Simultaneous Structural and Electronic Transitions in Epitaxial VO_{2}/TiO_{2}(001).

Recent reports have identified new metaphases of VO_{2} with strain and/or doping, suggesting the structural phase transition and the metal-to-insulator transition might be decoupled. Using epitaxially strained VO_{2}/TiO_{2} (001) thin films, which display a bulklike abrupt metal-to-insulator transition and rutile to monoclinic transition structural phase transition, we employ x-ray standing waves combined with hard x-ray photoelectron spectroscopy to simultaneously measure the structural and electronic transitions. This x-ray standing waves study elegantly demonstrates the structural and electronic transitions occur concurrently within experimental limits (±1 K).

Toll-like receptor 2 ligand-induced protection against bacterial endophthalmitis.

BACKGROUND: Activation of innate immunity plays a key role in determining the outcome of an infection. Here, we investigated whether Toll-like receptors (TLRs) are involved in retinal innate response and explored the prophylactic use of TLR2 ligand in preventing bacterial endophthalmitis. METHODS: C57BL/6 mice were given intravitreal injections of Pam3Cys, a synthetic ligand of TLR2, or vehicle (phosphate-buffered saline) 24 h prior to Staphylococcus aureus inoculation. The severity of endophthalmitis was graded by slit lamp, electroretinography, histological examinations, and determination of bacterial load in the retina. The expression of cytokines/chemokines and cathelicidin-related antimicrobial peptide was assessed by enzyme-linked immunosorbent assay and Western blot, respectively. RESULTS: Intravitreal injections of Pam3Cys up-regulated TLR2 expression in the retina of C57BL/6 mice, and Pam3Cys pretreatment significantly improved the outcome of S. aureus endophthalmitis, preserved retinal structural integrity, and maintained visual function as assessed by electroretinography in C57BL/6 mice. Furthermore, Pam3Cys pretreatment activated retinal microglia cells, induced the expression of cathelicidin-related antimicrobial peptide, and remarkably reduced the bacterial load. CONCLUSIONS: This is the first report that highlights the existence and role of TLR2 in retinal innate immune response to S. aureus infection and suggests that modulation of TLR activation provides a novel prophylactic approach to prevent bacterial endophthalmitis.

Intraocular pressure instability after 23-gauge vitrectomy.

PURPOSE: The purpose of this study was to describe outcomes, trends, risk factors, and protective factors for intraocular pressure (IOP) spikes in patients undergoing 23-gauge pars plana vitrectomy. METHODS: A retrospective review in an academic institution was performed on all eyes undergoing 23-gauge vitrectomy with at least 1-month follow-up. The main outcome measures included IOP and operative complications. RESULTS: Ninety-seven eyes of 93 patients were included. Intraocular pressure spikes >22 in the first month occurred in 73% of eyes with or suspect for glaucoma versus 46% of eyes without (P = 0.017); 76% of eyes with a gas fill versus 44% of eyes with a fluid fill (P = 0.0036); and 21% of eyes started on IOP-lowering drops on postoperative day 1 versus 49% of eyes who were not (P = 0.0033). Complications included retinal tears (3%), intraoperative retinal detachment (2%), and postoperative retinal detachment (2%). Fifteen percent of eyes required suturing of at least one sclerotomy. There were no cases of postoperative hypotony or endophthalmitis. CONCLUSION: Patients with or suspect for glaucoma or those with a gas fill may be at risk for high postoperative IOP during the first month. Aggressive early treatment of IOP may prevent IOP spikes in the early postoperative period.

Directly measuring the structural transition pathways of strain-engineered VO2 thin films.

Epitaxial films of vanadium dioxide (VO2) on rutile TiO2 substrates provide a means of strain-engineering the transition pathways and stabilizing of the intermediate phases between monoclinic (insulating) M1 and rutile (metal) R end phases. In this work, we investigate structural behavior of epitaxial VO2 thin films deposited on isostructural MgF2 (001) and (110) substrates via temperature-dependent Raman microscopy analysis. The choice of MgF2 substrate clearly reveals how elongation of V-V dimers accompanied by the shortening of V-O bonds triggers the intermediate M2 phase in the temperature range between 70-80 °C upon the heating-cooling cycles. Consistent with earlier claims of strain-induced electron correlation enhancement destabilizing the M2 phase our temperature-dependent Raman study supports a small temperature window for this phase. The similarity of the hysteretic behavior of structural and electronic transitions suggests that the structural transitions play key roles in the switching properties of epitaxial VO2 thin films.

Changes in retinal sensitivity from retained subretinal perfluorocarbon liquid.

PURPOSE: To study the effect of retained subretinal perfluorocarbon liquid (PFCL) on retinal function. METHODS: Scanning laser ophthalmoscope microperimetry was performed on four eyes with retained subretinal PFCL after vitreoretinal surgery for complicated retinal detachments with and without proliferative vitreoretinopathy. RESULTS: Scotomas to the highest intensity stimulus were noted in the area of the subretinal PFCL in all four eyes. All scotomas encompassed approximately the same area as the retained PFCL droplets. In the area vacated by a migrating PFCL droplet in one eye, the highest intensity stimulus could be perceived, but a relative scotoma (to a lower intensity stimulus) was present. CONCLUSIONS: There is a local reduction in retinal function in the area of retained subretinal PFCL. There may be partial recovery of retinal function in an area vacated by the subretinal PFCL. Subretinal PFCL beneath the fovea or at risk for migration beneath the fovea should be considered for removal.

Metastatic cutaneous melanoma to the ciliary body in familial atypical mole-melanoma (fam-m) syndrome.

