Mature cataracts

Although these are challenging cases, David F. Chang, MD discussed two useful techniques for mature white cataracts. Because of the cortical milk and the lack of a red reflex, the first problem is being able to visualize the capsulorhexis. The most effective method is the use of indocyanine green (ICG) dye*, said Dr. Chang, who has used this technique on 8 white cataracts. This provides excellent visualization of the anterior capsule without the need for any special illumination or colored filters, and also works on a brunescent lens with no red reflex.

The anterior chamber is first filled with air through a tiny paracentesis. A puddle of the ICG dye is then placed on the anterior capsule with a 30-gauge cannula. The air is exchanged for BSS, and an initial puncture is made in the central capsule with an irrigating cystotome to lavage away any cortical milk. The capsulorhexis is then performed with or without viscoelastic according to the surgeon's preference. As the tear is initiated, the green-stained capsule is easily visualized against the "white reflex" provided by the cortex.

*Reference: Horiguchi,M et.al., Archives of Ophthalmology 116: 535-537, 1998 (April). Dissolve 25 mg. lyophilized ICG (AKORN) in 0.5 cc sterile aqueous diluent (supplied). Add 4.5 cc BSS plus. Conc.= 0.5%; osmolarity = 270 mOsm. This is an off-label use.

Phaco chop

The second challenge in these cases is emulsifying the nucleus, which is often very large and brunescent . The absence of a red reflex makes it very difficult to judge the depth at which one is sculpting. This is a problem for cracking techniques which require a deeply sculpted trough and where an increasingly brighter red reflex is used to gauge the proximity of the posterior capsule. "Phaco chop is is a more kinesthetic technique in which visualization of the depth of the chopper tip or phaco tip is not as important," Dr. Chang said. "As long as the chopper tip passes beneath the anterior capsule, proper positioning of the tip is more tactile than visual."

"Large, firm nuclei more readily transmit the forces of sculpting, cracking and, rotation directly to the capsule and zonules, increasing the chances of a tear or dialysis. However, with phaco chop, the instrument forces are manual and are directed inwardly against each other. This can markedly reduce stress on the capsule and zonules".