Investigative ophthalmology & visual science
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Invest. Ophthalmol. Vis. Sci. · Dec 2007
Bidirectional modulation of primary visual cortex excitability: a combined tDCS and rTMS study.
In the motor cortex (M1), transcranial direct current stimulation (tDCS) can effectively prime excitability changes that are evoked by a subsequent train of repetitive transcranial magnetic stimulation (rTMS). The authors examined whether tDCS can also prime the cortical response to rTMS in the human visual cortex. ⋯ Compared with previous work on the M1, tDCS and rTMS of the visual cortex only produce short-lasting changes in cortical excitability. Moreover, the priming effects of tDCS on subsequent rTMS conditioning are relatively modest. These discrepancies point to substantial differences in the modifiability of human motor and visual cortex.
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Invest. Ophthalmol. Vis. Sci. · Dec 2007
A common founder mutation of CERKL underlies autosomal recessive retinal degeneration with early macular involvement among Yemenite Jews.
To investigate the genetic basis and clinical manifestations of a characteristic form of retinal degeneration in the Yemenite Jewish population. ⋯ c.238+1G>A is the second reported mutation of CERKL and is a prevalent founder mutation that underlies approximately 33% of autosomal recessive retinal degeneration cases in the Yemenite Jewish population. It is associated with a characteristic retinal degeneration phenotype with early macular involvement, concomitant progression of rod and cone impairment, and characteristic fundus findings. The identification of this mutation and phenotype will facilitate molecular diagnosis, carrier screening, and genetic counseling in the Yemenite Jewish population.
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Invest. Ophthalmol. Vis. Sci. · Nov 2007
Review Comparative StudyOptical coherence tomography versus stereoscopic fundus photography or biomicroscopy for diagnosing diabetic macular edema: a systematic review.
To review systematically the sensitivity and specificity of optical coherence tomography (OCT) for diagnosing macular edema attributable to diabetic retinopathy compared with well-established gold standard tests such as fundus stereophotography or contact and noncontact fundus biomicroscopy. ⋯ OCT performs well compared with fundus stereophotography or biomicroscopy to diagnose diabetic macular edema. The quality of reporting of such studies should be improved, and authors should present cross tabulations of index and reference test results. Data adjusted for within-subject correlation should also be provided, although this issue represents a challenge for systematic reviewers.
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Invest. Ophthalmol. Vis. Sci. · Nov 2007
Mutations in the UBIAD1 gene on chromosome short arm 1, region 36, cause Schnyder crystalline corneal dystrophy.
Schnyder crystalline corneal dystrophy (SCCD; MIM 121800) is a rare autosomal dominant disease characterized by an abnormal increase in cholesterol and phospholipid deposition in the cornea, leading to progressive corneal opacification. Although SCCD has been mapped to a genetic interval between markers D1S1160 and D1S1635, reclassification of a previously unaffected individual expanded the interval to D1S2667 and included nine additional genes. Three candidate genes that may be involved in lipid metabolism and/or are expressed in the cornea were analyzed. ⋯ Nonsynonymous mutations in the UBIAD1 gene were detected in six SCCD families, and a potential mutation hot spot was observed at amino acid N102. The mutations are expected to interfere with the function of the UBIAD1 protein, since they are located in highly conserved and structurally important domains.
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Invest. Ophthalmol. Vis. Sci. · Nov 2007
Evaluation of retinal status using chromatic pupil light reflex activity in healthy and diseased canine eyes.
To differentiate rod-cone-mediated pupil light reflexes (PLRs) from intrinsic melanopsin-mediated pupil light reflexes by comparing pupil responses with red and blue light stimuli of differing intensities in normal dog eyes and in those with sudden acquired retinal degeneration syndrome (SARDS) exhibiting a nonrecordable electroretinogram. ⋯ The PLR in healthy canine eyes can be elicited at very low light intensities using red and blue wavelengths of light, but in dogs with blindness caused by SARDS, the pupil reacts only to high-intensity blue wavelength light, implying loss of the rod-cone-mediated PLR and most likely the presence of intrinsic, melanopsin-mediated, retinal ganglion cell-mediated PLR.