Mean Anterior Chamber Depth Values Research Articles

Anterior Ocular Biometrics Using Placido-scanning-slit System, Rotating Scheimpflug Tomography, and Swept-source Optical Coherence Tomography.

PurposeTo compare anterior biometry measurements using placido-scanning-slit topography, rotating Scheimpflug tomography, and swept-source optical coherence tomography.MethodsA retrospective review consisted of 80 eyes of 49 participants who underwent anterior chamber depth (ACD), central corneal thickness (CCT), and keratometry examination on the same day. We used placido-scanning-slit topography (ORBscan II), rotating Scheimpflug tomography (Pentacam HR), and swept-source optical coherence tomography (CASIA SS-1000). The intraclass correlation coefficients and Bland-Altman plots were used to evaluate the agreement and differences between measurements.ResultsThe mean ACD values were 2.88 ± 0.43, 2.82 ± 0.50, and 2.68 ± 0.44 mm; and the mean CCT values were 536.96 ± 31.19, 543.79 ± 31.04, and 561.41 ± 32.60 μm; and the mean keratometry (Km) were 43.81 ± 1.69, 43.81 ± 1.77, and 44.65 ± 1.95 diopters; as measured by CASIA SS-1000, Pentacam HR, and ORBscan II, respectively. Among the three devices, ACD was deepest to shallowest in the order of CASIA SS-1000, Pentacam HR, and ORBscan II (p < 0.05). The CCT was thickest to thinnest in the order of ORBscan II, Pentacam HR, and CASIA SS-1000 (p < 0.05). No significant differences in Km values were examined between CASIA SS-1000 and Pentacam HR, whereas ORBscan II overestimated Km with a statistically significant difference compared to the other two devices.ConclusionsHigh level of agreement was found between CASIA SS-1000 and Pentacam HR for anterior parameters, including ACD, CCT, and Km, suggesting interchangeability. However, ORBscan II measurements differed considerably with the measurements obtained from the other two devices; therefore, it should not be used interchangeably. However, further studies with repeatability test should be considered in order to elucidate the reliability of each device.

Changes in Anterior Chamber Depth after Phacoemulsification in Pseudoexfoliative Eyes and their Effect on Accuracy of Intraocular Lens Power Calculation.

Objectives: To compare anterior chamber depth (ACD) changes after phacoemulsification surgery in patients with pseudoexfoliation syndrome (PEX) and normal patients using an anterior segment imaging method. Another aim of this study was to evaluate the effect of these changes on the accuracy of intraocular lens (IOL) power calculation and postoperative refraction.Materials and Methods: Twenty-two eyes of 22 patients with PEX and 30 eyes of 30 normal patients who underwent uneventful phacoemulsification surgery and IOL implantation were included in the study. The ACD of all patients was evaluated preoperatively and at 3 months postoperatively with the ALLEGRO Oculyzer (WaveLight® Oculyzer™ II, Alcon, Novartis)-Scheimpflug imaging system.Results: The postoperative mean ACD values were significantly larger than the preoperative ACD values in both groups (p<0.001 for both groups). The pre- to postoperative change in ACD was 0.46±0.3 mm in the PEX group, which was a larger change than seen in the normal patients (0.12±0.1 mm) (p=0.04). The mean absolute errors (MAE) calculated with different IOL formulas (SRK/T, Haigis, Hoffer and Holladay 1 formulas) were comparable and no statistically significant difference was observed between the two groups (p=0.21).Conclusion: Phacoemulsification induces more significant ACD changes in patients with PEX compared to normal patients. However, the MAE did not differ significantly between the groups.

Anterior segment parameters and eyelids in systemic sclerosis.

