Assessment of Night Vision Problems in Patients with Congenital Stationary Night Blindness

Congenital Stationary Night Blindness (CSNB) is a retinal disorder caused by a signal transmission defect between photoreceptors and bipolar cells. CSNB can be subdivided in CSNB2 (rod signal transmission reduced) and CSNB1 (rod signal transmission absent). The present study is the first in which night vision problems are assessed in CSNB patients in a systematic way, with the purpose of improving rehabilitation for these patients. We assessed the night vision problems of 13 CSNB2 patients and 9 CSNB1 patients by means of a questionnaire on low luminance situations. We furthermore investigated their dark adapted visual functions by the Goldmann Weekers dark adaptation curve, a dark adapted static visual field, and a two-dimensional version of the ‘‘Light Lab’’. In the latter test, a digital image of a living room with objects was projected on a screen. While increasing the luminance of the image, we asked the patients to report on detection and recognition of objects. The questionnaire showed that the CSNB2 patients hardly experienced any night vision problems, while all CSNB1 patients experienced some problems although they generally did not describe them as severe. The three scotopic tests showed minimally to moderately decreased dark adapted visual functions in the CSNB2 patients, with differences between patients. In contrast, the dark adapted visual functions of the CSNB1 patients were more severely affected, but showed almost no differences between patients. The results from the ‘‘2D Light Lab’’ showed that all CSNB1 patients were blind at low intensities (equal to starlight), but quickly regained vision at higher intensities (full moonlight). Just above their dark adapted thresholds both CSNB1 and CSNB2 patients had normal visual fields. From the results we conclude that night vision problems in CSNB, in contrast to what the name suggests, are not conspicuous and generally not disabling

Fatigue and creep behaviour of stainless steel/ glass / SentryGlas® joints

SentryGlas® foil has been used for over a decade as a laminating foil but also to bond metal inserts to glass. Most famously in the Apple cube and other Apple buildings and staircases. Although the joint is transparent and statically strong, little is known about the long term behaviour. Specimens were prepared of perforated stainless steel and glass. These were laminated using SentryGlas® foil. Tensile tests, fatigue tests and creep tests were conducted at room temperature and additional creep/fatigue tests at 40⁰C. The results are analysed and conclusions about the mechanisms involved and the safety are drawn.(undefined)info:eu-repo/semantics/publishedVersio

Chiasmal misrouting and foveal hypoplasia without albinism

BACKGROUND/AIMS: To present the ophthalmological and electrophysiological characteristics of three darkly pigmented, female patients with misrouting and foveal hypoplasia. One of the patients had primary ciliary dyskinesia and situs inversus totalis (Kartagener syndrome). METHODS: Fundus photographs were taken and the angles at which the main temporal arterial branches leave the optic nerve head (ONH) were analysed. Optical coherence tomography (OCT) was performed through the presumed foveal region. Pattern onset visually evoked potentials (VEPs) (check sizes 60′, 40/400 ms) were recorded and the chiasmal coefficient was calculated to detect misrouting. RESULTS: Fundus photography showed normally pigmented fundi with absence of the usual foveal hyperpigmentation, foveal avascular zone, and macular and foveal reflexes. On OCT no foveal pit was found. The VEP recordings showed the largest positive CI component over the right hemisphere for the left eye, and over the left hemisphere for the right eye, with the CI almost absent over the ipsilateral hemispheres. The differential derivations showed opposite polarity for the recordings of the two eyes. The chiasmal coefficients of all three patients were significantly indicative of misrouting (−0.99, −0.91, and −0.99, respectively). CONCLUSION: Based on the investigations in these patients the authors propose the hypothesis that foveal hypoplasia and misrouting exist as a distinct entity, and do not comprise the exclusive hallmark of albinism. The findings suggest that misrouting may exert a retrograde influence on foveal development

Morphology and function of the corneal endothelium after long-term contact lens wear

To examine whether corneal hydration control is impaired in corneas with endothelial morphologic changes (increased variation in cell size and cell angularity) due to long-term low gas-permeable contact lens wear. Twenty-one long-term wearers of low gas-permeable contact lenses (mean age, 41 years +/- 8 SD) and 18 age-matched controls (mean age, 42 years +/- 8 SD) were studied. To assess endothelial morphology, endothelial photographs were taken, enlarged 400X, scanned into a computer, and evaluated. Hydration control was assessed by a corneal stress test. Corneal swelling was induced by applying low gas-permeable soft contact lenses for 2 hours during eye closure. After the lenses were removed, the rate of deswelling was determined using optic pachometry. Morphologic analysis of the endothelial photographs showed a significant increase of polymegethism (P < 0.01) and pleomorphism (P < 0.01) in the group wearing contact lenses compared with the control group. The percentage of recovery of corneal thickness per hour (PRPH) from induced swelling proved to be significantly lower (P = 0.03) and the induced swelling proved to be significantly lower (P < 0.01) in the group wearing contact lenses than in the control group. Multiple regression analysis showed that the PRPH decreased as the morphologic alterations increased. However, this trend appeared not to be significant at the 5% level. A significant relationship was found between morphologic parameters and induced swelling, indicating that induced swelling decreased as the morphologic alterations increased. The results of this study indicate that increased endothelial polymegethism and pleomorphism may be accompanied by a decreased corneal hydration control in people who wear contact lense

A gene for X-linked optic atrophy is closely linked to the Xp11.4-Xp11.2 region of the X chromosome.

The aim of this study was to identify the chromosomal location of the disease-causing gene in a family apparently segregating X-linked optic atrophy. A large family of 45 individuals with a four-generation history of X-linked optic atrophy was reexamined in a full ophthalmic as well as electrophysiological examination. A DNA linkage analysis of the family was undertaken in order to identify the chromosomal location of the disease-causing gene. Linkage analysis was performed with 26 markers that spanned the entire X chromosome. The affected males showed very early onset and slow progression of the disease. Ophthalmic study of the female carriers did not reveal any abnormalities. Close linkage without recombination was found at the MAOB locus (maximum LOD score [Zmax] 4.19). The Zmax - 1 support interval was found at a recombination fraction of .076 distal and .018 proximal to MAOB. Multipoint linkage analysis placed the optic atrophy-causing gene in the Xp11.4-p11.21 interval between markers DXS993 and DXS991, whereas any other localization along the X chromosome could be excluded