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The Heidelberg retina tomograph in glaucoma
Ophthal. Physiol. Opt. Vol. 16, No. 4, pp. 355-361, 1996 The College of Optometrists. Published by Elsevier Science Ltd Printed in Great Britain
PII: SO2755408(96)00003-S
Abstracts Papers and posters presented Meeting, UMIST, Manchester,
at the 2 1 st Hospital Optometrists Annual UK, on 29 September1 October 1995
The Heidelberg retina tomograph in glaucoma S. I. Hosking Deparment of Ophthalmology, University of Manchester, Manchester Ml 3 9WH, UK
area (PCA) over a wide range of ametropia, and to investigate whether any of these optic disc parameters are related to axial length and/or ocular refraction. Method: The sample comprised 122 normal subjects, aged 18.5 to 35.4 years, free from any ocular or systemic disease, with refractive errors ranging from +4.00D to -25.75 D. Subjects were divided into four groups; (1) non-myopic controls; (2) myopes without peripapillary crescents: (3) myopes with small peripapillary crescents; and (4) myopes with larger crescents, having a CA at least 40% of the DA. All subjects underwent the following: cornea1 front surface keratometry, A-scan ultrasonography, cycloplegic refraction and fundus photography with the Carl Zeiss Jena camera using Kodak Ektachrome colour-slide film. A CCD camera linked to a computer was used to digitise the fundus slides. Optic disc features were delineated by computer-assisted techniques. Using a ray-tracing method (Bennett et al., 1994) and knowledge of the fundus camera magnification (Rudnicka et al.; 1992), the true dimensions of the optic disc parameters could be determined.
Purpose: To establish the ability of the Heidelberg retina tomograph (HRT) to detect morphological change of the optic nerve head in glaucomatous ~lptic neuropathy and to evaluate glaucomatous nerve fibre layer defects. Introduction: The HRT is a confocal laser scanning microscope designed for three-dimensional imaging and measurement of the in viva fundus. The light sot rce is a diode laser operating at a wavelength of 670mm. Thirtytwo single, two-dimensional sectional images are recorded within 0.032 s with a repetition rate of 20Hz, digitised in a frame of 2.5 X 256 pixels. Sequenual viewing of the plates permits three-dimensional resolution of the image. llse of the HRT enables comparison of change in optic nerve head morphology with change in visual function.
Results: In group 1, DA ranged from 1.36 to 2.88mm2; in group 2, from 1.30 to 2.79 mm*; in group 3, from 1.50 to 5.04 mm’, and in group 4, from 1.21 to 9.22 mm*. Groups 1, 2 and 3 did not differ significantly from each other for any optic disc parameter (values for the other optic disc parameters will be presented). DA and NRA are significantly larger in group 4 than in the other three groups. Cup area did not differ signii ficantly between the groups. DA, NRA and PCA increase with axial length elongation and increasing myopia in groups 3 and 4 only.
Methods: The sample consists of 30 early primary open angle glaucoma subjects showing repeatable glaucomatous field defects on Humphrey 30-2 analysis and 65 glaucoma suspects with normal Humphrey 30-Z fields but with multiple risk factors for the development of glaucoma. All subjects are evaluated using white-on-white and blue-on-yellow visual fields as well as HRT analysis of the optic nerve head and retina at three-month intervals over a 15.month period. Discussion: We have demonstrated the need for consistent image scaling in prospective follow-up (Hosking et al., 1995), a facility to be incorporated in the next software reviston; the importance of selecting an optimum scan; and that the correction of astigmatism required for quality image acquisition results ir image distortion. The application of nerve head analysis software to demonstrate localised wedge-shaped nerve fibre bundle defects is illustrated and further modification of the software to demonstrate more subtle subclmical nerve fibre layer defects will be discussed.
Knowledge of the dimensions of the optic nerve head and Conclusions: peripapillary crescents may aid in the diagnosis of pathologically disturbed optic discs. References
Hosking. S. L., Flanagan, J. G. and O’Donoghue, E. P. (1995). Prospective study design for the HRT: The effect of change in focus setting. Invest. Ophthalmol. Visual Sci. 36, Suppl., 4501.
Bennett, A. G., Rudnicka, A. R. and Edgar, D. F. (1994). Improvements on Littmann’s method of determining the size of retinal features by fundus photography. Graefes Arch. Clin. Exp. Ophthalmol. 232, 361-361. Rudnicka, A. R., Bennett, A. G. and Edgar, D. F. (1992). Construction of a model eye and its applications. Ophthal. Physiol. opt. 12, 485-490.