To evaluate main numerical parameters of anterior segment and the effects of eyelid skin changes on these parameters in patients with systemic sclerosis (SSc). Thirty-four patients with SSc and 34 healthy individuals were enrolled. Besides full eye examination, anterior segment measurements including anterior chamber depth (ACD), anterior chamber volume, anterior chamber angle width, central corneal thickness, pupil size, corneal volume and keratometry were obtained using a Sirius Scheimpflug/Placido photography-based topography system. Eyelid thickness was evaluated using the scala of the modified Rodnan skin score and the patients were subgrouped with respect to these scores to evaluate the effect of eyelid thickening on the anterior segment parameters. Age and sex distributions of the groups were similar (p>0.05). SSc patients had steeper and thinner corneas, smaller corneal volumes, narrower, shallower and smaller anterior segments but only the mean ACD value of right eyes was found significantly less than those of the controls (p=0.047). The mean ACD values of SSc subgroup patients with moderate to severe eyelid thickening (50%) had lower ACD measurements compared to those of control group. (p=0.043 for the right eyes, p=0.070 for the left eyes). However, SSc subgroup patients with none to mild eyelid thickening (50%) had similar anterior segment parameters with control subjects (p>0.05). Anterior chamber parameters of the SSc patients could show significant differences. These differences occur parallel to the eyelid changes but not secondary to it.

Measurements of anterior segment parameters using three different non-contact optical devices in keratoconus patients.

To evaluate the measurements of anterior segment parameters using three different non-contact optical devices in keratoconus patients. A hundred and one eyes of 55 keratoconus patients were enrolled in this study. The mean age was 26.2±8.9 years. The inclusion criteria were keratoconus stage I to III according to the Amsler-Krumeich keratoconus classification. All the measurements were done by the same operator, under the mesopic light condition and repeated with three different optical methods; Visante, Orbscan and Pentacam. The evaluated anterior segment parameters were anterior chamber depth (ACD), central and thinnest corneal thickness (CCT and TCT) and pupil diameter (PD). THE MEAN CCT MEASURED BY VISANTE, ORBSCAN AND PENTACAM WERE AS FOLLOWS: 462.0±48.1µm, 463.9±60.9µm, 476.5±45.3µm, respectively (P=0.873). The mean ACD values were 3.34±0.33mm, 3.26±0.33mm, 3.49±0.40mm, respectively (P=0.118). The mean PD measurements were 5.11±1.14mm, 4.80±0.85mm, 3.80±1.38mm, respectively (P<0.001). The mean TCT measurements of Visante, Orbscan and Pentacam were 437.9±48.2µm, 447.6±60.6µm and 459.9±44.0µm, respectively (P=0.214). The Visante and Orbscan measured CCT similarly, while Pentacam measured CCT thicker than the other two. The Visante measured TCT thinner than the other two devices. In ACD measurements, Orbscan was the one giving the lowest values. PD was measured differently by the devices. Although TCT, CCT and ACD measurements acquired by Visante, Orbscan and Pentacam in keratoconus patients are similar, PD measurements show large differences among the devices.

Central Corneal Thickness, Anterior Chamber Depth, and Pupil Diameter Measurements Using Visante OCT, Orbscan, and Pentacam

To evaluate the agreement among three different optical methods in measuring anterior chamber depth (ACD), central corneal thickness (CCT), and pupil diameter. One hundred eyes of 50 healthy patients (25 men, 25 women) were enrolled in the study. Mean patient age was 25 years (range: 21 to 32 years). Exclusion criteria were history of any intraocular or corneal surgery, contact lens wear, corneal anomalies, and spherical refraction >5.00 diopters (D) or cylindrical refraction >2.00 D. All measurements were done by the same operator under mesopic light conditions and repeated using three different optical methods: Visante optical coherence tomography (OCT) (Carl Zeiss Meditec), Orbscan (Bausch & Lomb), and Pentacam (Oculus Optikgeräte GmbH). Mean CCT as measured by Visante OCT, Orbscan, and Pentacam was 529+/-30.5 microm, 554+/-32.7 microm, and 552+/-29.3 microm, respectively. Mean ACD values were 2.94+/-0.34 mm, 2.84+/-0.33 mm, and 2.98+/-0.33 mm, respectively. Mean pupil diameter measurements were 4.87+/-1.09 mm, 4.0+/-0.67 mm, and 3.05+/-0.59 mm, respectively. The Visante OCT measured CCT thinner and Orbscan measured ACD shallower than the other two methods. All three methods measured pupil diameters significantly different. This study found some statistically significant but clinically insignificant differences among the optical methods assessed. The differences are small and do not influence decisions for refractive surgery in clinical practice.

