Reverse Pupillary Block Unmasked After Recurrent Cystoid Macular Edema Following Intra-Scleral-Fixated Intraocular Lens Implantation

To report a case of recurrent Cystoid Macular Edema (CME) in a 77-year-old patient after intra-scleral-fixated intraocular lens (IOL) implantation, where reverse pupillary block was considered a potential contributing factor. Laser peripheral iridotomy successfully resolved the subtotal block,  equalizing pressure between the anterior and posterior chambers, increasing the space between the anterior surface of the IOL and the iris and prevented the recurrence of CME.

Hippocrateio General Hospital of Thessaloniki

A 77-year-old male presented for further treatment following the explantation of an IOL due to zonular dehiscence and subluxation, after which he remained aphakic.In our department, he underwent intra-scleral fixation of an IOL in his left eye (Scharioth technique) with BCVA 0.10 logMAR. Postoperatively, he developed CME, confirmed by OCT with BCVA 0.30 logMAR. An intravitreal injection of triamcinolone led to an initial resolution of the CME; however, recurrence was observed 16 weeks later. AS-OCT revealed a deep anterior chamber, a concave iris configuration and contact between the IOL optic and the iris at the pupillary margin, suggestive of reverse pupillary block. A laser peripheral iridotomy was performed.

The Anterior Chamber Angle (ACA) was 102.1° before the iridotomy, decreased to 79.8° immediately post iridotomy and was measured at 75.6° at the 2-week follow-up. A change in the distance between the iris and the IOL was also observed. IOL–Iris Distance (at closest points): a) pre-iridotomy: Nasal: 9μm, Temporal: 16μm, b) immediately post iridotomy: Nasal: 169 μm, Temporal: 267 μm and c) at the 2-week follow-up post iridotomy: Nasal: 152 μm, Temporal: 291 μm. The patient was prescribed NSAID and steroid drops and was evaluated at the 2-week follow-up, where complete resolution of CME and improvement in visual acuity (logMAR 0.14) were observed.  It should be noted that the IOP remained normal despite the block. 

In cases of recurrent CME following intra-scleral-fixated IOL implantation, reverse pupillary block should be considered. Comprehensive anterior segment evaluation is crucial, and laser peripheral iridotomy can effectively restore normal aqueous dynamics, preventing iris-IOL contact and reducing the risk of future CME episodes.  Based on this case, we agree with other authors and suggest that intraoperative iridectomy should be performed routinely to prevent CME and, more importantly, the potential pupillary block that leads to elevated IOP.