The overall objectives are to relate the optical properties of normal, diseased and damaged corneas to their structures. The optical properties including transparency (or light scattering), haze, and polarized light scattering and propagation, and the structures include fibrillar and lamellar organization and keratocytes.
The Specific Aims are: 1) to elucidate structural bases for diffuse haze seen in edematous, and certain diseased and damaged corneas; 2) to use light scattering in fresh corneas to test different electron micrograph (EM) preparative procedures; 3) to evaluate the importance of specular and non-specular scattering from keratocytes; 4) to relate birefringence and small angle polarized light scattering in normal and diseased corneas to their lamellar and fibrillar structures; and 5) to correlate visual performance with objective measurements of haze following laser photokeratectomy. The general approach involves a strong interplay among theory, light scattering experiments, histology, and clinical techniques. Theoretical light scattering can indicate light scattering measurements that can be made or fresh tissue and test the validity of structural features depicted in EM. Understanding the structural bases for light, scattering in abnormal corneas has obvious health implications. Moreover, light scattering techniques have the potential of providing a non-invasive probe of characteristics of the structures responsible for the optical properties and structural integrity of cornea. The alterations of lamellae ultrastructures in keratoconus suggested by x-ray measurements should be detectable by birefringence measurements which can be made in vivo. Finally, the scatterometer can be used with clinical colleagues, to correlate degradation of visual function with the corneal haze that follows excimer laser keratectomy and assess the clinical significance of haze. The theoretical and experimental light scattering techniques will include transmissivity and angular scattering methods developed by this team, and confocal microscopy. The theoretical scattering analysis analyses will be based on the ultrastructures in EM an on cell models. All the scattering measurements will be made on fresh tissues, and comparisons with predictions test the validity of the structures shown in EM. Birefringence measurements will be combined with theoretical and numerical analyses to be developed by this team. Comparisons will be made between scatterometer and visual function measurements on patients.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
3R01EY012165-02S1
Application #
6222899
Study Section
Special Emphasis Panel (ZRG1 (03))
Program Officer
Fisher, Richard S
Project Start
1998-04-01
Project End
2001-03-31
Budget Start
1999-04-01
Budget End
2000-03-31
Support Year
2
Fiscal Year
2000
Total Cost
$58,712
Indirect Cost
Name
Johns Hopkins University
Department
Ophthalmology
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
Hindman, Holly B; McCally, Russell L; Myrowitz, Elliot et al. (2007) Evaluation of deep lamellar endothelial keratoplasty surgery using scatterometry and wavefront analyses. Ophthalmology 114:2006-12
McCally, Russell L; Bonney-Ray, Jennifer; de la Cruz, Zenaida et al. (2007) Corneal endothelial injury thresholds for exposures to 1.54 micro m radiation. Health Phys 92:205-11
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
Farrell, Richard A; Rouseff, Daniel; McCally, Russell L (2005) Propagation of polarized light through two- and three-layer anisotropic stacks. J Opt Soc Am A Opt Image Sci Vis 22:1981-92
McCally, Russell L; Bonney-Ray, Jennifer; Bargeron, C Brent (2004) corneal epithelial injury thresholds for exposures to 1.54 microm radiation-dependence on beam diameter. Health Phys 87:615-24
McCally, Russell L; Bargeron, C Brent (2003) Corneal epithelial injury thresholds for multiple-pulse exposures to Tm:YAG laser radiation at 2.02 microm. Health Phys 85:420-7
Jain, S; McCally, R L; Connolly, P J et al. (2001) Mitomycin C reduces corneal light scattering after excimer keratectomy. Cornea 20:45-9
McCally, R L; Bargeron, C B (2001) Epithelial damage thresholds for multiple-pulse exposures to 80 ns pulses of CO2 laser radiation. Health Phys 80:41-6
McCally, R L; Farrell, R A (1999) Small-angle light scattering and birefringence properties of chick cornea. J Refract Surg 15:706-10

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