Anterior Chamber Depth in Elderly Chinese: The Liwan Eye Study

To assess the anterior chamber depth (ACD) and its variation with age, gender, and angle width in elderly Chinese in an urban area of southern China. Cross-sectional study. Adults 50 and older were identified using cluster random sampling in Liwan District, Guangzhou. Gonioscopy was performed before ACD measurements to estimate the geometric angle width according to the Shaffer system. ACD was measured using optical pachymetry. True ACD was calculated by subtracting central corneal thickness from the distance between the anterior corneal epithelium and the anterior lens capsule. Data were presented for the right phakic eyes. Anterior chamber depth and gonioscopy. Among 1405 participants in the study, data from 1248 right eyes were available for analysis. The mean ACD values for men and women were 2.59 mm (95% confidence interval [CI], 2.56-2.62; 25th-75th percentile, 2.37-2.82) and 2.42 mm (95% CI, 2.39-2.44; 25th-75th percentile, 2.21-2.63). Mean ACD declined by 0.09 mm (95% CI, -0.011 to -0.008) per decade (adjusted for gender) and was 0.18 mm (95% CI, -0.213 to -0.141) shallower in women than men (adjusted for age). The ACD was found to be monotonically associated with gonioscopic angle width, decreasing from 2.73 mm (standard deviation [SD], 0.26) in Shaffer grade 4 to 1.94 mm (SD, 0.27) in Shaffer grade 0. There was also a relationship between ACD and refractive error; mean spherical equivalent decreased by 0.030 mm ACD per diopter. This study confirms an inverse association between ACD and age, female gender, and spherical refractive error. Eyes with shallower ACDs had narrower angles.

Comparability and Intra-/Interobserver Reliability of Anterior Chamber Depth Measurements With the Pentacam and IOLMaster

&lt;H4&gt;PURPOSE&lt;/H4&gt; &lt;p&gt;To assess the comparability and intra-/ interobsever reliability of central anterior chamber depth measurements obtained using the Pentacam and IOLMaster.&lt;/p&gt; &lt;H4&gt;METHODS&lt;/H4&gt; &lt;p&gt;Anterior chamber depth was measured in 50 eyes (25 healthy volunteers)—three times on each eye by two independent observers with each method. A total of 12 measurements were performed on each eye. Analysis of variance was used to analyze the data. Mean values, standard deviations, and confidence limits (95% confidence interval) of the two modalities, two observers, and every observer/modality interaction were calculated.&lt;/p&gt; &lt;H4&gt;RESULTS&lt;/H4&gt; &lt;p&gt;The mean anterior chamber depth values were 3.23±0.031 mm for the IOLMaster and 3.21±0.033 mm for the Pentacam. No statistically significant difference was noted in measurements between the two modalities (&lt;i&gt;P&lt;/i&gt;=.291) or between the two observers (&lt;i&gt;P&lt;/i&gt;=.903). Observer/modality interaction was not significant (&lt;i&gt;P&lt;/i&gt;=.643). The confi dence limits for observer 1 were 3.223±0.03 mm and 3.226±0.03 mm for observer 2. The confidence limits were: observer 1/IOLMaster, 3.23±0.04 mm; observer 2/IOLMaster, 3.24±0.04 mm; observer 1/Pentacam, 3.21±0.04 mm; and observer 2/Pentacam, 3.20±0.04 mm. The differences in measurements ranged from -0.14 to +0.10 mm for the IOLMaster and from -0.08 to +0.12 mm for the Pentacam. The worst deviation from the average eye reading of 3.23 mm was only 0.14 (4.3%).&lt;/p&gt; &lt;H4&gt;CONCLUSIONS&lt;/H4&gt; &lt;p&gt;Good agreement exists between anterior chamber depth measurements by the IOLMaster and Pentacam in the assessment of normal eyes, and they offer observer-independent results. Therefore, the modalities are interchangeable. [&lt;cite&gt;J Refract Surg&lt;/cite&gt;. 2008;24:615-618.]&lt;/p&gt; &lt;h4&gt;ABOUT THE AUTHORS&lt;/h4&gt; &lt;p&gt;From Birmingham and Midland Eye Centre, Birmingham (Savant); and Wolverhampton &amp; Midland Counties Eye Infirmary, Wolverhampton (Chavan, Pushpoth, Ilango), United Kingdom.&lt;/p&gt; &lt;p&gt;The authors have no financial or proprietary interest in the materials presented herein.&lt;/p&gt; &lt;p&gt;This study was presented as an E-paper at the International Society of Refractive Surgery of the American Academy of Ophthalmology Annual Regional Meeting; May 26-28, 2006; Istanbul, Turkey.&lt;/p&gt; &lt;p&gt;Correspondence: Vijay Savant, FRCS(Ed), MRCOphth, Birmingham and Midland Eye Centre, Dudley Road, Birmingham B18 7QH, United Kingdom. Tel: 44 1215 543801; Fax: 44 1902 645018; E-mail: &lt;a href="mailto:vijaysavant@hotmail.com"&gt;vijaysavant@hotmail.com&lt;/a&gt;&lt;/p&gt; &lt;p&gt;Received: December 25, 2006&lt;/p&gt; &lt;p&gt;Accepted: July 10, 2007&lt;/p&gt; &lt;p&gt;&lt;b&gt;Posted online: January 15, 2008&lt;/b&gt;&lt;/p&gt;

