Design & development of plastics tele microscope visual aids for vision impaired using state-of-art aspheric technology

Abstract

Low Vision indicates a visual acuity of less than 6/18 but better than 3/60 or / and field of vision reduced to 20° or less. As per the report published in journal of ophthalmology, every five seconds one person in our world goes blind; every minute, one child goes blind. As per Indian Council of Medical Research, India has more than 40 million persons with visual impairments of serious nature. Age-related macular degeneration is the leading cause of Low Vision, followed by diabetic retinopathy and glaucoma. A variety of other conditions such as in-operable or pre-operative cataracts and other hereditary diseases can also cause impaired vision. Most of these visual impairments cannot be corrected by surgical means, nor by conventional spectacles. Hence, it is vital to develop dedicated Visual Aids for Near Vision & Distance Vision to enable the person with low vision to perform their daily tasks independently. In current work light weight, tele-microscopes are developed by direct removal of material by ultra-precision machining method. This device employs plastic aspheric lenses in plano-convex and plano-concave configuration mounted in a lightweight housing with a power accommodation of +2 Dioptre. Plastic aspheric lenses are fabricated by single point diamond turning (SPDT) machine. Developed visual aids have controlled profile to improve the vision quality. The mechanical housing design provides flexibility to use the device in dual configuration i.e. hand-held and spectacle frame mounted.