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Vitreous Chamber Depth (vitreous + chamber_depth)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Refractive error and ocular biometry in Jordanian adults

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 4 2005
Edward A. H. Mallen
Abstract The aim of this study was to establish the prevalence of refractive errors in Jordanian adults of working age, and to study the ocular biometric correlates of refractive error in this population. Refractive error and ocular biometry were measured in 1093 Jordanian adult subjects aged 17,40 years to determine the prevalence of refractive error, and explore structural correlations of ametropia. Refractive error was measured using a Grand-Seiko GR-3100K closed-view infrared autorefractor. Ocular component measurements were made using A-scan ultrasonography and autokeratometry. The prevalence of myopia [spherical equivalent refraction (SER) less than ,0.50 DS] and hyperopia (SER greater than +0.50 DS) was 53.71 and 5.67% respectively; 40.62% of the sample was emmetropic (refraction between +0.50 D and ,0.50 D inclusive in both principal meridians). The distribution of SER was found to show marked leptokurtosis, exhibiting a peak between plano and 1 D of myopia. Corneal radius, anterior chamber depth, crystalline lens thickness, vitreous chamber depth and axial length (AL) parameters were normally distributed in the population studied. AL to corneal curvature ratio was not normally distributed, and showed marked leptokurtosis. Linear regression analysis showed that AL correlated most closely with spherical equivalent refractive error. This study has established a database of refractive error prevalence and ocular biometric correlates of ametropia in a Middle Eastern population of working age. [source]

Cling film as a barrier against CJD in corneal contact A-scan ultrasonography

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2003
Asha Rani
Abstract Purpose: To determine the validity of covering a corneal contact transducer probe with cling film as protection against the transmission of Creutzfeldt,Jakob disease (CJD). Methods: The anterior chamber depth, lens thickness and vitreous chamber depth of the right eyes of 10 subjects was recorded, under cycloplegia, with and without cling film covering over the transducer probe of a Storz Omega Compu-scan Biometric Ruler. Measurements were repeated on two occasions. Results: Cling film covering did not influence bias or repeatability. Although the 95% limits of agreement between measurements made with and without cling film covering tended to exceed the intrasessional repeatability, they did not exceed the intersessional repeatability of measurements taken without cling film. Conclusions: The results support the use of cling film as a disposable covering for corneal contact A-scan ultrasonography to avoid the risk of spreading CJD from one subject to another. [source]

Relative Axial Myopia Induced by Prolonged Light Exposure in C57BL/6 Mice

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2010
Xiangtian Zhou
Ambient lighting is essential for ocular development in many species, however, disruption in diurnal lighting cycle can affect the development in refraction and axial growth of the eye. This study investigated the effects of prolonged daily lighting on refraction and various optical components of the eye by raising C57BL/6 mice under three different light/dark cycles (18/6, 12/12 and 6/18). Egr-1 mRNA expression, apoptosis and histology of the retina and size of the scleral fibrils were evaluated in these three lighting cycles. Results showed that there was a trend of myopic development, increasing vitreous chamber depth and thinning of the retina in eyes from 6/18 to 18/6 groups. Retinal Egr-1 mRNA expression and diameter of scleral fibrils were reduced with the prolongation of daily lighting from 6/18 to 18/6. However, retinal apoptosis was not detected in all the groups. These results suggest that prolonged lighting can induce axial myopia in inbred mice. This model, which uses mice with similar genetic backgrounds, provides an alternative to the currently available models and therefore is useful for evaluation of refractive errors caused by changes in environmental illumination. [source]

Relationships between ocular dimensions and adult stature among participants in the Reykjavik Eye Study

ACTA OPHTHALMOLOGICA, Issue 6 2005
Thor Eysteinsson
Abstract. Purpose:,To examine the relationships between adult stature, age and ocular dimensions in a large homogenous, white population. Methods:,We used the national population census for Reykjavik to select a random sample of adults aged 50 years or older. A total of 846 persons were examined. Scheimpflug images were used to measure anterior chamber depth. Ultrasound was used to measure axial length, lens thickness and vitreous chamber depth. An autorefracto-keratometer was used to measure autorefractive and keratometric values, including the radius of the corneal curvature. Stereo fundus photographs were taken of the optic disc and measurements of the disc diameters were made using computer software. Results:,Height correlated positively with axial length in the multivariate model (B = 0.020, 95% CI 0.006,0.034, p < 0.01). Both age and height showed significant correlations with vitreous chamber depth, where the correlation with age was negative (B = , 0.016, 95% CI , 0.006 to , 0.025, p < 0.005) and the correlation with height was positive (B = 0.019, 95% CI 0.005,0.034, p < 0.01). Height also showed a positive correlation with the radius of the corneal curvature (B = 0.008, 95% CI 0.004,0.011, p < 0.001). Anterior chamber depth had a negative correlation with age (B = , 0.013, 95% CI , 0.010 to , 0.016, p < 0.001), whereas lens thickness had a significant positive correlation with age (B = 0.019, 95% CI 0.016,0.023, p < 0.001). We found a significant negative correlation between axial length and refraction/spherical equivalent (r = , 0.595, p < 0.0001). Discussion:,Our results indicate that there is a significant relationship between height and several ocular dimensions in this adult population and confirms a negative correlation between axial length and refraction. [source]