Surgery in eyes with white cataracts poses challenges

The key to maintaining control during the capsulorrhexis is to keep the anterior chamber deeply filled with a viscoelastic.

Uday Devgan

White cataracts pose a number of challenges during surgery: The capsulorrhexis is difficult, the lens nucleus is dense and the risk of complications is high. But there are techniques and devices that can be used intraoperatively to create a safer surgery and a better outcome for our patients.

Preoperative evaluation

Because the white cataract precludes a view of the posterior pole of the eye, examination of the retina and optic nerve is usually not possible. Flashlight testing to look for an afferent pupillary defect can detect gross pathology of the optic nerve or retina; however, ultrasound imaging gives a clearer picture of the posterior segment.

Careful slit lamp examination of the anterior segment can detect ocular comorbidities such as uveitis, narrow angles or vascular disease that often accompany white cataracts. Because of the opacity created by the white cataract, biometry is more difficult. Axial length measurements are typically not possible with optical coherence methods, so use of an A-scan ultrasound is preferred. Keratometry measurements can be centered over the pupil because the patient will not likely be able to fixate to locate the visual axis.

Intraoperative techniques

Visualization of the clear anterior capsule against the white cataract is difficult because the white cataract blocks the red reflex from the surgical microscope. Trypan blue dye can be used to stain the anterior capsule so that visualization is enhanced. A small amount of dye is applied to the anterior capsule under air or viscoelastic. This dye can lead to decreased elasticity of the lens capsule, so care should be taken during capsulorrhexis creation.

Because the white cataract can become partially liquefied in the capsular bag, it can cause problems during capsulorrhexis creation. Leakage of white, milky fluid as soon as the capsular bag is opened can impair visualization, and the pressure gradient created by the fluid can cause severe radialization of the rhexis edge, capsular rupture and a displaced nucleus.

Figure 1. A white cataract often has a dense nuclear core but may also have a liquid cortical layer that can pose a challenge during surgery. There can also be comorbidities such as glaucoma and uveitis, as seen in this patient.

Figure 2. By keeping the anterior chamber highly pressurized with a viscoadaptive device, such as Healon5, micro 25-gauge instruments can be used to perform the capsulorrhexis via a paracentesis incision. Images: Devgan U

This sudden, wraparound loss of the capsulorrhexis has been termed “Argentinian flag sign” by Daniel Mario Perrone, MD, because the blue/white/blue appearance resembles that country’s flag. Note that there is liquefied cortex in front of and behind the dense central nucleus, so care should be taken to release all of the fluid and decompress any pressure gradient.

The key to maintaining control during the capsulorrhexis is keeping the pressure in the anterior chamber higher than the pressure in the capsular bag. This can be achieved by keeping the anterior chamber deeply filled with a viscoelastic. This is a case in which a cohesive viscoelastic such as Healon GV (sodium hyaluronate 1.4%, Abbott Medical Optics), ProVisc (1% sodium hyaluronate, Alcon Laboratories) or Amvisc (sodium hyaluronate, Bausch & Lomb) would be preferred over a dispersive.

Even better, a viscoadaptive such as Healon5 (2.3% sodium hyaluronate, AMO) could be used throughout the case because it is retained in the eye at lower flow rates. Performing the capsulorrhexis via a small paracentesis incision and micro 25-gauge instrumentation allows the eye to be pressurized as a closed chamber.

Once the capsulorrhexis is successfully completed, the phacoemulsification can be performed. The nucleus is often dense, requiring increased phaco power levels and higher duty cycle settings. With these higher power levels, care should be taken to avoid heat build-up at the incision, which may cause a wound burn.

The white cataract can be more difficult to chop or split because the posterior plate is often fibrous or leathery. Because of the increased amount of ultrasound energy placed in the eye, care should be taken to re-protect the corneal endothelium with additional application of viscoelastic during surgery.

Postoperative recovery

Because of the increased complexity of the surgery, there may be more postoperative inflammation than usual, and the resolution of cells and flare may require additional weeks of treatment. Although this can often be managed with topical applications of steroids, it is sometimes beneficial to supplement this with injectable steroids at the end of the case.

Corneal edema may be present during the initial postop period, and this may impair the vision until it resolves. When the cornea is clear, the eye can be measured for any residual refractive error, which can be addressed with spectacles or refractive surgery.

Care should be taken to examine the posterior segment that was not directly visualized before surgery. Any retinal pathology may hamper vision and should be evaluated and treated, and certain diseases such as diabetic retinopathy may progress further after the cataract surgery. Other conditions such as glaucoma may be helped by the cataract surgery because the angle of the eye will be opened further but should be monitored carefully in the postop period.

Cataract surgery in eyes with white cataracts is more challenging but also more rewarding because we have the ability to restore vision to patients who were previously blind.

• Uday Devgan, MD, FACS, is in private practice in Los Angeles, chief of ophthalmology at Olive View-UCLA Medical Center and associate clinical professor at the UCLA School of Medicine. He can be reached at 11600 Wilshire Blvd., Suite 200, Los Angeles, CA 90025; 800-337-1969; fax 310-388-3028; email: devgan@gmail.com; Web site: www.udaydevgan.com. Dr. Devgan is a consultant to Abbott Medical Optics and Bausch & Lomb, and a stockholder in Alcon and formerly in Advanced Medical Optics. He has no direct financial interests in the products mentioned.