Eyeworld

EW REFRACTIVE 54 February 2018 by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer Presentation spotlight Six months after FLAAK, the pa- tient's cylinder was 10.5 D, the man- ifest refraction was –2.75 +4.50 @ 93, BDVA vision was 20/20, and the pa- tient was able to wear contact lenses. "It is important to perform FLAAK in pseudophakic eyes because incisions can throw off the biometry," Dr. Rocha said. "One thing is interesting to point out about this case and that is the importance of taking a good look at the graft. It can be deceptive because the donor/recipient inter- face creates a new limbus. I was not happy with where my incision was marked because it was right at that junction. So I went back and fixed the incision marking by moving the entire limbus up manually using the femtosecond laser's touch screen and made sure I was happy with the centration. Since these are non-inva- sive, in-office procedures, it is quick and easy to make these changes." FLAAK Femtosecond laser-assisted arcuate keratotomy (FLAAK) is an easy and effective method to reduce high post-PK astigmatism. They are gen- erally performed independently of other procedures to minimize poten- tially offsetting outcomes. Patients with keratometric astigmatism in excess of 4.0 D after suture removal stand to benefit from this proce- dure. The site and size of AKs are determined on the basis of corneal topography, and they are performed under direct visualization, usually on both sides of the steepest meridi- an, with an arc length of between 45 and 90 degrees. The femtosecond laser has been shown to increase safety and efficacy of LRIs. In a study that investigated the feasibility and initial outcomes of using femtosecond laser to per- form keratotomies to correct high post-keratoplasty astigmatism in 12 eyes of 12 patients, researchers found that arcuate keratotomies were effective in reducing post-PK astigmatism at the 6-month fol- low-up mark. The investigators re- ported that paired femtosecond laser incisions on the steepest meridian peripherally inside the graft, at an intended depth of 90% of the stro- mal thickness, significantly reduced the preoperative subjective astigma- tism from 7.16 ± 3.07 D to 2.23 ± 1.55 D, which remained stable for several months. 1 Anterior segment topography revealed a very high 12 D oblique astigmatism on corne- al topography, tomography, and optical biometry. Limbal relaxing incisions using FLAAK combined with a T9 IOL were undertaken as the best strategy for the patient. One week postoperatively, BDVA was 20/25 with a manifest refraction of –2.75 +2.50 @ 20. The patient's topography demonstrated a regular astigmatism of 5 D on the first day after surgery. "In the U.S., we only have certain options to handle these sorts of cases," Dr. Rocha said. "We know that either a T9 or ZCT600 lens will correct about 4 D of with- the-rule astigmatism and a little less in against-the-rule astigmatism patients. Combining a T9 IOL with LRIs was effective in reducing the patient's high astigmatism. We used topography to rule out any graft ectasia. Also, removing the DSAEK sutures was important in this patient as well." Case: BDVA hand motion, 14 D residual astigmatism Dr. Rocha also presented the case of a 69-year-old female patient who had undergone PKP 18 years prior. The patient presented with a mature, white cataract, manifest re- fraction of –4.25 +9.50 @ 95, and 14 D of residual astigmatism. LRI was performed in the pseudophakic eye using FLAAK with particular atten- tion to adjusting the laser manually. incisions (LRI), compression sutures, suture manipulation such as tension adjustments and selective interrupt- ed suture removal, laser refractive surgery, intracorneal ring segments, wedge resection, toric IOL implanta- tion, and different combinations of these modalities. Karolinne Maia Rocha, MD, director of cataract and refractive surgery, Medical University of South Carolina, Storm Eye Institute, Charleston, South Carolina, present- ed her experience using FLAAK for LRI in 12 post-PK patients with high residual astigmatism at the 2017 ASCRS•ASOA Symposium & Congress. "Astigmatism is the most com- mon cause of suboptimal vision af- ter corneal transplantation surgery," she said. "The astigmatism can be irregular with associated higher order aberrations that limit vision and reduce the efficacy of optical correction. We used a combination of different astigmatism reducing procedures to help us achieve maxi- mal reductions." Case: BDVA 20/400, 12 D oblique astigmatism Dr. Rocha presented the case of a 62-year-old male patient who had previously undergone Descemet's stripping automated endothelial keratoplasty (DSAEK) and now pre- sented with a dense 4+ cataract and best distance corrected visual acuity (BDVA) of 20/400. The patient's FLAAK, used for relaxing incisions to reduce astigmatism in post- corneal transplant eyes, shows unpredictable outcomes from case to case P ost-penetrating keratoplas- ty (post-PK) is frequently associated with substantial postoperative refractive error due to high regular or irregular graft astigmatism. Signifi- cant astigmatism may remain after PK suture removal, which cannot be sufficiently corrected by optical means. Post-PK eyes also carry the long-term risk of wound dehiscence due to the breach of structural integrity and the compromised tectonic strength that comes from a full thickness corneal wound. Eye surgeons can choose among several modalities to address post-PK astig- matism, however, finding the perfect option for diverse case scenarios is challenging. Combining different approaches seems to make the most sense to achieve maximal astigmatic reduction in highly astigmatic eyes, and in doing so the surgeon needs to understand the exact effect of the intervention on the graft steepness. Commonly practiced tech- niques for eyes with high post-PK astigmatism include limbal relaxing Correcting extreme astigmatism in post-PK eyes Topographic outcomes 6 months post-FLAAK Source: Karolinne Rocha, MD Cyl 5.75 D Cyl 2.00 D

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