PURPOSE: The authors evaluated whether the optic disc dimensions can be measured directly by ophthalmoscopy without the use of a fundus camera or special ophthalmoscope. MATERIALS AND METHODS: The horizontal and vertical disc diameters were measured ophthalmoscopically in 158 eyes of 95 subjects using a standard Goldmann three-mirror contact lens and a commercial slit lamp with adjustable length of the beam. The refractive error ranged from -7.25 to 3.5 diopters. Based on these direct measurements, the authors calculated the disc area by applying a modified formula for an ellipse, where area = pi/4 x the horizontal diameter x the vertical diameter. Additionally, the authors determined by planimetry the diameters and area of the disc on color photographs after correcting the ocular and photographic magnification. RESULTS: The values of the disc diameters as determined by photography were x1.27 larger than those measured with the Goldmann contact lens. Taking into account this constant correction factor of 1.27 for all eyes examined, the disc diameters, as measured by the Goldmann lens, varied by 0.11 +/- 0.06 mm or 5.8% +/- 3.5% from the values measured on the photographs. This error decreased slightly (P = 0.04) with increasing disc size. It was independent of the refractive error. The calculated disc area based on the ophthalmoscopically determined disc diameters differed by 9.4% +/- 6.6% from the disc area as measured by planimetry on the photographs. CONCLUSIONS: For clinical purposes, the optic disc and other structures of the posterior fundus can be measured by ophthalmoscopy using a Goldmann contact lens and a slit lamp with adjustable beam length. The optic disc area can be calculated by the formula: horizontal disc diameter x vertical disc diameter x pi/4.
PURPOSE: The authors evaluated whether the optic disc dimensions can be measured directly by ophthalmoscopy without the use of a fundus camera or special ophthalmoscope. MATERIALS AND METHODS: The horizontal and vertical disc diameters were measured ophthalmoscopically in 158 eyes of 95 subjects using a standard Goldmann three-mirror contact lens and a commercial slit lamp with adjustable length of the beam. The refractive error ranged from -7.25 to 3.5 diopters. Based on these direct measurements, the authors calculated the disc area by applying a modified formula for an ellipse, where area = pi/4 x the horizontal diameter x the vertical diameter. Additionally, the authors determined by planimetry the diameters and area of the disc on color photographs after correcting the ocular and photographic magnification. RESULTS: The values of the disc diameters as determined by photography were x1.27 larger than those measured with the Goldmann contact lens. Taking into account this constant correction factor of 1.27 for all eyes examined, the disc diameters, as measured by the Goldmann lens, varied by 0.11 +/- 0.06 mm or 5.8% +/- 3.5% from the values measured on the photographs. This error decreased slightly (P = 0.04) with increasing disc size. It was independent of the refractive error. The calculated disc area based on the ophthalmoscopically determined disc diameters differed by 9.4% +/- 6.6% from the disc area as measured by planimetry on the photographs. CONCLUSIONS: For clinical purposes, the optic disc and other structures of the posterior fundus can be measured by ophthalmoscopy using a Goldmann contact lens and a slit lamp with adjustable beam length. The optic disc area can be calculated by the formula: horizontal disc diameter x vertical disc diameter x pi/4.
Authors: Lorena Fernández-Martínez; Stef Letteboer; Christian Y Mardin; Nicole Weisschuh; Eugen Gramer; Bernhard Hf Weber; Bernd Rautenstrauss; Paulo A Ferreira; Friedrich E Kruse; André Reis; Ronald Roepman; Francesca Pasutto Journal: Eur J Hum Genet Date: 2011-01-12 Impact factor: 4.246
Authors: Virpi Hemminki; Mika Kähönen; Martti T Tuomisto; Väinö Turjanmaa; Hannu Uusitalo Journal: Graefes Arch Clin Exp Ophthalmol Date: 2006-07-11 Impact factor: 3.117
Authors: Francesca Pasutto; Tomoya Matsumoto; Christian Y Mardin; Heinrich Sticht; Johann H Brandstätter; Karin Michels-Rautenstrauss; Nicole Weisschuh; Eugen Gramer; Wishal D Ramdas; Leonieke M E van Koolwijk; Caroline C W Klaver; Johannes R Vingerling; Bernhard H F Weber; Friedrich E Kruse; Bernd Rautenstrauss; Yves-Alain Barde; André Reis Journal: Am J Hum Genet Date: 2009-09-17 Impact factor: 11.025
Authors: Evelyn C O'Neill; David A Mackey; Paul P Connell; Alex W Hewitt; Helen V Danesh-Meyer; Jonathan G Crowston Journal: Nat Rev Neurol Date: 2009-05 Impact factor: 42.937