|Year : 1983 | Volume
| Issue : 6 | Page : 773-776
A modification in trabeculectomy
A KJ Dubey, AP Shroff, OP Billore
Rotary Eye Institute, Navsari, Gujarat, India
A KJ Dubey
Rotary Eye Institute, Navsari, Gujarat
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Dubey A K, Shroff A P, Billore O P. A modification in trabeculectomy. Indian J Ophthalmol 1983;31:773-6
On a thorough gonioscopic & slit lamp examination of failed cases of trabecutectomy, we found the-iridectomy and trabeculectomy openings to be patent and yet the IOP was high, and there was no sub-conjunctival filtration blab. At the same time many cases wihtout a bleb showed a controlled IOP showing a possible filtration through the cut ends of schlemmn's canal. In the 1st group of cases, we thought the cause of failure was either a firm sub-conjunctival adhesion or firm healing of partial thickness scleral flap to its bed or both. On testing the mobility of conjunctiva over the site of surgery, we found in majority of cases, it was the scleral flap which was at FAULT. We tried a modification in our technique as below.
| Material and method|| |
60 eyes having primary glaucoma (both narrow and open angle) were subjected to this modified technique, average age of patients was 50 years. Cases were followed up to 9 months.
Standard trabeculectomy as described by Cairns was done. Having raised a conjunctival flap and dissected a partial thickness flap of sclera (4 x 6 mm) towards the limbus, we preplaced two 70' silk suture at the two ends of the rectangular scleral flap and drew them into loop. Two holes, either with a Nettleship's punctum dilator or with a number 18 needle were made, a little anterior to the sutures in each of the fornical ends of ther scleral flap.
An inner window of 1.5 + mm of deep corneosclaral tissue was cut and an iridectomy was performed. Scleral flap was stroked back into the position and edges rather properly secured with 4-5 sutures. Conjunctiva was sewn. No air or saline being injected into AC.
The idea was to effect a tight pontential space under scleral flap, with two holdes opening into the subcojunctival space at its fornical ends, so as to induce capillarity along the track of holes and thus to maintain a constant flow of aqueous in the potential space, under sclaral flap i.e. to keep a fluid level or fluid membrane in this space, which would prevent any firm healing of flap to its bed. Further sub-conjunctival adhesions will also be checked due to a constant trickling of aqueous in sub-conjurctival space thro' the two holes. Any overfiltration will be checked as the adges of the flap are securely tied & also because the entire flow takes place along the capillary force, which is not much.
Technique in depected in fig. (1).
| Observation|| |
60 eyes were studied. Tension was found to be controlled in all cases. No extraordinary complications were noted. The blebs, besides being thick' walled & well protected almost in all cases were 4-5 mm away from visible limbus & spread over a large area. In some cases blebs were found to be arc shaped, evenly distributed, with concavity towards the limbus.
Table below depicts the results, complications etc.
| Discussion|| |
From the observations above it is evident that all cases worked well with following additional advantages.
(1) In almost all cases blebs were, seen in immediate post operative period, ruling out the requirement of digital massage & proving that the force of capillarity really worked.
(2) No flat AC and/or no over filtration or marked hypotony resulted while the IOP remained controlled in immediate post operative period, showing that holes permitted an adequate, limited, regularised & constant flow of aqueous. (Not an excessive flow).
(3) Control of tension over a period of 9 months indicates that secure apposition of partial thickness scleral flap is immaterial, as long as the sub-scleral space can be kept open.
(4) Blebs were thick walled, 4-5 mm away , from the limbus & spread over a large area, because at the site of holes where main filtration took place, Tennon's capsule is thicker than areas anterior to it. Lid pressure is, also more over this area, resulting into a constant massage of the bleb & making it diffuse.
(5) No dissecting blebs were noted noted & no blebs were in close proximity of the limbus thus making both a subsequent cataract surgery or a contact lens wear much easier. In fact a low limbal based flap could be raised, clear off the bleb for subsequent cataract surgery. (6) To our mind the entirre filtration worked along a three step pressrure system. Fluid .sub from AC passed into sub scleral space along a negative force caused by right apposition of edges & capillarity induced by making holes. Fluid from this space trickled into sub-conjunctival space because of a hydrrostatic pressure built in the sub scleral space (which can be built in just by a small amount of fluid as the space is potential), the fluid in sub-conjunctival space resulted into a posterior bleb which was naturally massaged by the upper lid; spreading it over a large area thus reducing the total hydrostatic pressure here & inviting more fluid from the potential sub-sceleral space in turn & thus continues the cycle.
In nutshell it can be said that the random flow of aqueous was regularized & well directed.
| Summary|| |
A modification in Trabeculectomy by making two holes in the scleral flap was tried in 60 cases. All cases did well. Some additional advantages were noted, `FILTRATION SYSTEM' was regularized.
[Figure - 1]
[Table - 1]