Imaging System Enables Early Detection of Diabetic Retinopathy

People whose bodies cannot produce effective or sufficient insulin are said to have diabetes. This chronic disease has several serious long-term effects that are well documented: kidney failure, heart disease, foot disease that may require amputation, neuropathy (sensory loss), and blindness. Vision loss caused by diabetes is known as diabetic retinopathy. Retinopathy is define as non-inflammatory disorders in the retina. In diabetics, this condition manifests itself in the form of lesions, tears, or scratches on the retina. In the last few years, Montreal ophthalmologist Dr. Michael Flanders has noticed an increase in the number of patients with this condition. “There are more patients than before who are coming through my office and hospital clinics who have diabetic retinopathy,” he said.

The RetinaLyze® System analyzes fundus images for diabetic retinopathy, a common cause of blindness.

This is an observation of one doctor, in one city, in one country, but according to the World Health Organization, an estimated 300 million people will have diabetes by the year 2025. This disease has the potential to reach epidemic proportions, with far-reaching social consequences. Diabetic retinopathy is a serious complication, and the most common cause of blindness in people of working age in the Western world.

The good news is that early detection can prevent blindness in many patients. More often than not, surgery or laser treatments can correct the retinal damage; however, patients with minor retinopathy do not always notice a change in their vision. This is why early screening is important. “Patients with diabetes should be checked at least once a year. However, if they have a significant degree of diabetic retinopathy, they should be assessed at more frequent intervals, for example every six months or less,” recommended Dr. Flanders.

Such examinations are highly dependent on ophthalmic photography, an extremely specialized form of medical imaging dedicated to the study and treatment of eye disorders. All parts of the eye, the cornea, iris, optic nerve, and retina, are photographed using a sophisticated piece of equipment known as a fundus camera.

About four years ago, a group of researchers at Danish companies RETINALYZE and Visiopharm recognized the need for medical diagnostic equipment based on image analysis. According to Johan Doré, CSO of Visiopharm, “With our background in image analysis and experience in the development of devices based on image avnalysis, it was obvious there was a demand that needed to be satisfied.” The result is the RetinaLyze® System, a unique method that analyzes fundus images for diabetic retinopathy. RetinaLyze “is now installed in several hospitals and is an important tool in the screening of diabetic patients for retinopathy,” added Doré. Currently in use across the United Kingdom, Denmark, and Germany, the RetinaLyze System is a complete fundus image analysis and administration system; the Wokingham Hospital in the U.K. screens more than 19,000 patients annually. With its unique lesion detection functionality, RetinaLyze has many advantages over traditional screening.

Traditional Method

Extracting results from traditional fundus examinations is both time-consuming and tedious. Several fundus cameras photograph the full angle range at the back of the eye, but the film must be developed before an ophthalmologist can make a diagnosis. The number and location of lesions are manually assessed by the physician; diabetic patients with retinal lesions are said to have diabetic retinopathy and have a greater risk of going blind.

The RetinaLyze System uses the same fundus cameras, but the acquired images, either from the camera or digitized (scanned) 35-mm color slides, are analyzed by patented algorithms. Any retinal abnormalities, such as hemorrhages and microaneurisms, are automatically annotated. Typical results include the number, the areas, and spatial distribution of those lesions, so not only is the doctor’s attention immediately drawn to retinal damage, but patients with the most serious conditions can be identified and diagnosed quickly. These are just two time-saving factors that increase the efficiency of a busy clinic. Furthermore, RetinaLyze integrates all administrative functions such as patient management with image acquisition, making the system truly complete. For example, the system can track examinations, notifying the clinic of patients who are due for a checkup.

The RetinaLyze System

The system uses a Windows client-server application based on an ODBC database. The technology is COM components based and written in Microsoft Visual C++ and Microsoft VisualBasic. The enabling algorithms are based on the Imaging Utilities SDK developed by Visiopharm, while the graphical user interface utilizes UltraSuite library by Infragistics. The Matrox Imaging Library MIL-Lite package is used for grabbing images acquired by either a Matrox Meteor-II /Standard or /Multi-Channel frame grabber, depending on the fundus camera used.

Doré explained that developing medical devices based on image analysis represents a tremendous technological challenge. “In the life sciences in general, essential information for understanding complicated relationships in

living organisms with natural biological diversity is often found in images obtained from diagnostic equipment such as MRI, CT, PET, X-ray, ultrasound, or microscopes. The algorithms that analyze these images must be capable of handling this biological diversity in an intelligent and robust manner. At the same time, these methods must be accepted by the medical community.”

Quantitative medical image analysis is the key that unlocks complex organic relationships by turning images into objective knowledge of importance for assessing drug efficacy, disease progression, or toxicity. Added Doré, “Visiopharm’s technology is replacing operator-dependant grading, scoring, and ranking techniques with objective, sensitive, and quantitative image analysis technology.”

The RetinaLyze System is overcoming these challenges very effectively, by implementing algorithms capable of identifying all the normal anatomical elements of the eye, such as blood vessels, the optic nerve head, and the fovea. This allows other algorithms to identify abnormalities in the retina, in terms of pathological manifestations. Although all of these technological components represent major challenges, it is still necessary to develop technology capable of evaluating image quality. All of these technologies have been integrated in the RetinaLyze System.

Seeing Into the Future

RetinaLyze, in collaboration with Visiopharm, now plans to adapt the system for other retinal conditions. These include special applications for vascular morphology, glaucoma, age-related macular degeneration (AMD), and hypertension.

The social advantages of the RetinaLyze System are compounded. Since the examinations produce results very quickly, hospitals and clinics can implement diabetic retinopathy screening programs quite easily. Dr. Flanders also noted that diabetics can reduce their risk of retinopathy by maintaining a “blood sugar level in the normal range as much as possible. Weight reduction and control of hypertension and other related risk factors is also important.” In the long term, however, blindness can be prevented in most diabetics, improving the quality of life for patients and their families.

This article was contributed by Matrox Imaging, Dorval, Quebec, Canada. For more information, Click Here .