# Development of a Scheimpflug imaging equipped OCT system to measure gradient refractive index of the lens in the human eye in vivo

> **NIH NIH R21** · NEW ENGLAND COLLEGE OF OPTOMETRY · 2021 · $196,651

## Abstract

Project Summary/Abstract
 The crystalline lens of the human eye grows throughout life with continuous change in its size, shape
and internal structure. The lifetime growth of the lens generates a special structure inside the lens: the
gradient distribution. From the lens surface to the lens center, the gradient distribution is characterized in its
fiber cell concentration, water content and protein concentration at the cellular level. Meanwhile, a cellular
mechanism is also established inside the lens to maintain the gradient structure and health of the lens. At the
functional level, the gradient cellular structure produces a gradient refractive index (GRIN) of the lens. The lens
GRIN causes negative spherical aberration and improves optical quality of the eye by compensating positive
spherical aberration from the cornea in both relaxed and accommodated eyes. Better understanding of the
lens GRIN is important for eye care professionals in the areas of refractive and cataract surgeries to optimize
their surgery design and for vision scientists to explore the cellular mechanisms underlying the developments
of presbyopia and cataract. However, accessing the lens GRIN in the human eye in vivo has been a challenge
to vision researchers for more than a century.
 Recently, the Principal Investigator (PI) discovered a novel principle to approach this difficult task by
combining Scheimpflug imaging (SI) with anterior segment optical coherence tomography (AS-OCT). This
proposed project aims to develop a novel ray-tracing SI equipped AS-OCT system to measure the lens GRIN
of the human eye in vivo by applying breakthroughs the PI has recently achieved including: (1) discovery of the
principle of in vivo measurement of radial lens GRIN by using a combination of a ray-tracing SI and AS-OCT
imaging; (2) discovery of the ray-tracing SI method to identify the point at the posterior lens surface from where
the measured lights for both SI and AS-OCT systems were reflected. Advantages of the new system include:
(1) constructing a ray-tracing SI equipped AS-OCT system which provides a unique instrument to image the
anterior segment of the eye and to study the morphological and optical properties of the lens in vivo; (2) for the
first time, accurately measuring radial lens GRIN of the human eye in vivo without any assumption about the
optical property of the lens; (3) for the first time, accurately assessing radial lens thickness of the human eye in
vivo; (4) accurately deriving profiles of the posterior lens surface of the human eye in vivo; and (5) estimating
abnormalities of the refractive index in the aging eye or the eye with cataract development in vivo. Successful
accomplishment of the goals of this project will eventually allow us to better understand the functional role of
the lens GRIN and its underlying cellular mechanisms in normal and defective eyes and potentially to find
effective interventions to control presbyopia and cataract development. It will als...

## Key facts

- **NIH application ID:** 10249233
- **Project number:** 5R21EY030636-02
- **Recipient organization:** NEW ENGLAND COLLEGE OF OPTOMETRY
- **Principal Investigator:** Ji Chang He
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $196,651
- **Award type:** 5
- **Project period:** 2020-09-30 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10249233

## Citation

> US National Institutes of Health, RePORTER application 10249233, Development of a Scheimpflug imaging equipped OCT system to measure gradient refractive index of the lens in the human eye in vivo (5R21EY030636-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10249233. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*