Indian Journal of Ophthalmology

: 1981  |  Volume : 29  |  Issue : 3  |  Page : 161--165

Failure in glaucoma surgery

Daljit Singh, Arun Verma, Mohindar Singh 
 Department of Ophthalmology, Medical College, Amritsar, India

Correspondence Address:
Daljit Singh
Department of Ophthalmology, Medical College, Amritsar

How to cite this article:
Singh D, Verma A, Singh M. Failure in glaucoma surgery.Indian J Ophthalmol 1981;29:161-165

How to cite this URL:
Singh D, Verma A, Singh M. Failure in glaucoma surgery. Indian J Ophthalmol [serial online] 1981 [cited 2024 Mar 4 ];29:161-165
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Full Text

The present study was undertaken to find out the causes of failure of various antiglau�coma operations in our patients and to ascer�tain the best line of management under diffe�rent situations.


125 cases of glaucoma who had undergone anti-glaucoma surgery at least once and had remained uncontrolled even with miotics with tension above 24 mm Hg. schiotz were selected for this study. The history and examination were conducted as follows:�

History of present illness : Special refer�ences were made as regards (a) Date and place of previous glaucoma operation; (b) Duration of stay in the hospital; (c) History of getting injections in the eye, in the post-operative period; (d) History of operative interventions in the post operative period; (e) Advice and treatment at the time of discharge. Special enquiry was made about the use of miotics and acetazolamide tablets.Examination: (a) Complete general phy�sical examination was done; (b) Local exami�nation. A detailed ocular examination includ�ing the condition of conjunctiva and subcon�junctival tissue, cornea, Ac depth, state of iris lens and vitresous. The state of bleb was recor�ded. The IOP was recorded with a Schiotz tonometer. The gonioscopy and fundus examination was done wherever possible.


65 Cases agreed for reoperation were admi�tted. Each case was assessed individually and managed accordingly. Preoperative management:

(a) The intracular pressure was controlled with miotics, acetazolamide, oral gly�cerine or I/V mannitol as required.

(b) Antibiotic drops were instilled frequently.

2. Operative management: Local anaesthesia was employed. I/V dia�zepam 10 mg when needed.

Two types of operative procedures were adopted:

(a) Surgery at the original site.

(b) Surgery at a different site:

(i) Reoperation for glaucoma (Pretrabecu�lar Filtration).

(ii) Cataract extraction.

(iii) Combined cataract and glaucoma operation.

Steps of Operation:

A. Surgery at original site : The previous area of filtration was exposed after making a suitable sized conjunctival flap. Tenon's cap�sule and scar tissue around the area of filtra�tion was excised. Cyclodialysis spatula was introduced through the edges of the filtering wound to enter into the anterior chamber. All anterior peripheral synechiae, if present were broken by the spatula and a large iridectomy was performed in the area of filtering hiatus, if required. The conjunctival wound was restitched.

Surgery at the original site is reserved for cases who have moderate elevation of tension (below 40 mm Hg. Schiotz) and have a patent internal hiatus, with not too heavy subcon�junctival scarring.

B. Surgery at a different site : The details of the steps of Pretrabecular Filtration have been described earlier[1]. The combined opera�tion for cataract and glaucoma was performed by the same technique as described[2],(3).

Cataract extraction was done through a corneal incision.

Subconjunctival dexamethasone injection 2 mg. was given at the end of all the opera�tions. In aphakics, the anterior chamber was filled with air.

3. Postoperative management:

The dressing is changed on the second day. All patients are given capsule chloramphenical 250 mg. 6 hrly. for three days. Dexametha�sone eye drops were put three Limes a day in the postoperative period. Biomicroscopy was done at the end of 1 week and the patient dis�charged.

The patients were called for follow up at two weeks intervals for two months and then once every month thereafter. Every case was followed up for atleast 6 months - average follow up was 10 months.

Intraocular pressure was taken as a yard�stick for evaluating the success in the manage�ment of the failed cases.


In the present stu ly of 125 cases of failed glaucoma, 54 (43.2%) cases ware males and 71 (56.8%) were females. The majority of the failed cases were between the ages of 41-60 years (72.8%).

It was observed that majority of the patients had undergone the operations of Pre�trabecular Filtration and Scleral Punch as these two procedures are most commonly employed by the surgeons in are institution.

114 cases (91.2%) had undergone glaucoma operation only once. 9(7.2%) cases had been operated upon twice and 2 (1.6%) cases had been operated upon thrice. 58 (46.4%) cases were aphakic.

