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ORIGINAL ARTICLE
Year : 2017  |  Volume : 65  |  Issue : 3  |  Page : 223-227

Accommodative amplitude using the minus lens at different near distances


1 Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan; Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
2 Southern California College of Optometry, Marshall B. Ketchum University, Fullerton, California, USA
3 Department of Molecular and Translational Medicine, Biostatistics and Biomathematics Unit, University of Brescia, Brescia, Italy
4 Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences; Refractive Errors Research Center, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
5 Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran

Correspondence Address:
Hamed Momeni-Moghaddam
Department of Optometry, Parastar 2 Street, Ahmadabad Avenue, Mashhad
Iran
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_545_16

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Purpose: The purpose of this study was to compare the mean findings and the repeatability of the minus lens (ML) amplitude of accommodation (AA) at 33 cm and 40 cm. Materials and Methods: AA was measured from the dominant eye of 120 fully corrected subjects using the ML procedure when viewing the target at both 33 and 40 cm. Each measurement was repeated between 24 and 48 hours after the first trial. Results: Mean AA when tested at 33 cm and 40 cm was 10.20 diopter (D) (standard deviation [SD] =1.24) and 8.85 D (SD = 1.23), respectively (P < 0.001). The limits of agreement of the measured amplitude calculated with taking into account of the replicates at 33 and 40 cm were − 0.19 (95% confidence interval [CI]: −0.34 to −0.04) and 2.53 (95% CI: 2.38 to 2.68), respectively. The repeatability of testing at the two distances 33 and 40 cm was ± 1.24 and ± 0.99, respectively. In addition, the retest reliability of measured amplitude using the intraclass correlation coefficient was 0.87 (95% CI: 0.789–0.920) at 33 cm and 0.91 (95% CI: 0.872–0.945) at 40 cm. Conclusion: There is no agreement in the obtained amplitude at the two measurement distances. Testing the ML AA at 40 cm may be superior given that a lower repeatability coefficient was observed. However, it is unclear whether the larger amplitude measured at 33 cm reflects a larger increase in accommodation (greater proximity effect) or a decrease in the ability to perceive the first slight sustained blur.


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