Assessment of the efficacy of eyeball local vacuum compression with a new suction cup for impedance oculopneumoplethysmography depending on anatomical parameters of the eye

Abstract

The relationship between the eyeball size and convexity of its anterior part and the efficacy of local vacuum compression of the eye performed using a new design suction cup for impedance ophthalmopneumoplethysmography was studied. Based on the mathematical modeling of the geometric shape of the anterior segment of 75 eyes obtained by ultrasound biomicroscopy examination, it was found that the horizontal meridian curve of the anterior eye segment with a base diameter of 16.00 mm could be best approximated by a hyperbola. The surface area under the new suction cup with an inside diameter of about 16.5 mm was calculated using the formula for the segment surface area of a hyperboloid of revolution. It was determined by the convexity of the anterior part of the eye and varied from 247.3 to 271.4 mm2. The conversion coefficient of the level of applied vacuum to the level of IOP rise, calculated on the basis of individual combinations of the surface area of local vacuum compression and the eyeball size, was on average 0.83 ranging from 0.44 to 1.33. Using an individual conversion coefficient according to eyeball anatomical parameters will make it possible to measure diastolic ocular perfusion pressure during impedance OPPG with high sensitivity and accuracy.

Keywords

• impedance ophthalmopneumoplethysmography
• mathematical modeling of the shape of the anterior eye
• intraocular pressure
• ocular perfusion pressure
• local vacuum compression of the eyeball
• ultrasound biomicroscopy