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The light scattering characteristics of the eye
Author(s) -
Hennelly M. L.,
Barbur J. L.,
Edgar D. F.,
Woodward E. G.
Publication year - 1997
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1046/j.1475-1313.1997.97807351.x
Subject(s) - keratoconus , glare , optics , ophthalmology , variation (astronomy) , light scattering , optometry , scattering , medicine , physics , materials science , cornea , astrophysics , layer (electronics) , composite material
Aim: To validate a new method for the measurement of scattered light in the eye. In addition, normal values and results of subjects with keratoconus, cataract and corneal dystrophy will be demonstrated. Method: The scatter programme is implemented on the P__Scan 100 system. The system involves the use of high luminances and extended stimuli modulated sinusoidally. It reveals three parameters; n the scatter index which describes the distribution of scattered light from the scattering source; k , which describes the overall light scattered and a new index k ′ known as the integrated straylight parameter. k ′ provides an alternative to the commonly used straylight parameter, k . Results: Preliminary results in a small sample of normals showed k ′ to be affected by age, diurnally, and by the menstrual cycle. Little variation in k ′ was found between the ages of 16 and 42 years, with an increase found after the age of 60. A diurnal variation was found, with increased values of k ′ on waking, which may be related to variation in corneal thickness. A variation in k ′ with the menstrual cycle was noted. All values, i.e. n , k, k ′ were found to be affected by keratoconus, cataract and corneal dystrophy. Conclusion: k ′ is an important parameter in the quantification of scattered light. The results obtained give an insight into the patient's symptoms of glare, essential in the timing of conducting penetrating keratoplasty. Acknowledgement: M. L. Hennelly was supported by a College of Optometry Studentship.