Eyeworld

Patients in need of cataract surgery following lamellar or penetrating keratoplasty present a unique set of challenges. Often visualization into the eye is poor. Frequently the post-kerato- plasty eye has a lot of regular and irreg- ular corneal astigmatism. Should a toric lens be implanted in this situation? What if the axis of corneal astigmatism changes a few years later? What if the patient needs another transplant? What if the patient needs to wear a rigid con- tact lens because of irregular astigma- tism? How predictable are corneal relaxing incisions in the setting of pene- trating grafts? These are some of the many issues that must be considered. Post-transplant corneas often have a reduced endothelial cell count. What can be done to minimize further cell loss? Does cataract surgery increase the risk of graft rejection and, if so, what can be done to reduce it? Should anything be done differently during inci- sion closure in post-keratoplasty eyes? In this article, Dr. Olson discusses his approach to cataract surgery in the post-keratoplasty eye and offers advice for avoiding many common pitfalls. Kevin Miller, M.D., complicated cataract corner editor EW NEWS & OPINION 24 Randall J. Olson, M.D., pro- fessor, chair of Ophthalmol- ogy and Visual Sciences, and CEO, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, discusses how to get the best outcomes in cataract patients with prior keratoplasty W hile cataract surgery in and of itself may not seem to be com- plicated by previous penetrating kerato- plasty, there are a series of issues to consider that may impact not only the quality of the cataract surgery, but the long-term survival of the corneal transplant. Indeed, it is im- portant to understand just how cataract surgery should be ap- proached differently. Some of the key areas include concern about vi- sualization, being very careful about corneal fragility, both epithelial and endothelial sensitivity, considering the potential increased risk of rejec- tion, dealing with the pre-op astig- matism, and careful wound closure, which may be compromised in these situations. Visualization Neurotrophic keratitis is a common finding due to poor reinnervation of the cornea, so if the epithelium is not carefully babied during the pro- cedure, visualization can be severely compromised and the epithelium may slough, which can be a problem in the early post-op period. One way to minimize the amount of drops placed in the eye is to use only topi- cal antibiotics with artificial tears pre-op, and then dilate the pupil with intraocular lidocaine with epi- nephrine. This often provides more than adequate mydriasis without a lot of drops in the pre-op period. This, together with topical anes- thetic agents just prior to surgery (little topical anesthesia is usually necessary in that these corneas have partial hypoesthesia anyway) is suffi- cient. Frequent use of topical bal- anced salt solution (BSS, Alcon, Fort Worth, Texas) and, if the epithelium is in any way deteriorating, topically placing small amounts of dispersive viscoelastic such as Viscoat (Alcon) with some BSS as needed can make sure visualization through the corneal epithelium is non-problem- atic. Due to a combination of high regular and irregular astigmatism, the old corneal incision scar, any pre-existing peripheral corneal pathology, and corneal transplanta- tions, which are often lamellar pro- cedures today, the interface issue can also result in additional visualization problems. This is where a topical procedure can be quite helpful by having the patient refixate to avoid direct glare back into the operating microscope or to reposition the corneal scar or other corneal pathol- ogy so that what you need to see can now be visualized. Excellent illumi- nation, optical clarity, as well as en- hancement of the red reflex with products such as the OPMI Lumera operating microscope (Carl Zeiss Meditec, Dublin, Calif.) can help in regard to visualization. Capsu- lorhexis edges can be lost, particu- larly if the tear is anywhere near the penetrating keratoplasty incision or hidden by peripheral corneal pathol- ogy. Consider capsular staining if it looks like peripheral visualization might be a problem. Corneal fragility The corneal endothelium is never normal after any of the endothelial keratoplasties or penetrating kerato- plasties. Cataract surgery tradition- ally does do some endothelial damage, and a small marginal in- crease in endothelial loss can be enough for corneal failure to either occur or be hastened. It is, therefore, critical during the procedure to place dispersive viscoelastics up against the corneal dome, and if any part of the procedure is taking an in- ordinate amount of time, replace it at regular intervals. This type of pro- tection is critical in minimizing en- dothelial loss. 1 During nucleus removal, mini- mizing ultrasound time is another step that makes sense. We have me- chanical energy released with ultra- sound use as well as free radical formation and deflected nuclear fragments; small bubbles can also cause damage. Emphasis on me- chanical forces as well as working in the capsular bag (very posteriorly) are means of minimizing endothe- lial damage during this important phase. For these reasons, in a patient with a previous keratoplasty, I will often take out a cataract before it gets particularly hard and turn off the ultrasound and simply use me- chanical forces and high vacuum with phaco chop to remove the nu- October 2011 by Randall J. Olson, M.D. Cataract surgery in the case of prior keratoplasty Figure 1. A corneal astigmatism set created in partnership with Mastel and provided by the company. The set includes a subjective keratometer, guides for 7.5 and 7.0 mm optical zones, and diamond-bladed instruments with a micrometer handle Source: Randy Miller Complicated cataract corner

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