Mathematical Models of the Dynamics of the Human Eye

ISBN-13: 9783540097518 / Angielski / Miękka / 1980 / 99 str.

R. Collins; T. J. Van Der Werff

Opis

A rich and abundant literature has developed during the last half century dealing with mechanical aspects of the eye, mainly from clinical and, experimental points of view. For the most part, workers have attempted to shed light on the complex set of conditions known by the general term glaucoma. These conditions are characterised by an increase in intraocular pressure sufficient to cause de- generation of the optic disc and concomitant defects in the visual field, which, if not controlled, lead to inevitable permanent blindness. In the United States alone, an estimated 50,000 persons are blind as a result of glaucoma, which strikes about 2% of the population over 40 years of age (Vaughan and Asbury, 1974). An understanding of the underlying mechanisms of glaucoma is hindered by the fact that elevated intraocular pressure, like a runny nose, is but a symptom which may have a variety of causes. Only by turning to the initial pathology can one hope to understand this important class of medical problems.

Spis treści

1. Introduction.- 1. Anatomy of the eye.- 2. Regulation of intraocular pressure.- 3. Units and conventions.- 2. Volume Changes in the Eye.- 1. Ocular circulation.- 2. Pressure — flow relation for the vascular bed.- 3. Pressure-volume relation for the vascular bed.- 4. Aqueous humour dynamics.- A. Aqueous formation rate.- B. Aqueous outflow.- 5. Ocular rigidity function.- A. Friedenwald’s formulation.- B. Other empirical formulations.- C. Linear elastic model.- D. Nonlinear elastic model.- E. Comparison of ocular rigidity functions.- F. Viscoelasticity of corneo-scleral envelope.- 6. Causal relationships (influence diagram).- 7. The Standard Eye.- 8. A summary of normal values and relations.- 3. General Time-Dependent Model.- 1. Governing equations.- 2. Approximate analytical solutions.- A. Steady state pressure pulsations.- B. Non-steady state pressure pulsations.- 3. Numerical solutions.- 4. Neural Control of the Intraocular Pressure.- 5. Measurement Techniques.- 1. Measurement of intraocular pressure.- A. Tonometry.- B. Tonography.- C. Perilimbal suction cup method.- 6. Relation of Ocular Dynamics to the Cerebral Circulation.- 1. Clinical methods of assessing the cerebral circulation.- A. Ophthalmodynamometry.- B. Ophthalmodynamography.- C. Ocular pulse analysis.- D. Carotid compression.- E. Other methods.- 7. Summary and Conclusions.- Mathematical Notation.- References.