|Year : 1984 | Volume
| Issue : 2 | Page : 69-72
Subscleral goniotrepanation in primary glaucoma
Mathew Jacob, Anna Thomas
Department of Ophthalmology, Christian Medical College, Vellore, India
Department of Ophthalmology, Christian Medical College, Vellore
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Jacob M, Thomas A. Subscleral goniotrepanation in primary glaucoma. Indian J Ophthalmol 1984;32:69-72
Since its first description by Carins in 1968 the operation of trabeculectomy has under= gone many modifications The popular use of a trephine in glaucoma surgery was adapted to trabecular surgery by Fronimopoulos et al in the procedure named gonio trepanation, in which the Elliot trephination was covered with a lamellar scleral flap. We conducted a prospective study of 50 eyes in 40 patients who underwent the operation of gonio trepanation alone or in combination with cataract extraction for primary glaucoma.
| Materials and methods|| |
Subscleral gonio trepanation was done in 50 eyes of 40 patients, and in 14 of them it was combined with lens extraction. All the eyes had primary glaucoma, with open angles in 21 cases and angle closure in 29. Their visual status ranged from perception of light to 6/5 and the average intraocular pressure was 40 mmHg. The indications for surgery were primary angle-closure glaucoma (acute or chronic) and primary open-angle glaucoma not controlled with medication. Surgery was also done when the patients could not be trusted with regular use of medicine or follow-up. Whenever the lens opacities warranted cataract extraction, this also was done along with gonio trepanation.
The procedure of subscleral gonio trepanation described by Fronimopulos with a few modification was employed After abroad (10 mm) conjunctival flap and a 5 mm x 5 mm lamellar scleral flap were prepared, a 2 mm Grieshaber trephine was positioned astride the junction of the white an blue zones of the limbus (partly on clear cornea and partly over the trabecular meshwork) and a neat disc was cut with a few turns of the trephine. It was lifted up with forceps and any adhesions to the underlying tissue severed with corneal scissors. A peripheral iridectomy was performed through the trephine hole and the scleral flap was closed with four or five 8-0 virgin silk or monofilament nylon sutures. The conjunctival flap was closed by a running 6-0 silk suture.
In cases where a combined gonio trepanation and cataract extraction was done, a timbal section of 160° was made through the trephine hole by corneal scissors and the lens removed by a cryoprobe or Arruga's forceps. The section was closed by a suture (8-0 virgin silk or monofilament nylon) on either side of the lamellar scleral flap, after inserting the regular flap sutures. The conjunctival flap was closed by a running 6-0 silk suture.
The patients were discharged on the 6th postoperative day and followed up at biweekly and then monthly intervals. The average follow-up period was 18 weeks in the gonio trepanation group and 22 weeks in the gonio trepanation-cataract extraction group.
No systemic antibiotics or steroids were used for any of the patients. Topical antibiotic-steroid drops (Betnesol-N) and homatropine or atropine were used postoperatively.
| Observations|| |
The criterion for success in this study was the reduction and maintenance of intraocular pressure below 20 mmHg (applanation). This was achieved in all eyes except one in each group [Table - 1]. In the uncontrolled case in the gonio trepanation group, the procedure had been done as a second operation on an eye which had undergone a trabeculectomy and later cataract extraction. The only failure in the second group (combined gonio trepanation and cataract extraction) occurred in an eye with angle closure glaucoma and an initial tension of 64 mmHg which developed extensive posterior synechiae post-operatively. Thus the overall control of intraocular pressure was 96%.
With two groups combined, 52% of the eyes had their vision remaining stationary and 30% had improved vision. The vision was reduced in only 18% of cases [Table - 2]. The main cause for reduction in vision was progressive lens opacities. In the combined procedure group, all the cases which did not show improvement in vision were found to have advanced optic atrophy.
The important complications encountered during surgery or during the post-operative follow-up are listed in [Table - 3]. None of the intra operative or the transient post-operative complication were serious enough to interfere with the final outcome.
The Filtering Bleb
A uniform, smooth and diffuse filtering bleb was present in most cases. It is remarkable that in the cases where the intraocular pressure was not controlled post-operatively, a filtering bleb was absent. Cystic degeneration of the bleb was seen in 6 eyes, but in most of them only some parts of the bleb showed a cystic appearance and the wall was not very thin. There was no incidence of breaking down of the bleb or infection.
| Discussion|| |
The introduction of corneoscleral trephining for glaucoma by Elliot in 1909 was one of the milestones in ophthalmic surgery, and this operation, with hardly any modification, has been used with highly satisfactory results by many surgeons upto recent times,
Trephining, however, had many drawbacks, the most important of which were a shallow anterior chamber and a thin, multicystic bleb, predisposing the eye to the various sequelae of hypotony and also to infection. In the operation for gonio trepanation, these problems are redressed by the lamellar scleral flap which covers the trephination, thus enabling a controlled drainage and producing a diffuse and uniform bleb. Indeed, the most important innovation in "trabecular" surgery has been the lamellar scleral flap, because it has been proved by many histological studies, that trabeculectomy and its modifications act as filtering operations, differing from the classical glaucoma filtrations only by the introduction of the scleral flap.
It is noteworthy that with the popularity of trabeculectomy and its modifications the indication for surgery in glaucoma became more liberal, as the complications were found the minimal. It is also generally agreed now that trabecular surgery with cataract extraction does not carry any more risk than a standard cataract extraction,
It is to be noted that the results reported after subscleral trephining operations have been consistently better than those after trabeculectomy, 11-20 as a comparison of [Table 4] with [Table 5] shows. The complications are also less frequent in gonio trepanation than in trabeculectomy. In the present series too, the results were excellent and the complication insignificant.
The use of a trephine has certain distinct advantages over a standard trabeculectomy. It enables the surgeon to make a regular and even entry into the anterior chamber and the size of the opening is standardised. The cyclodialysis effect which is often produced in a trabeculectomy by inadvertently opening up the suprachoroidal space is avoided. Trephination is a technically easier and quicker method than a conventional trabeculectomy.
| Summary|| |
A prospective study of 50 eyes which underwent subscleral gonio trepanation, alone or in combination with cataract extraction, is presented. The success rate for control of intraocular pressure was 96% and the complications were negligible.
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[Table - 1], [Table - 2], [Table - 3]