JAN 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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Page 13 of 71

14 EW NEWS & OPINION Reversal continued from page 13 recurrent iris capture after scleral su- turing of a dislocated IOL, I did an IOL exchange first because I thought the IOL might have been sutured too anterior allowing the iris capture to occur. I replaced the three-piece silicone IOL with a more posteriorly fixated single-piece PMMA lens, and once again the patient presented with what I recognized as reverse pupillary block causing pigment dis- persion and elevated IOP (rather than iris capture of the IOL), which completely resolved with a simple laser iridotomy. I have no doubt that the lens exchange could have been avoided with a simple LI done in the first place. The other question these cases raise in my mind is whether or not it Figure 9 January 2012 Figure 10 is possible to have a "compartment" syndrome in the eye where there are different pressures in the anterior and posterior segments. Many of us have seen a compartment syndrome in the case of capsular distention syndrome after cataract surgery that is relieved dramatically with a small YAG laser opening in the posterior capsule. That appears to be similar to what is seen in these cases of re- verse pupillary block, and it would explain why the pressure drops so suddenly and dramatically after cre- ation of an iridotomy as the pressure in the anterior chamber and poste- rior segment equilibrate. If that is the case, one could postulate that perhaps some of the patients we see with normal pressure glaucoma and narrow angles actually have a higher pressure in the posterior segment than what is measured in the ante- rior segment due to the presence of a traditional relative pupillary block. We've all seen the rush of fluid when we first "break through" doing a laser PI. Perhaps some of the pa- tients we see in practice actually have higher pressures affecting the optic nerve than what we are meas- uring because of this "compartment- ing" phenomenon. In all of these patients with reverse pupillary block the rush of fluid seen immediately after LI is in the reverse direction than one sees after LIs are done for routine narrow angle pupillary block (where the fluid gushes through into the anterior from the posterior chamber as soon as the YAG laser "breaks through" the iris). In these reverse pupillary block cases, as soon as break-through is achieved, the iris opening looks like a "vacuum" at the slit lamp, sucking fluid and pig- ment from behind the iris into the posterior chamber. An immediate and sustained drop in measured IOP may follow this. The movement of fluid seen through the opening cre- ated is opposite of what one nor- mally sees when performing a PI in a narrow angle patient. This does sug- gest the possibility that pressure gra- dients can exist (in either direction) across the iris that are relieved with the creation of an iridotomy. Figure 9 shows a narrow angle with relative pupillary block prior to LI, and figure 10 is the same patient right after LI. Note the flattening of the iris and deepening of the angle. EW Editors' note: Drs. Condon, Devgan, Goldberg, Khan, and Nasser have no financial interests related to their comments. Contact information Safran: safran12@comcast.net

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