Ophthalmologists are very familiar with pseudo-exfoliation syndrome since it makes the cataract surgery more challenging due to poor dilation or weak capsular support. A fellow ophthalmologist brought her 88 year old mother to our clinic for consultation. Her left eye shows the presence of a nuclear cataract with a best corrected vision of 20/80 (see title pic above). She is monocular due to optic nerve damage of the other eye, so the stakes are high for this cataract surgery.
Pseudo-exfoliation is associated with glaucoma, iris abnormalities and zonular weakness, all of which can cause difficulty during phacoemulsification. Proper preparation and early intervention can make surgery easier for the surgeon and safer for the patient. Pseudo-exfoliative material can be dispersed throughout the anterior segment on the anterior lens capsule in a target manner as shown above, over the zonules and ciliary processes, on the iris and in the angle of the eye (referred to as Sampaolesi’s line on gonioscopy). Any iridodonesis or phacodonesis that is noted at the slit lamp is an indication of severe zonular weakness. A pearl that I learned from the late Alan Crandall, MD, is to beware of a shallow anterior chamber in patients with pseudo-exfoliation because it usually means that the entire lens-iris diaphragm is loose and pushing forward, thereby shallowing the anterior chamber. If a patient has an AC depth of just 2 mm in the setting of a 24 mm axial length, there is a high risk for loose zonular support.
The association with glaucoma is high, and patients should be screened for optic nerve damage and treated if an elevated IOP is detected. These pseudo-exfoliation patients may be more prone to inflammation, and they should receive preoperative topical nonsteroidal anti-inflammatory drugs, which will also help prevent intraoperative miosis.
When it comes to patients with pseudo-exfoliation (PXF) and cataracts, often the pre-operative examination can help predict the intra-operative challenges. During the pre-operative exam, the degree of pupil dilation was just shy of 4 mm after two sets of phenylephrine 2.5% and tropicamide 1%. On the morning of surgery we attempted to get more dilation by administering phenylephrine 10%, tropicamide 1%, and cyclopentolate 1%. Often the degree of dilation can help predict intra-operative challenges with a reasonable correlation of poor dilation to worse zonular support.
Intra-Operative Technique: Iris Plane Phaco Technique
For this case, we are going to use a technique of bringing the nucleus out of the capsular bag and tilting it into the iris plane so that the iris sphincter is holding it in place. This requires a capsulorrhexis of at least 5 mm in diameter, but our current pupil size is just 4 mm. Injecting viscoelastic at the pupil margin can help to push the iris and expand the pupil, a technique Robert Osher, MD, has called visco-mydriasis. We can then make the capsulorrhexis right at the pupil margin or, even better, just underneath it. Most experienced surgeons, having done thousands of procedures already, can make the capsulorrhexis larger than the pupil without directly visualizing it. Balanced salt solution is used to hydrodissect the nucleus out of the capsular bag and then tilt it into the iris plane. The iris sphincter will now hold the nucleus in place while the surgeon uses a phaco chop technique to emulsify and aspirate it (Figure 1). This technique brings the nucleus out of the capsular bag in order to minimize stress on the zonules. And even in cases in which there is zonular laxity, this supracapsular technique can be safer than intracapsular techniques such as divide-and-conquer.
For additional stability of the capsular bag, a capsular tension ring (CTR) is carefully inserted, using a hook to guide it without causing zonular stress (Figure 2). This will help keep the single-piece toric acrylic IOL centered and positioned at the correct astigmatic meridian. The CTR will also help prevent excessive capsular contraction and possible anterior capsular phimosis, both of which are more common in pseudo-exfoliation syndrome.
Performing phacoemulsification at the iris plane does bring the ultrasonic energy closer to the delicate corneal endothelium. We can prevent damage to these cells by using a dispersive visco-elastic to recoat the endothelium just prior to performing phaco. Using phaco chop and ultrasonic power modulations such as pulse mode with a low duty cycle, we can minimize the total amount of energy placed inside the eye. Even in this case with a relatively dense cataract and an elderly patient, we can achieve a clear cornea on post-op day 1 with excellent vision (Figure 3).
For patients with pseudo-exfoliation, poor dilation, and zonular weakness, using this iris plane phaco technique can make the surgery safer and more efficient. Despite the small pupil size, iris hooks or expansion rings are not needed for a successful outcome.