| 摘要 |
A retroilluminating indirect gonioprism comprising an optical prism, an oblique reflector and light baffle to reduce the intensity of light reflected from the gonioprism anterior surface back toward an observer, and an opaque surface to substantially prevent retinal burns when using the gonioprism with a directed energy beam. Retroillumination of anterior chamber structures is provided by fiber optics incorporated into the gonioprism housing which direct light from an external source into the limbal region of the eye. This retroillumination increases the accuracy of identification of structural landmarks (e.g., the scleral spur) which are important in argon laser trabeculoplasty. A directed energy beam, as from a high energy laser, may be directed through the gonioprism while an eye structure on which the beam is focussed is observed through the gonioprism. First-surface reflection of a portion of the directed energy beam passes obliquely toward a light baffle and is substantially absorbed, while the transmitted portion of the beam is slightly laterally displaced and strikes the gonioprism anterior surface. The portion of the beam reflected from the gonioprism anterior surface back toward the observer again undergoes partial reflection oblique to the visual axis and slight lateral displacement before reaching the observer. Thus, the amount of light reflected from the gonioprism anterior surface back toward an observer is reduced. Substantial optical correction for astigmatism of oblique incidence and for assuring substantial parallelism between the observer's line-of-sight to the gonioprism and the gonioprism optical axis is preferably provided through appropriate configuration of at least one substantially convex surface which comprises at least a portion of the optical prism anterior surface.
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