Faculty Bibliography

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 .

OBJECTIVE:UV-A/riboflavin cross-linking (CXL) of corneal collagen fibers is an established, highly promising therapy for corneal melting in physician-based ophthalmology. A prospective pilot study was conducted to demonstrate proof of principle of this novel method for the treatment of melting corneal ulcers in dogs and cats. PROCEDURES/METHODS:After obtaining owner consent, CXL was performed in three cats and three dogs with corneal melting, which either affected the entire corneal surface or was resistant to conventional antibiotic and anticollagenolytic therapy, and affected parts or all of the corneal surface. Medical therapy was continued in all patients. The available follow-up ranged from 2 to 22.5 months and involved slit-lamp examination, fluorescein staining, and photographic documentation during all rechecks. RESULTS:Surgical stabilization of the cornea was not necessary in any case, because progression of corneal melting was arrested in all cases within 1-20 days of CXL treatment. Corneal re-epithelization occurred within 7-40 days in all eyes. At 40 days after CXL, all eyes presented a quiescent corneal state without signs of active inflammation and with beginning scar formation. The complications observed in three of the six animals included a corneal sequestrum, superficial corneal stromal pigmentation, and bullous keratopathy. CONCLUSIONS:This study shows the feasibility of CXL to treat progressive corneal melting in veterinary patients. CXL may represent a cost-efficient and safe alternative therapy in the treatment for corneal melting in veterinary ophthalmology. More investigations comparing the effectivity and complication rate of CXL to those of standard medical treatment are necessary.

PURPOSE/OBJECTIVE:To introduce a constant-force technique for the analysis of corneal biomechanical changes induced after collagen cross-linking (CXL) that is better adapted to the natural loading in the eye than previous methods. METHODS:For the biomechanical testing, a total of 50 freshly enucleated eyes were obtained and subdivided in groups of 5 eyes each. A Zwicki-Line Testing Machine was used to analyze the strain of 11 mm long and 5 mm wide porcine corneal strips, with and without CXL. Before material testing, the corneal tissues were pre-stressed with 0.02 N until force stabilization. Standard strip extensiometry was performed as control technique. For the constant-force technique, tissue elongation (Δ strain, %) was analyzed for 180 seconds while different constant forces (0.25 N, 0.5 N, 1 N, 5 N) were applied. RESULTS:Using a constant force of 0.5 N, we observed a significant difference in Δstrain between 0.26±0.01% in controls and 0.12±0.03% in the CXL-treated group (p = 0.003) over baseline. Similarly, using a constant force of 1 N, Δstrain was 0.31±0.03% in controls and 0.19±0.02% after CXL treatment (p = 0.008). No significant differences were observed between CXL-treated groups and controls with 0.25 N or 5 N constant forces. Standard stress-strain extensiometry failed to show significant differences between CXL-treated groups and controls at all percentages of strains tested. CONCLUSION/CONCLUSIONS:We propose a constant-force technique to measure corneal biomechanics in a more physiologic way. When compared to standard stress-strain extensiometry, the constant-force technique provides less variability and thus reaches significant results with a lower sample number.

PURPOSE/OBJECTIVE:To compare a femtosecond laser with a microkeratome for flap creation during laser in situ keratomileusis (LASIK) in terms of flap thickness predictability and visual outcomes. PATIENTS AND METHODS/METHODS:This was a prospective, randomized, masked, paired-eye study. Forty-four patients (34 females) who received bilateral LASIK were included. Patients were stratified by ocular dominance, and they then underwent randomization of flap creation using the femtosecond laser on one eye and undergoing the microkeratome procedure on the other one. The visual outcome differences between the corrected distance visual acuity (CDVA) at baseline and the uncorrected distance visual acuity (UDVA) on the first day postoperatively were set as the efficiency index for both groups. All visual acuity outcome results and the deviation of flap thickness were evaluated. P-values <0.05 were considered statistically significant. RESULTS:The index of efficiency regarding the postoperative visual outcomes in the microkeratome group was lower (P<0.0001). This result was correlated with the difference between intended and achieved flap thickness (P=0.038; r=0.28), and a negative relationship in the regression analysis was confirmed (P<0.04; R (2)=0.1428). The UDVA in the microkeratome group improved significantly by the end of the first month (P<0.0271) in comparison to the baseline CDVA. The deviation between intended and postoperative flap thickness using either optical coherence pachymetry or Heidelberg Retinal Tomography II confocal microscopy was statistically significant (paired t-test; P<0.001) between the groups. The flap thickness deviation in the microkeratome group was higher. In the femtosecond laser group, the efficiency index was stable postoperatively (P=0.64) The UDVA improved significantly by the end of the first postoperative week (P=0.0043) in comparison to the baseline CDVA. Six months after surgery, improvement in the UDVA was significant in both groups (all P<0.001; one way analysis of variance). CONCLUSION/CONCLUSIONS:Femtosecond laser was superior to microkeratome-assisted LASIK in terms of flap thickness predictability and the speed of visual acuity recovery. A negative relationship in the regression analysis between increasing flap thickness deviation and visual acuity recovery was confirmed.