May 2012
Volume 53, Issue 6
Free
Glaucoma  |   May 2012
Factors Associated with Anterior Chamber Narrowing with Age: An Optical Coherence Tomography Study
Author Affiliations & Notes
  • Jae Hong Sun
    From the Department of Ophthalmology, and the Department of Clinical Epidemiology and Biostatistics, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea.
  • Kyung Rim Sung
    From the Department of Ophthalmology, and the Department of Clinical Epidemiology and Biostatistics, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea.
  • Sung-Cheol Yun
    From the Department of Ophthalmology, and the Department of Clinical Epidemiology and Biostatistics, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea.
  • Mi Hyun Cheon
    From the Department of Ophthalmology, and the Department of Clinical Epidemiology and Biostatistics, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea.
  • Hung Won Tchah
    From the Department of Ophthalmology, and the Department of Clinical Epidemiology and Biostatistics, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea.
  • Myoung Joon Kim
    From the Department of Ophthalmology, and the Department of Clinical Epidemiology and Biostatistics, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea.
  • Jae Yong Kim
    From the Department of Ophthalmology, and the Department of Clinical Epidemiology and Biostatistics, College of Medicine, University of Ulsan, Asan Medical Center, Seoul, Korea.
  • Corresponding author: Kyung Rim Sung, MD, PhD, Department of Ophthalmology, University of Ulsan, College of Medicine, Asan Medical Center, 388-1 Pungnap-2-dong, Songpa-gu, Seoul, Korea 138–736; Telephone +82-2-3010-3680; Fax +82-2-470-6440; sungeye@gmail.com
Investigative Ophthalmology & Visual Science May 2012, Vol.53, 2607-2610. doi:10.1167/iovs.11-9359
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      Jae Hong Sun, Kyung Rim Sung, Sung-Cheol Yun, Mi Hyun Cheon, Hung Won Tchah, Myoung Joon Kim, Jae Yong Kim; Factors Associated with Anterior Chamber Narrowing with Age: An Optical Coherence Tomography Study. Invest. Ophthalmol. Vis. Sci. 2012;53(6):2607-2610. doi: 10.1167/iovs.11-9359.

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Abstract

Purpose.: The purpose of our study is to evaluate the effect of age on various anterior segment (AS) parameters in healthy eyes using AS optical coherence tomography (OCT), and to examine their relationship to anterior chamber angle (ACA) narrowing with age.

Methods.: A total of 388 consecutive Korean subjects aged 30 to 89 years was imaged by AS OCT. Anterior chamber depth (ACD), iris cross-sectional area (IA), iris thickness at 750 and 1500 μ from the scleral spur (IT750, 1500), iris curvature (IC), lens vault (LV), and anterior chamber area (AA) were determined using Image J software (version 1.44). The absolute and normalized slopes of these parameters, adjusted for axial length and sex, were determined by linear mixed-effects modeling. Multivariate regression analysis was performed to evaluate factors associated with ACA narrowing, which was defined as the angle-opening distance (AOD500) at the temporal angle.

Results.: ACD and AA had significantly negative slopes (−0.0119 mm/year, −0.0845 mm2/year, P < 0.0001, <0.0001) with age, and LV, IC, IT750, IT1500, and IA had significantly positive slopes (0.0084 mm/year, 0.0019 mm/year, 0.0006 mm/year, 0.0008 mm/year, 0.0131 mm2/year, all P < 0.05). IC, ACD, LV, and AA underwent the greatest changes when analyzed by normalized slopes. IC, LV, age, and axial length were associated significantly with ACA narrowing (all P < 0.0001).

Conclusions.: Increments of LV, IC, IT, and IA with age led to a reduction in the dimensions of the AC and to narrowing of the ACA. This may explain why aging is a significant risk factor for primary angle closure glaucoma.

