CASE PRESENTATION
A 74-year-old white female was referred to our center by her optometrist for cataract evaluation. She had been a rigid contact lens wearer for 43 years, but cataracts that had been observed for the previous 6 years had recently begun to interfere with reading and caused glare when driving at night. The patient had a history of mild left amblyopia. Her refraction was +8.00 +1.25 X 125 OD and +7.25 +2.25 X 85 OS with acuities of 20/30 OU. The patient's glare test yielded 20/50 OU, and her examination revealed 2+ nuclear and 2+ cortical cataracts OU with early posterior subcapsular cataracts. Her anterior chamber axial depths were, subjectively, moderately shallow, and the globes were deep-set. The keratometry readings were 37.50/38.37 @ 90 OD and 37.00/38.75 @ 90 OS. Average axial lengths measured 22.27 mm OD and 21.31 mm OS with anterior chamber depths of 2.1 mm OU.
The patient's diagnosis included (1) cataracts, (2) hyperopia largely due to flat corneal curvature, with axial length on the low end of normal as a contributing factor, and (3) shallow anterior chambers. She wished to proceed with surgery and was also interested in reducing or eliminating her high hyperopia, as a bonus, to minimize or eliminate her dependence on contact lenses.
HOW WOULD YOU PROCEED?1. What unusual issues need to be discussed with this patient in advance?
2. Which type of anesthesia would you administer?
3. Which type of IOL (or lenses, ie, piggyback) would you choose?
4. What are the particular risks for this case?
SURGICAL COURSE
I discussed with this patient the usual risks, benefits, alternatives, and potential complications of phacoemulsification with IOL implantation. Ordinarily, I would advise that if a patient wanted to reduce or eliminate his or her high hyperopia or myopia, he or she would need to commit to bilateral surgery because of unacceptable anisometropia, or otherwise wear a contact lens in the fellow phakic eye. In this case, I explained to the patient that she would need a contact lens in the unoperated eye in the event that she elected not to proceed with surgery on that side.
IOL calculations for emmetropia in this patient using the SRK/T formula required lenses in the range of +30.0 D to +32.0 D, depending on the type of IOL used. A foldable lens was desirable to reduce the incision size in order to minimize postoperative astigmatism and permit a clear cornea approach. When possible, a single lens in the bag is preferable to piggyback lenses in order to avoid the risk of interlenticular pearls. Fortunately, several foldable lenses are available in this diopter range, including the lens that I chose to use in this case, the AcrySof SA60AT (Alcon Laboratories, Fort Worth, TX), which was recently made available in whole diopter increments in the +30 to +34 range.
First, I performed uneventful phacoemulsification on the right eye, with placement of an in-the-bag foldable lens, but the left eye presented complications. I chose to administer retrobulbar anesthesia, rather than topical, in order to maximize exposure of the eye with the additional orbital volume, and to minimize the intraoperative difficulties due to the other risk factors. I made a 1-mm stab incision at the limbus at 4:30 o'clock, and filled the anterior chamber with Amvisc (Bausch & Lomb, San Dimas, CA). Next, I made a clear corneal incision at 3 o'clock using the 3D Trapezoid Blade (Rhein Medical, Tampa, FL) to approximately 2.8 mm, taking extra care to minimize the length of the intrastromal portion of the incision due to the relatively flat cornea, which can promote late penetration of Descemet's membrane.
I performed a capsulorhexis, hydrodissected the nucleus, and then rotated and phacoemulsified the nucleus using a four-quadrant divide-and-conquer technique. Because of the shallow anterior chamber, I performed phacoemulsification of the quadrants as deeply in the bag as was practical and safe in order to minimize phaco energy exposure to the endothelium. I then placed the lens into the capsular bag and centered it. Using I/A, I removed the residual viscoelastic. Immediately after I removed the I/A tip in anticipation of reforming the anterior chamber to the correct tension, the chamber shallowed greatly over the course of 30 to 60 seconds, possibly with peripheral iris/cornea touch. There was no change in the red reflex.
At this point, my differential diagnosis included (1) a leaky wound due to wound anatomy or burn, (2) pseudophakic pupillary block/angle-closure glaucoma, (3) malignant glaucoma or an iridovitreal block (similar to malignant glaucoma with posterior diversion of aqueous due to crowding of the anterior segment by the IOL, particularly in hyperopic eyes) (Figure 1), and (4) suprachoroidal hemorrhage or detachment. Reforming the chamber required an unacceptably high pressure with an injection of BSS (Alcon Laboratories, Fort Worth, TX) to deepen the chamber even slightly, and the wound was secure, ruling out wound leak. I examined the peripheral retina with an indirect ophthalmoscope, and it was normal, ruling out a suprachoroidal hemorrhage or detachment. I was tempted to perform a conventional, surgical, peripheral iridectomy but did not do so, because the anterior chamber was extremely shallow. In addition, the incision anatomy and location was such that the iridectomy would be potentially unsightly and possibly visually significant being in the palpebral fissure, and it would probably be technically difficult and bloody. I could have created a new, more proper limbal incision superiorly for a surgical peripheral iridectomy, but I wanted a better view at the slit lamp in order to make a more definitive diagnosis before taking these steps.
I decided to reform the anterior chamber, and I achieved a compromise between very high pressure and a shallow chamber. The patient was brought out of the operating room to a slit lamp that revealed an IOP of greater than 50 mm Hg, and an iris bombe with a shallow chamber, particularly peripherally. Gonioscopy showed an occluded angle. At this point, the differential diagnosis was malignant glaucoma and pseudophakic pupillary block, perhaps augmented by a degree of intraoperative vitreous hydration/anterior displacement of the IOL. To determine the correct diagnosis and potentially cure the problem (and because the cornea was sufficiently clear to permit it), I performed an Nd:YAG laser peripheral iridectomy at 12 o'clock with a gratifying gush of aqueous anteriorly. I saw an immediate deepening of the chamber with an open angle on gonioscopy and the restoration of normal iris contour. Resolution of these findings ruled out iridovitreal block and malignant glaucoma with a posterior division of aqueous, the former more likely than the latter to respond to conservative surgical treatment with Nd:YAG disruption of the anterior hyaloid face.
One hour later, the patient's IOP was once again 52 mm Hg with an open angle, but it remained at 36 mm Hg and steadily lowered over the next 24 hours after a single burping of the paracentesis and short-term topical anti-glaucoma medications.OUTCOME
The patient's final outcome was OD plano -0.75 x 40 giving visual acuity of 20/25, and OS +1.50 sphere giving 20/30. Her UCVA was 20/30 OD and 20/60 OS, and her IOPs have remained normal OU postoperatively. The patient no longer wears contact lenses, and is extremely pleased with the outcome of the procedure.
Fortunately, pseudophakic pupillary block is a very unusual situation. If it were common, I would advise performing a peripheral iridectomy, but I am not aware of any surgeons who advocate this after the uncomplicated placement of a posterior chamber lens. I recommend proceeding as I did, but in the case of a superior scleral tunnel incision, I would consider performing the surgical peripheral iridectomy instead, if it were practical.
Mitchell Gossman, MD, is in private practice in Saint Cloud, Minnesota, at Eye Surgeons & Physicians, and is an Assistant Clinical Professor of Ophthalmology at the University of Minnesota. He does not hold a financial interest in any of the products mentioned herein. Dr. Gossman may be reached at gossman@iname.com. The author acknowledges Dr. David Sufka, OD, for his assistance with this article.
