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. 2014:2014:590978.
doi: 10.1155/2014/590978. Epub 2014 Aug 19.

Trabecular-iris circumference volume in open angle eyes using swept-source fourier domain anterior segment optical coherence tomography

Mohammed Rigi  1 , Lauren S Blieden  2 , Donna Nguyen  3 , Alice Z Chuang  4 , Laura A Baker  1 , Nicholas P Bell  2 , David A Lee  2 , Kimberly A Mankiewicz  4 , Robert M Feldman  2
Affiliations

Trabecular-iris circumference volume in open angle eyes using swept-source fourier domain anterior segment optical coherence tomography

Mohammed Rigi et al. J Ophthalmol. 2014.

Abstract

Purpose. To introduce a new anterior segment optical coherence tomography parameter, trabecular-iris circumference volume (TICV), which measures the integrated volume of the peripheral angle, and establish a reference range in normal, open angle eyes. Methods. One eye of each participant with open angles and a normal anterior segment was imaged using 3D mode by the CASIA SS-1000 (Tomey, Nagoya, Japan). Trabecular-iris space area (TISA) and TICV at 500 and 750 µm were calculated. Analysis of covariance was performed to examine the effect of age and its interaction with spherical equivalent. Results. The study included 100 participants with a mean age of 50 (±15) years (range 20-79). TICV showed a normal distribution with a mean (±SD) value of 4.75 µL (±2.30) for TICV500 and a mean (±SD) value of 8.90 µL (±3.88) for TICV750. Overall, TICV showed an age-related reduction (P = 0.035). In addition, angle volume increased with increased myopia for all age groups, except for those older than 65 years. Conclusions. This study introduces a new parameter to measure peripheral angle volume, TICV, with age-adjusted normal ranges for open angle eyes. Further investigation is warranted to determine the clinical utility of this new parameter.

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Figures

Figure 1
Figure 1
Trabecular-iris circumference volume (TICV). 3D anterior segment optical coherence tomography (ASOCT) image exhibiting TISA500 (light green space) and TICV500 (darker green spaces), along with the scleral spur landmark (red circle), iris (yellow), and cornea (violet line).
Figure 2
Figure 2
(a) Histogram and estimated density function for TICV500. (b) Histogram and estimated density function for TICV750.
Figure 3
Figure 3
Observed TICV500 (yellow) and TICV750 (white), estimated normal density functions (black for TICV500 and grey for TICV750), as well as means (red for TICV500 and blue for TICV750) for each age group.
Figure 4
Figure 4
(a) TICV500 versus spherical equivalent scatter plot with estimated regression line for each group (with outliers). (b) TICV500 versus spherical equivalent scatter plot with estimated regression line for each group (without outliers).
See this image and copyright information in PMC

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