Current options in the management of pellucid marginal degeneration.

PURPOSE: To review and evaluate current and future directions in the diagnosis and surgical management of pellucid marginal degeneration (PMD), including penetrating keratoplasty, full-thickness crescentic wedge resection (FTCWR), deep anterior lamellar keratoplasty (DALK), crescentic lamellar wedge resection (CLWR), crescentic lamellar keratoplasty, tuck-in lamellar keratoplasty (TILK), toric phakic intraocular lens (PIOL) implantation, intrastromal corneal ring segment implantation (ICRS), corneal collagen cross-linking (CXL), and combined therapies. This is the first review article looking at the literature specific to PMD. METHODS: Review of published studies. RESULTS: Reported data for each treatment is presented. Penetrating keratoplasty is the treatment of last resort in PMD and is effective, but with considerable complications. DALK provides visual outcomes similar to penetrating keratoplasty without the risk of immune-mediated graft rejection, but its complexity and relative novelty limit its acceptance. FTCWR has good visual outcomes, but with significant astigmatic drift. CLWR is effective, but lacks long-term results. Crescentic lamellar keratoplasty and TILK are effective, but technically difficult and without long-term results. Toric PIOL implantation is effective, but ectasia progression is a concern. ICRS implantation can delay penetrating keratoplasty and improve contact lens tolerance, but does not treat the underlying process. CXL demonstrates effectiveness without complications, although data are limited and long-term results are needed. Combining treatments such as ICRS, CXL, toric PIOL implantation, and refractive surgery is promising, but additional studies are needed to investigate their efficacy and safety. CONCLUSIONS: Although little is understood about the etiology, pathophysiology, epidemiology, and genetics of PMD, new treatments are improving visual outcomes and reducing complications. Corneal collagen cross-linking is especially exciting because it halts disease progression. Combined treatments and improved screening could eliminate the need for surgical management in most cases of PMD.

Corneal biomechanics in iatrogenic ectasia and keratoconus: A review of the literature.

The Ocular Response Analyzer (ORA) (Reichert Ophthalmic Instruments, Buffalo, NY) allows direct measurement of corneal biomechanical properties. Since its introduction, many studies have sought to elucidate the clinical applications of corneal hysteresis (CH) and corneal resistance factor (CRF). More recently, detailed corneal deformation signal waveform analysis (WA) has potentially expanded the diagnostic capabilities of the ORA. In this review, the role of CH, CRF, and WA are examined in keratoconus (KC) and iatrogenic ectasia (IE). The PubMed database was searched electronically for peer-reviewed literature in July 2012 and August 2012 without date restrictions. The search strategy included medical subject heading (MeSH) and natural language terms to retrieve references on corneal biomechanics, CH, CRF, corneal deformation signal WA, IE, and KC. The evidence suggests that while CH and CRF are poor screening tools when used alone, increased sensitivity and specificity of KC and IE screening result when these parameters are combined with tomography and topography. Recent advances in WA are promising, but little is currently understood about its biomechanical and clinical relevance. Future studies should seek to refine the screening protocols for KC and IE as well as define the clinical applicability of WA parameters.

Anesthetic keratopathy presenting as bilateral Mooren-like ulcers.

This observational case report describes the development of bilateral Mooren-like ulcers in a patient with anesthetic keratopathy. A 42-year-old man with a recent history of minor eye trauma and pain self-treated with tetracaine eye drops presented with complaints of acutely worsening vision and severe pain bilaterally. His visual acuity at presentation was limited to hand motion. Slit-lamp examination revealed bilateral epithelial defects at the center of the cornea, and an area of stromal infiltration and thinning with an undermining leading edge resembling a Mooren's ulcer in both eyes. Corneal haze and hypopyon were visible. Anesthetic use was halted immediately and the patient was started on prednisolone and mycophenolate mofetil (Cellcept(®)), after which visual acuity gradually improved and pain decreased. Despite improvement of symptoms, residual epithelial defects remained, and the patient was ultimately treated with keratoplasty for recovery of vision. We suggest that anesthetic keratopathy should be included in the differential diagnosis for any patient presenting with ring-shaped stromal infiltrates or nonhealing epithelial defects.