Correlating Lens Density, Axial Length, and Anterior Chamber Depth using Swept-Source OCT

Abstract

Purpose : This pilot study aims to determine the relationship between lens density, axial length, and anterior chamber depth using Swept-Source Optical Coherence Tomography (SS-OCT) from IOLMaster 700 (Zeiss). It has been previously noted that lens density measured by SS-OCT can correlate with subjective lens grading, and that lens density correlates with phacoemulsification energy and power. However it is unclear whether axial length or anterior chamber depth is an independent predictor of lens density. Establishing this relationship between lens density and axial length and/or anterior chamber depth could allow for more precise operative planning.

Methods : IOL Master 700 (Zeiss) biometry for 97 eyes of 55 patients between the ages of 20 and 80 years old were retrospectively reviewed. Pregnant, nursing, and patients with other anterior segment pathology were excluded. The SS-OCT B scans of the lens were exported to imageJ, where 15x15 pixel squares of a superior and inferior region of air anterior to the cornea and a superior and inferior region of the central nuclear lens were selected as regions of interest. The mean gray value of those squares were then calculated and the two squares within each region were averaged. The inverse of the mean gray value was then calculated (density), and the subsequent lens density was normalized by the respective air density. Axial length and anterior chamber depth were directly attained from the IOLMaster 700. Linear regressions were then performed using Excel (Microsoft).

Results : No correlation was noted between central nuclear lens density and axial length nor anterior chamber depth (R² = 0.0013 and R² = 0.0008, respectively). There was a positive correlation noted between anterior chamber depth and axial length (R² = 0.38).

Conclusions : As expected, eyes of longer axial length tend to have deeper anterior chambers. With regards to lens density, axial length and anterior chamber depth appear to have no relationship with lens density, and should be viewed as an independent metric. Density calculations of the lens from the IOLMaster 700 may be directly needed in order to better predict phacoemulsification demands.

This is a 2020 ARVO Annual Meeting abstract.

 

ImageJ analysis of the B-scan display exported from the IOLMaster 700 highlighting 15x15 pixel boxes in the air anterior to the cornea and the central nuclear lens.