Introduction
Age is one of the important risk factor for primary angle closure glaucoma (PACG). 1,2 In a previous study by anterior segment (AS) optical coherence tomography (OCT), Cheon et al. showed that the anterior chamber angle (ACA) gradually narrows with age. 3 Progressive narrowing of the ACA may predispose to higher risk of PACG with age. This raises several questions: why does the ACA narrow as one gets older? What makes the ACA narrow? How do the relevant AS structures cause ACA to narrow? In other words, what AS parameters change, and how, to bring about the ACA narrowing with age? Moreover, if multiple factors are implicated, which are the most important? To answer these questions, we must determine the effects of aging on the relevant AS parameters. 
In the past, measurement of AS structures depended entirely on slit-lamp and gonioscopic examination. Although these measurements remain the reference standards for AS evaluation, they do not provide quantitative and objective data, and hence depend on the individual examiner. 
Recently, non-invasive imaging devices that display the structures of the AS with high resolution have become available. One of these is AS OCT (Visante, version 2.0; Carl Zeiss Meditec, Dublin, CA). This technique can generate cross-sectional images showing the full features of the iris, anterior lens surface, anterior chamber (AC) dimensions and ACA, all in the same image frame. The reproducibility of measurements and clinical use of this device have been demonstrated in previous studies. 48  
The aim of our study was to use OCT to evaluate the effect of age on the various AS parameters of healthy eyes, and to identify AS parameters related to ACA narrowing with age. Since the ACA is composed of several neighboring structures, namely lens, iris and cornea, the changes in these factors may be interrelated. Therefore, we also performed a multivariate analysis involving these structural parameters to identify the factors with the greater effect on ACA narrowing. 
Methods
Subjects
Our study was a clinic-based, cross-sectional study of 388 Korean men and women, aged 30 to 89 years. The subjects who were enrolled either attended a general ophthalmology clinic for routine eye examinations or minor external ocular discomforts, such as dryness or blepharoconjunctivitis, or were volunteers, or employees or families of employees of the Asan Medical Center, Seoul, Korea. They were recruited consecutively from March to October 2009. All participants underwent a comprehensive eye examination. This included best corrected visual acuity (BCVA) measurements using the logarithm of minimum angle of resolution (logMAR chart, The Lighthouse, Long Island, NY), slit-lamp (model BQ 900, Haag-Streit, Bern, Switzerland) examination of the anterior segment, and intraocular pressure (IOP) measurement by Goldmann applanation tonometry, as well as stereoscopic optic disc examination with a 90 diopter lens (Volk Optical Inc., Mentor, OH) through an undilated pupil, gonioscopy, ultrasound pachymetry, keratometry, A scan biometry (IOL Master, Carl Zeiss Meditec Inc., Dublin, CA), and AS-OCT (Visante, version 2.0). 
For inclusion, all enrolled subjects met the following criteria: BCVA of 20/30 or better, open angle by gonioscopy, no existing pathology by slit-lamp, no significant media opacity that obscured fundus examination, and no retinal pathology. Exclusion criteria were a history of any intraocular surgery, including laser treatment, as well as the use of topical drugs affecting pupil diameter, and history of ocular disease or trauma. If both eyes qualified for the study, one eye was chosen at random. More details have been reported previously. 3 Our study was approved by the Institutional Review Board of the Asan Medical Center (Seoul, Korea), and followed the tenets of the Declaration of Helsinki. 
Imaging of the Anterior Segment by OCT
All imaging was performed under constant dim light (0.5 cd/m2), with the patient in a sitting position. Images were captured at the nasal and temporal angle quadrants (3 and 9 o'clock meridians, nasal-temporal angles at 0 to 180°) using an AS OCT operating in the enhanced AS single mode (scan length 16 mm, 256 A-scans). Internal fixation was used in all subjects, and all scans were taken by a single well-trained operator who was masked to other clinical findings to minimize operator-related measurement variability. Three images were acquired from each eye, and the highest-quality image, defined as showing good visibility of the scleral spur, was selected for analysis. A single examiner (JHS), who was masked to other test results and all clinical information of the participants, analyzed all images. Image J software (version 1.44, National Institutes of Health, Fig. 1) was used to measure anterior chamber depth (ACD), iris cross-sectional area (IA), iris thickness at 750 and 1500 μ from the scleral spur (IT750, 1500), iris curvature (IC), lens vault (LV), and anterior chamber area (AA).  
Figure 1.
 