Validity and Repeatability of Anterior Chamber Depth Measurements With Pentacam and Orbscan

The purpose of this study was to determine the validity and repeatability of anterior chamber depth (ACD) measurements obtained with a novel rotating Scheimpflug camera (Pentacam; Oculus Optikgeräte GmbH, Wetzlar, Germany) to scanning slit topography (Orbscan; Bausch & Lomb, Rochester, NY). ACD in 60 healthy eyes was measured twice by two independent observers with each modality in random order. A total of eight measurements was performed on each eye. The mean differences between measurements, between observers, and between modalities were calculated, and 95% limits of agreement (LoA) were given as mean +/- 1.96 * standard deviation (SD) of the mean. The mean ACD values as determined with the different modalities (+/- SD) were 3.18 +/- 0.38 mm for Pentacam imaging and 3.23 +/- 0.40 for Orbscan. The mean difference between the two modalities was 0.047 mm (LoA: 0.176 to -0.081 mm). Within each modality, the limits of agreement of the differences between individual measurements and between different observers were within 0.073 mm or 4% of total ACD. The total variance in the observed data was 0.145. The variance resulting from interindividual differences in ACD was 85%, as a result of the two different modalities 15%, as a result of different observers 0.007%, and as a result of different measurements 0.007%. In the assessment of normal eyes, the differences of ACD values measured with Orbscan and Pentacam were within clinically acceptable levels, and inter- and intraobserver variability was considerably below clinically significant levels. Thus, these two modalities can be regarded as interchangeable.

Measuring anterior chamber depth with the Orbscan Topography System

Purpose: To assess the reliability of the Orbscan Topography System in measuring anterior chamber depth (ACD).Setting: Department of Ophthalmology, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany.Methods: The Orbscan Topography System is a 3-D, scanning slit beam system for analyzing corneal surfaces as well as structures of the anterior segment, e.g., iris, lens. Reflected surface data points are measured in the x, y, and z axes, creating color-coded true surface topography maps. We measured ACID prior to cataract surgery in 56 eyes of 37 patients (mean age 70.4 years + 13.2 [SD]) using the Orbscan system and, as a control, the Grieshaber Biometric System (ultrasound) and the Jager ACD slitlamp measurement system.Results: Mean ACD values measured with the Orbscan system were 3.23 0.55 mm; ultrasound measurements were 3.27 ± 0.54 mm and Jäger measurements, 3.10 ± 0.55 mm. The average difference between Orbscan and ultrasound values was 0.04 ± 0.15 mm. The correlation coefficient between Orbscan and ultrasound was 0.96 (P < .00001) and between Orbscan and Jäger, 0.899 (P < .0001).Conclusion: The ACID measurements by the Orbscan system were equivalent to common reference measurements.