PubMed · 13952635
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H HANSON. 1962. Proteolytic enzymes.. https://doi.org/10.1016/s0014-4835(62)80040-2
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PURPOSE: The aim of the study is to find out how the way of tying the suture around the haptics creates the tilt of the lens around the axis of the suture. MATERIAL AND METHODS: The study was carried out using a transparent polyethylene cylinder 30 cm long 12 mm in diameter similar to the one of the eyeball in the area of sulcus ciliaris. The lenses were sutured about 5 mm from one of the ends of the cylinder using 9-0 suture. The deviation of the lens was evaluated be measuring the distance of the circumference of the haptic from the edge of the cylinder. The study was carried out using lenses without fixation holes in loops with the holes in one loop and holes in both loops. Various ways of tying the suture in the holes of the haptic were applied. RESULTS: The lenses without holes in loops were tilting around the axis of the suture. Stabilisation of these lenses was received after using two sutures on one of the loops. Similarly, lenses with hole in one loop were not tilting just after using two sutures in loop without hole. The lenses with two holes in loops were not tilting when fixation sutures were tying in a way which balances the tilt forces of sutures on each loop. CONCLUSIONS: A kind of tying the suture around the haptic has significant importance on tilt of the lens around the axis of the suture. In case of necessity to suture lenses without holes in the haptics three or four sutures (two or one on each haptic) should be applied and they must be pierced in the sclera at the distance of 5 mm from each other. Lenses with hole on one loop should have two fixation sutures on loop without hole. Lenses with holes in two loops should have sutures tying in a way which balances the tilt forces of sutures on each loop.
A new computing scheme was developed for calculating the radius of curvature of the anterior and posterior surfaces of the crystalline lens from the measured heights of the Purkinje images. The scheme can be applied to objects at any distance from the corneal vertex, for both a stationary object mounted independently of the camera and for a mobile object attached to the camera where the distance of the object to the corneal vertex will change as the camera is refocused from image PI to PIII and PIV. The method can also be used if different objects are employed to form each Purkinje image. The scheme also avoids the need to collimate objects in order to employ the equivalent mirror theorem or to calibrate phakometers with known spherical surfaces where exact relationships are unknown.
A new method for calculating the radius of curvature of the anterior surface of the crystalline lens from the measured heights of the Purkinje image PI and PIII is given. Equations are developed for determination of the radius of curvature of the equivalent mirror for three configurations commonly used in phakometry. The method can be applied to targets at any distance from the corneal vertex, for both a stationary target mounted independently of the camera, and for a mobile source attached to the camera where the distance of the target to the corneal vertex will change as the camera is refocused from image PI to PIII. The situation where only one recording is made of images PI and PIII, where the camera is focused on image PI, and the height of the defocused image of PIII is measured is also considered. The errors in calculating the anterior lens radius with the equivalent mirror method if no allowance is made for an object at a finite distance is examined. The new method described is an alternative to collimating targets to overcome the errors in phakometry that occur with targets at finite distances.