A 62-year-old Caucasian woman with a 12-month history of progressive paresthesias below the first lumbar level (L1) was hospitalized for rapid onset of ascending sensory impairment to the sixth thoracic level (T6), ataxia, saddle anesthesia, and diminishing central vision. Best-corrected visual acuity (BCVA) was 20/40 in the right eye and 20/400 in the left eye. Her BCVA had been 20/25 bilaterally two years prior. Color discrimination was severely diminished at 4/12 Ishihara color plates in the right and 1/12 in the left. Dilated fundus exams showed small flat yellowish deposits limited to wellcircumscribed subfoveal areas of retinal pigment epithelium (RPE) atrophy (Figure 1). There was no optic nerve pallor. The fundus appearance and fluorescein angiogram findings were similar to those described in cases of congenital MMA. 4,5 Full-field electroretinograms revealed mildly reduced scotopic and photopic responses in the left eye.Despite a low normal level of vitamin B12 (298 pg/ml; reference 180-914 pg/ml), the patient's serum methylmalonic acid (0.30 mM/l; reference o0.30 mM/l) and homocysteine (22.2 mM/l; reference 6.2-15.0 mM/l) levels were elevated, consistent with a diagnosis of vitamin B12 deficiency. Furthermore, brain and spinal cord magnetic resonance imaging revealed T2-weighed hyperintensity of the entire dorsal columns, characteristic of vitamin B12 deficiency.The patient was treated with cyanocobalamin injections by the inpatient Neurology service. Six weeks after treatment, her ataxia, paresthesias, as well as bowel and bladder function improved. Color discrimination improved to 8/12 in the right and 5/12 in the left eye.

ABSTRACT. Long-term radiation exposure is hazardous to health; late-onset effects of exposure to ionizing radiation (IR) pose risks to the lens, and are associated with other non-cancerous diseases. Individuals occupationally exposed to low-dose IR are prone to developing eye cataracts. Cytogenetic evaluations suggest that IR is associated with chromosomal aberrations in occupationally exposed individuals. However, data regarding the association between chromosomal aberrations in cataract patients and occupational exposure to IR is scarce. Therefore, we aimed to report the characteristics of chromosomal aberrations in cataract patients from a Chinese population, occupationally exposed to IR. We found that the average age and frequency of numerical chromosomal aberrations were significantly lower in the exposed patients as compared with that in the non-exposed patients. In addition, the frequencies of dicentric and acentric chromosomes were significantly higher in the exposed patients as compared with those in the non-exposed patients. Therefore, chronic occupational exposure to IR affects cataract development in the Chinese population. The age of cataract patients exposed to IR was significantly lower than the age of cataract onset in normal individuals. Based on this study, we suggest that there is an urgent need for improved radiation safety and eye protection in individuals exposed to IR in the work place.