PURPOSE: To report a case of metastatic melanoma to the ciliary body in familial atypical mole-melanoma syndrome. METHODS: Retrospective case report. PATIENTS: A 46-year-old woman presented with a ciliary body melanoma and tumor seeding of the anterior chamber structures. RESULTS: Biopsy and systemic workup suggested metastatic origin. CONCLUSIONS: Correlation is noted between the noncohesive epithelioid cell type and seeding of the anterior chamber.

Combination treatment with reduced-fluence photodynamic therapy and intravitreal injection of triamcinolone for subfoveal choroidal neovascularization in macular degeneration.

PURPOSE: To evaluate combination treatment with reduced-fluence photodynamic therapy (PDT) and intravitreal triamcinolone acetonide (IVT) injection for choroidal neovascularization (CNV) in age-related macular degeneration (AMD). METHODS: This is a retrospective consecutive case series of 23 previously untreated eyes of 22 patients with subfoveal CNV secondary to AMD. Six eyes were treated with 50 J/cm; 8, with 40 J/cm; and 9, with 25 J/cm. PDT was immediately followed by a 4-mg IVT injection. Patients were observed for 6 months at 6-week intervals. RESULTS: : The 50 J/cm subset lost a mean of 2.2 lines of Snellen visual acuity at the 6-month follow-up compared with a 1-line lost in the 40 J/cm subset and a 0.9-line gain in the 25 J/cm subset. In the 50 J/cm subset, 60% lost < or =3 lines of Snellen visual acuity, 33% gained > or =0 line, and 33% gained > or =3 lines. In the 40 J/cm subset, 75% lost < or =3 lines of Snellen visual acuity, 50% gained > or =0 line, and 25% gained > or =3 lines. In the 25 J/cm subset, 89% lost < or =3 lines of Snellen visual acuity, 56% gained > or =0 line, and 33% gained > or =3 lines. Fifty percent of the 50 J/cm subset, 50% of the 40 J/cm subset, and 33% of the 25 J/cm subset required retreatment by 6 months. CONCLUSION: Although the sample in this study was small, there was a dose-response trend toward better visual outcomes and fewer treatments in the group treated with IVT injection and reduced-fluence PDT. This study along with other previously reported work suggests that studies using PDT in combination treatment for CNV should consider adding a reduced-fluence PDT arm.

Orbital compartment syndrome in burn patients.

PURPOSE: To identify clinical characteristics of burn patients requiring emergent orbital decompression for vision-threatening orbital compartment syndrome. METHODS: A retrospective review of 28 burn patients at a trauma center provided data regarding demographics, physical examination findings, and resuscitation fluid volumes. Patients requiring orbital decompression were compared with those who did not, using t tests and Fisher exact test. Linear regression was used to test for an association between peak intraocular pressure and fluid volume. Logistic regression was used to assess associations between need for orbital decompression and fluid volume. RESULTS: Eight of 28 patients required emergent orbital decompression, which immediately reduced intraocular pressure from 59.4 +/- 15.9 mm Hg to 28.6 +/- 8.2 mm Hg (p < 0.001). There was a positive relationship between fluid volume in the first 24 hours and peak intraocular pressure (p < 0.001). Patients who were treated with orbital decompression were resuscitated with a higher fluid volume in the first 24 hours than those who were not (37,218 +/- 14,405 ml versus 24,649 +/- 12,339 ml, p = 0.015). This was no longer statistically significant when adjusted for periocular burns. The relative risk for undergoing orbital decompression in patients receiving > or =8.6 ml/kg/% total body surface area burned in the first 24 hours was 4.4 (p = 0.03). CONCLUSIONS: Risk factors for vision-threatening orbital compartment syndrome include fluid volume and periocular burns. Signs of vision-threatening orbital compartment syndrome should be addressed early with orbital decompression.

Pyogenic granuloma associated with chronic Actinomyces canaliculitis.

A case of chronic Actinomyces canaliculitis with associated pyogenic granuloma formation and bloody tears is described. Although Actinomyces is a well-known cause of canaliculitis, the authors are not aware that it has been reported in association with pyogenic granulomas.

Elevated orbital pressure: another untoward effect of massive resuscitation after burn injury.

BACKGROUND: Fluid resuscitation remains a fundamental component of early burn care management. However, recent studies suggest that excessive volumes of resuscitation are being administered. Overresuscitation results in negative sequelae including abdominal and extremity compartment syndromes. Elevated intraocular pressure (IOP) has been described as another potentially devastating effect of massive fluid resuscitation in trauma patients. The orbit, similar to the abdomen and extremity, is a compartment, limited to expansion from edema anteriorly by the eyelids and orbital septum, and posteriorly by the bony orbital walls. The purpose of this study was to review the incidence of elevated IOP in a series of patients with major burn injury. METHODS: We retrospectively reviewed the charts of 13 consecutive patients admitted to our burn center with burn sizes >25% total body surface area (TBSA). All patients underwent serial IOP measurements for the first 72 hours following admission. Medical records were reviewed for fluid resuscitation volume, IOP measurements, need for canthotomy, and results of canthotomy procedures. RESULTS: Five of 13 patients had IOP >30 mm Hg and required lateral canthotomy. Canthotomy immediately reduced IOP (p = 0.009). Patients who developed elevated IOP received a significantly larger fluid resuscitation (9.0 cc/kg/%TBSA versus 6.0 cc/kg/%TBSA, p = 0.02). Elevated IOP was significantly associated with delivery of larger fluid resuscitation volume (p = 0.027). CONCLUSIONS: Massive fluid resuscitation following burn injury can result in orbital compartment syndrome requiring lateral canthotomy. Early diagnosis and treatment of orbital compartment syndrome should be incorporated into the management of patients with major burn injury receiving large fluid resuscitation volume.