EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78708
February 2011 A refractive continued from page 32 June 2012 EW REFRACTIVE SURGERY 35 Another image from the Pentacam using the BAD II analysis. This shows a normal anterior and posterior elevation, but there are yellow flags indicating a concern over the pachymetric progression This image shows a refractive screen from the Pentacam showing all normal indices this software does not screen out all suspect corneas. The Clinical Advi- sory Group at TLC has reviewed cases with subclinical pellucid mar- ginal degeneration topographic pat- terns and a normal Pentacam BAD II analysis that we have recommended for PRK rather than LASIK. "The key message is that our di- agnostic instruments and analysis software are tools to help us provide the best and safest options for our patients. While all these tools are useful, none should trump our clinical judgment." Dr. Lindstrom: "I personally am OK with LASIK or PRK. There's a small 'but' here. I look at the history, it's a 21-year-old, which is young. We want to be on the lookout for any evidence of corneal abnormali- ties that might suggest keratoconus. "On the positive side, the pa- Another view of a refractive screen from the Pentacam showing all normal indices Source (all): Kerry Solomon, M.D. [Meditec, Jena, Germany] Pathfinder II software indicated no abnormali- ties, the Pentacam BAD II analysis software [Oculus, Lynnwood, Wash.] detected a pachymetric progression in both eyes that is 2 SD below nor- mal, and therefore the eyes are flagged as 'suspicious.' This means that the patient may need to un- dergo further testing for 'better' maps, cancelled, or relegated to PRK. As physicians we clearly want to do the safest procedure for our patients, however the extended healing with PRK is rarely popular with the pa- tients, referring doctors, or surgeons. "While these analysis programs are generally very beneficial, there are costs. The first cost is that clini- cal judgment becomes secondary to the results of the analysis software. In this case, the corneas have been flagged suspicious due to the 'pachy- metric progression,' however there is no study to support that the predisposition for keratoconus can be detected with an 'abnormal' pachymetric progression, although this is a very interesting hypothesis. The second cost is clinical judgment becomes secondary to perceived medico-legal risk. Now that the Pentacam BAD II analysis 'yellow flag' is part of the patient record, only the most confident and experi- enced surgeons would be comfort- able performing LASIK, as prosecuting attorneys would be very happy to show juries the 'yellow flags' in the rare event that any of these patients did develop post-oper- ative ectasia. The final issue is that tient is corrected 20/20 in both eyes, the keratometry is regular, [and] the cornea is mildly thin but within nor- mal. To me, both the keratometry and the Pentacam are within normal limits. But there is one issue that makes me think of a couple of things. The corneal irregularity index of the Humphrey is more ele- vated in the left eye than in the right. So the corneal irregularity seems greater in the left eye than in the right. And there are also more higher order aberrations in the left eye than in the right. "That makes me concerned. The first thing I think of is the patient might not have left the contact lenses out long enough to eliminate any corneal molding. There's also a possibility of dry eye. It would be nice to be certain that the contact lenses had been out long enough and that the patient didn't have a dry eye. Those are the things I would be looking for. "The corneal shape is a little borderline as far as the typical aver- age increase of thickness that occurs as you go inferiorly, but to me it's within the normal limits. "I would usually be willing to do LASIK on this patient presuming no positive family history of kerato- conus. The irregularity is a bit of an issue, so I think we need to keep the contacts out for another few weeks and make sure there's no dry eye." EW Editors' note: The doctors mentioned have no financial interests related to this article. Contact information Belin: mwbelin@aol.com Lindstrom: Brenda L. Boff, assistant to Dr. Lindstrom, blboff@mneye.com Probst: leprobst@gmail.com EyeWorld factoid An estimated 153 million people world- wide live with visual impairment due to uncorrected refractive errors. This figure does not include people living with uncorrected presbyopia Source: World Health Organization