Dimensional characteristics of the optic nerve head and peripapillary crescents in myopia Alicja R. Rudnicka Applied Vision Research Centre, Department of Optometry and Visual Science, City University, London EClV OHB, UK
Mood, pain and the menstrual cycle: potential confounding factors in automated perimetry? Nancy Guttridge Applied Vision Research Centre, City University, London EClV OHB, UK
Purpose: To establish typical normal values for the optic disc area (DA), neuroretinal rim area (NRA). cup area (CA) and peripapillary crescent
The main purpose of this study was to investigate the effect of the normal human menstrual cycle on the central visual field as measured with
Reference
355
PII: SO2755408(96)00003-S
Abstracts Papers and posters presented Meeting, UMIST, Manchester,
at the 2 1 st Hospital Optometrists Annual UK, on 29 September1 October 1995
The Heidelberg retina tomograph in glaucoma S. I. Hosking Deparment of Ophthalmology, University of Manchester, Manchester Ml 3 9WH, UK
area (PCA) over a wide range of ametropia, and to investigate whether any of these optic disc parameters are related to axial length and/or ocular refraction. Method: The sample comprised 122 normal subjects, aged 18.5 to 35.4 years, free from any ocular or systemic disease, with refractive errors ranging from +4.00D to -25.75 D. Subjects were divided into four groups; (1) non-myopic controls; (2) myopes without peripapillary crescents: (3) myopes with small peripapillary crescents; and (4) myopes with larger crescents, having a CA at least 40% of the DA. All subjects underwent the following: cornea1 front surface keratometry, A-scan ultrasonography, cycloplegic refraction and fundus photography with the Carl Zeiss Jena camera using Kodak Ektachrome colour-slide film. A CCD camera linked to a computer was used to digitise the fundus slides. Optic disc features were delineated by computer-assisted techniques. Using a ray-tracing method (Bennett et al., 1994) and knowledge of the fundus camera magnification (Rudnicka et al.; 1992), the true dimensions of the optic disc parameters could be determined.
Purpose: To establish the ability of the Heidelberg retina tomograph (HRT) to detect morphological change of the optic nerve head in glaucomatous ~lptic neuropathy and to evaluate glaucomatous nerve fibre layer defects. Introduction: The HRT is a confocal laser scanning microscope designed for three-dimensional imaging and measurement of the in viva fundus. The light sot rce is a diode laser operating at a wavelength of 670mm. Thirtytwo single, two-dimensional sectional images are recorded within 0.032 s with a repetition rate of 20Hz, digitised in a frame of 2.5 X 256 pixels. Sequenual viewing of the plates permits three-dimensional resolution of the image. llse of the HRT enables comparison of change in optic nerve head morphology with change in visual function.
Results: In group 1, DA ranged from 1.36 to 2.88mm2; in group 2, from 1.30 to 2.79 mm*; in group 3, from 1.50 to 5.04 mm’, and in group 4, from 1.21 to 9.22 mm*. Groups 1, 2 and 3 did not differ significantly from each other for any optic disc parameter (values for the other optic disc parameters will be presented). DA and NRA are significantly larger in group 4 than in the other three groups. Cup area did not differ signii ficantly between the groups. DA, NRA and PCA increase with axial length elongation and increasing myopia in groups 3 and 4 only.
Methods: The sample consists of 30 early primary open angle glaucoma subjects showing repeatable glaucomatous field defects on Humphrey 30-2 analysis and 65 glaucoma suspects with normal Humphrey 30-Z fields but with multiple risk factors for the development of glaucoma. All subjects are evaluated using white-on-white and blue-on-yellow visual fields as well as HRT analysis of the optic nerve head and retina at three-month intervals over a 15.month period. Discussion: We have demonstrated the need for consistent image scaling in prospective follow-up (Hosking et al., 1995), a facility to be incorporated in the next software reviston; the importance of selecting an optimum scan; and that the correction of astigmatism required for quality image acquisition results ir image distortion. The application of nerve head analysis software to demonstrate localised wedge-shaped nerve fibre bundle defects is illustrated and further modification of the software to demonstrate more subtle subclmical nerve fibre layer defects will be discussed.
Knowledge of the dimensions of the optic nerve head and Conclusions: peripapillary crescents may aid in the diagnosis of pathologically disturbed optic discs. References
Hosking. S. L., Flanagan, J. G. and O’Donoghue, E. P. (1995). Prospective study design for the HRT: The effect of change in focus setting. Invest. Ophthalmol. Visual Sci. 36, Suppl., 4501.
Bennett, A. G., Rudnicka, A. R. and Edgar, D. F. (1994). Improvements on Littmann’s method of determining the size of retinal features by fundus photography. Graefes Arch. Clin. Exp. Ophthalmol. 232, 361-361. Rudnicka, A. R., Bennett, A. G. and Edgar, D. F. (1992). Construction of a model eye and its applications. Ophthal. Physiol. opt. 12, 485-490.
Dimensional characteristics of the optic nerve head and peripapillary crescents in myopia Alicja R. Rudnicka Applied Vision Research Centre, Department of Optometry and Visual Science, City University, London EClV OHB, UK
Mood, pain and the menstrual cycle: potential confounding factors in automated perimetry? Nancy Guttridge Applied Vision Research Centre, City University, London EClV OHB, UK
Purpose: To establish typical normal values for the optic disc area (DA), neuroretinal rim area (NRA). cup area (CA) and peripapillary crescent
The main purpose of this study was to investigate the effect of the normal human menstrual cycle on the central visual field as measured with
Reference
355