New objective classification system for nuclear opacification.

We have developed an autonomous objective classification scheme for degree of nuclear opacification. The algorithm was developed by using a series of color 35-mm slides acquired with a Topcon photo slit-lamp microscope and use of standard camera settings. The photographs were digitized, and first, and second-order gray-level statistics were extracted from within circular regions of the nucleus. Classifications of severity were performed by using these features as input to a neural network. Training versus classification performance was tested by using photographs of different eyes, and test/retest classification reproducibility was evaluated by using paired photographs of the same eyes. We demonstrate good performance of the classifier against subjective assessments rendered by the Wilmer grading system [Invest. Ophthalmol. Visual Sci. 29, 73 (1988)] and markedly better test/retest reproducibility.

[1]  P M Khu,et al.  Quantitating nuclear opacification in color Scheimpflug photographs. , 1993, Investigative ophthalmology & visual science.

[2]  J K Wolfe,et al.  Objective line spread function measurements, Snellen acuity, and LOCS II classification in patients with cataract. , 1993, Optometry and vision science : official publication of the American Academy of Optometry.

[3]  Anders Krogh,et al.  Introduction to the theory of neural computation , 1994, The advanced book program.

[4]  Akira Ishimaru,et al.  Wave propagation and scattering in random media , 1997 .

[5]  S. Pizer,et al.  The Image Processing Handbook , 1994 .

[6]  R. Palmer,et al.  Introduction to the theory of neural computation , 1994, The advanced book program.

[7]  L T Chylack,et al.  Evaluation of a Lens Opacities Classification System. , 1988, Archives of ophthalmology.

[8]  P Pasquini,et al.  Influence of type and severity of pure forms of age-related cataract on visual acuity and contrast sensitivity. Italian American Cataract Study Group. , 1994, Investigative ophthalmology & visual science.

[9]  F Wang,et al.  Plasma Antioxidants and Risk of Cortical and Nuclear Cataract , 1993, Epidemiology.

[10]  H R Taylor,et al.  The lens opacity meter: a method of quantification of lens opacity by measurement of scattering of incident light. , 1990, Lens and eye toxicity research.

[11]  M B Datiles,et al.  Reproducibility study on the Scheimpflug Cataract Video Camera. , 1988, Current eye research.

[12]  H R Taylor,et al.  A comparison of two photographic systems for grading cataract. , 1991, Investigative ophthalmology & visual science.

[13]  K L Linton,et al.  Assessment of cataracts from photographs in the Beaver Dam Eye Study. , 1990, Ophthalmology.

[14]  J K Wolfe,et al.  Indirect spectral transmission ratio measurements of the aging crystalline lens nucleus , 1992, Acta ophthalmologica.

[15]  S. West,et al.  Use of photographic techniques to grade nuclear cataracts. , 1988, Investigative ophthalmology & visual science.

[16]  J C Javitt,et al.  The content and cost of cataract surgery. , 1993, Archives of ophthalmology.

[17]  L T Chylack,et al.  Lens opacities classification system II (LOCS II) , 1989, Archives of ophthalmology.

[18]  B V Magno,et al.  Study of nuclear cataract progression using the National Eye Institute Scheimpflug system. , 1995, The British journal of ophthalmology.

[19]  K. Sasaki,et al.  Quantitative evaluation of nuclear cataract using image analysis. , 1992, Ophthalmic research.

[20]  S. West,et al.  The clinical grading of lens opacities. , 1989, Australian and New Zealand journal of ophthalmology.

[21]  J K Wolfe,et al.  Quantitating cataract and nuclear brunescence, the Harvard and LOCS systems. , 1993, Optometry and vision science : official publication of the American Academy of Optometry.

[22]  B. Munoz,et al.  Cigarette smoking and risk of nuclear cataracts. , 1989, Archives of ophthalmology.

[23]  B. Munoz,et al.  Measuring progression of lens opacities for longitudinal studies. , 1993, Current eye research.

[24]  M. Unser,et al.  Computerized cataract detection and classification. , 1990, Current eye research.

[25]  J. Salonen,et al.  Comparison of the lens opacities classification system II and Lensmeter 701. , 1993, American journal of ophthalmology.

[26]  Lawrence H. Staib,et al.  The image processing handbook, 2nd edition J. C. Russ , 1998, Journal of nuclear cardiology : official publication of the American Society of Nuclear Cardiology.

[27]  S. West,et al.  A simple system for the clinical grading of lens opacities. , 1988, Yan ke xue bao = Eye science.

[28]  D. Signorini,et al.  Neural networks , 1995, The Lancet.

[29]  Nicholas A P Brown,et al.  The objective assessment of cataract , 1987, Eye.