Correspondence Address:
Ravi Thomas
Christian Medical College (Schell Eye Hospital) Vellore
India

Full Text

Phacoemulsification (phaco) offers rapid visual rehabilitation and is becoming increasingly popular among Indian ophthalmologists. I remember learning phaco three years ago in what we considered an ideal model.[1] It was thrilling to be at the cutting edge of technology. However, considering the magnitude of cataract blindness in India, it is important to realize that at 6 weeks postoperative follow-up visit the visual outcome with phaco is the same as with standard extracapsular cataract extraction (ECCE).[2] Considering the cost-risk ratio, it is obvious that phaco is appropriate only for a selected minority of cases.

As we grapple with the question of "appropriate technology," the use of phaco, at least in the developed countries, seems to be expanding. A recent editorial, as well as a spate of other articles in the literature claim that the triple procedure using phacoemulsification is now the state-of-the-art technique in the management of cataract with coexisting glaucoma. From past experience, it is only a matter of time before Indian ophthalmologists take the cue.

It is true that our current procedure of choice in this situation - trabeculectomy combined with ECCE may not provide adequate control of intraocular pressure in the long-term.[3] However, on what evidence do we decide to change our current therapy or select another?

There are three ways to chose a treatment.[4] First, the method of Induction. Based on the retrospective analysis of our own (uncontrolled) clinical experience or that of others, we logically arrive at the therapy that seems to or ought to work. This is the basis for most reports on the phaco triple.[5][6][7][8] However, there is a major flaw with induction. It assumes that the new therapy is as good or better than the one currently used, but does not consider the possibility that it could be worse or could have unacceptable complications. The observations on which induction is based may indeed be true, but can lead to erroneous conclusions.

Most studies on the phaco triples were uncontrolled trials. A few studies compared the visual outcome with the phaco triple retrospectively to patients who had undergone the accepted treatment - standard triple. However, the majority of these surgeries were done about a decade ago. Recent advances in instrumentation, irrigating solutions and microsurgical techniques, and use of antimetabolites such as mitomycin,[9] laser suturolysis and releasable sutures in routine glaucoma surgery, especially triple procedures have made these retrospective studies baseless. In fact, according to a recent review, incision length per se may be of minimal importance in the glaucoma triple procedure. What seems to make the difference is the use of mitomycin.[9]

Second, is the method of Deduction. This relies on prospective, randomized clinical trials designed to expose the risk factors of treatments under trial. Here, a therapy that successfully withstands the trial is selected. Despite the increasing reports on the success of the phaco triple, no scientific validity of the procedure is available. To our knowledge, conduct of such a trial is not on the anvil either.

Third, is the method of Abdication.[4] Here, a therapy is selected with blind faith on the basis of recommendations from experts in the field. From the exponential increase in the number of investigators claiming to do phaco and phaco triples, the method of abdication appears to be the most popular way to select a therapy. We seem to be well on the way to accepting an invalid method as the gold standard therapy.

One theoretical advantage of the phaco triple over ECCE is that the small incision done in phaco causes minimal fluctuation in the intraocular pressure resulting in less disruption of the blood- aqueous barrier and increase in the number of successful filters. A small self-sealing incision is also the feature of manual techniques. However, the Blumenthal's technique causes less peroperative fluctuation in intraocular pressure than compared to phaco.[10] The phaco triple is, therefore, an expensive technique.

So what do we conclude? Is mitomycin the key to success in the glaucoma triple? Would it adequately enhance the success in the current treatment of choice? Or, is incision length the major determinant? If so, is it sufficient to achieve the smaller incision by a manual technique, or are we to believe that it is the use of ultrasound per se that makes the difference? Only a prospective, randomised clinical trial can provide valid answers. Until then, it is important to be cognizant of the complications of the phaco triple (indeed phaco), especially those that mandate vitreoretinal intervention. Without a good vitreoretinal backup, it may be not be advisable to cross the limit.

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