EyeWorld Asia-Pacific March 2011 Issue

March 2011 9 EW FEATURE Refractive surgeons, he said, must also invest effort in detecting “mines”. A lot of information, he said, can be used “to suss out which patients may be a potential minefield”. Dr. Chan prefers to avoid these potential refractive surgery minefields. “After all, refractive surgery is an elective surgery,” he said. “You can say no to that patient.” In his practice, Dr. Chan looks at several factors: best spectacle- corrected visual acuity; the axis of astigmatism; the topography; and an examination of the crystalline lens. In the refraction, if you cannot get a cooperative, young patient to 6/6, “you have to assume that there is irregular astigmatism.” This, he said, could very well develop into keratoconus later on. The axis of the astigmatism is the next clue in the refraction. He recommended being wary of patients with astigmatisms that are oblique—that is, not at the 90- or 180-degree axis. In the topography, look for inferior corneal steepening, a finding very commonly associated with keratoconus and forme fruste keratoconus. When screening for inferior corneal steepening, Dr. Chan recommended using a 0.5-D scale on your topography machine of choice, amplifying to 0.25-D scale when necessary. Some experience may be necessary to properly read these scales; while a 1.0-D scale can miss slight but significant steepening, amplifying the scale can also increase “noise” and make it difficult to read the topography map. Finally, always dilate the eye to look for any signs of nucleus sclerosis, particularly in patients who 40- or 50-year-old patients. “If you do LASIK in these patients, they are not going to get a good correction,” said Dr. Chan. To screen patients for refractive correction, Dr. Chan uses a three strike rule: just one of these factors isn’t enough to make him turn a patient away, and two will make him cautious but not necessarily reluctant. With three or more of these factors, however, he will not recommend going through with the correction. In such cases, “the only fault you make is not operating on the patient,” he said. “And that’s OK.” “It is one of the biggest minefield problems in refractive surgery ... We cannot predict for sure who will develop ectasia three or five days later. So I’d rather exclude you, than see what happens after.” The biggest refractive challenge “I feel I was picked for this because I’m the only one who has battles in refractive surgery,” said Jodhbir Mehta, MD (Singapore). As Dr. Chan had previously noted, refractive surgery can be a minefield, but the fact that it is generally an elective procedure means that, in most cases, refractive surgeons can choose not to go have to go into battle. Nonetheless, Dr. Mehta said battles in refractive surgery can be thought of as occurring preoperatively and intraoperatively. Early in his career, Dr. Mehta had a patient who had previously undergone penetrating keratoplasty in his right eye. The results were initially satisfactory—a visual acuity of 6/12—but a year later, the patient developed steroid-induced glaucoma. The removal of sutures and the way the graft healed also increased myopia and astigmatism. While IOP was eventually stabilized, saving the optic disc despite a certain degree of cupping, the patient’s visual acuity had become so severe (6/120) that he had begun to develop a slight exotropia from preferential disuse of the eye. Although the patient had also developed contact lens intolerance, Dr. Mehta decided to use contact lenses to prevent progression of the exotropia and give him time to contemplate his options for refractive correction: Surface ablation with a graft, he said, has been associated with increased scarring despite the use of mitomycin C; LASIK at the patient’s high level of astigmatism and in the presence of a graft has been shown to “not be so accurate”, and Dr. Mehta was reluctant to use a laser procedure in a patient with a cupped disc; AK was an option, but would correct astigmatism at the expense of increasing the myopia. In the end, he decided to use a toric implantable collamer lens (ICL, STAAR Surgical, Monrovia, Calif., USA/Nidau, Switzerland). Combining the procedure with an intraoperative peripheral iridotomy, Dr. Mehta was able to achieve a visual acuity of 6/12 one day post- op, improving to 6/6 two months later, with just a small amount of residual astigmatism. The battle, in this case, was in deciding what to do with the patient beforehand. Dr. Mehta’s “intraoperative battle” came with a patient he had decided to include in a study comparing SNEC’s newly acquired Visumax laser (Carl Zeiss Meditec, Dublin, Calif., USA/Jena, Germany) with the IntraLase (Abbott Medical Optics, Santa Ana, Calif., USA)— the patient would have LASIK done with one machine in one eye, the other machine in the other. In both eyes, Dr. Mehta lost suction while creating the flap— twice, in the case of the IntraLase. With the Visumax, Dr. Mehta identified excessive tear film as the culprit, and he was able to proceed by first drying the surface of the eye; he adapted to the failed first attempt at flap creation by making a smaller rim cut than he had initially intended. With the IntraLase, the problem was an unusually small eye. Rather than exerting suction at the limbus, the machine had been exerting suction further out, at the conjunctiva. Dr. Mehta solved the problem by eventually going with a “soft dock”, exerting minimal suction. In retrospect, Dr. Mehta said, because the patient was part of a study, they had all the information beforehand to avoid the complications he ran into: they performed a Schirmer’s test and complete eye measurements on all patients in the study. He concluded: “When you’re entering a battle with refractive surgery or any surgery, having as much knowledge beforehand of how to cope with any unexpected events will allow you to overcome your opponent.” Avoiding minefields & battles When Peng T. Khaw, MD (UK), took the stage, he began by saying he wanted to take a different approach to the discussion of minefields and battles in ophthalmology. He isn’t, he said, as interested in talking about how doctors manage complications as he is in discussing what steps they could have taken to avoid these complications in the first place. “The biggest problem with a minefield is before you even start the battle,” said. Dr. Khaw. Before beginning any procedure, he said, it is important to manage expectations. Any outcome is modified by the level of expectations both surgeon and patient have for a procedure: inordinately high expectations can scupper even the best outcomes, and have the patient judge the procedure a failure, while even moderately good outcomes can be judged a success with the right expectations. Intraoperatively, talking specifically about trabeculectomy and glaucoma surgery, Dr. Khaw said that even the smallest modifications in technique can improve outcomes exponentially. For instance, he talked about how the use of infusion, an anterior chamber maintainer, is often neglected as a routine part of drainage surgery. “I don’t know how many of you would do a phaco if I took away your bottle, and you weren’t allowed infusion—none of you continued on page 10