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absorption, leading to insufficient or failed reduction of the IOP. 1 , 6 , 7 Ultrasound biomicroscopy (UBM) using a 50-MHz transducer has a resolution of approximately 20 to 50 μm, which is almost 10 times higher than that of standard ultrasonography (10

Open access
in American Journal of Veterinary Research

anterior segment, including the cornea, iridocorneal angle, iris, posterior chamber, iridociliary sulcus, and ciliary body. 7 Ultrasound biomicroscopy has a resolution 5 to 10 times that of a 10-MHz ultrasound probe. 7 With UBM, resolution to 200 üm is

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in American Journal of Veterinary Research

Ultrasound biomicroscopy operates at frequencies of 50 to 100 MHz and was developed to evaluate the anterior chamber of the human eye. 1 Ultrasound biomicroscopy has been used prior to and after phacoemulsification in humans to evaluate the AOD

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in American Journal of Veterinary Research

Abstract

Objective

To determine anterior chamber ocular measurements of adult porcine globes without histologic fixation by use of ultrasound biomicroscopy scanning.

Sample Population

25 porcine globes obtained at an abattoir.

Procedure

Globes were packed on ice for transport. In the laboratory, globes were trimmed, rinsed with antibiotic solution, secured on a single gauze-fold in a latex holder, then were ultrasonogrammed unreformed. Ultrasound biomicroscopy scanning was done, using a 50-MHz transducer, 17-mm cup, and 2% methyl cellulose.

Results

Average young adult pig external ocular measurements were: nasal-temporal corneal diameter, 16.61mm; superior-inferior corneal diameter, 14.00 mm; nasal-temporal globe diameter, 25.48 mm; superior-inferior globe diameter, 24.48 mm; and axial length 21.64 mm. Ultrasound biomicroscopy anterior chamber measurements were: iris sulcus, 30.45°; ciliary sulcus, 18.89°; central corneal thickness, 0.98 mm; corneal thickness at limbus, 1.19 mm; central iris thickness, 0.58 mm; iris tip to ciliary apex, 1.73 mm; iris tip to iris sulcus origin, 3.83 mm; iris tip to ciliary sulcus origin, 2.98 mm; anterior chamber depth from iris tip to cornea, 2.21 mm; central anterior chamber depth, 2.47 mm; ciliary process mid-thickness, 0.65 mm; ciliary process apex to origin of iris sulcus, 2.32 mm; ciliary process apex to origin of ciliary sulcus, 1.34 mm; zonular bundle diameter, 0.10 mm; and interzonular bundle space, 0.11 mm.

Conclusions

Anatomic anterior chamber measurements and relations in porcine globes can be used to describe trauma, confirm existence of lesions, and help explain theory.

Clinical Relevance

Ultrasound biomicroscopy is a clinical decision aid facilitating noninvasive anatomic or pathologic description without histologic fixation. (Am J Vet Res 1997;58:942–948)

Free access
in American Journal of Veterinary Research

Objective

To compare iridocorneal angle grading systems on the basis of gonioscopy and ultrasound biomicroscopy (UBM).

Design

Original cross-sectional observational study.

Animals

22 dogs.

Procedure

Gonioscopy, goniophotography, and UBM were performed on 38 eyes from dogs without clinical evidence of glaucoma in the eyes examined.

Results

Predominant gonioscopic grades derived from goniophotographs were considered normal (n = 26) and mild (12). Ultrasound biomicroscopy angle measurements ranged from 16 to 38° (mean ± SD, 26.2 ± 4.5°). Ciliary clefts depicted on UBM images were graded as open (n = 4), compact/narrow (23), and closed (11). Significant differences were not found between UBM-derived ciliary cleft grades and goniophotography-derived dysgenesis grades, nor between UBM-derived ciliary cleft grades and subjective gonioscopic grades.

Clinical Implications

Because gonioscopy allows evaluation of the anterior face of the ciliary cleft, whereas UBM provides cross-sectional information of the iridocorneal filtration angle, UBM may yield more information regarding pathogenesis and prognosis of, and preferred management approaches to, glaucoma. Ultrasound biomicroscopy may also be useful as a predictor of glaucoma or to diagnose early stages of glaucoma. (J Am Vet Med Assoc 1998;213:635-638)

Free access
in Journal of the American Veterinary Medical Association

Comments on pathophysiology of angle changes caused by iris bowing We would like to address the article titled, “Ultrasound biomicroscopy of the iridocorneal angle of the eye before and after phacoemulsification and intraocular lens

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in American Journal of Veterinary Research

not required. Ultrasonography performed with ultrasound frequencies of 40 to 60 MHz provides image resolution of approximately 50 μm (similar to that achieved via low-power light microscopy) and is commonly referred to as ultrasound biomicroscopy. 17

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in American Journal of Veterinary Research

Evaluating corneal thickness is important in both clinical and research settings. There are a variety of methods to measure corneal thickness in vivo, such as high-resolution ultrasound biomicroscopy and confocal microscopy. 1,2 Inadvertent

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in American Journal of Veterinary Research

study requiring measurements, there was concern about intraobserver reproducibility of ocular dimensions. As noted in previous studies, 25 , 34 , 35 ultrasound biomicroscopy was considered to have acceptable intraobserver and interobserver repeatability

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in American Journal of Veterinary Research

increased IOP in dogs, 5 cats, 6 and humans. 7,8 Results of an ultrasound biomicroscopy study 9 indicate that, in dogs, a slight narrowing of the ciliary cleft entry is associated with pupil dilation induced by topical instillation of tropicamide in the

Full access
in American Journal of Veterinary Research