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A. K. Dexl, H. Schlögel, M. Wolfbauer, G. Grabner; A New Device for Clinical Testing of Distance Corrected Reading Acuity Under Fully Standardized Conditions: The Salzburg Reading Desk-Advanced (SRD-adv) - Proof of Concept. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1795.
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© ARVO (1962-2015); The Authors (2016-present)
To develop a new device for testing distance corrected reading acuity under standardized circumstances.
The determination of reading performance is still the most relevant clinical examination, whenever the potential benefits of surgical procedures for the correction of presbyopia are assessed. A comparison of the results of different centres cannot be easily performed without adequate test methods and meticulous standardization. Based on the "Radner-Reading-Charts", the SRD-adv was developed for testing reading acuity under different luminance levels (5-100 cd/m2) and -in addition- different contrast levels by the implementation of a high-resolution computer-display (0,16 mm pixel-interspace) in the original SRD prototype.One has to be aware that all at present commercially available reading charts are using high contrast levels (approximately 85-95%). The added feature of testing with different, especially reduced contrast levels (as an example a "standard" newspaper has only about 40-60% of contrast) will allow to discriminate even smaller differences regarding every day reading abilities. As measuring reading acuity with fixed distance does also not allow to draw conclusions on the "every day reading ability" of patients, the continuously changing reading distance is monitored by stereo-photometry, and is mathematically taken into consideration. The reading angle (= inclination of the display), as an additional variable parameter, can be chosen freely by the patient, to offer the most convenient test circumstances.
Testing for validity and reliability has been performed with 924 single measurements in distances between 15 and 63 cm, and reading angles between 60° and 90°. Based on the Radner Reading Charts an error range between logRad ± 0,0034 at 63 cm and logRad ± 0,0143 at 15 cm has been found (this is of no clinical relevance).
With the SRD-adv it is possible to obtain objective, valid and comparable results as far as the true "reading abilities" of patients are concerned. This encompasses reading acuity, reading speed and critical print size, under different contrast and luminance levels, and subjectively convenient reading distance. Studies testing reading acuity following a variety of surgical methods are currently under way in different European centres with the use of the SRD-adv in order to confirm the potential of this highly refined method for reading acuity evaluation.
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