Comment on: Limited vitrectomy in phacomorphic glaucoma.

Dear Sir,

We read with great interest the article – “Limited vitrectomy in phacomorphic glaucoma” by Sachdev et al.[1] The article describes a very innovative technique, but we had a few doubts for which we would like clarifications and would like to give a few suggestions.

In the technique, it has been said that the cannula is passed transconjunctivally through the pars plana, posterior to the limbus in a quadrant opposite to the site of corneal incision,[1] though from the photographs it is evident that they are not exactly placed opposite to the incision.

The safest position for making a sclerotomy and placing a cannula would be inferotemporal in any corneal incision, be it temporal, superior, or very uncommonly superonasal.[2] Placing a cannula opposite to the incision, i.e., nasally in case of temporal incision, will increase the risk and chances of the cannula hitting the lids during phacoemulsification and causing inadvertent movement of the cannula with possible retinal damage.

The authors have mentioned that the vitreous is cut as and when it prolapses through the cannula. Does that mean that the cannula is not plugged while cataract extraction is carried out?

Convention teaches us that vitreous should be undisturbed as far as possible and during vitrectomy the probe should move toward the vitreous and not vice versa. This technique causes the vitreous to prolapse from the sclerotomy before it is cut. Does this not increase the traction at the vitreous base opposite to the sclerotomy site?

Was a retinal examination done at the end of surgery or in the postoperative period to rule out any retinal tears? How many patients were treated in the above manner and were there any retinal complications seen in these patients?

The technique we follow is slightly different from the above. We place a valved cannula (which gets sealed after the instrument is removed – thus preventing vitreous prolapse) inferotemporally. A 23G cutter is inserted through the cannula and a limited vitrectomy is done to soften the eye and deepen the chamber. This is a blind procedure, but the risk of inadvertent retinal damage is very low.[34] Phacoemulsification is carried out and whenever necessary a further limited vitrectomy is done to the extent necessary. The retina is examined at the end of surgery using a light pipe through the valved cannula and wide-angled viewing system before removing the cannula. If for some reason the retina is not fully evaluated due to small pupil, hazy media, etc., a detailed evaluation is done postoperatively whenever the opportunity arises. We have done a few cases like this with no retinal injury so far. It is fortunate that we do not see many cases which require this procedure.

Needless to say, a preoperative B-scan to ensure a normal posterior segment is done in each case.

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