Faculty Bibliography

BACKGROUND:Epidural anesthesia (EA) is known to reduce postoperative thromboembolic complications, but the mechanisms are poorly understood. Review of the literature revealed no reports about the ability of epidural anesthesia (EA) to reduce the risk of venous thromboembolism (VTE) in abdominal contouring surgery and/or liposuction. Most medical publications in this field are based on orthopedic cases. OBJECTIVES/OBJECTIVE:The authors investigate the hypothesis that the differential nerve-blocking effect of bupivacaine, which spares motor function and permits leg movement during the operation, is the most important mechanism by which EA prevents thromboembolism. METHODS:From June 1992 to August 1995, 24 cases of abdominoplasty were performed under general anesthesia (Group 1). From September 1995 to December 2009, 371 cases of concurrent abdominoplasty and liposuction were performed under EA (Group 2). Eighteen cases (4.8%) from Group 2 were ultimately excluded from the study because of unsuccessful EA. All surgeries were performed by the senior author (FH). RESULTS:One thromboembolic event (pulmonary embolism [PE]) occurred in Group 1 (4%). No cases of deep vein thrombosis (DVT) or PE occurred among Group 2 patients. CONCLUSIONS:Together, differential epidural nerve blocks and purposeful intraoperative movement of lower-limb muscles represent an effective prophylactic mechanism that may prevent devastating DVT and resultant PE.

BACKGROUND:In certain cases of endoscopic forehead lift without muscle resection, patients were incidentally noted to develop weakness or loss of their ability to frown during the postoperative period despite intact musculature. This finding suggested the possibility of decreasing frown strength using the disinsertion of the relevant muscles. This finding persuaded the authors to try to eliminate or decrease the sensory problems resulting from open or endoscopic frowning muscle resection by disinserting these muscles. We therefore sought to determine the efficacy of a brow/forehead lift that involved disinsertion rather than muscle resection. METHODS:From September 2004 through December 2006, 22 endoscopic forehead lifts (20 females and 2 males) were performed using the conventional corrugator muscle resection technique (group 1). From January 2007 through October 2009, 43 patients (38 females and 5 males) underwent endoscopic forehead lift with a muscle-preserving technique (group 2). In both groups, small scalp incisions were made, and an endoscope was used to elevate the brows and forehead to perform glabellar and forehead muscle resection in group 1 and disinsertion of the frowning muscles in group 2. The skin of the forehead was then reanchored to a more superior location using sutures attached to deep temporal fascia as well as outer table screws and skin staples. RESULTS:Aesthetically pleasing eyebrow and forehead with reduced power in the frowning muscles were achieved in the majority of patients in both groups. A significant decrease in the depth of vertical and horizontal glabellar creases was obtained in these patients. In group 1, 19 of 22 patients completely lost the ability to frown and 3 patients (13.6%) suffered permanent sensory loss. In group 2, 33 of 43 patients lost their ability to frown but only 2 cases (4.5%) developed minimal unilateral forehead partial sensory deficit after a 12-month follow-up period. CONCLUSION/CONCLUSIONS:Disinsertion of the corrugator supercilli, procerus, or orbicularis oculi muscles can decrease contractility with less chance of damaging nearby or intermingled sensory nerves than offered by resection.

PURPOSE/OBJECTIVE:We report a case of failure of corneal collagen cross-linking (CXL) for progressive keratoconus after preoperative stromal swelling with hypoosmolar riboflavin solution in an extremely thin cornea. METHODS:CXL was performed using the protocol established for the treatment of thin corneas. Preoperative minimal thickness after abrasion was 268 μm and increased to 406 μm after swelling with hypoosmolar riboflavin solution. RESULTS:Despite CXL, a distinct progression of up to 1.9 diopters was observed at 3 months after the procedure on the anterior corneal surface. At 6 months after CXL, progression had increased to 2.3 diopters. Although swelling with hypoosmolar riboflavin solution was effective and led to a preoperative thickness of more than 400 μm, the increase in biomechanical resistance was not sufficient to arrest the progression of the disease. CONCLUSIONS:Little is known about the minimal stromal thickness required for effective CXL to occur. Although swelling with hypoosmolar riboflavin solution over 400 μm and safety of the procedure can be achieved in even thinner corneas, the outcome of this case suggests that a minimal preoperative stromal thickness of 330 μm needs to be respected for a successful CXL procedure.

