Indian Journal of Ophthalmology

: 1982  |  Volume : 30  |  Issue : 1  |  Page : 1--5

A comparative study of some filtering procedures in glaucoma

Radha Natarajan, JC Das, T Rajini Kanta 
 Guru Nanak Eye Centre, Maulana Azad Medical College and Lok Nayak Jai Prakash Hospital New, Delhi, India

Correspondence Address:
Radha Natarajan
Guru Nanak Eye Centre Maulana Azad Medical College & Lok Nayak Jai Prakash Hospital, New Delhi

How to cite this article:
Natarajan R, Das J C, Kanta T R. A comparative study of some filtering procedures in glaucoma.Indian J Ophthalmol 1982;30:1-5

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Natarajan R, Das J C, Kanta T R. A comparative study of some filtering procedures in glaucoma. Indian J Ophthalmol [serial online] 1982 [cited 2021 Jun 13 ];30:1-5
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Full Text

Therapy of Glaucoma is still an open chapter for the ophthalmic surgeons. The search for an ideal operation for Glaucoma continues, as it has for almost a century.

The surgical means of reducing the pressure are merely mechanical expedients which are resorted to when medical therapy is ineffective.

A comparative study of the three opera­tions-trabeculectomy, posterior lip punch sclerectomy and scheies was carried out in the Indian population.


Sixty eyes of primary Glaucoma requiring Glaucoma surgery were investigated pre and post operatively. Cases of secondary Glaucoma, Congenital Glaucoma and Buphthalmos were not considered in the study. The three procedures-Trabeculectomy, Posterior lip punch sclerectomy and Scheies operations were carried out on twenty eyes each. The patients were followed up post operatively for a period of six months.

A detailed ophthalmological history was taken The visual acuity, visual fields (where possible), slit lamp examination, tonometry, tonography, Gonioscopy were the parameters which were analysed and recorded both pre and post-operatively.


A 7 mm limbal based conjunctival flap and a Triangular partial thickness scleral flap (6 x 4 x 4 mm) was made under 2.5-4 X magnification. A rectangular block of trabecular tissue 2 mm/ 2 mm was removed with the help of vannas scissors. A peripheral iridectomy was done. The scleral flap was sutured at three sites; (one each at the sides and one at the tip of the triangle) and the Conjunctive was sutured with continuous sutures.


A 7 mm limbal based conjuntivotenon flap was made. A 4 mm horizontal incision was made just posterior to the anatomical limbus with knife. A single bite of the posterior lip was taken with a punch of 1.5 mm size. Two bites were taken if the tension was greater than 40 mm of Hg. After a peripheral iridectomy, a continuous conjunctival suture was passed using 6.0 black silk.


The classical Scheie's operation with a peripheral iridectomy was done.


Visual acuity

[Table 1] depicts the change in Visual acquity at the end of six month's follow up with maximum refractive correction.

Intra Ocular Pressure

The post operative intra ocular pressure ranges achieved at the end of six month's follow up is depicted in [Table 2]. In 59 out of 60 cases belonging to all series the tension was maintained at or below 20 mm of Hg. Only in one case of trabeculectomy the tension was 26 mm of Hg applanation at the end of one month In this case also the tension was maintained below 16 mm of Hg with the help of miotics.

Post operative Drainage Bleb

In 75% of cases of trabeculectomy, a drainage bleb was noticed which was thick walled, fiat and diffuse. All the cases of sclerectomy and scheies operation exhibited a thin bleb. Only one case of Scheie's developed a bicystic bleb at the end of three months follow up.

`C' Value : (T3)

The post operative `C' value at the end of six months' follow up was greater than 0.3 in 10% of trabeculectomy and 70% of Sclerectomy and 70% of Scheies operated series.


