The now ubiquitous nature of touch-screen displays in cell phones and tablet computers makes them an attractive option for vision testing outside of the laboratory or clinic. Accurate measurement of parameters such as contrast sensitivity, however, requires precise control of absolute and relative screen luminances. The nonlinearity of the display response ("gamma") can be measured or checked u...

The importance of including an adequate test for the discovery of deficiencies in color vision in any thorough medical examination of students has long been recognized; it is obviously desirable to detect at an early age those individuals who will be excluded from pursuing careers in occupations which require good color perception. For several years the Ishihara color vision test was used as pa...

CONTEXT Children with learning disabilities might have difficulties to communicate effectively and give reliable responses as required in various visual function testing procedures. AIMS The purpose of this study was to compare the testability of visual acuity using the modified Early Treatment Diabetic Retinopathy Study (ETDRS) and Cambridge Crowding Cards, stereo acuity using Lang Stereo te...

In 2003 the American Association for Pediatric Ophthalmology and Strabismus Vision Screening Committee proposed criteria for automated preschool vision screening. Recent literature from epidemiologic and natural history studies, randomized controlled trials of amblyopia treatment, and field studies of screening technologies have been reviewed for the purpose of updating these criteria. The prev...

We have developed 3 series of pseudoisochromatic plates for colour vision testing. The plates are arranged in order of increasing difficulty. In the first (red/green) series, a red Landolt C is shown in front of a green background. This series is used to determine the severity of colour vision deficiency. In the second series, colours are located on the protan confusion line, whereas in the thi...

PURPOSE The purpose of this study was to determine the testability of the "Co or Vision Testing Made Easy" color vision test, marketed as a screening test for young children, in a population of individuals with mental retardation. The test uses simple geometric figures that are easily identified. Previously, the test has demonstrated validity as a measure of color deficiency. METHODS The test...

1 Health and Safety Executive. Colour vision. London: HMSO, 1987:1-8. (Medical series guidance notes MS7). 2 Holroyd E, Hall DMB. A re-appraisal of screening for colour vision impairments. Child Care Health Dev 1997;23:391-8. 3 Essen J, Fogelman K, Ghodsian M. Long-term changes in the school attainment of a national sample of children. Educ Res 1978;20:300-5. 4 Jefferis BJMH, Power C, Hertzman ...

BACKGROUND The Mallett Unit is a clinical test designed to detect the fixation disparity that is most likely to occur in the presence of a decompensated heterophoria. It measures the associated phoria, which is the "aligning prism" needed to nullify the subjective disparity. The technique has gained widespread acceptance within professions such as optometry, for investigating suspected cases of...

Objectives: To compare shade matching skills of color normal males and females. Material and Methods: A total of 174 dental students of both genders (117 females and 57 males, 20 to 25 years old), with no experience in color matching in dentistry, participated in the study. All recruited students passed the Ishihara color vision test for color deficiency, and matched the colors of eight shade t...

a 35-year-old lady presented with a history of decreased vision in her right eye from one week before her referral. she did not report any significant systemic disease. ocular findings were compatible with the diagnosis of central retinal vein occlusion. systemic laboratory tests were all within normal limits except for mantoux test (ppd) which was positive, 18 mm induration and 2+ redness. che...