In the present study, majority of the cases (81.6%) had ocular tension between 31 to 50 mm Hg. Schiotz.

Routine gonioscopy was possible in 100 (80%) cases only. The filtering hiatus was absent in. 18 % cases. It was found to be partially or completely blocked in 63 % cases. Iris tissue contributed to the blocking of the hiatus in 58 % cases. Extensive peripheral synechiae were seen in 27 % cases. The angle of the anterior chamber was narrow or closed in 69 % cases. 68 % cases showed grade III to IV pigmentation in the region of the angle.

Thorough examination of the conjunctiva and subconjunctival tissues was conducted and it was found that 93 (74.4%) cases had trachoma. 71 (56.8%) cases showed evidence of subconjunctival fibrosis.

The filtering bleb was either absent or mini�mal in majority of the cases (60%).

There were different probable causes of failure.

It was seen that in majority of the cases (75.2%) 2 or more factors were responsible for the failure of surgery. In 6 (4.8%) cases the failure was due to the wrong choice of operation. In these cases of open angle glau�coma, iridectomy had been performed, instead of a filtering operation.

Surgical Management:

Out of the 125 cases examined, on by 65 (52%) cases agreed to admission for reopera�tion. In 18 (27.7%) cases, the original site was reopened. Pretrahecular Filtration was performed at a new site in 36 (55.5%) cases. Combined cataract operation was per�formed on 7 (10.7%) cases, while only cata�ract extraction was done in 4 (6.1%) cases.

Operative complications:

Excessive bleeding was encountered in 7 (10.7%) cases and vitreous loss occured. in 3 (4.6%) cases.

Postoperative Complications:

Hyphaema was observed in 7 (10.7%) cases, flat a.c. in 5 (7.7%) cases, iritis in 4 (6.1%) cases, choroidal detachment in 1 (1.5%) case and malignant glaucoma in 1 (1.5%) case.

Postoperative tension:

[Table 3] shows the control of ocular tension with and without medication over a period of more than 6 months.

Postoperative gonioscopy:

This was possible in 46 (70.7%) of cases out of the total of 65. The opening was patent in 41 cases, whereas blocked (partially or completely) opening was seen in 5 cases.

A majority of the case (80%) had promi�nent filtering blebs.


Analysis of results of various surgical pro�cedures clearly shows that in all of them the initial lowering of intraocular tension is much lower than what one sees in later years. The early success is due to the tissue shock, the final outcome of which can only be assessed three to six months after the operation.

Any operative technique designed to com�bat glaucoma should ideally be such as to pre�serve the function of the eye. Restore the fluid dynamics of the eye to a normal equilibrium and to retain the integrity of the globe. The multitude of procedures designed from time to time is evidence in itself that this ideal has not been achieved.

In our series, failure in majority of the cases was due to localized overgrowth of fibrous tissue at the external fistulous opening. Subconjunctival fibrosis was judged to be present if the conjunctiva was adherent to the scleral opening or was obviously blocking it. If conjunctiva could be separated from the sclera and the scleral opening with ease, then no pathological subconjunctival fibrosis was thought to be present, This was tried by in�jecting local anaesthetic solution subconjuncti�vally in the region of the previous surgery and observing the ease with which the conjunctiva ballooned out.

Excessive subconjuctival fibrosis was evi�dent in 71 (56.8%) of our cases. In 5 (7.7%) cases during surgery, we found the external scleral opening to be so blocked by the tissues, probably derived from the scleral or the Tenon's tissues that we had to search for the position of the iridectomy, in order to find out the site of previous drainage operation. In all these five case we could not determine the type of previous antiglaucoma operation done.

Maumenee[1] has enumerated the following causes of failure of glaucoma surgery :

A. .Intraocular:

Plugging of the filteration hole by - iris. lens, cilliary processes or vitreous.

B. Scleral:

This scleral opening may be closed by fibrous issue, narrow angle cleft or persistence of Descemet's membrane, inadequate fistula, which is either too small or incorrectly placed.

C. Extraocular causes:

Scarring and condensation of Tenon's cap�sule, trauma, haemorrhage or inflammation of the flap, or foreign body under the flaps.

According to Maumeneel the intraocular and scleral causes of failure are uncommon and they are usually due to faulty surgical tech�nique. According to him, extraocular causes account for failure in the majority.

All the above factors contributed to failure in our cases, but the iris, sclera, Tenon's cap�sule and conjunctiva showed more severe reac�tion to the surgical trauma of the previous operation (71.2%). The basic cause of failure in most of our cases might have been the increased amount of pigmentation in the iris and the postoperative iritis and flat anterior chamber.

