LAUSR

To the Editor: The article by Ramakrishnan et al1 was a very interesting read and we would like to congratulate them for successfully conducting their study “To Study the Efficacy of Laser Peripheral Iridoplasty in the Treatment of Eyes With Primary Angle Closure and Plateau Iris Syndrome, unresponsive to Laser Peripheral Iridotomy, using Anterior-Segment OCT as a Tool.” Primary angle closure glaucoma is a protean disease with a varied presentation. It forms the larger picture in Indian scenario and is visually more debilitating than primary open angle glaucoma.2 Angle anatomy plays a pivotal role in the pathomechanism and its various dimensions are well studied by anterior segement optical coherence tomography (ASOCT), which is very well highlighted in this study. The results of the study are useful from a clinical point as one third of the patients of primary angle closure suspect/primary angle closure are found to have plateau iris configuration in addition to pupillary block and which may require further management. However there are few points which need further discussion. The study design as mentioned in the article was a “cross sectional case control study” but all the measurements were compared within the same group of patients in a ‘before after pattern.’ The control arm taken is thus not clear in the methodology and we request the authors to elaborate their methodology for our better understanding. Earlier literature3,4 quotes laser peripheral iridotomy (LPI) as a treatment of choice in primary angle closure but almost one third of the angles have been found to remain closed even after a patent peripheral iridotomy.5 With the advent of ultrasound biomicrosocpe,6 a separate clinical entity of Plateau iris configuration has been devised which can even be picked up clinically by a meticulous gonioscopy. Laser iridoplasty (LIP) contracts the peripheral iris and hence relieves the peripheral crowding in plateau iris configuration. We conducted a similar trial in our hospital in North India in which 100 eyes of primary angle closure were randomized either to undergo LPI or LPI plus LIP. It was a double-stratified randomization so that each group gets similar number of appositional and synechial closure patients. Stratification was done for the amount of synechiae also. Both groups 1 and 2 underwent a LPI and group 2 subsequently underwent an additional LIP using a double frequency Neodymium-doped Yttrium Aluminium garnet laser 2 weeks later. In our unpublished data it was observed that after 1 month of the initial laser procedures, the iridoplasty group had significantly lower intraocular pressure (IOP) as compared with the only LPI group till 1 year of followup [18.53±2.2mm Hg (LPI) and 15.34±2.8mm Hg (LIP)]. On subgroup analysis, iridoplasty did better in eyes which had only appositional closure, and in eyes with synechiae <180 degree. However, in eyes with extensive synechiae (>180 degree) both the procedures failed as none was able to achieve significant IOP lowering and these patients had to be started on topical antiglaucoma medications. There was no difference in the amount of synechiae between the 2 groups at the end of the study. This present study is exclusive as it has documented the anatomic effect of iridoplasty on angle structures with the help of ASOCT. ASOCT provides an objective picture as to what is happening to the angle structures over time and after interventions. The study was very well conducted and all the results were very well analyzed. Thus we agree with the authors that iridoplasty definitely relieves the appositional closure due to plateau iris though the effect on synechiae is minimal after a critical period of time which is still not well defined. Hence, we recommend iridoplasty in eyes having synechia of short duration but the same may not be applicable in established synechiae of long duration presenting with raised IOP. We also recommend post LPI gonioscopy in all primary angle closure suspect/primary angle closure patients as angle may continue to close even with a patent PI and in which cases iridoplasty may be a good option to open the angle.