Anterior segment parameters measured by AS OCT and calculated using Image J software. SS, scleral spur.
Figure 1.
 
Anterior segment parameters measured by AS OCT and calculated using Image J software. SS, scleral spur.
ACD was defined as the distance from the corneal endothelium to the anterior surface of the lens capsule. The scleral spur was defined as the point at which a change in curvature of the inner surface of the angle wall became apparent; it often presented as an inward protrusion of the sclera. 9 After locating the scleral spur, IT750 and IT1500 were defined as iris thickness measured at 750 and 1500 μ from the spur, respectively. 10 IA was defined as the cross-sectional area of the nasal and temporal sides. IC was defined as the maximum perpendicular distance between the iris pigment epithelium and the line connecting the most peripheral to the most central point of the epithelium, LV was defined as the perpendicular distance between the anterior pole of the crystalline lens and the horizontal line joining the 2 scleral spurs, 11 and angle-opening distance (AOD500) was defined as the linear distance between the point of the inner corneoscleral wall (which is 500 μm anterior to the scleral spur) and the iris. AOD500 was provided by the manufacturer.  
Statistical Analysis
All statistical analysis was performed with SAS version 9.1 (SAS Inc., Cary, NC) and SPSS version 15.0 (SPSS Inc., Chicago, IL). The slopes of each parameter with age, adjusted for axial length and sex, were derived to assess age-dependent differences by use of a linear mixed effect model. Based on the absolute slopes of the various AS-OCT parameters, normalized slopes were calculated as (absolute slope)/(mean parameter value). This allowed us to compare the relative rates of change of all parameters. Univariate and multivariate regression analysis was performed to evaluate the factors associated with ACA narrowing. ACA narrowing was defined as AOD500 at the temporal angle. P values less than 0.05 were considered significant. Confidence intervals are presented where appropriate. 
Results
Of the 388 subjects, 136 were men and 252 women, and all were Asian (Koreans). The average age ± SD of the participants was 66.0 ± 11.3 years. Table 1 shows the averages and SDs of the AS parameters in the different age groups. ACD, AA, and axial length had a tendency to decrease as subjects got older, while LV, IC, IA, and IT750, 1500 tended to increase. 
Table 1.
 
Anterior Segment Parameters (Mean ± SD) in the Different Age Groups, as Determined by AS-OCT
Table 1.
 
Anterior Segment Parameters (Mean ± SD) in the Different Age Groups, as Determined by AS-OCT
Total (388) <50 Yrs. (41) 50∼60 Yrs. (49) 60∼70 Yrs. (140) 70∼80 Yrs. (118) ≥80 Yrs. (40)
Age Group Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD
ACD (mm) 2.834 0.522 3.337 0.363 2.936 0.416 2.849 0.507 2.693 0.495 2.554 0.535
LV (mm) 0.459 0.377 0.170 0.212 0.349 0.310 0.432 0.372 0.561 0.375 0.684 0.378
IC (mm) 0.103 0.076 0.026 0.029 0.084 0.075 0.103 0.069 0.130 0.079 0.126 0.069
IT750 (mm) 0.458 0.051 0.426 0.046 0.453 0.053 0.461 0.051 0.467 0.051 0.460 0.044
IT1500 (mm) 0.527 0.053 0.497 0.043 0.516 0.054 0.527 0.055 0.539 0.052 0.537 0.047
IA (mm2) 3.054 0.720 2.963 0.752 2.710 0.597 3.065 0.717 3.188 0.685 3.133 0.813
AA (mm2) 16.464 3.669 19.715 2.064 17.414 3.202 16.687 3.568 15.273 3.599 14.701 3.532
Mean K (diopter) 44.041 1.965 43.140 2.749 43.937 1.735 44.079 1.907 44.240 1.831 44.369 1.663
AL (mm) 24.002 1.811 26.019 2.977 24.183 1.379 23.951 1.850 23.519 0.997 23.312 0.645
Table 2 gives the slopes of the AS-OCT parameters with age adjusted for the effects of sex and axial length. ACD and AA had negative slopes (P < 0.0001, <0.0001), and LV, IC, IT750, 1500, and IA had positive slopes (all P < 0.05). However, the mean keratometry value did not change significantly in the different age groups. Thus, all the analyzed AS parameters, except mean keratometry value, changed significantly with age when adjusted by axial length and sex. Of these parameters, IC, ACD, LV, and AA changed the most when analyzed by normalized slope. 
Table 2.
 
