Investigation of the effect of lens refractive index on the measurement of axial length of the human eye for accommodation and cataract surgery

New England College Of Optometry, Boston MA

Investigators

Abstract

SUMMARY/ABSTRACT Measurements of the axial length (AL) of the eye have wide applications in eye research and the clinical practices of optometry and ophthalmology. The accuracy of AL measurements directly affects research studies results and the quality of vision-related clinical treatments. Current methods to measure AL make assumptions of the refractive index of the crystalline lens (NLens) that may induce significant measurement errors. It is therefore highly important to measure the NLens of individual eyes. Measurement of the NLens of the human eye in vivo has for long been a challenge, and as of today there are no practical methods to measure the NLens. One of the PIs (Dr. He) has recently developed a method to measure the NLens in vivo using a ray-traceable Scheimpflug imaging (RTSI) system combined with an anterior segment OCT. Another PI (Dr. Wang) has used a whole-eye OCT (WE-OCT) to measure AL before. The primary goal of the proposed project is to combine the RTSI with a whole-eye OCT (WE-OCT) to simultaneously measure the NLens and AL in human eyes in vivo. With this novel, non-contact system, the measured NLens will be used to derive accurate AL measurements for individual eyes. The system will be used to measure the change in the NLens and AL for a group of young adults during accommodation. The results of this study may provide highly significant insights in the possible role of accommodation in myopia development, as well as a method that can be used in clinic when measuring AL for myopia control purposes. This novel system will also be used to measure the NLens and AL for a group of patients with cataracts, both pre- and post-operatively. The results of this second study may be used to analyze the impact of measurement error of the AL due to using an average NLens on the visual quality of these patients after IOL implantation. Successful completion of the studies proposed here will allow us to: (1) better understand the mechanism underlying myopia development, (2) obtain more accurate measurements of AL during clinical care of patients with myopia, and (3) understand the impact of NLens measurement on AL measurement prior to cataract surgery. The proposed technique is highly impactful and will pose a substantial breakthrough in the methodology for accurately measuring AL of the human eye in research and clinical practice.