Indian Journal of Ophthalmology

: 1988  |  Volume : 36  |  Issue : 2  |  Page : 67--70

Failure in glaucoma surgery and its management

Sandeep Mithal, AG Mathur, Alka Gupta, Sushil Kumar 
 L L R M. Medical College, Meerut, India

Correspondence Address:
Sandeep Mithal
L L R M. Medical College, Meerut


Surgical management of glaucoma may include many different procedures, but filtering surgery is the most frequent. The subject of operative failure following glaucoma surgery is extremely important to every ophthalmo­logist who does glaucoma surgery. More over, it is most distressing; that what initially appears to he a clinical success eventually proves to be a failure. If we can analyse the patients operated for glaucoma where satisfactory control is not achieved, we can choose a safer and more successful procedure.

How to cite this article:
Mithal S, Mathur A G, Gupta A, Kumar S. Failure in glaucoma surgery and its management.Indian J Ophthalmol 1988;36:67-70

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Mithal S, Mathur A G, Gupta A, Kumar S. Failure in glaucoma surgery and its management. Indian J Ophthalmol [serial online] 1988 [cited 2020 Apr 1 ];36:67-70
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Any operation devised for the relief of glaucoma should ideally be such, as to preserve the functions of the eye, maintain its tension within normal limits and retain the integrity of the globe. The fact that there are a number of operations designed for the relief of glaucoma suggests, that as yet, a surgical procedure which will produce a reliable and permanent effect in maintaining intra­ocular pressure within safe limits has not been found. The surgical management of glaucoma may include many different procedures, but filtering surgery is the most frequently done antiglaucoma procedure today.

The management of operated patients not adequately controlled has always been as big a problem as of a fresh glaucoma patient This study was therefore aimed to find out the causes of failure in glaucoma surgery and to decide the best line of management under different situations.

 Material and Methods

The present study was carried out on patients who had undergone glaucoma surgery atleast once and had remained inadequately controlled.

Detailed history from 148 patients (160 eyes) was taken regarding the duration of glaucoma, details about previous glaucoma operations, duration of stay in hospi­tal after operation, history of operative interventions in the post-operative period, history of getting infections in the eye in the post-operative period, advice at the time of discharge and treatment like use of pilocarpine, timolol and tab acetazolamide after surgery was recorded.

Complete general physical examination was done especially to find out any evidence of excessive fabrosis. Detailed examination of the anterior segment including the conjunctiva, subconjunctival tissue, cornea, anterior chamber depth, state of iris, pupil, and anterior vitreous was performed with a torch and slit lamp. The state of the filtering bleb was recorded with special care. Examination of the posterior segment was done with a direct ophthalmoscope. Vision was recorded and tono­metry was done with the help of a Schiotz tonometer. Repeated tensions of more than 21 mm Hg were taken as abnormal. Gonioscopy was done with a Goldman three mirror gonio-prism.

Patients having borderline or slightly raised intraocular pressure were put on pilocarpine. If required pilocarpine was combined with timolol or epinephrine in chronic simple glaucoma in early post-operative cases bleb massage was done where no bleb or a poor bleb were present All cases were followed up after medical treatment and then tension controlled. Reoperation was done keeping in mind the probable cause of failure of previous glaucoma surgery.


This study was carried out on 148 (160 eyes) cases showing failure of glaucoma surgery. Majority of cases were between the age group of 41-60 years (64.86%).

In 86 eyes (58.1%) reoperation was done. In 25 cases (29.0%) the original site was reopened. Trabeculectomy was performed at a new site in 61 cases (70.9%). Excessive bleeding vitreous loss and button holing of the conjunctiva were the operative complications. Post­operative complications were hyphaema, flat anterior chamber, iritis, choroidal detachment and malignant glaucoma


The causes for failure of filtration operations has been adequately dealt with in the past Maumenee', Welsh'. Sollom [3] and others have showed that the causes were intraocular (due to the lens, iris, vitreous and in­adequacy of the scleral opening due to retention of Descemet's membrane or scleral tissue) and extraocular (closure of external opening by connective tissue such as scarring and condensation of Tenori s capsule, trauma, haemorrhage, inflammation of the flap or foreign body under the flap). Only one of the above factors or a` combination of these maybe responsible for the surgical failure