Absolute and Normalized Slopes of Anterior Segment Parameters Adjusted by AL and Sex in Terms of Age as Determined by AS-OCT (with Confidence Intervals and P Values for Absolute Slopes)
Table 2.
 
Absolute and Normalized Slopes of Anterior Segment Parameters Adjusted by AL and Sex in Terms of Age as Determined by AS-OCT (with Confidence Intervals and P Values for Absolute Slopes)
Absolute Slope SE CI P Value Normalized Slope
LL UL
ACD −0.0119 0.0023 −0.0164 −0.0075 <0.0001 −5.2810
LV 0.0084 0.0017 0.0051 0.0118 <0.0001 4.9720
IC 0.0019 0.0003 0.0012 0.0025 <0.0001 5.4638
IT750 0.0006 0.0003 0.0001 0.0011 0.0212 2.3143
IT1500 0.0008 0.0003 0.0003 0.0013 0.0028 3.0132
IA 0.0131 0.0036 0.0060 0.0202 0.0003 3.6247
Mean K −0.0016 0.0090 −0.0193 0.0161 0.8596 −0.1770
AA −0.0845 0.0163 −0.1164 −0.0526 <0.0001 −5.1946
LV and ACD values showed strong correlation. IT750, 1500, and IA values also showed strong correlation. To overcome this multicollinearity, ACD, IT1500, and IA were excluded in regression analysis. In univariate regression analysis, LV, IC, IT750, age, IA, and axial length were associated significantly with ACA narrowing. All these factors were incorporated into a multivariate model, which showed that LV, IC, age, and axial length were associated significantly with ACA narrowing (Table 3). 
Table 3.
 
Univariate and Multivariate Linear Regression Analysis of the Association between Various Parameters and Anterior Chamber Angle Narrowing (AOD500)
Table 3.
 
