Assessment and comparison of anterior chamber dimensions using various imaging techniques.
ABSTRACT To assess and compare the horizontal dimensions of the anterior chamber by different anterior segment imaging techniques.
Eighty eyes of 40 patients without any ocular disease or previous ocular surgery were recruited and three consecutive measurements of internal anterior chamber diameter and white-to-white distance (WTW) parameters were determined.
Mean internal anterior chamber diameter was 11.80 +/- 0.39, 11.56 +/- 0.47, and 11.61 +/- 0.58 mm with Visante-OCT, SL-OCT, and Pentacam, respectively. Mean WTW distance was 11.87 +/- 0.35 and 11.65 +/- 0.32 mm by IOLMaster and OrbscanIIz, respectively. There was no significant difference between Visante-OCT and Pentacam, IOLMaster, and OrbscanIIz (P = .125, .918, and .314). However, detection of mean internal anterior chamber diameter was significantly greater by Visante-OCT than SL-OCT (P = .026). All devices displayed a high intrasession repeatability (repeated measured ANOVA, P > .05).
Internal anterior chamber diameter measurements using Visante-OCT, SL-OCT, and Pentacam, and WTW measurements using IOLMaster and OrbscanIIz were easy to handle and demonstrated good repeatability. Although similar results of horizontal anterior chamber diameter were determined by Visante-OCT, Pentacam, IOLMaster, and OrbscanIIz, the inter-device differences should be considered during clinical practice.
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ABSTRACT: To compare 2 manual methods and 2 automated devices for measuring the horizontal corneal diameter (white-to-white [WTW] distance). Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. In 100 eyes of 61 patients, the WTW distance was measured independently by 2 examiners using the following techniques: the Holladay-Godwin gauge, a measuring caliper, Zeiss IOLMaster, and Orbscan II topography system (Bausch & Lomb). The results were compared with measurements on magnified slitlamp photographs of the anterior eye segment. Statistical evaluation was performed using the Bland-Altman method for comparison of measurement techniques. The mean horizontal corneal diameter was 11.91 mm +/- 0.71 (SD) with the measuring caliper, 11.8 +/- 0.60 mm with the Holladay-Godwin gauge, 11.78 +/- 0.43 mm with the Orbscan II, and 12.02 +/- 0.38 mm with the IOLMaster. The coefficient of inter-rater repeatability was 1.30 for the caliper, 0.92 for the Holladay-Godwin gauge, 0.76 for the Orbscan II, 0.50 for the IOLMaster, and 1.16 for the manual measurement in anterior segment images. The results obtained with the caliper were statistically significantly different between the 2 examiners (P<.001). The measurements of examiner 2 using the caliper were significantly different from the measurements of the same examiner using the Holladay-Godwin gauge. This was not the case with the 2 automated devices. Automated measurement of the WTW distance provides more precise results than measurements using manual methods. The Zeiss IOLMaster had the highest reliability in measuring corneal diameter.Journal of Cataract [?] Refractive Surgery 02/2004; 30(2):374-80. · 2.53 Impact Factor
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ABSTRACT: To measure anterior chamber (AC) width and other dimensions relevant to the sizing of phakic intraocular lenses (IOLs) with a high-speed optical coherence tomography (OCT) system. Cross-sectional observational study. Both eyes of 20 normal volunteers. A novel high-speed (4000 axial scans/second) OCT prototype was developed for anterior segment scanning. The system uses long wavelength (1310 nm) for deeper angle penetration, rectangular scanning for undistorted imaging, and short image acquisition time (0.125 seconds) to reduce motion error. Three horizontal cross-sectional OCT images (15.5 mm wide and 6 mm deep) of the anterior segment were obtained from each eye with real-time image display to guide centration on the corneal apex. Image processing software was developed to correct for image warping resulting from index transitions. Anterior chamber dimensions were measured using computer calipers by 3 expert raters (ophthalmologists). Analysis of variance was used to determine interrater, interimage, right versus left eye, and intersubject standard deviation (SD) of OCT measurements. Anterior chamber width (recess to recess), AC depth, and crystalline lens vault as measured by OCT; external white-to-white (WTW) corneal diameter (CD) as measured by Holladay-Godwin gauge. The mean AC width was 12.53+/-0.47 mm (intereye SD), and the mean corneal diameter was 11.78+/-0.57 mm. Optical coherence tomography measurement of AC width has good repeatability from image to image (SD, 0.134 mm), but there was significant difference between raters (SD, 0.215 mm). Estimation of AC width from WTW CD by linear regression was relatively inaccurate (residual SD, 0.41 mm). The mean AC depth was 2.99+/-0.323 mm (intereye SD), with repeatability of less than 0.001 mm (interimage SD), and the mean crystalline lens vault was 0.39+/-0.27 mm with 0.023 mm repeatability. Reproducible OCT AC biometry was demonstrated using a high-speed OCT prototype. Further improvement in reproducibility may be achieved by automating the measurements with a computer. Direct OCT AC width measurement may improve sizing of angle-supported AC IOLs over conventional estimation by WTW CD. The measurement of AC depth and lens vault also may be useful for other types of phakic AC IOLs.Ophthalmology 03/2005; 112(2):238-44. · 5.56 Impact Factor
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ABSTRACT: To obtain measurements of the white-to-white distance and the anterior chamber and ciliary sulcus diameters in phakic human eyes obtained post-mortem to find a correlation between these measurements. David J. Apple, MD Laboratories for Ophthalmic Devices Research, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. Twenty-two phakic human eyes obtained from eye banks within 24 hours of death were evaluated. The following measurements were performed: white-to-white distance, anterior chamber diameter with a plastic sizer after a small limbal incision, and anterior chamber and ciliary sulcus diameters after fixation and sagittal section of the eyes. The first 10 eyes were studied at the 6 o'clock to 12 o'clock meridian and the last 12 eyes, at the 3 o'clock to 9 o'clock meridian. A positive correlation was found between the white-to-white measurements and the anterior chamber diameter in the 10 eyes studied at the 6 o'clock to 12 o'clock meridian but not in the 12 eyes studied at the 3 o'clock to 9 o'clock meridian. The latter is the meridian frequently used by surgeons to perform white-to-white measurements and thus choose the overall size of the phakic intraocular lens to be implanted. No correlation was found between the white-to-white measurements and the ciliary sulcus diameter in the 2 meridians. Experimental studies using cadaver eyes are helpful in evaluating sizing techniques for phakic IOL implantation as well as in better understanding the anatomical relationships between ocular structures.Journal of Cataract [?] Refractive Surgery 10/2004; 30(9):1982-8. · 2.53 Impact Factor