1. The vertical line of the optical axis (eye axis) passing through the central part of the corneal surface (anterior pole), the node and gyration point of the eye are on the optical axis. The intersection point of the axis behind the sclera is the posterior pole of the eyeball, and the distance between the anterior and posterior poles is the length of the eye axis. 2. The extraocular fixation point of the visual axis, the line connecting the node and the macula. 3. The line connecting the extraocular fixation point of the fixed axis and the gyration point (gyration point: assuming that the eyeball rotates around the center point in the orbit, the center is approximately 13.5mm behind the simplified cornea).
4. Angle of view (angle a): The angle formed by the two ends of an external object at the node in the eye. 5. Angle Kappa: The angle between the line connecting the extraocular gaze point and the anterior pole of the cornea and the optical axis. The angle of view and angle Kappa can be roughly considered the same angle clinically. Since angle Kappa is not easy to measure, it is often calculated by the angle formed by the optical axis and the visual axis at the reflective point of the cornea.
The simplest method is to have the patient look at the light 33cm away and observe the corneal reflection point. If it coincides with the optical axis in the center of the cornea, the Kappa angle is 0. If it is on the nasal side (temporal side) of the center of the cornea, it is a positive (negative) Kappa angle, which is usually within 5°. If it is greater than 7, it seems to be exotropia.
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Post time: Nov-15-2024