Skip Navigation LinksHome > November 2013 - Volume 90 - Issue 11 > Hyperopic Defocus and Diurnal Changes in Human Choroid and A...
Optometry & Vision Science:
doi: 10.1097/OPX.0000000000000035
Original Articles

Hyperopic Defocus and Diurnal Changes in Human Choroid and Axial Length

Chakraborty, Ranjay*; Read, Scott A.; Collins, Michael J.

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Abstract

Purpose

To investigate the influence of monocular hyperopic defocus on the normal diurnal rhythms in axial length and choroidal thickness of young adults.

Methods

A series of axial length and choroidal thickness measurements (collected at ∼3 hourly intervals, with the first measurement at ∼9 am and the final measurement at ∼9 pm) were obtained for 15 emmetropic young adults over three consecutive days. The natural diurnal rhythms (day 1, no defocus), diurnal rhythms with monocular hyperopic defocus (day 2, −2.00 DS spectacle lens over the right eye), and the recovery from any defocus induced changes (day 3, no defocus) in diurnal rhythms were examined.

Results

Both axial length and choroidal thickness underwent significant diurnal changes on each of the three measurement days (p < 0.0001). The introduction of monocular hyperopic defocus resulted in significant changes in the diurnal variations observed in both parameters (p < 0.05). A significant (p < 0.001) increase in the mean amplitude (peak to trough) of change in axial length (mean increase, 0.016 ± 0.005 mm) and choroidal thickness (mean increase, 0.011 ± 0.003 mm) was observed on day 2 with hyperopic defocus compared to the two “no defocus” days (days 1 and 3). At the second measurement (mean time 12:10 pm) on the day with hyperopic defocus, the eye was significantly longer by 0.012 ± 0.002 mm compared to the other two days (p < 0.05). No significant difference was observed in the average timing of the daily peaks in axial length (mean peak time 12:12 pm) and choroidal thickness (21:02 pm) over the three days.

Conclusions

The introduction of monocular hyperopic defocus resulted in a significant increase in the amplitude of the diurnal change in axial length and choroidal thickness that returned to normal the following day after removal of the blur stimulus.

Copyright © 2013 American Academy of Optometry

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