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Amy L. Sheppard, Alison Alderson, Leon N. Davies, Edward A. Mallen; Application Of High Resolution Low Coherence Reflectometry To Track Ocular Biometric Changes During Disaccommodation. Invest. Ophthalmol. Vis. Sci. 2011;52(14):819. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To utilise a high resolution optical low coherence reflectometry device (LenStar; Haag-Streit Koeniz, Switzerland) to track changes in ocular biometry during disaccommodation.
Ten pre-presbyopic subjects (5 female, 5 male; aged 22 to 40 years) participated in the study. Five measures of anterior chamber depth (ACD), lens thickness (LT) and axial length (AL) were acquired from the right eye whilst subjects viewed a 0 D, followed by a 5 D accommodative stimulus in a Badal system, which was visible through a pellicle mirror mounted at 45° in front of the LenStar measuring beam. Following the 5 D measures, stimulus demand was immediately reduced to 0 D and ocular biometric measures recorded at 5- 15 second intervals (depending on time required to adjust the instrument position between measurements) for one minute. The measurement process was performed three times on each subject. The speed of disaccommodative change for each biometric parameter was analysed by calculating and plotting the regression quotients of all measurements. An exponential decay function was fitted to the regression quotient data and used to determine the time period for biometric measures to regress to 90 % of the original (unaccommodated) level.
During accommodation, ACD reduced by 0.21 ± 0.05 mm, whilst LT and AL measures increased by 0.243 ± 0.08 mm and 0.03 ± 0.02, respectively. There was broad variation between subjects in the time taken for biometric measures to regress to 90 % of the unaccommodated level (ranges: 4.65- 48; 4.40- 57.0 and 0.50- 59.0 seconds for ACD, LT and AL, respectively). No relationship was identified between subject age and 90 % regression time period for any of the parameters investigated (P = 0.207; 0.290 and 0.96, for ACD, LT and AL, respectively).
The LenStar device facilitates high-resolution measurements of changes in ocular biometry during disaccommodation. Further application of the technique will enable identification of the cause of nearwork-induced transient myopia in affected subjects.
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