Cataracts left to progress to a hypermature state are a potential nightmare for the cataract surgeon if the necessary precautions are not taken. Not only has the crystalline lens swelled and softened—triggering liquefaction that leads to leakage of lens proteins—but the swollen contents of the capsular bag increase the intralenticular pressure and induce stretching of the lens capsule. This article and an accompanying video (http://eyetube.net/?v=fuwed) detail two precautions that every surgeon should take during cataract surgery of a hypermature white intumescent cataract.
Hypermature intumescent cataracts can present with a bulging anterior capsule and a shallowing anterior chamber. This situation should alert the surgeon to proceed with caution, as a swollen lens likely contains a milky cortex that, if punctured without care, can suddenly explode. When this happens, instantaneous anterior capsular rupture can result and extend into the zonules. This phenomenon is known as the Argentinean flag sign because the clear white cataract zone between the trypan–blue-dyed capsule mimics the striped pattern of the Argentinean flag.
Upon suspicion of a swollen hypermature cataract, the surgeon should take the following precautions.
No. 1: Overfill the anterior chamber. Topping up the anterior chamber with an ophthalmic viscosurgical device (OVD) will flatten the bulging anterior capsule and exert counter-pressure on the swollen capsular bag.
No. 2: Relieve the elevated pressure in the capsular bag. Aspirating the liquefied lens material and simultaneously puncturing the lens with a sharp 27-gauge needle should decrease the amount of pressure in the capsular bag (Figure 1). Introducing the needle into the anterior chamber through a small sideport incision should avoid OVD leakage and maintain high pressure in the anterior chamber.
If these two precautions are followed, the result should be seamless cataract surgery. However, in rare cases it is possible to be faced with an anterior capsular rupture. Below I lay out the surgical courses for these two possible outcomes.
No. 1: Successful decompression. Once the hypermature is decompressed, spontaneous explosive extension of the anterior capsulotomy should no longer occur. However, it is advisable to proceed with a careful and controlled surgical technique to minimize the threat of complications. This includes dyeing the anterior capsule with trypan blue. I suggest painting the capsule underneath the protection of an OVD. Without trypan blue, capsulorrhexis formation may be tricky, as there is a risk for the rhexis to extend to the perimeter.
After the capsulorrhexis is created, phacoemulsification should be relatively standard. The posterior capsule can be weaker than normal, but if handled with care these cases can be properly managed with good visual outcomes.
No. 2: Instantaneous anterior capsular rupture. It is rare that an anterior capsular rupture should occur. However, if I were to encounter this complication, I would proceed in the following manner: To avoid significant changes in intraocular pressure, the bottle height should be lowered to 40 to 50 cm, similar to what is done for a posterior capsular rupture. Hydrodissection, which normally is not necessary due to the liquefied cortex, should not be attemped.
Very careful debulking of the nucleus can be performed with moderate fluidics settings to ensure a stable anterior chamber and avoid sudden fluid movements and changes in IOP. After careful irrigation and aspiration and injection of an OVD, the lens can be implanted. I often implant a three-piece IOL in the bag or in the sulcus, depending on the exact situation. A one-piece IOL potentially lacks sufficient capsular support for satisfactory centration, and therefore a three-piece IOL is the safest option for the most predictable outcome.
Hypermature intumescent white cataracts require few mandatory steps before proceeding to an otherwise relatively normal emulsification process. Following the two precautionary rules described here should avoid complications.
Khiun F. Tjia, MD, is an Anterior Segment Specialist at the Isala Clinics, Zwolle, Netherlands. Dr. Tjia states that he is a consultant to Alcon Laboratories, Inc., and Hoya Corp. He is the Co- Chief Medical Editor of CRST Europe. Dr. Tjia may be reached at e-mail: firstname.lastname@example.org.