Novel Glaucoma Diagnostics

Objective:

The purpose of this research is to evaluate a new technology, optical coherence tomography (OCT), to image diseases of the eye and to compare the measurements obtained using OCT with those of other imaging and visual field devices. OCT may be useful for the early diagnosis and monitoring of a variety of eye diseases such as age-related macular degeneration (ARMD), glaucoma, diabetic retinopathy, macular edema, and other pathologies.

Specific Aims:

There are four sub-studies: cross-sectional, longitudinal, reproducibility, and an Alzheimer's Disease (AD) sub-study. The cross-sectional and longitudinal arms study the effectiveness of the OCT technology in terms of detecting and monitoring eye diseases. The reproducibility study is designed to test the measurement likeness of the OCT. The AD sub-study will use high resolution ocular imaging technologies to determine ocular biomarkers for sensitive detection of AD.

Background:

This is a continuation of an ongoing study from the New England Eye Center (NEEC), Tufts Medical Center, Boston, MA. This study started when our research group was located at NEEC and in collaboration with the Massachusetts Institute of Technology (MIT) where we conducted the first clinical studies with OCT. The first investigation using OCT was published in Science in 1991 and showed in vitro imaging of the human retina and atherosclerotic plaque. We developed an OCT prototype system for performing preliminary ophthalmic clinical studies and in 1993, began clinical OCT imaging studies.

The prototype ophthalmic OCT instrument acquired OCT images of the retina with an axial resolution of 10µm within an acquisition time of 2.5 sec. The OCT imaging system was integrated with a slit-lamp biomicroscope for in vivo tomography of the anterior and posterior eye. The beam is directed into the eye using computer controlled galvonometric scanners, which can scan arbitrary transverse patterns. The beam focus is coincident with the slit-lamp image plane to permit simultaneous scanning and visualization of the eye through the slit-lamp or via a CCD camera. For tomography of the anterior eye, the microscope is focused directly on the structure, while for retinal imaging, a lens relay images of the retina onto the slit-lamp image plane. A computer provides real-time display of the tomogram, image processing, and data management.

OCT technology was patented and subsequently transferred to industry (Zeiss Humphrey Systems, CA). Our prototype ophthalmic OCT system was developed into a clinical instrument and was introduced into the ophthalmic market in 1996. The commercial OCT technology has an axial resolution of 10 µm and can acquire a 100 transverse pixel retinal tomogram in 1 second. A third generation ophthalmic OCT imaging device, OCT3, was introduced three years ago. OCT imaging is now used as a standard diagnostic procedure as part of an ophthalmic examination for many retina and glaucoma patients at the University of Pittsburgh Medical Center (UPMC) Eye Center and New England Eye Center (NEEC). OCT imaging is in use in major research and clinical centers internationally. The OCT has been approved by the Food and Drug Administration for use in ophthalmology.

Significance:

OCT enables tissue pathology to be imaged in situ and in real time with a resolution approaching that of conventional histopathology but without the need for excising and processing specimens. OCT provides a quantitative method of directly measuring ocular structures with high precision and could provide an objective, early diagnosis for glaucoma, age related macular degeneration (ARMD), diabetic retinopathy, macular edema, and other pathologies. Extensive studies have been performed with OCT in cross-sectional as well as longitudinal setting. In this ongoing protocol, our objective is to continue these studies using the commercial ophthalmic OCT imaging instruments to develop methods for early detection and improve longitudinal assessment for the above mentioned ocular pathologies.