Influences of prisms on accommodative response and microfluctuation in emmetropias

Authors: Wang Kai,  Li Yan,  Shi Xiaoqing,  Wu Xi,  Zhao Mingwei,  Li Xiaoxin
DOI: 10.3760/cma.j.issn.2095-0160.2015.06.007
Published 2015-06-10
Cite as Chin J Exp Ophthalmol, 2015,33(6): 513-517.

Abstract                              [Download PDF] [Read Full Text]

Background

How to control progression of myopia is a central issue in clinical optometry.Some clinical trials showed that wearing base-in (BI) prism can slow down progression of myopia to certain degree.However, whether BI prism or base-out (BO) prism should be used is worth discussing.

Objective

This study was to investigate the influences of different prisms on accommodative response and microfluctuation in emmetropias.

Methods

This clinical trail was approved by Ethic Committee of Peking University People’s Hospital.During July in 2014, twenty-two emmetropias of 22 normal volunteers aged 21-27 years were recruited from Peking University People’s Hospital under the written informed consent.An open-field infrared refractometer was used to monitor and record pupil diameter and accommodative response under three conditions including non-prism, 3ΔBI prism, and 3ΔBO prism.The accommodative response value was calculated as the difference between reading value and -3.0 D, and root mean square (RMS) of accommodative response value served as amplitude of accommodative microfluctuation.Spectrum of accommodative response was analyzed by one dimension discrete Fourier transformation.The differences of accommodative response value, amplitude of accommodative microfluctuation and pupil diameter among three conditions were compared using repeated one-way ANOVA.

Results

The accommodative response values were (+ 0.31±0.78), (+ 0.51±0.75) and (+ 0.18±0.72) D under the non-prism, 3ΔBI prism and 3ΔBO prism conditions, respectively, with a significant difference among them (F=28.078, P=0.000), and compared with the non-prism condition, the accommodative lag of 3ΔBI prism condition was increased and that of 3ΔBO prism condition was reduced (P=0.000, 0.012). No significant difference was found in the amplitude of accommodative microfluctuation among the three conditions (F=0.062, P=0.879). The percentages of low frequency signal power (0-0.5 Hz)/total power (0-2.5 Hz) was 97.5%, 98.3% and 91.4% under the non-prism, 3ΔBI prism and 3ΔBO prism condition, respectively.The pupil diameter was (5.37±0.69) mm under the 3ΔBI prism condition, which was larger than (5.07±0.66) mm under the non-prism condition and (5.01±0.69) mm under the 3ΔBO prism condition (both at P=0.000).

Conclusions

Compared with wearing 3ΔBI prism, wearing 3ΔBO prism lessens the accommodative lag, decreases the pupil diameter and reduces the power of low frequency component in accommodative response.

Key words:

Accommodation, ocular/physiology; Myopia/prevention & control; Refraction, ocular/physiology; Eyeglasses/prism; Humans; Emmetropia

Contributor Information

Wang Kai
Laboratory of Vision Loss and Restoration, Ministry of Education, Department of Ophthalmology, Peking University People’s Hospital, Beijing 100044, China
Li Yan
Shi Xiaoqing
Wu Xi
Zhao Mingwei
Li Xiaoxin
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