Simulation of heat exposure and damage to the eye lens in a neighborhood bakery.

Epidemiological studies indicated a link between high temperature environment and cataract. The purpose of the study was to investigate if the high temperature in neighborhood bakeries can cause damage to the eye lens. Measurements were done to determine the temperature and exposure time in the neighborhood bakeries during a workday. Thermal analysis was done using finite volume and finite element Computational Fluid Dynamics (CFD) codes in order to determine the temperature in the eye lens when exposed to environmental temperature fluctuations. A simulation of heat exposure was carried out using a bovine lens organ culture system. Two-hundred and seventy bovine lenses were divided into five groups. (1) Control group kept in culture for 11-14 days (2) Lenses exposed to 39.5 degrees C, 6h daily starting on the second day of the culture and kept in culture for 13 days (3) Lenses exposed to 39.5 degrees C, 4h daily starting on the second day of the culture and kept in culture for 11 days (4) Lenses exposed to 39.5 degrees C, 2h daily for 3 days starting on the second day of the culture and kept in culture for 12 days (5) Lenses exposed to 39.5 degrees C, 1h on the second day of the culture and kept in culture for 14 days. Lens optical quality was assessed during the culture period. At the end of the culture lens damage was demonstrated by inverted microscopy. Lens epithelial samples were taken for analysis of Catalase activities. Control lenses maintained their optical quality throughout the 14 days of the culture. Exposure to heat caused optical damage to the cultured lenses. The damage appeared earlier in the 6h exposure group and progressed from the lens anterior suture to its center. Optical damage was recovered in lenses exposed 1h to 39.5 degrees C, but the damage remained in the lens epithelial cells. Our study indicates that exposure to heat in bakeries can cause damage to the eye lens and that the damage is dependent on the length of exposure.

Non-thermal electromagnetic radiation damage to lens epithelium.

High frequency microwave electromagnetic radiation from mobile phones and other modern devices has the potential to damage eye tissues, but its effect on the lens epithelium is unknown at present. The objective of this study was to investigate the non-thermal effects of high frequency microwave electromagnetic radiation (1.1GHz, 2.22 mW) on the eye lens epithelium in situ. Bovine lenses were incubated in organ culture at 35°C for 10-15 days. A novel computer-controlled microwave source was used to investigate the effects of microwave radiation on the lenses. 58 lenses were used in this study. The lenses were divided into four groups: (1) Control lenses incubated in organ culture for 10 to15 days. (2) Electromagnetic radiation exposure group treated with 1.1 GHz, 2.22 mW microwave radiation for 90 cycles of 50 minutes irradiation followed by 10 minutes pause and cultured up to 10 days. (3) Electromagnetic radiation exposure group treated as group 2 with 192 cycles of radiation and cultured for 15 days. (4) Lenses exposed to 39.5°C for 2 hours 3 times with 24 hours interval after each treatment beginning on the second day of the culture and cultured for 11 days. During the culture period, lens optical quality was followed daily by a computer-operated scanning laser beam. At the end of the culture period, control and treated lenses were analyzed morphologically and by assessment of the lens epithelial ATPase activity. Exposure to 1.1 GHz, 2.22 mW microwaves caused a reversible decrease in lens optical quality accompanied by irreversible morphological and biochemical damage to the lens epithelial cell layer. The effect of the electromagnetic radiation on the lens epithelium was remarkably different from those of conductive heat. The results of this investigation showed that electromagnetic fields from microwave radiation have a negative impact on the eye lens. The lens damage by electromagnetic fields was distinctly different from that caused by conductive heat.

Zinc-desferrioxamine reduces damage to lenses exposed to hyperbaric oxygen and has an ameliorative effect on catalase and Na, K-ATPase activities.

Our purpose was to investigate the effects of exposure to high partial pressure of oxygen on lens optical quality and on the activities of lenticular catalase and Na, K-ATPase in culture and to examine the effect of zinc-desferrioxamine (Zn-DFO) addition to cultured lenses exposed to high oxygen partial pressure on these parameters. Bovine lenses, kept in organ culture, were exposed to different combinations of partial pressure of oxygen with and without addition of Zn-DFO complex (20 microM) and examined during a 14-day period. Lens optical quality, catalase, and Na, K-ATPase activity were compared between study and control groups. Two hundred lenses were included in the present study. Decreased lenticular optical quality and decreased catalase and Na, K-ATPase activities were observed in lenses exposed to hyperbaric oxygen. Lenses exposed to normobaric oxygen showed a reduction in these parameters to a lesser degree. The damaging optical and enzymatic effects of oxygen on lenses in culture increased in magnitude along the culture period. Addition of Zn-DFO to the culture just before the exposure to hyperbaric oxygen eliminated most of the optical and enzymatic oxygen-induced damage. Addition of Zn-DFO after the first exposure demonstrated reduction in the oxidative damage induced reduction of optical quality in a time-dependent manner - the later the addition of Zn-DFO took place the smaller the protective effect observed. High oxygen load has toxic effects on bovine lenses in organ culture conditions as determined by optical parameters as well as reduction of catalase and Na, K-ATPase activities. These toxic effects can be attenuated by introducing Zn-DFO just before lenses are exposed to oxygen. The beneficial effect of Zn-DFO, applied after lenses have been exposed to hyperbaric oxygen, on the oxidative damage was time-dependent - the earlier the application the more significant the observed protective effect. The present results may indicate a possible future role for Zn-DFO as a protective agent against oxygen-induced human cataract formation.