Univariate and Multivariate Linear Regression Analysis of the Association between Various Parameters and Anterior Chamber Angle Narrowing (AOD500)
Coefficient SE 95% CI P Value
LL UL
Univariate analysis
LV −0.542 0.036 −0.613 −0.471 <0.0001
IC −0.03 0.008 −0.046 −0.014 <0.0001
IT750 −1.885 0.321 −2.407 −1.144 <0.0001
Age −0.013 0.001 −0.015 −0.01 <0.0001
Mean K −0.030 0.008 −0.046 −0.014 <0.0001
AXL 0.082 0.008 0.066 0.098 <0.0001
Multivariate analysis
LV −0.215 0.045 −0.304 −0.126 <0.0001
IC −1.502 0.225 −1.944 −1.06 <0.0001
Age −0.003 0.225 −0.006 −0.001 0.009
AL 0.029 0.007 0.015 0.044 <0.0001
Discussion
Unlike primary open-angle glaucoma, PACG without other identifiable cause is observed rarely in young patients and mainly is a disease of the old. Therefore, aging may be related significantly to the pathogenesis of PACG. Reduction of ACD and narrowing of the ACA with age have been demonstrated with several devices, including optical pachymeters, Orbscan II systems, and AS OCT. 3,1214 AS OCT is an imaging device that reveals the configuration of cornea, ACA, anterior surface of the lens, and iris. Currently, manufacturers of AS OCT provide ACD and various ACA parameters, including AOD500, with minimal user input. Additionally, we calculated several indicators that can estimate AS features, such as LV and IC, IT, IA, and AA. Iris bowing was measured by IC. The main advantage of AS OCT over ultrasound biomicroscopy (UBM) is that it can display all the features of the AS in a single frame, and does not require eye contact or a supine position during imaging, which may alter the configuration of the ACA. 
When we compared the different age groups, ACD and IA decreased, and LV, IC, and IT increased as subjects aged. All such changes would force the anterior chamber to narrow and reduce its size. It is noteworthy that the eyes of the older participant groups had shorter axial lengths. Eyes with shorter axial lengths tend to have smaller anterior chamber dimensions. 1518 Sex also is known to affect anterior chamber dimensions. 1,14 Hence, we adjusted for the effects of axial length and sex to explore the effects of aging on AS parameters when calculating the slopes of these parameters with age. After adjusting for the effects of axial length and sex, ACD and AA had significantly negative slopes, and LV, IC, IT750, 1500, and IA significantly positive slopes. However, the mean keratometry value did not change significantly. Thus, we may speculate that the changes of LV, dimensions and configuration of the iris were responsible for the reduction of AA, in other words, AC dimensions. 
The various parameters have different units and scales, and thus the extents of their changes are not comparable. Therefore, we calculated normalized slopes to assess the relative rates of change of the parameters. IC, ACD, LV, and AA underwent relatively greater change than IT and IA when analyzed by normalized slope. Given that AA is determined by other parameters, and ACD is determined largely by LV, since the mean keratometry value did not change significantly with age, the main contributions to the decline in AA came from LV and IC. Although they changed less, IT and IA increased significantly with age, and this may have contributed to the reduction of AC dimensions. 
Since the iris and lens are neighboring structures, the changes of iris-related parameters and lens position may be correlated. For instance, forward movement of the lens may increase iridolenticular contact, which may cause LV and IC to increase at the same time. We, therefore, performed a multivariate analysis to explore the relationship between these parameters and ACA narrowing. According to the multivariate analysis, LV and IC are associated independently with ACA narrowing. In previous studies, IC was shown to be related to ACA narrowing independently of ACD. 17 Thus, our findings were in line with that conclusion. However, lens position was not included in that study, and our analysis revealed that LV and IC were independent factors related to ACA narrowing. 
In summary, the iris underwent significant changes with age; specifically, peripheral iris thickness, iris bowing, cross-sectional iris area, and lens vault increased with age after adjusting for axial length and sex. Of these changes, the changes of the lens vault and iris bowing were more prominent than those of the other parameters. Also lens vault and iris bowing values were associated independently with ACA narrowing. Therefore, the reduction of AC dimensions and ACA narrowing may be caused by multiple factors, the strongest of which are LV and iris bowing. Increased LV, IT, IA, and IC were shown to be related to ACA narrowing in previous studies. 10,11,1517 In our study, we confirmed that these anatomical predisposing conditions increase with age. 
