Gonioscopic changes after glaucoma surgery.

Trantas (I 907) made the first recorded observations on the angle of the anterior chamber, which he viewed through an ophthalmoscope while indenting the sclera at the limbus on the opposite side. He introduced the term gonioscopy, and found that a view could be obtained using either direct or indirect ophthalmoscopy. A few years later the first attempt to view the angle through a contact lens was made by Salzmann (I9I5), but his work was troubled by problems of distortion of the view. Then Koeppe (I 920) used a slit lamp in conjunction with a contact lens. His design of lens contained a central pit so that the lens could be secured at this place by the knot of a thin bandage. The next development was the uniocular hand microscope designed by Troncoso (I 925), who was able to obtain nearly coaxial illumination. He used this with his own contact lens which was more convex than that designed by Koeppe, giving a higher magnification. These events were summarized by Sugar (1949). The quality of the view with the first lenses cannot have been comparable with those obtained by modern gonioscopy. The first design on which modern lenses are based was produced by Goldmann (I938). Curran (I920) wrote that the anterior chamber deepened after iridectomy or iridotomy for conditions in which the passage of aqueous was impeded on account of the iris hugging the lens over too large a surface. Then Raeder (I923) proposed the classification of glaucoma into cases with wide and narrow angles. Barkan, Boyle, and Maisler (I936) found the angle to be no longer of functional value in many trephine cases, it being occluded in a large percentage by peripheral angle adhesions. In some of these they believed the adhesion to have followed, and to have resulted from, the trephine procedure rather than to have antedated it. Later glaucoma was divided into trabecular (wide-angle) and iris block (narrow-angle) types (Barkan, I941). He recorded that after basal excision of the iris a tag of the iris root might remain. The pillars of the coloboma were frequently found to be adherent to the angle wall, or to be entangled in the inner lip of the wound, thus increasing closure.of the angle and obstruction. Sugar (1 942) stated that the main value of gonioscopy lay in aetiological classification and hence in indications for various operative procedures. He considered that synechiae never formed with a narrow angle except after congestion, and that inclusion of tags of iris after iridectomy was common and was to be desired so that a filtering cicatrix might form. He mentioned the use of postoperative gonioscopy to show (i) why a trephine is blocked; (2) deepening of the anterior chamber after iridectomy; (3) the cleft after cyclodialysis. Peripheral anterior synechiae as a result of surgery received scant mention. He also assessed the trephine operation: 52 patients had open angles before operationtwo (5 per cent.) remained open, 34 (65 per cent.) were partly closed, and sixteen (30 per cent.) were entirely closed. He also analysed 33 cases with open angles which were treated by iridencleisis: 26 were partly open postoperatively, and in seven the angle was obliterated (Sugar, I94I).