|Year : 1983 | Volume
| Issue : 5 | Page : 623-626
Trepanotrabeculectomy-A clinical study
DN Gangwar, IS Jain, GV Murthy, P Pillai, SL Bansal
Deptt. of Ophthalmology, Post-graduate Institute of Medical Education and Research, Chandigarh, India
D N Gangwar
Deptt. Of Ophthalmology, Post-graduate Institute of Medical Education and Research, Chandigarh-160 012
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Gangwar D N, Jain I S, Murthy G V, Pillai P, Bansal S L. Trepanotrabeculectomy-A clinical study. Indian J Ophthalmol 1983;31:623-6
|How to cite this URL:|
Gangwar D N, Jain I S, Murthy G V, Pillai P, Bansal S L. Trepanotrabeculectomy-A clinical study. Indian J Ophthalmol [serial online] 1983 [cited 2020 Jan 22];31:623-6. Available from: http://www.ijo.in/text.asp?1983/31/5/623/36608
Iridencliesis and Schie's cautery have been in vogue as antiglaucoma procedures for long. Ever since the introduction of trabeculectomy by Cairns in 1961,  the advantages of sub-scleral filteration have been recognised. To this effect many modifications of the initial procedures have been divised and surgical results in this have been reported , .
We are reporting a prospective study of trepanotrabeculectomy in 30 patients of glaucoma.
| Material and Methods|| |
Trepanotrabeculectomy was performed as the primary procedure on all cases of glaucoma requiring filtration, presenting to us between Feb. 1980 and March, 1981, the majority of the patients (21 patients) were in the age group 30-60 years, only two patients were younger than 30 years.
In addition to a routine, thorough ophthalmic examination, including gonioscopy and applanation tonometry. Most patients had cataractous changes in the lens.
Our indications for surgical intervention in primary gluacomas was the inability to control IOP with medical therapy. This included use of Pilocarpine drops 2% four times daily with Tab. Diamox 250 mg thrice daily. Two eyes were operated inspite of medically controlled IN because these eyes had advanced glaucomatous disease with poor vision and the patients could not be relied on to use their medications regularly.
All operations were performed under local anesthesia. A limbus-based, semilunar conjunctival flap was made from 10-2° clock position. Blood vessels in the superficial area were cauterized. A 4 mm x 4 mm, one third thickness scleral flap was raised. Its width was slightly increased towards the limbus and care was taken to keep the two radial a little short of the limbus. [Figure - 1]
Trephination was done over the trabeculum with 1.5 mm Elliot's trephine. Once the anterior chamber was entered, the button was excised with Vanna's scissors. A peripheral iridectomy was performed the scleral flap was replaced and sutured into place with two virgin silk sutures near the superior corner. Additional sutures were only used when a need was felt to ensure the proper reposition of the scleral flap. A running suture of 7.0 black silk was used to suture the conjunctival flap. The eye was patched after subconjunctival injection of Gentamycin 20 mg. Binocular bandage was in-place for 24 hrs.
When performing a combined extraction, we proceded in an identical manner till the iridectomy stage.
A limb of vana's scissors was introduced into the trephine opening and cuts made on either sides. These were further extended on other sides, for 180° by corneal scissors. Lens was dilivered with a cryoprobe. Cornea was sutured to the sclera with two 6-0 black-silk sutures on either sides of the scleral flap. The scleral flap and conjunctiva were sutured back as usual.
The eyes were cleaned daily with instillation of a drop of anti-biotic and l % Atropine. Most patients were discharged between 5 and 10 days postoperatively.
Gonioscopy was done on the first followup visit after one week. Visual acuity was recorded, visual fields charted where possible and IOP recorded in every subsequent follow up visit.
| Observations|| |
Of the 32 eyes operated, 23 had primary glaucoma and 9 had secondary glaucoma. This included 4 cases of phakomorphic glaucoma, where a combined extraction was done.
The average preoperative IOP's after administration of the medical therapy is shown in [Table - 1].
The majority of the patients had poor visual acuity due to associated cataractous changes in the lens. Some patients in addition had corneal edema due to the high IOP, further jeopardizing the vision. The break up of eyes according to visual acuity is shown in [Figure - 2].
The optic disc could be seen preoperatively in only 15 eyes due to opacification of the media. [Table - 4]
The follow up period ranged from 2-16 months. The average postoperative pressure are shown in [Table - 2].
The tension remained uncontrolled in 3 eyes. The first was a 15 year old female patient who had a perforating injury of corneo-sclera with fibrous ingrowth into the anterior chamber and secondary glaucoma. The second was a 60 years male patient with aphakic glaucoma, in whom three prior applications of cyclocryopexy had failed to control the tension. The third patient had a cilio choroidal detachment, which persisted for about 3 weeks postoperatively. On reformation of the anterior chamber, the IOP was recorded as 54 mm. Five eyes had an IOP of 10 mm Hg of less. None of them, however, showed any deterioration of visual acuity in the following period.
