Time-dependent stress and displacement of the eye wall tissue of the human eye.
Myopia or short sightedness, is the most important predisposing factor to retinal detachment. The relative risk of detachment rises with increasing myopia. The model characterizes that because the severity of myopia increases with the axial length (antero-posterior diameter) of the eyeball, the relative risk of retinal detachment rises with increasing eye size. We present a mathematical model of the time-dependent shear stress force that occurs in the thin eye wall shell supporting the vitreous humour inside the eye globe during the acceleration and deceleration phases of saccadic eye movement. Results show that the shear force increases as the thickness of the eye wall decreases. It is common for myopes to have thinner eye wall tissue than emmetropes. In addition, if account is taken of the increased force required to provide normal saccadic movement of myopic (larger) eyes, then the shear force is up to seven times greater than that experienced for emmetropes.
David
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Department of Mechanical Engineering, University of Leeds, UK.
Smye
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James
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Dabbs
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D001696:Biomechanical Phenomena; D055592:Biophysical Phenomena; D001703:Biophysics; D005123:Eye / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D008433:Mathematics; D008954:Models, Biological; D009216:Myopia / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D012163:Retinal Detachment / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D012307:Risk Factors; D012438:Saccades / Q000502:physiology; D013314:Stress, Mechanical; D013997:Time Factors; D014822:Vitreous Body / Q000503:physiopathology