It would be desirable to evaluate the effect of aging by longitudinal follow-up. However, it is difficult to follow the same subjects for several decades using the same measurement instruments in the actual clinical setting, and as far as we know no one has reported such longitudinal studies. We, like other investigators, recruited a relatively large number of participants of various ages to determine the effect of age on AS parameters. 1214 Therefore, this is a limitation of the current cross-sectional study, and the outcomes should be interpreted with caution. In addition, our data were derived from a single ethnic population (Koreans), and this must be kept in mind when generalizing from our results. Another limitation of the current study is that, since AS OCT has limited tissue penetration and scan depth, the ciliary body and posterior surface of the lens could not be well visualized. Finally, as our study was clinic-based, not population-based, our sampling may have suffered from selection bias despite the consecutive enrollment. However, since the subjects were recruited in a general ophthalmology clinic for routine eye examination or mild external ocular discomfort, such as dryness or blepharoconjunctivitis, we believe these pre-examination conditions did not affect the outcomes. 
In conclusion, aging substantially affects AS parameters. The most prominent changes are increases of LV and IC. IT and IA also increase. All these changes lead to a reduction in AC dimensions and a narrowing of the ACA. These changes may help to explain why aging is a significant risk factor for PACG. 
References
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Markowitz SN Morin JD . Angle-closure glaucoma: relation between lens thickness, anterior chamber depth and age. Can J Ophthalmol . 1984;19:300–302. [PubMed]
Cheon MH Sung KR Choi EH Effect of age on anterior chamber angle configuration in Asians determined by anterior segment optical coherence tomography; clinic-based study. Acta Ophthalmol . 2010;88:205–210. [CrossRef]
Kim DY Sung KR Kang SY Characteristics and reproducibility of anterior chamber angle assessment by anterior-segment optical coherence tomography. Acta Ophthalmol . 2011;89:435–441. [CrossRef] [PubMed]
Park SB Sung KR Kang SY Jo JW Lee KS Kook MS . Assessment of narrow angles by gonioscopy, Van Herick method and anterior segment optical coherence tomography. Jpn J Ophthalmol . 2011;55:343–350. [CrossRef] [PubMed]
Lee KS Sung KR Kang SY Cho JW Kim DY Kook MS . Residual anterior chamber angle closure in narrow-angle eyes following laser peripheral iridotomy: anterior segment optical coherence tomography quantitative study. Jpn J Ophthalmol . 2011;55:213–219. [CrossRef] [PubMed]
Narayanaswamy A Sakata LM He MG Diagnostic performance of anterior chamber angle measurements for detecting eyes with narrow angles: an anterior segment OCT study. Arch Ophthalmol . 2010;128:1321–1327. [CrossRef] [PubMed]
Leung CK Cheung CY Li H Dynamic analysis of dark-light changes of the anterior chamber angle with anterior segment OCT. Invest Ophthalmol Vis Sci . 2007;48:4116–4122. [CrossRef] [PubMed]
Sakata LM Lavanya R Friedman DS Assessment of the scleral spur in anterior segment optical coherence tomography images. Arch Ophthalmol . 2008;126:181–185. [CrossRef] [PubMed]
Wang B Sakata LM Friedman DS Quantitative iris parameters and association with narrow angles. Ophthalmology . 2010;117:11–17. [CrossRef] [PubMed]
Nongpiur ME He M Amerasinghe N Lens vault, thickness, and position in Chinese subjects with angle closure. Ophthalmology . 2011;118:474–479. [CrossRef] [PubMed]
He M Huang W Zheng Y Alsbirk PH Foster PJ . Anterior chamber depth in elderly Chinese: the Liwan eye study. Ophthalmology . 2008;115:1286–1290. [CrossRef] [PubMed]
Rufer F Schröder A Klettner A Frimpong-Boateng A Roider JB Erb C . Anterior chamber depth and iridocorneal angle in healthy White subjects: effects of age, gender and refraction. Acta Ophthalmol . 2010;88:885–890. [CrossRef] [PubMed]
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Footnotes
 The authors have no proprietary interest or financial support in the development or marketing of instruments or equipment mentioned in this article, or any competing instruments or pieces of equipment.
Footnotes
 Disclosure: J.H. Sun, None; K.R. Sung, None; S.-C. Yun, None; M.H. Cheon, None; H.W. Tchah, None; M.J. Kim, None; J.Y. Kim, None
Figure 1.
 
