An inexpensive, flexible and simple solution for developing countries.

A simple subjective telescopic refraction system has been custom designed and built. The telescopic refraction accommodates a range of refractive errors from +0.62D to -9.37D, which is skewed towards the various amounts of myopia due to the prevalence of myopia in Asia. This range can be modified in order to capture the specific distribution of refractive errors of a population.

In using the calibrated 2.4X telescope for subjective refraction, the length of the telescope and the position of the stenopaic slit are adjusted by the examiner while the subject focuses a target on a distant visual acuity chart. The slit’s size and position can be changed easily thus enabling the examiner to obtain the refractive error findings easily by changing the length of the telescope. Refractive error can be measured in a few minutes. Since it is subjectively determined, it is generally more reliable than those findings obtained with objective refraction techniques. 

Special Features and Advantages

• The device is developed based on advanced    designation which is small in size and cheaper.
• With short period of training it can be easily    used. 
• Efficient, reliable and accurate assessment of refractive error.

Applications

• The device can be used as a portable subjective refraction system determining the refractive errors of patients who cannot access the services of an optometrist or ophthalmologist.
• The device can be used as a pair of full field binoculars without the stenopaic slits.
• The device can be used as a low vision aid for the partially sighted.

Award

Prize of Minister Fientje Moerman & Gold Award, Brussels Eureka 2004 – the 53rd World Exhibition of Innovation, Research and New Technology (November 2004)

The Principal Investigator of this innovation is Prof. George WOO and the School of Optometry is The Hong Kong Polytechnic University.