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[Ophthalmological reading tests : Part 1: historical aspects]
1Österreichische Akademie für Augenheilkunde und Optometrie, Mollgasse 11, 1180, Wien, Österreich. wolfgang.radner@inode.at.
Summary
Historical reading charts lacked standardized print sizes and logarithmic scaling, impacting comparability and potentially leading to underestimation as diagnostic tools. These early charts, however, paved the way for modern visual acuity testing.
Area of Science:
- Ophthalmology and Optometry
- Visual Acuity Testing
- History of Medicine
Background:
- Review of historical reading charts (Jaeger, Snellen, Nieden, Birkhäuser) focusing on historical context, printing techniques, quality, and size.
- Analysis of the evolution of visual acuity measurement tools.
Observation:
- Microscopic investigation of original historical reading charts using precise measurement tools.
- Calculations performed according to EN ISO 8596 and International Research Council recommendations.
Findings:
- Mid-nineteenth century reading cards lacked standardized lowercase letter printing, rendering them non-comparable across languages and editions.
- Print sizes exhibited no logarithmic progression, and number sizes were inconsistent with letter sizes in most historical charts.
- Calculated visual acuities varied significantly: Jaeger No. 1 (1856) was 0.72, Snellen (1862) was 0.55, Nieden No. 1 (1882) was 0.59, and Birkhäuser (1911) was 1.5.
Implications:
- Deficits in standardization and comparability of historical reading charts may have led to their underestimation as diagnostic instruments.
- Historical reading charts, despite limitations, served as crucial precursors to contemporary, standardized visual acuity testing methods.
- Understanding historical chart limitations informs the development and validation of modern optometric diagnostic tools.
