A novel approach to suprachoroidal drainage for the surgical treatment of intractable glaucoma.

PURPOSE: In glaucoma surgery, scarring of the artificial fistula is the limiting factor for long-term control of intraocular pressure (IOP). Several devices and surgical techniques have been developed for artificial aqueous humor drainage in intractable glaucoma. The authors describe a novel surgical technique that uses a silicone tube as a shunt for aqueous flow from the anterior chamber to the suprachoroidal space. PATIENTS AND METHODS: Thirty-one eyes of 31 patients with uncontrollable refractory glaucoma were included in this prospective consecutive case-control study. Each eye had undergone an average of 3.5+/-1.9 previous interventions for glaucoma. The baseline IOP was 44.25+/-8.7 mm Hg despite maximum therapy. As in trabeculectomy, a limbus-based scleral flap was prepared. The suprachoroidal space was accessed via a deep posterior scleral flap. The silicone tube was inserted as an intrascleral connection from the anterior chamber to the suprachoroidal space. Cyclodialysis was avoided by this surgical approach. Success was defined as a lowering of IOP to below 21 mm Hg without the need for further medication or intervention. RESULTS: The mean functional shunt survival was 55.9+/-45.6 weeks. IOP was reduced to 12.9+/-5.2 mm Hg in 70% of all eyes after 30 weeks postoperatively. After 52 weeks, 60% of the eyes could be classified as representing success, and 76 weeks after surgery, 40% of the eyes still showed controlled IOP. In none of the eyes were severe postoperative hypotony or suprachoroidal bleeding observed. No localized or general inflammation or infection was seen in connection with the silicon tube. Two patients needed anterior chamber lavage because of bleeding. In 2 patients the tube had to be removed because of corneal endothelial contact. Shunt failure of the tube was caused in some cases by connective tissue formation at the posterior lumen of the tube. CONCLUSION: This novel surgical approach and the placement of the silicone tube described here have several advantages. Its intrascleral course minimizes the risk of conjunctival erosion and associated infections. No cyclodialysis is performed. Connection to the suprachoroidal space exploits the resorptive capability of the choroid. It guarantees drainage but also provides a natural counterpressure, avoiding severe postoperative hypotony. The suprachoroidal shunt presented here achieves good follow-up results in terms of IOP control. No serious complications have been observed. This new method promises to be an effective surgical technique and presents a new therapeutic option in intractable glaucoma. Fibroblast reaction obstructing the posterior lumen, seemed to be the only factor limiting drainage. Further studies and experiments will be needed to elucidate the exact physiologic mechanisms underlying the draining, the capacity and duration of the draining effect, and the histologic background of suprachoroidal scarring.

Late hypotony as a complication of viscocanalostomy: a case report.

BACKGROUND: We report a long-term hypotony syndrome after deep sclerectomy, associated with intermittent rise in intraocular pressure (IOP) due to steroid response. PATIENT PRESENTATION: A 55-year-old woman with high myopia (RE -9.25, LE -10.50) suffering from uncontrolled pigment open-angle glaucoma, despite laser trabeculoplasty and a cyclodestructive procedure, underwent an uneventful viscocanalostomy. FOLLOW-UP: Intraocular pressure was between 9 and 17 mm Hg with local steroid medication 5 times a day, but became unstable with steroid reduction to 3 times a day and the patient developed hypotonous IOP (3-5 mm Hg) in the fourth postoperative month. With intensification of local steroid therapy, IOP rose to 49 mm Hg, and a reduction in medication was followed by hypotony. The instability of IOP with steroid medication could not be controlled and the IOP response due to steroids diminished with time; a long-term hypotony syndrome with maculopathy developed. Surgical inspection 10 months later with repeated preparation of the scleral flap showed (like ultrasound biomicroscope examination) a normal status after viscocanalostomy, without signs of leakage. CONCLUSIONS: Late hypotony syndrome should be considered as a potential complication of viscocanalostomy, perhaps especially in cases of myopia and former cyclodestructive procedures. In our case, despite nonpenetrating glaucoma surgery, the steroid response at first observed indicated additional outflow via the trabecular meshwork. After some months it could not be provoked any longer, leaving us to consider whether a gradual change in the trabecular meshwork hinders steroid medication changing aqueous outflow facility.

Ultrasound biomicroscopy in chronic ocular hypotony: its impact on diagnosis and management.

PURPOSE: To determine the value of ultrasound biomicroscopy (UBM) in the assessment of ocular hypotony in cases where the underlying pathologic mechanism remains unclear after extensive clinical examination. METHODS: In a retrospective study, the records of 60 patients who had undergone UBM to elucidate the underlying structural abnormalities of chronic ocular hypotony (intraocular pressure of 0-8 mmHg) were evaluated. Most patients (47 of 60 eyes) had a history of intraocular surgery or of other ocular diseases (e.g., uveitis), and after careful clinical examination, the cause had remained unclear. All patients were observed up for a minimum of 12 months. RESULTS: The associated pathoanatomy of the hypotony was demonstrated by UBM in 95% of the cases. Ciliary body abnormalities were present in 80% of the eyes. Therapeutic intervention was associated with restoration of normal ocular pressure in 50% of the cases. Often more than one intervention was necessary. A long duration of hypotony did not impede reaching the therapeutic goal of normalizing intraocular pressure and preventing phthisis. CONCLUSIONS: Ultrasound biomicroscopy is a new tool for detecting the underlying structural abnormalities in ocular hypotony. In cases where clinical examination is not sufficient it can be of great help in deciding on a course of treatment.

Typical ultrasound biomicroscopic findings seen in ocular hypotony.

UNLABELLED: Detailed imaging of the ciliary body region by means of ultrasound biomicroscopy can provide information that is crucial for further treatment whereas clinical evaluation and 10-MHz standard B scan are less helpful. BACKGROUND: To evaluate the suitability of ultrasound biomicroscopy (UBM) for elucidating the causes of ocular hypotony. PATIENTS AND METHODS: A retrospective chart review was performed to determine the usefulness of UBM in the evaluation of ocular hypotony. UBM, B scan, and a detailed clinical examination had been performed. Sixty patient charts with prolonged ocular hypotony of different causes were reviewed from January 1994 to December 1998. The information obtained by the UBM was classified into three groups: 'diagnostic' (group 1), 'helpful' (group 2), 'not helpful' (group 3). RESULTS: Of the 60 eyes, 45 UBM examinations (75%) were in group 1, 9 eyes (15%) were assigned to group 2 and 6 eyes (10%) were in group 3. The duration of hypotony had no influence. CONCLUSION: In cases of ocular hypotony, the cause was related to ciliary body pathologies in 80%. Only UBM could distinguish tractional from dehiscence ciliary body detachment which required a different management approach. UBM with its high resolution imaging of the anterior segment - including the ciliary body - is highly suitable for diagnostic clarification.