Our overall objective is to determine the extent to which light scattering measurements can be used as a tool to probe structures in normal and abnormal corneas. This is to be accomplished by quantitating light scattering through careful experimental measurements, complemented by theoretical analyses based on the structural features determined from electron microscopy (EM), from structure models, or from both. Comparisons test the validity of the structural models, or of the EM, and permit us to relate the cornea's structure to its scattering properties. Indeed we have used this method to elucidate characteristics of the fibril arrangement in the transparent normal cornea and in turbid swollen corneas, and to show that significant reductions in the fibril tension produce a small angle light scattering pattern. More recently, we used it to interpret our angular scattering measurements in terms of scattering from fibrils. We also have developed a capability to make quantitative calculations for abnormal corneas by devising a tractable direct summation of fields calculational technique and by improving our variational methods for scattering calculations. Our specific goals are to employ this methodology to examine fibrillar structures in scar tissue, to obtain more quantitative information in swollen corneas, and to follow subtle post-surgical changes in light scattering as an indication of healing. In addition, lamellar structures in normal corneas will be investigated using electron microscopy, polarized light scattering and (scanning-slit) specular microscopy. Success in these studies will give better understanding of the structural basis for the transparency and mechanical properties of normal corneas, elucidate the factors responsible for the transparency loss in scar tissue, and provide a non-invasive test of structural repair.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY001019-16
Application #
3255655
Study Section
Visual Sciences A Study Section (VISA)
Project Start
1986-09-30
Project End
1990-03-31
Budget Start
1988-09-30
Budget End
1990-03-31
Support Year
16
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Johns Hopkins University
Department
Type
Schools of Medicine
DUNS #
045911138
City
Baltimore
State
MD
Country
United States
Zip Code
21218
McCally, Russell L; Freund, David E; Zorn, Andrew et al. (2007) Light-scattering and ultrastructure of healed penetrating corneal wounds. Invest Ophthalmol Vis Sci 48:157-65
McCally, Russell L; Connolly, Patrick J; Stark, Walter J et al. (2006) Identical excimer laser PTK treatments in rabbits result in two distinct haze responses. Invest Ophthalmol Vis Sci 47:4288-94
Jain, S; McCally, R L; Connolly, P J et al. (2001) Mitomycin C reduces corneal light scattering after excimer keratectomy. Cornea 20:45-9
Christens-Barry, W A; Green, W J; Connolly, P J et al. (1996) Spatial mapping of polarized light transmission in the central rabbit cornea. Exp Eye Res 62:651-62
Braunstein, R E; Jain, S; McCally, R L et al. (1996) Objective measurement of corneal light scattering after excimer laser keratectomy. Ophthalmology 103:439-43
Donohue, D J; Stoyanov, B J; McCally, R L et al. (1996) A numerical test of the normal incidence uniaxial model of corneal birefringence. Cornea 15:278-85
Freund, D E; McCally, R L; Farrell, R A et al. (1995) Ultrastructure in anterior and posterior stroma of perfused human and rabbit corneas. Relation to transparency. Invest Ophthalmol Vis Sci 36:1508-23
Jain, S; Hahn, T W; McCally, R L et al. (1995) Antioxidants reduce corneal light scattering after excimer keratectomy in rabbits. Lasers Surg Med 17:160-5
Silver, D M; Farrell, R A (1994) Validity of pulsatile ocular blood flow measurements. Surv Ophthalmol 38 Suppl:S72-80
Freund, D E; McCally, R L; Goldfinger, A D et al. (1993) Image processing of electron micrographs for light scattering calculations. Cornea 12:466-74

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