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Year : 1988  |  Volume : 36  |  Issue : 2  |  Page : 76-78

A new modified filteration surgery for neovascular glaucoma

E-1/100, Arera Colony, Bhopal (M P) India-462 016, India

Correspondence Address:
Gurdeep Singh
E-1/100, Arera Colony, Bhopal (M P) India-462 016
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Source of Support: None, Conflict of Interest: None

PMID: 3235167

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A new modified surgical technique is described in five cases of advanced neovascular glaucoma. The procedure included excision of a large trabecular segment, non penetrating cyclodiathermy, destruction of iris new vessels and wide sector iridectomy. The preliminary results are evaluated and are quite encouraging.

How to cite this article:
Singh G, Kaur J. A new modified filteration surgery for neovascular glaucoma. Indian J Ophthalmol 1988;36:76-8

How to cite this URL:
Singh G, Kaur J. A new modified filteration surgery for neovascular glaucoma. Indian J Ophthalmol [serial online] 1988 [cited 2020 Jul 6];36:76-8. Available from: http://www.ijo.in/text.asp?1988/36/2/76/26143

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  Introduction Top

Neovascular glaucoma occurs as a result of retinal ischaemia most commonly following retinal vein occlusion and proliferative diabetic retinopathy.

The management of this is a big challenge to an ophthalmologist. Various methods including pan-retinal photo coagulation [1] and cyclocryotherapy have been tried but the results are not encouraging [2]. More recently gonio photo coagulation of new vessels at the chamber angle has been used but although the results are encouraging, they are limited to the early stages only [3]

Conventional drainage procedures are often ineffective either because of severe haemorrhage or due to late blockage of the opening by fibrovascular membranes.

As an alternative to drainage procedures, insertion of plastic tubes as described by Molteno et a1 [4] and Krupin et all have been advocated, but these are still under review.

We describe a modified external filtering procedure which may be used as an alternative measure for advanced cases of neovascular glaucoma with good residual visual functions.

  Material and methods Top

Five eyes with advanced neovascular glaucoma and reasonably good visual functions were selected for this preliminary study.

The age of the patients varied from 45 to 68 years and all the patients were males.

The cause of neovascular glaucoma was diabetes mellitus in 4 eyes and central retinal vein occlusion in only eye.

Only cases in which intra ocular pressure could not be controlled with maximal medical therapy were selected for this study.

The average pre-operative IOP was 43.0 mm Hg in this group and the pre-operative visual acuity ranged between CF 2 feet to 5/60.

A summary of the clinical findings in all the five cases is shown in [Table - 1].

  Technique Top

We performed this procedure under local anesthesia and retrobulbar block with 2 cc Marcaine. A paracentesis was made in the temporal part of the limbus with a Zeigler's knife. A limbal based conjunctival flap was then made between 3 to 9 O'clock positions After identifying the surgical limbus a4 x 12 mm long cautery mark was made behind and parallel to the limbs extending between 9.30 to 1.30 O'clock positions. Along these cautery marks a limbal based half thickness scleral flap was made using a no. 67 Beaver's blade. Bleeding from superficial vessels was controlled with cautery.

On the now remaining scleral portion, a similar cautery mark was made 2 mm behind and parallel to the original superficial marks Using a sharp razor blade an incision was then made along the second row of cautery marks until the uveal blue colour was visible.

The anterior chamber was then filled with 2% methyl cellulose and under magnification gentle fine dissection and separation of adherent iris tissue along with neo­vascular membrane was done.

This dissection was carried out until adequate incision could be made. A 2 x 8 mm scleral bed and trabecular segment was then excised with Vannus scissors After this excision light bipolar cautery was applied in the form of a radial track at 11, 12 and 1 O'clock positions in

the scleral bed connecting the posterior border of the scleral flap. This resulted in a groove formation which later enhanced the outflow of aqueous from the anterior chamber to the sub-tenon space posteriorly.

After these radial markings, light bipolar cautery was again applied in a semilunar fashion to the exposed portion of iris tissue extending as near as possible to the pupillary border.

A broad basal iridectomy was then performed in the area of the previously cauterised iris. Care was taken to make the iridectomy larger than the scleral wall in all the dimensions The scleral flap was then sutured with three interrupted 8-0 silk sutures and the conjunctival flap was sutured with 6-0 catgut The anterior chamber was reformed with BSS and a mixture of 2 mg Dexa­methasune phosphate and 20 mg Triamcinelone diacet­ate was injected in the lower fomix sub-conjunctivally.

  Results Top

The evaluation of this procedure was based on the following factors

1. Ease of performance and problems during surgery. 2. Immediate and late complications like iritis,

hyphaema anterior chamber depth, lenticular

changes ,

3. Nature of filtering blebs

4. Preservation of visual functions

5. Reliable and permanent control of IOP.

In all the patients the IOP was controlled without any supplementary medication during the follow up period ranging between 6 months to one year. The mean IOP postoperatively was 16.4 mm Hg. The filteration blebs in all the cases were diffuse and uniform and the post­operative visual acuity was same in 2 eyes, better in 2 eyes and reduced in one eye. This was due to the onset of lenticular opacity, probably due to surgical trauma during cauterisation. Shallow anterior chamber was observed in one case but it was formed by the 5th postoperative day. Mild hyphaema and iritis were observed in all cases but they were adequately controlled medically. No late complication was observed with this procedure except that lens extraction was done in one case.

Postoperative gonioscopy showed partial regression of new vessels in all cases.

  Discussion Top

Neovascularisation involving the trabecular mesnwork eventually forming a neovascular membrane constitutes the pathology of this type of secondary angle closure glaucoma The exact pathogenesis of this neo­vascularisation is still understudy but the most accepted view is that a vasoformative factor is produced secondary to posterior segment ischaemia. This leads to formation of neovascularisation upto the chamber angle leading to secondary glaucoma. This development of secondary neovascular glaucoma adds further insult to the vascular supply of the ocular tissues resulting in more ischaemia Thus, a vicious circle of ishaemia­rubeosis iridis- secondary glaucoma- ischaernia is established.

The mechanism and rationale of this modified surgical procedure in the treatment of neovascular glaucoma is to establish a good filteration which is unlikely to be closed by fibrovascular tissues Secondly the partial coagulation of the ciliary body also helps in the reduced formation of aqueous and thirdly a large iridectomy reduces the requirement of blood supply to the anterior segment thus reducing the chances of ischaemia and its future complications

Looking at the results of this small preliminary study regarding the control of IOP and the preservation of visual functions we recommend this procedure as a primary therapy in cases of neovascular glaucoma which are not controlled with maximal medical therapy[6].

  References Top

Black R K, Hitchings R A Laatikainen L Thrombotic glaucoma prophylaxis and management Trans ophthalmol Soc. U. K 97 :275­ 9, 1977.  Back to cited text no. 1
Boniuk M : Cryotherapy in Neovascularglaucoma Trans Am. Acad Ophthalmol Otolaryngol, 78 :337-343, 1974.  Back to cited text no. 2
Simmons RJ. et al Goniophotocoagulation for Neovascular Glaucoma Trans Am Acad. Ophthalmol Otolaryngol 83:80-89, 1977.  Back to cited text no. 3
Molteno A C B et at Drainage Operation for Neovascular Glaucoma Trans Ophth. Soc. NZ 32: 101-5, 1980.  Back to cited text no. 4
Krupin et al Valve implants in filtering surgery. Am J. Oph. 81 : 232-235, 1976.  Back to cited text no. 5
Schulze RR Rubeosis iridis Am J. Oph. 63 : 487-495, 1967.  Back to cited text no. 6


  [Table - 1]


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