This review gives an overview of the current status of standardization by statistical evaluation of reading charts. First begun only 20 years ago, the statistical evaluation of reading charts now reflects an increasing clinical and scientific interest in standardized, comparable, and reproducible reading charts.
For clinical or research purposes in human subjects, standardization of psychophysical tests and their test items by statistical evaluation is mandatory because it provides experimental control. Initial attempts at reading chart standardization were made by characterizing the test items, either in terms of a selection of unrelated words or in terms of sentences representing a constant number of characters, including spaces. As initiated by the RADNER Reading Charts, standardization of reading charts (and test items) by statistical evaluation has gained increasing clinical and scientific interest in the last two decades and has later also been applied to some of the other modern reading charts. A literature search was performed with respect to reading charts that (a) have been produced in accordance with the recommendations of the International Council of Ophthalmology (geometrical print size progression), (b) have been statistically analyzed, and/or (c) use clearly characterized test items (conceptually and statistically). These reading charts are as follows: the Bailey-Lovie Word Reading Charts, the Colenbrander Cards, the RADNER Reading Charts, the MNREAD Acuity Charts, the Smith-Kettlewell Reading Test (SKread Test), the C-Read Charts, and the Balsam Alabdulkader-Leat (BAL) Chart. The test items of these charts have been characterized either empirically or by statistical analysis and selection. The extent of the statistical evaluation of the reading charts varies. Despite their different methodological approaches, these reading charts represent an advancement that has made possible the useful comparison and reproducible evaluation of near visual performance.
1Austrian Academy of Ophthalmology, Vienna, Austria
2Department of Ophthalmology, University Hospital St. Pölten, Karl Landsteiner University for Health Sciences, St. Pölten, Austria
Submitted: March 19, 2019
Accepted: July 13, 2019
Funding/Support: None of the authors have reported funding/support.
Conflict of Interest Disclosure: WR receives royalties for the RADNER Reading Charts.
Author Contributions and Acknowledgments: Conceptualization: WR; Formal Analysis: WR; Methodology: WR; Supervision: WR; Validation: WR; Writing – Original Draft: WR.
The author would like to thank Prof. Susan Leat, PhD, Balsam Alabdulkader, BScOptom, MSc, PhD; Lei Liu, PhD; and Cong Yu, PhD, for their valuable contributions in writing the paragraphs explaining their reading charts and for their factual input with regard to the context of the scientific background. He would also like to thank Prof. August Colenbrander, MD, PhD, for his valuable contribution in writing the paragraph about the stages of visual perception and Deborah McClellan, PhD, for editorial assistance.