Myopia (nearsightedness) is the most prevalent of all eye disorders. Many causes have been suggested for myopia ranging from heredity, nutritional deficiency, hormonal imbalance and childhood fever to excessive accommodation (focusing of the eye on close objects) and near work, such as studying. The experiments proposed here are intended to shed light on several of the variables that may cause or exacerbate this disorder. The subjects of these experiments are domestic chicks. These inexpensive and plentiful animals have eyes that are very similar to those of humans in many features, including excellent vision. We have devised a technique for producing experimenttal myopia in chicks by degrading their retinal images during their development. Among the variables to be examined are the effects of near work (close examination of an object with fine details), elevated eye temperature, as might occur in a childhood disease such as measles or eye inflammation, the effects of prolonged accommodation induced by electrical stimulation of the brain region that controls this function and the effects of deficiencies of calcium and vitamin D, which are important for the structure of the sclera (the tough coat of the eye), elongation of which is the cause of the common form of myopia. Not only does the chick provide an excellent model in which to study the causes of myopia, it also can provide a suitable preparation to investigate new and improved methods of treatment, especially by surgical intervention.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY004742-08
Application #
3259214
Study Section
Visual Sciences B Study Section (VISB)
Project Start
1983-07-01
Project End
1992-05-31
Budget Start
1990-06-01
Budget End
1992-05-31
Support Year
8
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Maryland College Park
Department
Type
Schools of Arts and Sciences
DUNS #
City
College Park
State
MD
Country
United States
Zip Code
20742
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Hodos, W; Kuenzel, W J (1993) Thermal gradients in the eyes of lid-sutured chicks. Curr Eye Res 12:479-87
Porciatti, V; Hodos, W; Signorini, G et al. (1991) Electroretinographic changes in aged pigeons. Vision Res 31:661-8
Hodos, W; Miller, R F; Fite, K V (1991) Age-dependent changes in visual acuity and retinal morphology in pigeons. Vision Res 31:669-77
Hodos, W; Erichsen, J T (1990) Lower-field myopia in birds: an adaptation that keeps the ground in focus. Vision Res 30:653-7
Hodos, W; Revzin, A M; Kuenzel, W J (1987) Thermal gradients in the chick eye: a contributing factor in experimental myopia. Invest Ophthalmol Vis Sci 28:1859-66
Hodos, W; Fitzke, F W; Hayes, B P et al. (1985) Experimental myopia in chicks: ocular refraction by electroretinography. Invest Ophthalmol Vis Sci 26:1423-30