Ophthalmic complications of dengue

We report 13 cases of ophthalmic complications resulting from dengue infection in Singapore. We performed a retrospective analysis of a series of 13 patients with dengue fever who had visual impairment. Investigations included Humphrey automated visual field analyzer, Amsler charting, fundus fluorescein angiography, and optical coherence tomography. Twenty-two eyes of 13 patients were affected. The mean age of patients was 31.7 years. Visual acuity varied from 20/25 to counting fingers only. Twelve patients (92.3%) noted central vision impairment. Onset of visual impairment coincided with the nadir of serum thrombocytopenia. Ophthalmologic findings include macular edema and blot hemorrhages (10), cotton wool spots (1), retinal vasculitis (4), exudative retinal detachment (2), and anterior uveitis (1). All patients recovered visual acuity to 20/30 or better with residual central scotoma by 12 weeks. These new complications suggest a widening spectrum of ophthalmic complications in dengue infection.     

O'nyong-nyong Virus, Chad

We report the first laboratory-confirmed human infection with O'nyong-nyong virus in Chad. This virus was isolated from peripheral blood mononuclear cells of a patient with evidence of a seroconversion to a virus related to Chikungunya virus. Genome sequence was partly determined, and phylogenetic studies were conducted.     

Corneal transmissibility of diode versus argon lasers and their photothermal effects on the cornea and iris

Purpose : Diode laser (810 nm) may possess theoretical advantages over the argon blue‐green laser (488 nm) for iridotomy/iridoplasty in an eye with oedematous cornea, such as the acute angle‐closure glaucoma (AACG) patient, because of better diode laser tissue penetration in opaque media. We assessed the transmissibility of diode and argon lasers through corneas of varying clarity and evaluated the histopathological features of cornea and iris burns produced by these lasers. Methods : The transmission of diode and argon lasers through human donor corneal buttons of three grades of clarity – clear, intermediate, and hazy – were compared. Corneal buttons of these varying levels of clarity were also treated with argon and diode lasers, with the beams deliberately focused onto the mid‐stroma to assess their photothermal effects. Exposed pigmented irides from whole human eyes were treated directly with argon and diode lasers. The lasers were delivered via slit‐lamp systems and the energy settings used were 1000 mW for argon and 980 mW for diode; spot sizes for both lasers were 100 μm, with exposure durations of 0.1 s. Light microscopy studies of these tissues were performed. Results : Transmissibility of diode laser in clear, intermediate, and hazy corneas were 89, 87 and 85% respectively and was significantly superior to argon laser (78, 73 and 70% respectively; P < 0.001, paired Student’s t‐test). Diode laser did not produce morphological changes in all three grades of corneas whereas argon‐laser‐treated hazy corneas showed photothermal damage. Both lasers produced deep iris burns, with the diode laser tending to produce deeper burns. Conclusion : Our findings suggest that diode laser may be the ideal laser for iridotomy/iridoplasty in the AACG patient with hazy cornea.     

The pathology of cartilage in chondrodysplasias.

The pathology of four types of chondrodysplasias, viz., type II achondrogenesis, thanatophoric dwarfism, Saldino-Noonan syndrome, and chondrodysplasia punctata were studied. In each of these disorders, cells with features similar to the chief and dark chondrocytes of normal hyaline cartilage were seen to be altered in different ways. There was a total absence of chief cells in type II achondrogenesis. All the chondrocytes present were of one variety at different states of maturation, with the fully matured cell having features of dark chondrocytes. The absence of chief cells was associated with marked diminution of interlacunar matrix and failure of growth plate development. The chief chondrocytes in thanatophoric dwarfism appeared diminished in number. They were probably abnormal functionally as evident by their lack of cytoplasmic vacuolation and the formation of thick, occasionally branched collagen in the matrix. The growth plate was stunted and poorly developed. Striking changes involving the dark cells were noted in Saldino-Noonan syndrome, where unusually elongated dark cells were found in groups within abnormal cystic spaces. The chief cells were large and contained abnormal cytoplasmic filaments. There was no formation of a growth plate. In chondrodysplasia punctata, the chief cells were enlarged and abnormally vacuolated. The matrix showed excessive aggregates of coarse granular material. In addition, there were focal accumulations of highly abnormal chief and dark cells with abnormal matrix which contained increased amount of keratan sulphate and culminated in spotty calcification.     

Development of the Interpretation Bias Index for PTSD

Cognitive models of posttraumatic stress disorder (PTSD) implicate interpretation biases as a maintaining factor of symptoms. Existing measures index symptoms and negative beliefs in PTSD patients, but not threatening interpretation of socially-ambiguous information, which would further inform cognitive models of PTSD. Here we describe the development of a measure of interpretation bias specific to individuals with PTSD. Studies 1 and 2 utilized analog samples to identify the smallest set of items capable of differentiating PTSD-specific interpretation biases. Study 3 utilized a clinical sample to examine the factor structure of the 9-item Interpretation Bias Index for PTSD (IBIP). A bifactor model fit the IBIP best, comprising a general PTSD factor and two subfactors. The IBIP was most strongly related to PTSD symptoms and demonstrated sensitivity and specificity to detecting true PTSD cases. The IBIP has potential clinical utility for tracking interpretation bias in PTSD, or even screening for PTSD diagnoses.