March 2012
Volume 53, Issue 14
Free
ARVO Annual Meeting Abstract  |   March 2012
A Comparison Of Axial Lens Lengths In A Relaxed State And Accommodative State Using Anterior Segment Optical Coherence Tomography And A-scan Ultrasonography
Author Affiliations & Notes
  • Kyle D. Klute
    Illinois College of Optometry, Chicago, Illinois
  • Marc Landes
    Illinois College of Optometry, Chicago, Illinois
  • Jennifer S. Harthan
    Cornea Center for Clinical Excellence,
    Illinois College of Optometry, Chicago, Illinois
  • Rebecca K. Zoltoski
    Didactic Education,
    Illinois College of Optometry, Chicago, Illinois
  • Footnotes
    Commercial Relationships  Kyle D. Klute, None; Marc Landes, None; Jennifer S. Harthan, None; Rebecca K. Zoltoski, None
  • Footnotes
    Support  ICO RRC
Investigative Ophthalmology & Visual Science March 2012, Vol.53, 1345. doi:
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      Kyle D. Klute, Marc Landes, Jennifer S. Harthan, Rebecca K. Zoltoski; A Comparison Of Axial Lens Lengths In A Relaxed State And Accommodative State Using Anterior Segment Optical Coherence Tomography And A-scan Ultrasonography. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1345.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : During dynamic focusing, the shape of the lens changes. Our lab investigates these changes in lens ultrastructure during accommodation. One means to document changes during accommodation is to measure lens thickness. For our research, a technique is needed to measure lens thickness that can be easily used in all patients. Both anterior segment optical coherence tomography (OCT) and A-Scan ultrasonography (A-Scan) may be used clinically to measure the thickness of anterior segment structures. However, a comparison of the two instruments has not been thoroughly documented. Therefore, we compared Visante™ OCT with Accutome™ A-Scan.

Methods: : OCT, A-Scan, and accommodative response was collected on eight subjects, 23-41 years of age, all having normal age-related accommodation. Measurements (right eye only) were first taken with accommodation relaxed while the subject viewed a standard target. Then subjects were given increasing minus lenses to stimulate an increase in accommodation as successive measurements were taken as the subject viewed the same target. iTrace™ wavefront analysis was used with the same accommodative demands to measure the objective accommodative response. Data were analyzed using Systat v11 to correlate accommodative response with lens thickness. Data are presented as mean ± SEM and Spearman Rank Correlation coefficients and p values are presented.

Results: : Overall, the lens thickness measured using OCT was higher than the measurements obtained using the A-scan (4.04 ± 0.06 mm vs 3.58 ± 0.06 mm, p<0.001, n=22). Both Visante and A-scan measured an increase in the lens axial thickness as accommodative demand increased; however, the difference between the two methods was not significant (Visante 0.14 ± 0.08 µm/D vs A-Scan 0.10 ± 0.04 µm/D, p=0.64). The accommodative response was correlated with lens thickness, using both instruments (Visante r2= 0.431, p = 0.043, A-Scan r2= 0.564, p = 0.005) and the values were highly correlated to each other (r2= 0.905, p < 0.001). A preliminary Bland-Altman analysis indicates that there is no difference between the instruments for measuring changes in lens thickness with accommodation.

Conclusions: : The higher variability and numbers seen in the Visante can be related to operator error in measuring the lens because it can be difficult to isolate the back surface of the lens on the viewing screen. Better techniques for measuring are being evaluated. This preliminary evidence indicates that Visante OCT can be used in subjects as a non-invasive measure for changes in lens thickness with increased accommodative demand as an accurate alternative to A-Scan ultrasonography.

Keywords: accommodation • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) 
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