Routine gonioscopy in our cases showed that the iris tissue contributed to the blockage of the hiatus in the majority (58%). Quite a significant number of cases (27%) showed extensive anterior synechiae. 68% cases showed increased pigmentation grade III and IV in the region of the angle.

According to Maumeneel subcon�junctival condensation was exaggerated by trachoma, previous surgical trauma and use of strong miotics. The association of glaucoma and trachoma is well known. In our study 71 (56.8%) cases showed evidence of advanced trachoma with extensive subconjunctival fibrosis. Therefore it is probable that trachoma may play an important role in the failure of glaucoma procedures.

Glaucoma procedures themselves cause significant gonioscopic changes which may affect the prognosis and management of the failed cases.

In our study 6 (4.8%) cases of chronic simple glaucoma had undergone the operation of peripheral iridectomy. Wrong choice of sur�gery ire these cases probably caused failure.

In our cases flat anterior chamber was noted in 6 (9.2%) out of which one had choroidal detachment. The suprachoroidal space was drained in this case on the 5th postoperative day and air was injectedinto the anterior chamber which remained well formed thereafter. Intraocular tension in this case remained well controlled without miotics. In 4 patients the anterior chamber remained absent for more than three weeks. During this period, to stimulate chamber formation, alternate dilatation and contraction of the pupil by drugs was tried. Anterior chamber was reformed in all these cases, and intraocular pressure remained well controlled in all of them.

Uveitis or iritis after glaucoma operation turns out to be more severe and lasts longer than the usual minimal postoperative inflam�amtion after other intraocular surgery. 4 (6.9%) in our series developed postoperative iritis. Three of them were adequately treated without any subsequent adverse effect on the tension control. The fourth case though apparently normal at the time of discharge, developed late endopthalmitis, leading to phthisis bulbi.

In our study, 7 (10.8)%) cases developed postoperative hyphaema, In five of them, history of accidental trauma and straining by cough was present prior to the development of hyphaema. In all or them, hyphaema cleared spontaneously and tension remained well controlled.

Damage to the lens, either directly by in�jury or secondarily to rapid pressure changes induced at the time of operation may cause failure. The lens may get swollen, which because of its size may physically block a functioning fistula or due to its complimentary uveitis may cause an inflammatory closure of the filtering track. Control may be obtained by an immediate removal of the lens.

In the present study, cataract extraction through a corneal incision was done in 4 cases. All these cases had moderately eleva�ted tension with swollen and opaque lenses, pushing the iris forwards. All of them did well after surgery.

Problems of malignant glaucoma are usually present in chronic non-congestive glaucoma, where after the operation the anterior chamber had remained asent or shallow along postope�rative uveitis for a long period. In our study, one, (1.5%) case developed malignant glauco�ma during the the postoperative period. In this case lens was removed and vitrectomy done. Later anothor filtration operation was tried, but the tension remained high and the vision was lost.

Most of our patients come after a long delay. Reoperations should never be delayed because the delay increases the chances of failures of the reoperations.

In majority of our cases (52%) failed -glua�coma had already lasted for more than one year before they could be hospitalized by us. All of the ten (15.3%) cases who could not be controlled by us in the first instance, the raised ocular tension in them had already lasted for more than 10 months.

To reduce the incidence of failure after glaucoma surgery by any of the available filter�ing operations, the following points should be kept in mind

Proper preoperative assessment and diagnosis.Avoid unnecessary delay in surgery, since most of our patients are less likely to cooperate in an extended treatment progra�sub mme.The conjunctival flap should be large and thick.The operative site should be free from shrinkage and scarring of conjunctiva.Minimum cautery should be applied to the surface of the sclera.The fistulous opening should have an adequate size and should preferably have a cover of scleral flap.Excessive use of cotton tipped swabs is likely to contaminate the area and excite fibrous tissue reaction.The peripheral iridectomy should be of liberal size to avoid incarceration of the iris in the filtering hiatus.The use of blunt instruments produces excessive scleral reaction.Topical use of steroids before and after operation and subconjunctival injection at the end of operation are helpful in avoiding postoperative inflammatory reaction, which is an important cause of failure.Prolonged proper follow up of the patients is essential to detect failing blebs and to take remedial measures to avoid damage to the sight.

We should not enumerate our many suc�cesses only, but also subject our few failed cases to in-depth study and critical analysis so as to find out the cause of failure and to take all possible preventive steps in our subsequent cases.


1Maumenee AE, 1967.
2Cairns, J.E., 1968, Amer. J. Ophthalmol . 66:673.