M.Phil. (Optometry) / Significant vision impairment caused by uncorrected distance or near vision (at a level defined by The World Health Organization as a disability) affects over 600 million people globally (9% of the world’s population). Over 3.5 billion people (52% of the world’s population) need some form of vision correction to see clearly. By 2020, this number is projected to reach 6.1 billion, 66% of the world’s population. Vision impairment is an important issue affecting the everyday lives of these 3.5 billion people worldwide. Two thirds of those affected live in the less developed world where the majority do not have easy access to eye care, eye examinations and affordable spectacles. Purpose If an ametrope or presbyope pricks a small hole into a leaf, piece of paper or cardboard and looks through it, he or she will usually experience improved acuity providing there is no central cataract or any ocular pathology. Rural communities, who have no access to eye-care or vision specialists, with vision problems, may benefit from looking through a pinhole while looking far and near. Many who are longsighted or presbyopic, may have problems reading their Bibles for example. They may only have candles as a source of light at night. They could improve their vision by looking through a small hole while reading. The purpose of this study is to explore the possibility of such a simple and almost cost free device contributing to solving this need. Method Uncompensated (without the pinhole) near or proximal visual acuities (VAs) were measured and recorded on one eye of 45 presbyopic subjects over the age of 50 years in photopic (250 lux) and then scotopic (20 lux) conditions. There were 36 male and 9 female subjects. Their ages ranged between 50 and 74 years with an average of 59 (SD = ±7.52) years. The ambient room illumination for photopic conditions was measured using a Sekonic Lumi Model 246 light-meter. No visual or pathological conditions or requirements were set for the subjects. The subjects were asked to read the smallest letters on the near chart by moving their head closer ...
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:13787 |
| Date | 15 July 2015 |
| Creators | Carlson, Anthony Stephen |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
Page generated in 0.0034 seconds