Anterior segment parameters measured by AS OCT and calculated using Image J software. SS, scleral spur.
Figure 1.
 
Anterior segment parameters measured by AS OCT and calculated using Image J software. SS, scleral spur.
Table 1.
 
Anterior Segment Parameters (Mean ± SD) in the Different Age Groups, as Determined by AS-OCT
Table 1.
 
Anterior Segment Parameters (Mean ± SD) in the Different Age Groups, as Determined by AS-OCT
Total (388) <50 Yrs. (41) 50∼60 Yrs. (49) 60∼70 Yrs. (140) 70∼80 Yrs. (118) ≥80 Yrs. (40)
Age Group Mean SD Mean SD Mean SD Mean SD Mean SD Mean SD
ACD (mm) 2.834 0.522 3.337 0.363 2.936 0.416 2.849 0.507 2.693 0.495 2.554 0.535
LV (mm) 0.459 0.377 0.170 0.212 0.349 0.310 0.432 0.372 0.561 0.375 0.684 0.378
IC (mm) 0.103 0.076 0.026 0.029 0.084 0.075 0.103 0.069 0.130 0.079 0.126 0.069
IT750 (mm) 0.458 0.051 0.426 0.046 0.453 0.053 0.461 0.051 0.467 0.051 0.460 0.044
IT1500 (mm) 0.527 0.053 0.497 0.043 0.516 0.054 0.527 0.055 0.539 0.052 0.537 0.047
IA (mm2) 3.054 0.720 2.963 0.752 2.710 0.597 3.065 0.717 3.188 0.685 3.133 0.813
AA (mm2) 16.464 3.669 19.715 2.064 17.414 3.202 16.687 3.568 15.273 3.599 14.701 3.532
Mean K (diopter) 44.041 1.965 43.140 2.749 43.937 1.735 44.079 1.907 44.240 1.831 44.369 1.663
AL (mm) 24.002 1.811 26.019 2.977 24.183 1.379 23.951 1.850 23.519 0.997 23.312 0.645
Table 2.
 
Absolute and Normalized Slopes of Anterior Segment Parameters Adjusted by AL and Sex in Terms of Age as Determined by AS-OCT (with Confidence Intervals and P Values for Absolute Slopes)
Table 2.
 
Absolute and Normalized Slopes of Anterior Segment Parameters Adjusted by AL and Sex in Terms of Age as Determined by AS-OCT (with Confidence Intervals and P Values for Absolute Slopes)
Absolute Slope SE CI P Value Normalized Slope
LL UL
ACD −0.0119 0.0023 −0.0164 −0.0075 <0.0001 −5.2810
LV 0.0084 0.0017 0.0051 0.0118 <0.0001 4.9720
IC 0.0019 0.0003 0.0012 0.0025 <0.0001 5.4638
IT750 0.0006 0.0003 0.0001 0.0011 0.0212 2.3143
IT1500 0.0008 0.0003 0.0003 0.0013 0.0028 3.0132
IA 0.0131 0.0036 0.0060 0.0202 0.0003 3.6247
Mean K −0.0016 0.0090 −0.0193 0.0161 0.8596 −0.1770
AA −0.0845 0.0163 −0.1164 −0.0526 <0.0001 −5.1946
Table 3.
 
Univariate and Multivariate Linear Regression Analysis of the Association between Various Parameters and Anterior Chamber Angle Narrowing (AOD500)
Table 3.
 
Univariate and Multivariate Linear Regression Analysis of the Association between Various Parameters and Anterior Chamber Angle Narrowing (AOD500)
Coefficient SE 95% CI P Value
LL UL
Univariate analysis
LV −0.542 0.036 −0.613 −0.471 <0.0001
IC −0.03 0.008 −0.046 −0.014 <0.0001
IT750 −1.885 0.321 −2.407 −1.144 <0.0001
Age −0.013 0.001 −0.015 −0.01 <0.0001
Mean K −0.030 0.008 −0.046 −0.014 <0.0001
AXL 0.082 0.008 0.066 0.098 <0.0001
Multivariate analysis
LV −0.215 0.045 −0.304 −0.126 <0.0001
IC −1.502 0.225 −1.944 −1.06 <0.0001
Age −0.003 0.225 −0.006 −0.001 0.009
AL 0.029 0.007 0.015 0.044 <0.0001
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