Friday, November 21, 2008
Uday Devgan, MD shares pearls for converting to microincisional phacoemulsification in an interview with Dr. David Goldman. Microincisional cataract surgery (MICS) is becoming very popular and may soon become the predominant method for performing this surgery.
Phacoemulsification systems have better fluidics and software to allow for the use of normal settings, yet the incisions are smaller. To some extent this results from improved engineering of the phaco tip and tubing. For 2.0mm phaco everything basically remains the same.
Capsulorrhexis can sometimes be a challenge, but thin capsulorrhexis forceps usually make this task much easier, obviating the need for a cystotome needle. Dr. Devgan has designed his own set of capsulorrhexis forceps that are cross-action, thin armed, and laser marked so that the size of the rrhexis can be measured. Single piece acrylic lenses can still be passed through 2.0 to 2.2 mm incisions. Most lenses work. For the right lens however, Dr. Devgan would be willing to use a 3.0mm incision. Wound integrity at 3mm is still quite good provided the phaco is done at around 2.2 and the incision expanded for lens implant. From the patient perspective, smaller incisions do not affect the postop burning and foreign body sensation.
Most surgeons are used to making astigmatically neutral incisions, so from this point of view, 2.8 to 2.0mm is largely the same. A small incision that seals well is hopefully of a lesser risk in developing endophthalmitis. Dr. Devgan then weighs the benefits of subsequent astigmatism correction methods, limbal relaxing incisions, toric IOLs, refractive procedures. LRI if <1.5d. Any bigger, use a toric IOL. But in cases where the patient demands an accommodating IOL, a refractive procedure on top of the IOL may be required.
Dr. Devgan then tackles the difficult decisions required when a patient is dissatisfied postoperatively. Does one offer a piggy back lens, a lens exchange, or refractive procedure? Glare and halos associated with a multi-focal IOL usually result in lens-exchange. If a small degree of power + or – is required, then refractive procedures are the way to go. But if a large degree of correction is required, as would be the case in a prior RK patient, the calculations are much more complicated, and the cornea is too weak for LASIK. This may be the ideal case for a piggy-back lens. What is key to remember is NOT to implant acrylic lens over an existing acrylic lens. Inter-lenticular opacification may result and is refractory to YAG laser treatment. The solution is to use either silicone or collamer lens in the sulcus. Also, the piggy-back lens (placed anterior to the existing lens) always has to be a 3-piece lens because the haptics are finer and less apt to scrape the back of the iris and cause pigment dispersion and chronic uveitis.