changes in contact lenses in connection with radiation from welding arcs. Scand. j. work environ. & health 5 (1979) [271][272][273][274][275][276][277][278][279]. Because of reports of risks associated with the use of contact lenses during exposure to welding arcs, the temperature changes in soft contact lenses were recorded in connection with certain types of welding [manual metal arc (MMA) welding, tungsten inert-gas (TIG) welding, and metal inert-gas (MIG) welding], both with free-hanging lenses and lenses applied to the eyes of anesthetized rabbits. A great increase in temperature was noted, especially with MMA welding. At a distance of 0.4 m the temperature of a lens on a rabbit eye rose from about 35 to 50°C within 6 min, whereas the air temperature only increased from 23 to 30°C. The increase was the greatest at the beginning of the welding period. Most of the lenses completely dried out during the experiment, and there would seem to be a potential risk that the lens would adhere to the cornea. One safety glass screen (DIN 10 A) proved effective in preventing the rise in temperature in contact lenses during MMA welding. Even though it is impossible to direct the eyes at the arc for a prolonged period of time, the use of contact lenses in connection with at least certain types of welding is not to be recommended without the use of a suitable safety glass screen (or safety glasses). With regard to the large number of particles in the welding environment, also a risk factor for contact lens wearers, it is doubtful whether even safety glasses or screens are satisfactory unless they fit closely.
Ten subjects wearing soft contact lenses on a daily basis and working in an environment moderately contaminated with metal particles were followed for an average of 24 months. There were no signs of ocular damage and no history of eye irritation. Some contact lenses showed occasional brownish excavations, representing earlier lesions from burning particles, the lens thus having protected the cornea. Very few metal particles were seen on the lens when still on the eye and extremely few when studying removed lenses in light microscopy. Apparently particles were eliminated fairly easily be the tear fluid, by blinking and by daily cleaning. Atom absorption analysis of worn lenses showed only nanogram amounts of metal, not dissimilar to those in lenses worn by office employees. The lenses did not need to be replaced more often than for a group of office employees. Soft contact lenses apparently may be worn without damaging the eye in an environment moderately contaminated with metal particles, provided the lenses are properly cleaned. Contact lenses allow closer fitting of protective goggles compared to glasses; which is advantageous.
In a group of 66 daily hydrogel contact lens wearers, all lenses were cleaned and disinfected daily using a regular daily cleaner and a 3% hydrogen peroxide system. In addition, one of the lenses for each subject was subjected to weekly enzymatic cleaning with a multi-enzyme pancreatin preparation. After 6 months there were highly significant differences (P less than 0.001) between the lenses, the enzymatically cleaned ones showing less deposits and longer break-up time (BUT) on the lens. Also, comfort was significantly (P less than 0.05) better for these latter lenses. No adverse reactions that could be attributed with certainty to the preparations used were observed. The effectiveness of the pancreatin preparation employed in this study is of interest, since it has been demonstrated that enzymatic removal of deposits from hydrogel lenses reduces complications such as acute red eye reaction, contact lens-induced papillary conjunctivitis, and presumably also corneal ulceration because of decreased bacterial adherence to the lenses.
One hundred subjects wearing contact lenses (mainly soft lenses) on a daily basis for non-medical reasons were followed for 3 years. Visual performance was very satisfactory. The lenses were replaced at an average interval of 20.3 months. During the 3 year period 18 patients suffered from eye disease/changes, 17 of which had to be treated by an ophthalmologist: 8 cases of conjunctivitis, 5 cases of virus keratitis, 4 cases of corneal oedema (2 caused by overwear of lens, 1 by a too step fit and 1 by intolerance despite a perfect fit), and 1 case of unacceptable vascular reaction. Some of the infections might not have been related to contact lens wear. All changes healed well with no sequelae. One patient was hospitalized for 2 days. Each incident required 2.8 visits to an ophthalmologist and 7.4 weeks of discountinued lens wear, on the average. Details from patient history and objective findings recorded at the first examination of subjects accepted for lens wear did not seem to correlate well with later eye disease/changes. 11 subjects stopped lens wear. This was in no case mandatory, the most common reason being decreasing motivation. The results appear quite satisfactory.
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