In this study of 160 eyes of failed glaucoma surgery, 60 cases were of males and 88 were of females. Majority of cases were between the age of 41-60 years. 49 cases (33.10%) were of chronic simple glaucoma and 99 cases (66.89%) were of narrow angle glaucoma Intraocular pressure was between 21-45 mm Hg in majority of cases though it went up to 89 mm Hg in a few cases. Various antiglaucoma procedures done were trabeculectomy (55.0%), Scheie s operation (29.3%), posterior sclerec­tomy (4.37%), trephine (3.75%), iridectomy (6.25%) and in 1.25% cases the exact procedure could not be made out

Some eyes showed increase in intraocular pressure in the early post-operative period In majority of cases failure was evident within 6 months of glaucoma surgery. Excessive conjunctival fibrosis was noted in 96 eyes.

The filtering bleb was absent in 81 eyes (50-62%) r minimal in 59 eyes (38.87%) and moderate in 12 eyes (7.50%). In 8 eyes the bleb was of fair size and shape but without any function. Foreign bodies in the form of cotton fibres and suture materials were found under the scleral flap.

Gonioscopy showed that iris tissue contributed to the blockage of the filtering site in the majority of cases (58.12%). Significant number of cases (27.5%) showed peripheral anterior synechiae. Other causes of blockage were ciliary body, vitreous and lens [4],[5]. The filtering fistula was partially or completely blocked because it was made anterior to the canal of Schlemn. It was not possible to makeout the site of the fistula in 18 cases.

There were 3 cases in which drainage operation had been performed on both eyes but was successful in one eye only. In each eye where tension was controlled a drainage bleb was present and in the eyes which were uncontrolled there was no bleb. All eyes showed anterior synechiae and the drainage fistula had been placed anterior to the canal of Schlemn.

Reoperation was done in 58.1 % of the cases out of which bleb revision was done in 29.06% cases and trabeculec­tomy in 70.97% of cases [5]. Condition of the filtering bleb in the post-operative period was fair in 36.04%, moderate in 48.83% and minimal in 15.11 %. Intraocular pressure was controlled in 60.0% of the cases in bleb revision and 80.32% cases in trabeculectomy.

Gonioscopic findings after repeat surgery showed that 74.41% cases had patent fistula, while 19.76% had partially blocked and 5.81% had completely blocked fistula. So any operative technique designed to combat glaucoma should ideally be such as to preserve the function of eye.


The factors which mainly contributed to failure in this study were the iris, sclera, Tenon s capsule and conjunc­tiva The most common causes responsible for filtration failure, either singly, or in combination, were blockage of the internal opening (fistula) by iris tissue, scarring under the conjunctiva and closure of the scleral edges.

It was seen that once glaucoma surgery failed often ended in failure. If there has been no technical reason for failure of the first operation, a rationale choice for reoperation becomes very difficult It may be wise to shift to another type of filtering procedure or to modify the original approach in the hope of a more favourable response by the eye. For example one may reduce the thickness of the scleral flap in trabe­culectomy or sew it down more loosely in an effort to achieve better filtration. If one or more trabeculecto­mies have failed a full thickness sclerectomy might be considered. Reoperation by any of the external filtering procedures probably has at least a 50% chance of being successful Such operations should always be placed where there is unscarred conjunctiva and under the upper or lower lid if possible. Steroids should be consi­dered in cases of repeated filtering procedures after an initial failure[6].


1Maumenee, A.E. External filtering operations for glaucoma The mechanism of function and failure. Trans. Am. Ophth. Soc., 58: 319, 1960.
2Welsh, N.H. Failure of filtration operation in the Africans. Brit J. Ophth., 54: 594, 1970.
3Sollom; A W. Gonioscopic changes after glaucoma surgery. Brit J. Ophth., 53 : 561, 1969.
4Teng et at Histology and Mechanism of filtering operations. Am. J. Ophth., 47: 16, 1959.
5Sugar, H. S. Complications, repair and reoperation of antiglaucoma filtering bleb. Am J. Ophth, 63 : 825, 1967.
6Shridhar Rao, Failure of glaucoma surgery. National symposium on glaucoma ARMS, New Delhi 1987.