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1 Neurobiology & Behavior Cornell University Ithaca NY
Commercial Relationships: H.C. Howland, None; J.E. Kelly, None; J. Shapiro, None.
Grant Identification: NIH EY02994
Abstract
Purpose: Reading spectacles have been proposed as a method to alleviate the progression of myopia. Their postulated efficacy is thought to be the reduction of hyperopic blur due to under-accommodation in normal reading Yet, to date, little is known about the focusing and fixation behavior of non-presbyopes using reading spectacles. Thus we wished to determine the state of accommodation and convergence of emmetropic, or near emmetropic young adults while reading with +2 and +3D spectacles.
Methods:. We measured the accommodation and convergence of subjects reading text from a standard near reading card at 33 cm using a binocular infrared Power Refractor (Multichannel Systems, Reutlingen, Germany), which measured convergence and accommodation (the latter in the vertical meridians) simultaneously. Convergence angles were calibrated individually for each subject. The reading card was mounted slightly above the axis of refraction, but the angle between the refracted axis and the line of sight was generally < 5°. Subjects were given a complete refraction. All subjects were within 1 D of emmetropia on their initial visit. Phorias at far and near (33 cm) were also measured using an IR filter.
Results:. Nine subjects exhibited over-accommodation while reading through +2 D spectacles (difference between mean focus with and without spectacles: -.71D ± 0.14 SE, p < 0.0009), and also while reading through +3 D spectacles (-1.37 D ± 0.26 SE, p<0.0007). At the same time subjects were not over-converged (difference in convergence with and without spectacles: +2 D spectacles: -0.44 PD, ±0.75 SE; +3 D spectacles: 0.04 PD ± .69 SE)
Conclusion:. Initial results show that reading through positive lenses causes over-accommodation but not over-convergence in young adults. Future work will determine if the accommodative posture changes after wearing reading spectacles for longer durations.
Keywords: 304 accommodation 397 emmetropization 407 eye movements: conjugate
© 2002, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. For permission to reproduce any part of this abstract, contact the ARVO Office at arvo{at}arvo.org.
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