Indian Journal of Ophthalmology

: 1983  |  Volume : 31  |  Issue : 6  |  Page : 793--795

Quantitative trabeculectomy

CB Patel, OP Billore, AP Shroff 
 Rotary Eye Institute, Navsari, Gujarat, India

Correspondence Address:
C B Patel
Rotary Eye Institute, Navsari, Gujarat

How to cite this article:
Patel C B, Billore O P, Shroff A P. Quantitative trabeculectomy.Indian J Ophthalmol 1983;31:793-795

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Patel C B, Billore O P, Shroff A P. Quantitative trabeculectomy. Indian J Ophthalmol [serial online] 1983 [cited 2022 Jul 6 ];31:793-795
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Full Text

Trabeculectomy is the most accepted proce­dure for Glaucoma. Failures are uncommon yet the final IOP following surgery remains unpredictable. Several modifications to the original technique of Cairns have been de­scribed, but it seems that the common aim of all is the production of optimal sub-conjuncti­val filtration, avoiding the potentially danger­ous cystic blebs and to achieve desired IOP post operatively.

In the present study, the technique and re­sults of Trabeculectomy are presented, where the thickness of the scleral flap was decided ac­cording to the height of the untreated Pre­operative IOP and a desired decrease in pres­sure aimed for.


In 50 cases we tried this method by which some prediction of final IOP after surgery could be made. The priniciple underlining the technique is that thicker flap will result into stronger healing and snug fitting and therefore it requires a greater force to raise the bleb; not to mention thicker the flap mose impervious will it be for percolation of aqueous, on the contrary a thinner flap will not fit on its bed so snuggly and will have a poor fibrous adher­ence, consequently formation of a sub-con­junctival bleb will be effected more easily and pressure will fall to a large extent.

Raised on this principle Standard Trabeculectomy described by Cairns was modified. Having dissected conjunctival flap, a 6 x 6 mm scleral area was demarcated. A flap of this size was raised with Bard Parker knife judging the thickness of flap under mic­roscope between one fifth to one half, accord­ing to the height of untreated pre operative IOP flap was dissected into clear cornea.

1.5 mm x 4.0 mm area of corneo-scleral tis­sue overlying the root of iris and ciliary body was removed with Vannas' scissors and basal iridectomy performed. The scleral flap was re­placed back and two stitches were taken with 8.0 silk sutures at the fornicial end. Conjuncti­val flap was closed as usual.

Post operative care included dressing with antibiotics, steroids and atropine. Light digital massage at 6 o'clock position in few cases was given where bleb did not appear. Cases were followed up for 6 months to 18 months.


(i) Trabeculectomy was performed on 50 eyes of 46 patients.

(ii) The different type of Glaucoma which were included in this series are listed in [Table 1].

(iii) The Pre operative IOP varied from 23 to 60 mm of Hg.

(iv) The thickness of the superficial scleral flap was according to initial IOP (See [Table 2]).

(v) 45 operations were successful and re­sulted in constantly low IOP (less than 21 mm of Hg.) with or without additional which 29 cases had shallow diffuse fil­tering bleb; 6 cases had no visible bled and 10 cases without visible bled, needed additional medication for 4-6 weeks.

Complications :­

(1) Choroidal Detechment :­

In 7 cases a choroidal detechment was visible. In 5 cases the chamber reformed under conservative treatment within 8 to 10 days. In 2 eyes however, it took 12 to 15 days for chamber to reform properly and choroidal detechment to settle.

(2) Transient Rise of IOP

In 22 cases transient rise of IOP was ob­served between 2 to 4 weeks after the surgery. In most cases it was treated by massaging the globe and the pressure de­creased gradually, usually, with bleb for­mation. In few cases medication was given in addition to massage. This successed in reducing IOP and the drugs could be with­drawn after 4 to 6 weeks.

(3) Flat AC was observed in 2 cases which did not respond to either medical or surgical treatment.

(4) Hyphema : : There was transient hyphema in 2 cases which did not clear. IOP had remained high (between 42-50 mm ofHg) even with additional treat­ment.

(5) Lens Opacity:­

In one case contract appeared.

Discussion :­

(1) Quantitative Trabeculectomy based on the principle that increased outflow after Trabeculectomy is inversely related to the thickness of the scleral flap. Therefore a thinner flap reduces the resistance to aqueous flow and by carefully adjusting its thickness, the desired reduction in the I.O.P. can be obtained.

(2) The advantage of Quantitative

Trabeculectomy is that, it does not aim only to provide filtration, but one can plan ahead for desired final post-operative pressure, which obviously should differ from patient to patient.

(3) The relatively law rate of complications 5 cases out of 50 and the fact getting a de­sired decrease in pressure aimed for, suggest the procedure can still be clas­sified among the well grarded filtration as all Trabeculectomy (90%).

29 eyes had a shallow, diffuse filtration bleb and the IOP pressure was controlled. had nor­mal IOP without visible bleb. 10 eyes without bleb needed additional medcation.

Five eyes, one with Chronio Angle Closure Glaucoma, 2 with congeital Glaucoma and 2 with secondary Glaucoma needed re-opera­tion 3 to 8 months after initial Trabeculec­tomy.


The technique of Quantitative trabeculec­tomy in 50 cases with all types of glaucoma was tried. The desired final IOP could be obtained by adjusting the thickness of scleral flag raised. JOP in present series could be control­led in 90% of cases. No extra ordinary compli­cations were noted.[1]


1Cairns J.E.; 1968, Trabeculectomy. Amer. J. Opthalmol 66: 673-9.