|Year : 1978 | Volume
| Issue : 1 | Page : 17-21
Peritrabecular filtration in aphakic glaucoma
Daljit Singh, Mohinder Singh
Department of Ophthalmology Medical College, Amritsar, India
Department of Ophthalmology Medical College, Amritsar
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Singh D, Singh M. Peritrabecular filtration in aphakic glaucoma. Indian J Ophthalmol 1978;26:17-21
Aphakic glaucoma was first recognized by Bowman in 1865. Over the years the following procedures have been tried to control intraocular tension in this condition: Trephination,, Iridencleisis, Cyclodialysis,,, Cyclodiathermy, Schie's limbal cautery and Scleral punch
In recent years trabeculectomy has been tried for cases of aphakic glaucoma by Schwartz et al and Mehta et al.
In this paper are presented the results obtained in 40 cases of aphakic glaucoma treated over the last two years by a new drainage procedure called "Peritrabecular filtration" or PTF.
| Materials and Methods|| |
40 consecutive cases of aphakic glaucoma which could not be controlled with pilocarpine were selected for PTF. Each patient was thoroughly examined with biomicroscopy, funduscopy, Schiotz tonometry and gonioscopy.
Preoperatively the intraocular tension was brought down with miotics, acetazolamide, oral glycerin and intravenous mannitol as required.
Anaesthesia: In addition to the routine local anaesthesia, the inferior rectus muscle was infiltrated with lignocaine.
Operation: As the operation is generally done at the lower limbus, the surgeon has to sit by the side of the patient. The operation is done without the help of an operating microscope.
1. An inferior rectus stitch is passed and the eye pulled up for good exposure at the lower limbus.
2. An 8-10mm limbus based conjunctival flap is fashioned. The area of the limbus is cleared of loose connective tissue. The superficial vessel--s near the limbus are lightly cauterized.
3. With the help of a razor blade two incisions about half scleral depth are made such that they make an equilateral triangle with the limbus, each side of the triangle being about 4-5mm. When making these incisions the anterior ciliary vessels are avoided.
4. The apex of the scleral triangle is held with a fine forceps and the scleral is split towards the limbus. The thickness of the flap is kept at about half scleral thickness. The splitting of the flap is continued beyond the limbus into the cornea for about 1_mm [Figure - 1].
5. The inferior rectus stitch is loosened to reduce pressure on the eyeball.
6. Two 1-llmm long parallel incisions about 1-1, mm apart are made in the deep layers of the cornea anterior to the posterior limit of the limbus. Both these incisions open into the anterior chamber in the central part of the base of the dissected triangle. Generally little or no aqueous is lost upto this stage. The anterior end of these incisions are joined together [Figure - 2]. At this stage there is some loss of aqueous.
7. The corneal flap thus formed is cut on the proximal side with a scissors. Peripheral iridectomy is done and if need be, the iris is reposited [Figure - 3].
8. The apex of the scleral flap is stitched back to its original place with a single fine stitch [Figure - 4].
9. Sterile air is injected into the anterior chamber with a fine cannula passed under the scleral flap and through the corneal opening.
10. The conjunctiva is stitched with three or four interrupted stitches.
| Results|| |
40 cases of aphakic glaucoma have been operated by PTF and followed for more than nine months.
[Table - 1] shows the operative complications:
The postoperative complications are listed in [Table - 2].
[Table - 3] shows the postoperative intraocular tension.
[Table - 4] shows the relationship of the intraocular tension and the type of the filtering bleb and
[Table - 5] shows the final results achieved.
Cases having less than 20 mm Hg. postoperative tension, with or without the use of pilocarpine were labeled as controlled. In 32 (80.0%) of the 40 cases the intraocular pressure below 20 mm Hg. was achieved without pilocarpine. 3(7.5%) out of the 5 cases where intraocular pressure remained higher than 21 mm
Hg., were adequately controlled with pilocarpine 2% drops instilled three times a day. Out of five (12.5%) failed cases, two agreed to re-operation and were controlled.
A majority of the cases (52.5%) showed a non-prominent bleb in the form of subconjunctival oedema, easily detected by slit-lamp examination. All the failed cases showed absence of filtration.
| Discussion|| |
The surgical management of non-pupillary block glaucoma in aphakic eyes has been fairly difficult in the past. This in part explains the multitude of procedures that have been attempted.
Since its introduction by Hein in 1905, cyclodialysis and many of its subsequent modifications have been the most favourable operative procedure for the control of aphakic glaucoma. The high rate of complications like hyphaema, vitreous haemorrhage, closure of the cleft by blood and vitreous and anterior as well as posterior chamber disturbances led to much disappointment with this operation.
Cyclodiathermy has been advocated as second best operation after cyclodialysis,,. It has also given unpredictable results,,.
With standard trabeculectomy, Schwartz et a! reported a success rate of 25% in cases of aphakic glaucoma, while Mehta et al 1-' controlled 69.6% of their cases.
In the present series of 40 cases operated by Peritrabecular Filtration (PTF), the overall control of intraocular pressure was achieved in 87.5% of the cases with the first operation. Operative and postoperative complications were relatively rare and minor. Choroidal detachment in one case and excessive drainage in two were responsible for three cases of shallow anterior chamber. The presence of even a small amount of blood in the lower part of the anterior chamber should be looked upon as serious because it results in the blockage of the filtering track. This happened in one of our cases in whom tension had to be controlled by reoperation.
Most of the controlled cases showed the presence of a bleb. The filtering bleb formed after PTF is usually thick walled and relatively flat. It is hoped that this non-cystic bleb will be resistant to infection, perforation and encystment.
The gonioscopic examination revealed the presence of a hiatus in every case. In 36 out of 40 cases the hiatus was found to be situated anterior to the Schwalbe's line. In four cases the anterior part of the trabeculum was also involved in hiatus formation.
PTF does not increase the drainage of aqueous by the production of cyclodialysis or by the opening of the Schlemm's canal and the collector channels. The only mechanism of action of PTF is the passage of aqueous through the corneal opening under the scleral flap, through the edges of the scleral incision under the subconjunctival tissues.
We agree with Khanna and Ramachandran and Schwartz et a that surgery in aphakic glaucoma has greater chances of success if performed at the lower limbus. The reason is that the scarring of the subconjunctival tissues, incarceration of the iris and the vitreous are less likely to be encountered in this region.
Peritrabecular filtration can be easily repeated in another part of the limbus.
The main advantages of PTF are:
1. It can be easily performed without an operating microscope.
2. There is no risk of injury to the ciliary body.
3. The filtering bleb obtained is near the ideal.
| Summary|| |
The technique of Peritrabecular Filtration as applied to cases of aphakic glaucoma is described. The results of this technique in 40 consecutive cases of aphakic glaucoma, with over 9 months follow up have been discussed. Ease of performance, low rate of complications and satisfactory results appear to be the chief merits of this technique.
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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]