EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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33 EW CORNEA August 2014 Best in cornea intrinsic thickening of Descemet's membrane from the generalized thickening of the whole cornea and was computed as DMT divided by CCT multiplied by a constant. This constant was chosen to be 33 so that the mean DRI of the age matched control group equates to 1. Results: DRI of functional grafts showed no statistically significant difference from DRI of the con- trol group (1.09 vs. 1; P=0.06). In actively rejecting grafts, DRI was significantly higher than in func- tional grafts (1.7 vs. 1.09; P<0.001). Rejected grafts showed significantly higher DRI than functional and actively rejecting grafts (1.95; P<0.001 and P=0.02, respective- ly). Despite that CCT of rejected grafts and grafts failed secondary to non-immunological causes were not significantly different (P=0.4), DRI showed a highly significant differ- ence between the two groups (1.95 vs. 1.04; P<0.001). Conclusion: Descemet's membrane undergoes thickening in corneal graft rejection that can be quantified using DRI. DRI can detect active rejection and differentiate between rejection and failure secondary to non-immunological causes. Evaluating the use of DRI to detect subclinical active rejection and response to treatment for rejection reversal is warranted. Dr. Jeng: Corneal graft rejection is one of the most undesired complications of corneal transplant surgery. The diagnosis is typically made by clinical examination, but sometimes it can be difficult to differentiate between rejec- tion and graft failure due to non-im- munologic causes. In this paper, the authors utilized spectral domain optical coherent tomography (SD-OCT) to measure the thickness of Descemet's membrane (DM), and in comparison with the thickness of the overall cornea, they defined a calculated value for a Descemet's rejection index (DRI). Ac- cording to the authors, this DRI can be used to diagnose active graft rejection as well as differentiate between rejection and failure secondary to non-immuno- logic causes. This new DRI is potential- ly useful because it can help the clini- cian decide on the appropriate therapy to institute: corticosteroids for active rejection vs. potential surgical planning for graft failure due to non-immunolog- ic causes. The one drawback to this DRI is that it requires an SD-OCT, which is not widely available in some parts of the world. Nonetheless, for those practitioners with access to the technology, the DRI can make an impact in clinical decision-making. Initial clinical experience of topography-customized very high fluence, pulsed CXL applications for myopic, hyperopic (presby) and toric refractive corneal change A. John Kanellopoulos, MD, and colleagues Purpose: To evaluate the safety and efficacy of very high fluence, topography customized CXL (PiXL) treatments. Methods: A total of 23 cases (12 for myopic and 11 for hyperopic) were subjected to the PiXL proce- dure using excimer laser epithelial removal, 0.25% riboflavin solution soaking and 12 Joules total UV energy applied for CXL. We eval- uated preoperatively and 1, 3, 6 months postoperatively for visual acuity, keratometry, corneal clarity and scatter, and topography (Placido disc, Scheimpflug). Results: In the myopic cases, an average of 2.2 diopters of central corneal flattening was document- ed, with no endothelial or clarity changes. In the hyperopic cases, an average of 2.1 diopters of central corneal steepening was documented, with no endothelial or clarity chang- es. There was a slight regression of 1 diopter regression of the effect with- in the first month, which appeared stable thereafter. Conclusion: The novel PiXL proce- dure appears safe and effective in significant myopic and hyperopic corrective changes without the need for corneal stroma tissue removal. In the case of hyperopic treatments, these changes may aid with presby- opic vision as well. Longer follow-up and further studies may be needed to refine the dose-effect nomogram and further validate these findings. Dr. Jeng: Corneal collagen crosslinking (CXL) has continued to gain popular- ity as an effective modality to halt the progression of corneal ectasia. Early data suggested that in addition to this effect, CXL could result in some degree of corneal flattening, which reduces the refractive error. Longer-term data has suggested that this flattening effect can be sustained. In this paper, the author described the use of CXL in selective patterns on the cornea to enhance a refractive effect. Selective crosslinking of the mid-peripheral cornea, for example, was used to induce a myopic shift and treat hyperopia. In addition, topogra- phy-guided customized patterns were used to treat astigmatism. These results are compelling for the use of this tech- nique and technology to enhance the final refractive outcome of an eye un- dergoing CXL. For example, in addition to stabilizing a cornea with keratoco- nus, differential CXL can be employed to optimize a refractive result at the same time. As these are relatively early results, longer-term follow-up is needed, and more data are required to better understand the dose-effect nomogram. However, these early results are indeed exciting and encouraging. EW Editors' note: Dr. Jeng has no financial interests related to his comments. Contact information Jeng: BJeng@som.umaryland.edu View Dr. Jeng's presentation at Clinical.EWrePlay.org.