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Fig. 10.8 Chamber angle before the surgery. The angle is wide open with a broad anterior ciliary band and a white scleral spur. Adjacent is the pigmented, functional trabecular meshwork (grade +2), the non-functional trabecular meshwork and SchwalbeÕs ring (Courtesy D. Baerveldt)
Fig. 10.10 Goniotomy with the goniotomy knife in an eye with congenital glaucoma using a special wide-angle contact lens and the microscope tilt at 45¡. Deepening of the chamber angle parts to the right of the knife is visible and a good prognostic sign (Surgeon and courtesy P. Khaw)
Fig. 10.9 The same eye as shown in Fig. 10.6 after Trabectome surgery. The white cleft is perfectly located between the non-functional trabecular meshwork and the scleral spur. Two small hemorrhages are visible (Courtesy D. Baerveldt, surgeon W. L. Alward)
10.4Trabeculectomy Ab Interno
The ÒTrabectome,Ó a device which is used ab interno after having Þlled the anterior chamber with an OVD, is used to excise trabecular tissue by means of heat with a bent probe. Hyphema occurs quite often as a minor transient complication. Extension too posterior will create a cyclodialysis and should be avoided (Figs. 10.8 and 10.9).
In trabeculotomy, the trabecular meshwork is opened ab externo. The Þrst steps of the procedure are the same as in trabeculectomy. When SchlemmÕs canal is clearly identiÞed, it is cannulated with probes from both sides. These probes are turned into the anterior chamber to tear parts of the inner wall of SchlemmÕs canal and of the trabecular meshwork. Usually some bleeding will occur. Always check the position of the probes by gonioscopy before turning them into the anterior chamber! After some months, on gonioscopy you may Þnd a whitish line within the clock hours where the surgery was done.
In goniotomy, parts of the trabecular meshwork and of the inner wall of SchlemmÕs canal are opened ab interno with a special knife. Direct gonioscopy is mandatory to locate the structures exactly (Fig. 10.10).
10.6Surgery of the Ciliary Body: Cyclodialysis
In cyclodialysis, a small, full-thickness incision
10.5Trabeculotomy, Goniotomy is created in the sclera to Þnd the outer surface of
Both procedures are primarily indicated in congenital glaucoma, but they are also performed in glaucoma in myopic or aphakic/pseudophakic eyes.
the ciliary body. With a Þne spatula, the ciliary body is detached from the sclera for about 3 oÕclock h. Aqueous humor will ßow into the suprachoroidal space. On gonioscopy you will
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Þnd a cleft between the sclera and the ciliary body with the white sclera visible. It has the same appearance as after a blunt trauma with detachment of the ciliary body.
10.7Peripheral Iridectomy
A pupillary block or an eye with an occludable angle can be treated by creating a hole in the peripheral iris. This iridectomy was invented by A. von Graefe in 1857. Nowadays, it is done by Nd:YAG laser (see Sect. 9.3), but in very thick irises it is still performed surgically (Fig. 10.11). The advantage of surgery is that a tiny part of the iris is removed out of the eye. The trabecular meshwork need not deal with the debris and pigment which are released during a Nd:YAG iridotomy. The second advantage is that a redeepening of the anterior chamber with (probable) opening of peripheral anterior synechiae may be done with ßuid or a viscoelastic agent (goniosynechialysis).
Fig. 10.11 Peripheral surgical iridectomy at 12 oÕclock
Bibliography
Alward WL, Longmuir RA (2008) Color atlas of gonioscopy, 2nd edn. American Academy of Ophthalmology, San Francisco
European Glaucoma Society (2008) Terminology and guidelines for glaucoma, 3rd edn. European Glaucoma Society/Dogma, Savona