Flat chamber was seen only in 5% of trabeculectomy cases, while, 30% of sclerectomy and 20% of Scheies showed a flat anterior chamber. Moderate degree of Uveitis was noticed in 20% cases of sclerectomy. The other two operations did not lead to post-operative Uveitis. Anterior and posterior synechiae were noted in 20% trabeculectomy, 35% of sclerectomy and 50% of Scheie's cases. Progression of cataract was observed in 10% of trabeculectomy, 20% of sclerectomy and 30% of Scheie's operation respectively. Mild hyphaema was noticed in 5% of trabeculectomy and 10% of sclerectomy operation. Iris atrophy occurred in 10% of sclerectomy and 20% of Scheie's. Hypotony (Intra ocular pressure less than 8 mm of Hg) occurred in 15% of trabeculectomy, 30% of sclerectomy and 50% of scheies operation.

Complications like endophthalmitis, malignant Glaucoma, Vitrous heamorrhage and macular oedema were not observed in this series.


Many surgeons [2],[5],[7],[8],[9],[15] feel that trabeculectomy almost fulfills the criteria for an ideal operation because of high success rate, decreased incidence of flat anterior chamber post operatively, the apparent infrequency of cataract formation after the procedure and the usual development of a thick diffuse bleb that is more resistant to infection than cystic bleb often occurring after scheie's and sclerectomy operations. In this particular study the intra ocular pressure was controlled in all sixty eyes (100%). Only one case of trabeculectomy needed miotics post opera­tively, to maintain the tension within normal limits. This high success rate could be due to proper selection of cases, for only cases of primary Glaucoma were selected for this study.

Very little difference was noticed in the post operative control of I.O.P. in both trabeculectomy and sclerectomy, a finding similar to that of Sandford Smith [11]. The 100% control of intra ocular pressure in cases of scheies operation, corroborates with the high success rate found by Scheie [12]. The type of Glaucoma did not have any influence over the success of these operations. Similar is our observation to that of Ridgway [10] who found pressure control effect of both Scheies and trabeculectomy operations to be almost the same.

The blebs after trabeculectomy were found to be thick walled and diffuse and, therefore, was less prone to intra ocular infection.

The visual improvement occurred in 45% cases of trabeculectomy, 30% cases of sclerectomy and 20% cases of scheies opera­tion. The visual deterioration after sclerectomy (30%) and scheies operation (30%) was found to be one and half times greater than that after trabeculectomy (19%). This shows that trabeculectomy is least traumatising with almost equal intraocular pressure contro­lling effect.

Only two operative complications were noticed (1) Hyphaema (2) Injury to lens. The latter occurred in two cases of scheies opera­tion, for the patients developed a mature cataract on the second post operative day. Transfer of heat from the site of application to cause a physiological and or anatomical disturbances of the lens is the probable cause of it.

Only two cases (10%) of sclerectomy had a severe degree of Uveits. Synechiae which occurred in 20% cases of trabeculectomy was perhaps due to shallow or flat anterior chamber. The infrequency of Uveitis in this series may be due to minimal handling of the ocular tissues during surgery and due to generous use of local steroids and atropine from the very first post-operative day (Pre­operative conjunctival swabs was either sterile or showed non pathogenic organisms). Hypotony, that is tension less than 8 mm of Hg occurred in 60% of eyes of trabeculectomy, 70% of eyes of sclerectomy and 100% of scheies, when recordings were taken on the third post operative day. This may be due to excessive drainage and ciliary shock, in the first week following surgery.

10% eyes after trabeculectomy, 20% of eyes after sclerectomy and 30% of eyes which underwent a Scheie's operation showed pro­gression in lenticular opacities. As far as lens is concerned, trabeculectomy seems to be the safest of the three procedures.

The facility of aqueous outflow after trabeculectomy was found to be lower than after sclerectomy and scheie's at each period of follow up. This may be due to an easier and free flow of aqueous through a passage which directly connects the anterior chamber to the bleb area in the sclerectomy and Scheies operations.


Though the pressure control was the same after all the three procedures, trabeculectomy appears to have an upper hand as far as visual acuity and post operative complications are concerned.[16]


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