[A study on visual development among preschool children].

OBJECTIVE: To evaluate the visual development and prevalence of amblyopia, strabismus among preschool children. METHODS: A random sample survey was performed in 4 610 preschool children from both urban and rural, aged 3 to 6 years. Participants underwent eye examination including visual acuity, refractive status, eye position, strabismus and amblyopia. RESULTS: Percentage of visual acuity above 1.0 was 28.4%, 39.3%, 46.2% and 76.5% in children of 3, 4, 5 and 6-year-old group, respectively. The mean visual acuity of each group was 0.63 ± 0.19 in 3-years old, 0.69 ± 0.16 in 4-year-old, 0.71 ± 0.22 in 5-year-old, 0.79 ± 0.29 in 6-year-old. Rural children have better vision acuity compared with those from urban. Hypermetropic was frequent refractive errors. Manifeststrabismus was found in 2.21%, with exotropia being more prevalence than esotropia; detection rate of recessive strabismus was 33.52%, mainly being exophoria; Based on current diagnostic criteria, the prevalence of amblyopia were 2.93% in 6 year-old group, 4.81% in 5-year-old group, 16.21% in 4-year-old group, 33.33% in 3-year-old group. CONCLUSION: Vision acuity is increasing with age in preschool population. A diagnosis standard of amblyopia suitable for each age group should be established to substitute the current one which has a high visual standard for amblyopia. Refractive error, strabismus and amblyopia are the leading causes of visual impairment among preschool-aged children, which represent the focus of prevention of blindness in preschool children.

Inactivation and Damage of Histamine-Forming Bacteria by Treatment with High Hydrostatic Pressure.

The inactivation and damage of histamine-forming bacteria (HFB), Enterobacter aerogenes and Staphylococcus capitis, in a 0.1 M potassium phosphate buffer (pH 6.8) and marlin meat slurry by high hydrostatic pressure (HHP) treatments were studied using viability measurement and scanning electron microscopy (SEM). HHP treatments showed first order destruction kinetics to E. aerogenes and S. capitis during the pressure holding period. HFB in marlin meat slurry had higher D values and were more resistant to HHP treatments than in phosphate buffer. In phosphate buffer, E. aerogenes had higher D values than S. capitis at >380 MPa of pressure, whereas the reverse trend was noticed at lower pressures (<380 MPa). In marlin meat slurry, S. capitis had a higher D value than E. aerogenes at the same treatment pressure, indicating that S. capitis was more resistant to HHP treatment. To our knowledge, this is the first report to demonstrate that HHP can be used to inactivate HFB, E. aerogenes, and S. capitis, by causing disruption to bacterial cell membrane and cell wall as demonstrated by SEM micrographs.