Abstract
Abstract: :
Purpose: To evaluate a wide angle panoramic aspheric lens system, that provides a 360° real image of the anterior chamber angle structures without the use of reflective surfaces. Methods: The lens system has two lens groups. The first lens group has a concave posterior surface [Radius of curvature (ROC) = 7.8 mm],for placement on the patient’s cornea. As the ROC of the lens is almost equal to the ROC of the anterior corneal surface, a coupling agent is not required. The group I lens system consists of a biconcave lens, and a bi–convex lens sub–group. This group acts to direct light rays originating at the anterior chamber angle towards the second lens group II for focusing. The group I lens system collimates the light rays. The bi–convex lens sub–group A2 comprises of number of lens elements. Second group II is located in a spaced–apart relationship with respect to first lens group I. This allows an air space between them. The lens group II is bi–convex. A meniscus lens is cemented on the bi–convex lens. B2 is slightly negatively–powered. The group II lens system is achromatic and minimizes chromatic aberrations. The group II focuses the light rays and provides magnification of the angle. Image contrast of the lens is further improved by incorporating a circular or disc shape stop (Figure) in the lens system at the air space between the two groups I & II. This stop is opaque, and it prevents light rays from propagating through the central region of the group II. This prevents superfluous and aberrant light from propagating the gonioscopic lens system thus improving the image quality from the anterior chamber angle. Results: The lens system provides real and inverted panoramic image of the angle.The lens system is configured to minimize chromatic aberration and provide improved image as compared to the other lens systems. Conclusions: This newly designed gonioscpy lens provides a real inverted panoramic view of the whole 360°s of the anterior chamber angle without rotating the lens and facilitates gonioobservation and surgery.
Keywords: optical properties • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)