PURPOSE/OBJECTIVE:To determine the effect of Ultraviolet-A collagen cross-linking with hypo-osmolar and iso-osmolar riboflavin solutions on stromal collagen ultrastructure in normal and keratoconus ex vivo human corneas. METHODS:Using small-angle X-ray scattering, measurements of collagen D-periodicity, fibril diameter and interfibrillar spacing were made at 1 mm intervals across six normal post-mortem corneas (two above physiological hydration (swollen) and four below (unswollen)) and two post-transplant keratoconus corneal buttons (one swollen; one unswollen), before and after hypo-osmolar cross-linking. The same parameters were measured in three other unswollen normal corneas before and after iso-osmolar cross-linking and in three pairs of swollen normal corneas, in which only the left was cross-linked (with iso-osmolar riboflavin). RESULTS:Hypo-osmolar cross-linking resulted in an increase in corneal hydration in all corneas. In the keratoconus corneas and unswollen normal corneas, this was accompanied by an increase in collagen interfibrillar spacing (p<0.001); an increase in fibril diameter was also seen in two out of four unswollen normal corneas and one unswollen keratoconus cornea (p<0.001). Iso-osmolar cross-linking resulted in a decrease in tissue hydration in the swollen normal corneas only. Although there was no consistent treatment-induced change in hydration in the unswollen normal samples, iso-osmolar cross-linking of these corneas did result in a compaction of collagen fibrils and a reduced fibril diameter (p<0.001); these changes were not seen in the swollen normal corneas. Collagen D-periodicity was not affected by either treatment. CONCLUSION/CONCLUSIONS:The observed structural changes following Ultraviolet-A cross-linking with hypo-osmolar or iso-osmolar riboflavin solutions are more likely a consequence of treatment-induced changes in tissue hydration rather than cross-linking.

PURPOSE/OBJECTIVE:To report the effect of corneal collagen cross-linking (CXL) with riboflavin and ultraviolet A (UVA) on the optical and material characteristics of a posterior chamber phakic intraocular lens (Visian ICL, STAAR Surgical). METHODS:Optical and material characteristics were assessed in vitro, analyzing potential changes in riboflavin staining, dioptric power, transmission characteristics, and surface structure. A total of 9 lenses were analyzed: 3 lenses were irradiated with 0.23 mW/cm², the maximal intensity that may be encountered during actual surgery; 3 lenses were irradiated with 2.3 mW/cm², 10 times the maximal intensity encountered during surgery; and 3 lenses served as controls. RESULTS:Following CXL with UVA and riboflavin, no changes were observed in the parameters tested; in particular, dioptric power and transmission characteristics were similar before and after CXL. CONCLUSIONS:Cross-linking with UVA and riboflavin does not affect the optical and material characteristics of the Visian ICL after irradiation with the maximal UVA energy levels that may be encountered during surgery. Even when the UVA irradiation dose was increased by a factor of 10, no changes were observed.

PURPOSE/OBJECTIVE:To analyze intra- and postoperative variation in Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments) parameters in 24 keratoconic eyes undergoing corneal cross-linking (CXL). METHODS:In a prospective clinical study, corneal hysteresis (CH), corneal resistance factor (CRF), peak 1 and peak 2 amplitude, corneal-compensated and Goldmann-correlated intraocular pressure (IOP) were evaluated using the ORA. The thinnest cornea point was measured with the Pentacam (Oculus Inc). Corneal topography and endothelial cell count were performed. Measurements were recorded at baseline; intraoperatively after epithelium removal, riboflavin impregnation, and ultraviolet A irradiation; and postoperatively after corneal re-epithelialization and at 1, 6, and 12 months. RESULTS:A statistically significant reduction of the thinnest cornea point from 462±23.24 μm was observed at the end of the CXL procedure intraoperatively and at 1- and 6-month follow-up (P<.05). A significant increase in the thinnest cornea point to 624±31.72 μm was found after re-epithelialization (P<.05), and no significant changes were observed at 1 year postoperatively. Mean CH and CRF did not change significantly after de-epithelialization, but were noted to significantly increase after CXL intraoperatively and postoperatively at 1-month follow-up. At 6 and 12 months postoperatively, CH and CRF were not statistically significantly different from pre-operatively. Peak 1 and peak 2 decreased intraoperatively from 276±52 and 228±47 to 172±42 and 131±42, respectively, at the conclusion of CXL (P<.05), and were noted to increase to 493±41 and 444±51, respectively, at 6-month follow-up. Corneal-compensated IOP and Goldmann-correlated IOP increased at 1 month after CXL (P>.05). CONCLUSIONS:The results showed a significant change in ORA parameters and the thinnest cornea point during and after the CXL procedure and a high correlation between peak amplitudes and corneal asymmetry, providing insight to the bioelastic and biomechanical behavior of the cornea during and after CXL.