Year : 1983 | Volume
: 31 | Issue : 7 | Page : 833--835
Trabeculectomy-filtering or non-filtering
Deptt. of Ophthalmology, Rajendra Medical College, Ranchi, India
B P Kashyap
Deptt. of Ophthalmology, Rajendra Medical College, Ranchi
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Kashyap B P. Trabeculectomy-filtering or non-filtering.Indian J Ophthalmol 1983;31:833-835
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Kashyap B P. Trabeculectomy-filtering or non-filtering. Indian J Ophthalmol [serial online] 1983 [cited 2021 Sep 17 ];31:833-835
Available from: https://www.ijo.in/text.asp?1983/31/7/833/29679
Trabeculectomy has come into general use as a surgical procedure, since the paper of Cairn's 1968.
Filtering trabeculectomy was being done as a routine in our institution. The paper was presented in the 23rd International Congress of Ophthalmology held at Kyoto, where it was pointed out by Dr. Rao, that even non-filtering trabeculecomy was as effective as filtering trabeculectomy. Moreover it was observed that filtering trabeculectomy done in lower intraocular pressure groups i.e. (22.4-30.00 mm. Hg. Schiotz) led to hypotony. It was therefore thought proper to compare the evaluation of non-filtering trabeculectomy and filtering trabeculectomy in different intraocular pressure groups.
MATERIAL AND METHOD
Well established cases of open angle glaucoma were divided into 2 groups - Group -AI -
Non-filtering trabeculectomy was done in patients with intraocular pressure Group -A2 -
Filtering trabeculectomy was done in patients with intraocular pressure >30 mm. Hg. Schiotz i.e. between (22.4 - 30.00 mm. Hg. Schiotz).
Group -BI -
Non-filtering trabeculectomy was done in patients with intraocular pressure >30 mm. Hg. Schiotz.
Group -B2 -
Filtering trabeculectomy was done in patients with intraocular pressure Operative procedure:
Trabeculectomy is done as usual. In cases of filtering trabeculectomy part of the superficial flap in excised at its base.
The post operative intraocular pressure ranges, achieved at the end of six months follow up in depicted in [Table 1]. In 35 out - of 37 cases in which non-filtering trabeculectomy was done the tension was maintained at or below 22.4 mm. Hg. Schiotz. and in all the 42 cases where filtering trabeculectomy was done the tension was maintained within the normal limits.
Post operative bleb:
In 94.60% of cases of n on-filtering trabeculectomy drainage bleb was noted which was thick walled, flat and diffuse.. In 97.57% of cases of filtering trabeculectomy drainage bleb was noted, which was thick walled and less diffuse.
Shallow anterior chamber was seen in 8% of patients,with filtering trabeculectomy while 20 % on nonfiltering trabeculectomy Patients showed shallow anterior chamber, paticularly in patients with higher intraocular pressure groups ( i.e. >30 mm. Hg. Schiotz).
Hypotomy was observed in 23.07 % of cases of lower intraocular pressure groups ( i.e. between 22.4 - 30.00 mm. Hg. Schiotz), in which filtering trabeculectomy was done. Hyphaema and iritis were observed in negligible percentage of cases i.e. 6 % and 3 % respectively.
From [Table 2] it is evident that bleb has no relation with the post operative control of pressure except, in Group 131, where it is seen that in 2 cases where bleb was not formed postoperative intraocular pressure did not reach the normal limits. Moreover from [Table 2] it is evident that 20% of cases of B1 developed a shallow anterior chamber. However it could be observed that in [Table 2] group B 1 nonfiltering trabeculectomy lower the intraocular pressure by 31.76% and in the 2 cases of failure the initial preoperative intraocular pressure was (37.6 mm. Hg Schiotz) and (37.8 mm. Hg. Schiotz) and if we just calculate the reduction of intraocular pressure by 31.76% it comes to 26.6 mm.Hg. Schiotz and 26.7 mm.Hg. Schiotz which is higher than the normal intraocular pressure. The remaining 3 cases of group B1, where the bleb was present, initial intraocular pressure were (34.5 mm.Hg. Schiotz) (31.76 mm.Hg. Schiotz) and (33.00 mm. Hg. Schiotz) and after deducting 31.76 `Yo of the preoperative tension caused by nonfiltering trabeculectomy their pressure amounts to (22.4) and 20.4) mm. Hg. Schiotz respectively, which falls within the normal limits. This shows that the failure in the 2 cases were due to nonfiltering trabeculectomy performed in higher pressure groups, rather than due to absence of blebs.
Moreover the hypotony observed in 23.07% of cases of group A2 patients with intraocular pressure between (22.4 - 30.00 mm. of Hg Schiotz), could be explained by the fact that 52.42% of fall of pressure following filtering trabeculectomy would lower the post-operative intraocular pressure to very low levels, thus leading to hypotony.
In the present study it was observed that the fall of post operative intaocular pressure was 31.76% after nonfiltering trabeculectomy and 52.42% following filtering trabeculectomy. Thus it is concluded that if the intraocular pressure falls within normal limits after reducing 30% from the basal intraocular pressure nonfiltering trabeculectomy is indicated otherwise we go in far a filtering trabeculectomy.