), CC (p = 0.00), AL (p = 0.00) and VCD (p = 0.00) were statistically significant. There were similar strong linear relationships between refractive error astigmatism vectors and corneal astigmatism vectors in bilateral eyes. There were negative correlations of RJ₄₅ and CJ₄₅ between bilateral eyes. A potentially clinically important interocular symmetry in SE, BCVA, CC, CJ_0, CJ_45, IOP, CCT, AL, ACD, LT and VCD is found in this research, while the differences of RJ₀, RJ₄₅ and Q between left and right eyes seem a bit large. The negative interocular relationships of RJ₄₅ and CJ₄₅ demonstrate moderate mirror symmetry exists among fellow eyes. High interocular symmetry in bilateral eyes may be helpful in intraocular lens power calculation, intraocular pressure evaluation, post-operative visual acuity and refraction prediction at the time the fellow eye is undergoing refractive surgery.

• Interocular difference
• mirror symmetry
• ocular biometric parameters

Acknowledgements

The authors indicate no financial conflict of interest. The authors thank Professor Ahmed Elsheikh from the School of Engineering, University of Liverpool, for expert technical assistance.