Faculty Bibliography

PURPOSE/OBJECTIVE:To investigate the efficacy and safety of corneal collagen cross-linking (CXL) with photoactivated riboflavin (photoactivated chromophore for infectious keratitis [PACK]-CXL) in the management of infectious keratitis with corneal melting. DESIGN/METHODS:Prospective clinical trial. PARTICIPANTS/METHODS:Forty eyes from 40 patients with advanced infectious keratitis and coexisting corneal melting. METHODS:Twenty-one patients (21 eyes) underwent PACK-CXL treatment in addition to antimicrobial therapy. The control group consisted of 19 patients (19 eyes) who received only antimicrobial therapy. MAIN OUTCOME MEASURES/METHODS:The slit-lamp characteristics of the corneal ulceration, corrected distance visual acuity, duration until healing, and complications were documented in each group. The Mann-Whitney U test was used for statistical analysis. P values less than 0.05 were considered statistically significant. RESULTS:The average time until healing was 39.76 ± 18.22 days in the PACK-CXL group and 46.05 ± 27.44 days in the control group (P = 0.68). After treatment and healing, corrected distance visual acuity was 1.64 ± 0.62 in the PACK-CXL group and 1.67 ± 0.48 in the control group (P = 0.68). The corneal ulceration's width and length was significantly bigger in the PACK-CXL group (P = 0.004 and P = 0.007). Three patients in the control group demonstrated corneal perforation; infection recurred in 1 of them. No serious complications occurred in the PACK-CXL group. CONCLUSIONS:Corneal CXL with photoactivated riboflavin did not shorten the time to corneal healing; however, the complication rate was 21% in the control group, whereas there was no incidence of corneal perforation or recurrence of the infection in the PACK-CXL group. These results indicate that PACK-CXL may be an effective adjuvant therapy in the management of severe infectious keratitis associated with corneal melting.

PURPOSE/OBJECTIVE:To report the long-term clinical outcome of a patient diagnosed as having Terrien marginal degeneration (TMD) who was subjected to corneal collagen cross-linking (CXL) with ultraviolet-A and riboflavin in both eyes. METHODS:Topographical changes were assessed by high-resolution Scheimpflug imaging and anterior segment optical coherence tomography. Eccentric epithelium-off CXL was performed in both eyes while protecting the corneal limbus. Irradiation was performed with a fluence of 5.4 J/cm(2), using 3 mW/cm(2) for 30 minutes. RESULTS:Five years of postoperative follow-up showed regression of the keratometric values, a local thickening of the corneal stroma, and bilateral improvement of corrected distance visual acuity. CONCLUSIONS:CXL may arrest progression in TMD and even reverse the catabolic process in the corneal stroma. CXL might represent an alternative therapeutic approach for the management of TMD.

Keratoconus is a disease of the cornea that usually begins during puberty and progressively weakens its biomechanical structure. Keratoconic eyes show a conic shape and progressive thinning, both leading to irregular astigmatism and reduced vision that cannot be corrected by glasses. In early cases, special contact lens can partly compensate for the visual loss while they do not stop disease progression. Until recently, the only treatment option was a corneal transplant. In 1999, a technique called corneal collagen cross-linking (CXL) was used in human corneas suffering from keratoconus for the first time. CXL uses a process called photopolymerization to halt the progression of keratoconus with an efficacy of more than 95%. Today our challenge is to screen and identify patients early enough to offer a treatment on time before irreversible vision loss develops.