The restoration of IOP to the physiological range did result in improved projection of light in 4 eyes. Resolution of corneal edema with resultant improved vision was seen in 2 others. All the 4 eyes which had a lens extraction done as well, showed a markedly improved vision. Persistent post-operative hyphae na with rapidly advancing cataractous changes and low IOP (4-6 mm) in the initial 6 weeks of follow up, resulted in deterioration of vision in one patient. A successful cataract extraction a year later has resulted in a corrected vision of 6/12. The tension is well under control (10 mm-12 mm Hg).
Sub conjunctival filtering blebs were observed in almost all out patients. Most were diffuse and situated well away from the limbus. Two eyes had cystic blebs.
Gonioscopy was performed postoperatively in all the eyes and showed a patent trephine cleft. One eye showed a white, web like hyaline material in the opening. The IOP was, however, controlled, indicating that this must be permeable to aqueous.
The postoperative visual fields were found to be unaffected in most patients.
Hyphaema was noticed in 5 eyes (15.6%) in the immediate post-operative period. In all but one eye, it resolved with conservative management.
Transitory shallowing of the anterior chamber was seen in 5 eyes (15.6%). Bed rest and pressure bandage resulted in adequate deepening, maximum by the 5th day. Two eyes developed cilio-choroidal detachment conservative treatment was sufficient to settle the detachment.
Persistent IOP of 10 mm or less in 5 eyes was a cause of concern during the follow up period. The visual acuity however, remained stable in these eyes.
| Discussion|| |
Dellaporta  and Fronimopoulus (1970, 1971) suggested a modification viz. trephining of the iridocorneal angle. This modification is easier to perform and retains the advantages of the standard trabeculectomy. Excellent control of IOP has been reported with this modification. (Vetkovic et al.  reported a control of IOP in 87% with surgery alone and an additional 8% with miotics in a series of 100 eyes.
Most of our patients had poor visual acuity with advanced glacucomatous disease and immature cataract. IOP was controlled in all but three of the thirty two eyes. All these 3, were patients having secondary glaucoma. A final IOP 10 mm Hg or less noticed in five eyes was an untoward observation noticed with the procedure. Cvetkovic et al .  mention hypotony in only 2% of the eyes. Through the vision did not deteriorate in the period of observation, a longer follow up period is needed to finally comment on its adverse effect on vision, if any. More secure suturing of the scleral flaps may help in reducing the incidence of hypotony.
Almost all of the post operative hyphaemas were seen in those eyes where larger perforating anterior ciliary vessels were present in the region of the scleral flap. Inability to produce complete haemostasis from these several vessels despite cautery, might be the cause of hyphaerna in these eyes. Selection of the scleral flap site away from these blood vessels in subsequent cases prevented the complication totally.
A slight increase in the width of the scleral flap near the limbus helped in reaching the desired site of trephination, despite keeping the ends of the radial incision away from the limbus. This prevented the filtering bleb from encroaching on the cornea by keeping them more posteriorily and appears a noticeable modification.
We feel that a trephine size of 1.5 mm is adequate to fashion the required opening in the trabecular region. A larger sized opening would increase the risk of postoperative hypotomy. The average of IOP was 23.5 mm Hg. The fall was greater in those eyes with higher IOP. In those eyes with postoperative hypotomy, the drop in IOP was around 33 mm Hg. It has been observed with the conventional trabeculectomy that IOP was restored to the physiological range dispute wide variation in the preoperative IOP , . The reduction in pressure is found to be proportional to the initial IOP. Our observations seen to be in agreement with this. The presence of a hyaline plug and iris adhesions at the trabecular opening were frequently observed on gonioscopy by Watson  . We however, noticed a whitish hyaline like membrane at the site of the trephine cleft in only one of our patients.
| Summary|| |
32 eyes were subjected to trepanotrabeculectomy for different types of glaucoma. IOP was controlled in all but 3 of the 32 eyes. A slight modification of the surgical technique is suggested. The procedure is reliable as the primary surgical procedure for all types of glaucomas.
| References|| |
Cairns, J.E., Am. J. Ophth., 66,
Cairns, J.E., Trans. Ophth. Soc. UK. 89,481-490, 1969.
Dellaporta, A., and Franrenbruck, R.C., Trapanotrabeculectorny. Trans. Am. Acad. Ophth. and 8 to. 75, 283, 1971.
Cvetkovic D., Blagojivic M., Dodic, V, Experience with trapano trabeculectomy, Acta Ophth., 56,
Jay, J.L. and Murray, S.B., B.J.O., 64, 432-435, 1980.
Watson, P. and Ian Grierson, Ophthalmology, 88/3, 175, 1981.
[Figure - 1], [Figure - 2]
[Table - 1], [Table - 2], [Table - 3], [Table - 4]