Iris plane phaco technique facilitates surgery in pseudoexfoliation cases
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Ophthalmologists are familiar with pseudoexfoliation syndrome because it makes 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 showed the presence of a nuclear cataract with best corrected vision of 20/80 (Figure 1). She was monocular due to optic nerve damage of the other eye, so the stakes were high for this cataract surgery.
1. The patient is monocular with a nuclear cataract, pseudoexfoliation syndrome and poor dilation. Fortunately, this eye has a healthy optic nerve without glaucomatous damage.
Source: Uday Devgan, MD
Preoperative consultation
Pseudoexfoliation 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. Pseudoexfoliative material can be dispersed throughout the anterior segment on the anterior lens capsule in a target manner, over the zonules and ciliary processes, on the iris and in the angle of the eye (referred to as Sampaolesi 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 pseudoexfoliation 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 anterior chamber 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 elevated IOP is detected. These pseudoexfoliation patients may be more prone to inflammation, and they should receive preoperative topical NSAIDs, which will also help prevent intraoperative miosis.
When it comes to patients with pseudoexfoliation and cataracts, often the preoperative examination can help predict the intraoperative challenges. During the preoperative 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 intraoperative challenges with a reasonable correlation of poor dilation to worse zonular support.
Intraoperative techniques
For this case, we planned 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 was 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 viscomydriasis. 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 2). 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 3). 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 pseudoexfoliation syndrome.
Postoperative course
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 viscoelastic to recoat the endothelium just before 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 postop day 1 with excellent vision (Figure 4).
For patients with pseudoexfoliation, 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.
A video of this surgery can be found at https://cataractcoach.com/category/pseudo-exfoliation/.
- For more information:
- Uday Devgan, MD, in private practice at Devgan Eye Surgery and a partner at Specialty Surgical Center in Beverly Hills, California, can be reached at devgan@gmail.com; website: www.CataractCoach.com.
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