A Simple and Robust Method to Screen Cataracts Using Specular Reflection Appearance Retno Supriyanti 1 , Hitoshi Habe 1 , Masatsugu Kidode 1 and Satoru Nagata 2 1 Graduate School of Information Science, Nara Institute of Science and Technology Japan Email: {retno-s|habe|kidode}@is.naist.jp 2 Dept. of Medical Informatics and Biomedical Engineering, Shiga Medical University Japan Email: nagata@belle.shiga-med.ac.jp ABSTRACT The high prevalence of cataracts is still a serious public health problem as a leading cause of blindness, especially in developing countries with limited health facilities. In this paper we propose a new screening method for cataract diagnosis by easy-to-use and low cost imaging equipment such as commercially available digital cameras. The difficulties in using this sort of digital camera equipment are seen in the observed images, the quality of which is not sufficiently controlled; there is no control of illumination, for example. A sign of cataracts is a whitish color in the pupil which usually is black, but it is difficult to automatically analyze color information under uncontrolled illumination conditions. To cope with this problem, we analyze specular reflection in the pupil region. When an illumination light hits the pupil, it makes a specular reflection on the frontal surface of the lens of the pupil area. Also the light goes through the rear side of the lens and might be reflected again. Specular reflection always appears brighter than the surrounding area and is also independent of the illumination condition, so this characteristic enables us to screen out serious cataract robustly by analyzing reflections observed in the eye image. In this paper, we demonstrate the validity of our method through theoretical discussion and experimental results. By following the simple guidelines shown in this paper, anyone would be able to screen for cataracts. Keywords: screening, cataract, specular reflection analysis 1. INTRODUCTION A cataract is a clouding of the lens in the eye that interferes with vision. The World Health Report published in 2001 estimated that there were 20 million people who are bilaterally blind (i.e., eyesight less than 3/60 in the better eye) from age-related cataracts and the number will have swelled to 40 million by the year 2020 [1]. Developing countries like Indonesia have the highest number of cases. On the other hand, Indonesia has only about 750 eye specialists for a population of more than 200 million (one for every 350,000 people) many of whom have no access to eye care because of geographic conditions[2]. For tele-medical environments like in Indonesia, it is crucial to implement a compact screening system for several diseases common there. In current diagnosis, eye specialists focus on the pupil region to get information about cataracts using a slit lamp camera to get clear information about any whitish color inside the pupil. Three classes of cataract, immature, mature and hypermature, differ in seriousness as shown in Figure 1. An immature cataract shows appearance of a whitish color inside the pupil, but less so than the mature or hypermature types, and is usually not yet a serious condition. Hypermature cataracts show much whitish color inside the pupil and can cause the eyeball to break if surgery is not carried out. This condition is very dangerous. Hypermature Mature Immature Normal Figure1. Examples of eye conditions