EyeWorld Asia-Pacific December 2013 Issue

18 EWAP CAtArACt/IOL December 2013 by Kevin L. Waltz, OD, MD Small, scarred pupil and previous filtering surgery Insights into the manage- ment of cataract in the post-trabeculectomy eye W hile the number of patients undergoing trabeculectomy is declining in general, 1 cataract patients still present who have undergone previous filtering surgery. Previous trabeculectomy presents a number of potential challenges during cataract surgery including posterior synechiae and corneal astigmatism. In addition, it is necessary to keep turbulence during cataract surgery to a minimum so as not to compromise the function of the bleb. When there are a number of challenges at the start of a case, any small deviation can cause surgical plans to be changed in a major way. As a surgeon, I never want to start a case such as this without 100% confidence in my equipment. An 80-year-old white male patient presented who had been previously diagnosed with glaucoma and had undergone trabeculectomy in both eyes. As a result, he had posterior synechiae, his pupils did not dilate well, and I had no way of assessing his ciliary zonules prior to surgery. The prior trabeculectomies had also left this patient with significant corneal astigmatism that he wanted corrected via a toric IOL. The patient understood the complicated nature of the case. The capsular bag and ciliary zonules must be intact to receive a toric IOL. I could not evaluate the zonules and capsular bag until the time of surgery. With the patient fully aware of the complexity and uncertainties of the surgery, I turned my attention to planning how to achieve the best outcomes possible for him. Such a surgery requires a viscoelastic. I decided to use Healon Endocoat (Abbott Medical Optics, AMO, Santa Ana, Calif., USA) for the initial part of the surgery. I performed a temporal clear corneal incision and a superior paracentesis within the clear cornea away from the filtering bleb. All incisions were made in the clear cornea to preserve the conjunctiva, a process generally considered important in cases of cataract surgery with previous glaucoma surgery. Excessive trauma to the eye or problems with loss of the vitreous can jeopardize the efficacy of the filtering bleb, necessitating a very efficient cataract surgery. In addition, excessive trauma may cause miosis of the pupil during surgery, which is why a preoperative nonsteroidal anti-inflammatory drug and viscoelastic are suggested. Following the initial incisions, the anterior chamber was inflated with Healon Endocoat. Once the chamber was stabilized, posterior synechiolysis was performed using a pair of Kuglen hooks. The pupil was enlarged sufficiently that a Malyugin ring (MicroSurgical Technology, Redmond, Wash., USA) was not necessary. After the pupil was stretched with the Kuglen hooks, I further enlarged it with the injection of additional Healon Endocoat. A good dispersive viscoelastic tends to keep the pupil stable throughout surgery. I then completed a capsulotomy followed by hydrodissection in a normal fashion. As the pupil was still not that wide, I injected additional viscoelastic between the phaco handpiece and the temporal iris to discourage any rubbing and subsequent iris atrophy. The dispersive nature of the viscoelastic allows it to stay in the intended location. The use of viscoelastic to aid in the stretching of the pupil and maintain stability in the chamber will work as long as the surgery is quick and efficient. Phaco power must be applied in a controlled fashion and the fluidics must cause minimal turbulence inside the eye or a number of complications may arise including: loss of pupillary diameter necessitating use of a Malyugin ring, loss of the function of the bleb, or breakage of the capsule due to poor visualization. I use the WhiteStar Signature System (AMO) with peristaltic fluidics because the phaco is very powerful while at the same time controlled. The fluidics on this machine are The pupil was very small and dilation was limited due to scarring. The pupil was stretched with two opposing metal instruments and then further dilated with the OVD. The phaco is now complete and the eye is ready to receive the IOL. Note the clear cornea, the non-traumatized iris, and the well-centered capsulotomy. These are all possible due to the protective qualities of the OVD. Source (all): Kevin L. Waltz, OD, MD