Fabrizio Zeri1, Paolo Calcatelli2, Eleonora Funaro3, Marialuisa Martelli4, Shehzad A Naroo5. 1. Ophthalmic Research Group, School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK. f.zeri@aston.ac.uk. 2. Istituto Ottico Carli, L'Aquila, Italy. 3. Department of Sciences, Roma TRE University, Rome, Italy. 4. Department of Psychology, Sapienza University of Rome, Rome, Italy. 5. Ophthalmic Research Group, School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK.
Abstract
PURPOSE: To evaluate the accuracy and repeatability of a computer-generated Pelli-Robson test displayed on liquid crystal display (LCD) systems compared to a standard Pelli-Robson chart. METHODS: Two different randomized crossover experiments were carried out for two different LCD systems for 32 subjects: 6 females and 10 males (40.5 ± 13.0 years) and 9 females and 7 males (27.8 ± 12.2 years), respectively, in the first and second experiment. Two repeated measurements were taken with the printed Pelli-Robson test and with the LCDs at 1 and 3 m. To test LCD reliability, measurements were repeated after 1 week. RESULTS: In Experiment 1, contrast sensitivity (CS) measured with LCD1 resulted significantly higher than Pelli-Robson both at 1 and at 3 m of about 0.20 log 1/C in both eyes (p < 0.01). Bland-Altman plots showed a proportional bias for LCD1 measures. LCD1 measurements showed reasonable repeatability: ICC was 0.83 and 0.65 at 1 and 3 m, respectively. In Experiment 2, CS measured with LCD2 resulted significantly lower than Pelli-Robson both at 1 and at 3 m of about 0.10 log 1/C in both eyes (p < 0.01). Bland-Altman plots did not show any proportional bias for LCD2 measures. LCD2 measurements showed sufficient repeatability: ICC resulted 0.51 and 0.65 at 1 and 3 m, respectively. CONCLUSIONS: Computer-generated versions of Pelli-Robson test, displayed on LCD systems, do not provide accurate results compared to classic Pelli-Robson printed version. Clinicians should consider that Pelli-Robson computer-generated versions could be non-interchangeable to the printed version.
RCT Entities:
PURPOSE: To evaluate the accuracy and repeatability of a computer-generated Pelli-Robson test displayed on liquid crystal display (LCD) systems compared to a standard Pelli-Robson chart. METHODS: Two different randomized crossover experiments were carried out for two different LCD systems for 32 subjects: 6 females and 10 males (40.5 ± 13.0 years) and 9 females and 7 males (27.8 ± 12.2 years), respectively, in the first and second experiment. Two repeated measurements were taken with the printed Pelli-Robson test and with the LCDs at 1 and 3 m. To test LCD reliability, measurements were repeated after 1 week. RESULTS: In Experiment 1, contrast sensitivity (CS) measured with LCD1 resulted significantly higher than Pelli-Robson both at 1 and at 3 m of about 0.20 log 1/C in both eyes (p < 0.01). Bland-Altman plots showed a proportional bias for LCD1 measures. LCD1 measurements showed reasonable repeatability: ICC was 0.83 and 0.65 at 1 and 3 m, respectively. In Experiment 2, CS measured with LCD2 resulted significantly lower than Pelli-Robson both at 1 and at 3 m of about 0.10 log 1/C in both eyes (p < 0.01). Bland-Altman plots did not show any proportional bias for LCD2 measures. LCD2 measurements showed sufficient repeatability: ICC resulted 0.51 and 0.65 at 1 and 3 m, respectively. CONCLUSIONS: Computer-generated versions of Pelli-Robson test, displayed on LCD systems, do not provide accurate results compared to classic Pelli-Robson printed version. Clinicians should consider that Pelli-Robson computer-generated versions could be non-interchangeable to the printed version.
Entities:
Keywords:
Computerized-based stimuli; Contrast sensitivity; LCD systems; Pelli–Robson test
Authors: Bettina Hohberger; Robert Laemmer; Werner Adler; Anselm G M Juenemann; Folkert K Horn Journal: Graefes Arch Clin Exp Ophthalmol Date: 2007-08-11 Impact factor: 3.117