• Journal of Korean Ophthalmic Optics Society
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• v.20 no.3
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• pp.355-362
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• 2015

Purpose: To investigate the effects of the transmittance of diffusive blurson visual acuity and contrast sensitivity. Methods: Visual acuity and contrast sensitivity were measured by using Optec$^{(R)}$ 6500 in Healthy 30 subjects aged $22.83{\pm}0.50$ (male 13, female 17) who were recruited from university students. Cataract simulator was used as a tool for diffusive blur. Visual acuity and contrast sensitivity were measured with varying the transmittance of diffusive blur in order to simulate progression of cataract and concentration in fog. Results: Visual acuity was reduced proportionally with decreasing the transmittance of the diffusive blur as follows: $VA(T)=1.84{\times}10^{-2}T-0.645$. Contrast sensitivity was decreased in all spatial frequencies. Contrast sensitivity in a high spatial frequency band was a greater effect and was off the normal range of contrast sensitivity. The peak of contrast sensitivity was moved in the direction to low frequency. From an intersection point of contrast sensitivity function, we could calculated the transmittance of the diffusive blur being off the normal range and the shift to peak spatial frequency. The peak of contrast sensitivity function was observed to move from 6 to 3 cpd at transmittance of about 78.70%, the contrast sensitivities for all frequencies at transmittance of about 69.71% were deviated from the normal range. Conclusions: The transmittance of diffusive blur causes a reduction in visual acuity and contrast sensitivity, a deviation of normal range of contrast sensitivity, and a shift of peak contrast sensitivity. Therefore the more attention is required when suffering from cataracts or driving in fog.

• Journal of the Korean Society of Radiology
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• v.84 no.6
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• pp.1367-1372
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• 2023

Primary angiitis of the central nervous system (PACNS) is a rare vasculitis in the central nervous system. Herein, we report a case of diagnosis and treatment of necrotic pattern PACNS, which was difficult to differentiate from a brain abscess. A 19-year-old male presented with blurred vision and a headache. Brain MRI revealed irregular rim-enhancing necrotic masses with central diffusion-high signal intensity in the corpus callosum and peripheral diffusion-high signal intensity in the left parietotemporal periventricular area. Susceptibility-weighted imaging revealed multiple punctate hemorrhages in the lesions. The patient was diagnosed with unusual abscess or tumefactive PACNS. Therefore, we initially treated the patient with antibiotics to rule out brain abscess. However, the brain lesions did not improve on follow-up MRI after the antibiotic treatment. Surgical biopsy was performed, and the histopathological diagnosis was PACNS with a necrotic pattern. The necrotic lesions became smaller on follow-up MRI after high-dose corticosteroid treatment.