PURPOSE/OBJECTIVE:New corneal cross-linking (CXL) devices are capable of using higher UV-A light irradiances than used in original CXL protocols. The Bunsen-Roscoe law states that a photochemical reaction should stay constant if the delivered total energy is kept constant; however, little clinical data are available to support this hypothesis. METHODS:We investigated the biomechanical properties of four groups (n = 50 each) of porcine corneas. Three groups were exposed to riboflavin 0.1 % and UV-A irradiation of equal total energy (3 mW/cm(2) for 30 minutes, 9 mW/cm(2) for 10 minutes, and 18 mW/cm(2) for 5 minutes). Controls were exposed to riboflavin 0.1% without irradiation. Young's modulus of 5-mm wide corneal strips was used as an indicator of corneal stiffness. RESULTS:We observed a decreased stiffening effect with increasing UV-A intensity. Young's modulus at 10% strain showed significant differences between 3 mW/cm(2) and 9 mW/cm(2) (P = 0.002), 3 mW/cm(2) and 18 mW/cm(2) (P = 0.0002), 3 mW/cm(2) and the control group (P < 0.0001), and 9 mW/cm(2) and the control group (P = 0.015). There was no difference between 18 mW/cm(2) and the control group (P = 0.064) and between 9 mW/cm(2) and 18 mW/cm(2) (P = 0.503). CONCLUSIONS:The biomechanical effect of CXL decreased significantly when using high irradiance/short irradiation time settings. Intrastromal oxygen diffusion capacity and increased oxygen consumption associated with higher irradiances may be a limiting factor leading to reduced treatment efficiency. Our results regarding the efficiency of high-irradiance collagen cross-linking (CXL) raise concerns about the clinical efficiency of the new high-irradiance CXL devices already used in clinical practice without proper validation.

BACKGROUND:To quantify the corneal subbasal nerve density and the total number of nerve fibers in primary congenital glaucoma (PCG) and to evaluate their impact on corneal sensitivity. METHODS:Forty eyes of 26 PCG patients were compared with 40 eyes randomly selected from 40 non-glaucoma patients who populated the control group. Central corneal sensitivity (CCS) was assessed by means of Cochet-Bonnet esthesiometry. The mean subbasal nerve density and the total number of nerve fibers were quantified by laser-scanning confocal microscopy. Normality of data was assessed by Kolmogorov-Smirnov testing. Differences in parameters were assessed with Student's t-test, while correlations with CSS were assessed with Pearson's correlation. RESULTS:Significant differences were identified in the mean subbasal nerve density (2108 ± 692 μm in PCG, 2642 ± 484 μm in controls, P = 0.003) and in the total number of nerve fibers (12.3 ± 4.2 in PCG, 15.4 ± 3.1 in controls, P = 0.02). Both groups presented comparable mean CCS and tortuosity. Both groups presented strong correlations between CCS and mean nerve density (r = 0.57 in PCG, r = 0.67 in controls, all P < 0.05), and between CCS and total number of nerve fibers (r = 0.55 in PCG, r = 0.56 in controls, all P < 0.05). CONCLUSION/CONCLUSIONS:PCG exerts significant changes in both the mean subbasal nerve density and the total number of nerve fibers. However, these changes do not appear to affect central corneal sensitivity.

INTRODUCTION/BACKGROUND:Asymmetric facial skeletal growth is a common finding in the rhinoplasty patient population. This common abnormality affects all facial components, including the upper lateral cartilages (ULCs). The asymmetric growth also may produce uneven thickness, consistency, curvature, and elastic recoil of the ULC. Ignoring this asymmetry may have a marked impact on the outcome of any rhinoplasty operation, especially in the management of crooked noses. MATERIALS AND METHODS/METHODS:The files of 89 consecutive rhinoplasty patients who underwent surgery by a single surgeon were reviewed for deformities of the middle vault and to tabulate the procedures performed in each individual case. RESULTS:Of the 89 rhinoplasty cases, 72 (81 %) had asymmetric ULCs. Approximately 30 % (27/89) of the cases had a straight septum with asymmetric ULCs which required appropriate correction. CONCLUSIONS:Awareness of an asymmetric ULC in a crooked nose and an attempt to correct this condition in addition to straightening of the septum is key to decreasing postoperative residual or recurrent mid-vault deviation. LEVEL OF EVIDENCE IV/METHODS:This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .