Those Dark Glasses!

New Zealand Listener, Volume 31, Issue 801, 26 November 1954, Page 30

Those Dark Glasses!

This is the text of a talk on heath broadcast recently from ZB, YA and YZ stations of the NZBS by

DR

H. B.

TURBOTT

Deputy-

Director-General of Heaith

‘THE warm half of the year liés ahead, within it bright and strong sunlight. Of recent years the custom of wearing dark glasses has grown, particularly among our womenfolk. If this is a fashion development, nothing a mere man may say will make any difference. It may, however, be born of the idea that eyes Should be shielded from bright sunlight, or that they help to avoid eye-strain-so here’s for the facts about dark glasses! * Unless you ate going to look straight at the sun itself, sunlight doesn’t. hurt the eyes. Even dark glasses may let some dangerous ultra-violet and heat rays through so that the retina-the part responsible for seeing-is burnt, when you gaze directly at the sun. Very few of us try such a thing, so having excluded such foolishness, we are left with the fact that sunlight, indirect, is meant to assist the eyes, not harm them. Glare is the thing that hurts eyes. Reading in direct sunlight is bad because of the glare on the paper. Children should be warned against this practice. The paper or book can easily be tipped or turned or shaded so that only indirect sunlight is used. Sunlight diffused over the landscape in our country should be enjoyed and not spoilt with dark glasses.

. > an LL Sunlight played up to cause glare in certain situations should be softened with dark glasses. These situations are those of annoying glare, where sunlight is reflected from bright surroundings, such as bitumen main roads, or’ lake, sea or water surfaces, or snow on our mountains. These glare situations are properly countered with dark glasses. Motoring in the daytime, if you sense reflection from the highway, the donning of dark glasses is protective and restful. Motoring at night-time brings glare from oncoming car headlights, where drivers fail to dip their beam. The practice is growing of wearing dark glasses, when night driving. Now ophthalmolbgiststhat is; doctors specialising in eye diseases aitd optical defects; oculists is another name for them (don’t confuse these terms with opticians, who are people who grind, fit and supply glasses) -ophthalmologists consider that car driving at night becomes dangérous

when the driver wears coloured glasses. All dark glasses reduce good vision-a matter of commonsense when you remember dark glasses cut down the visible light rays. Tests have been made between colourless glasses ‘and tinted ones under night driving conditions. Yellow tints compare’ unfavourably, pink shades feduce the keenness of sight more than yellow, and green shades make the biggest reduction. Tinted glasses interfere not only with the keenness of the sight. but also with the ability to distinguish and separate objects at a distance. Wearing colourless glasses two people walking on the road are picked out by the eyes as two individuals instead of one at a much

greater distance away than when tinted glasses were worn. The driver has less time with dark glasses to give the pedestrians the wider berth required for the two than for one. In keenness of sight, the power of separating objects, perception of depth and contrast and other eye functions, there is a reduction of effectiveness. In short, the risk of accidents in night driving is increased if the driver wears dark glasses! Folk with defective vision are further hindered, of course, and therefore should never wear tinted glasses motoring in the dark. I suppose the idea of wearing dark glasses is to avoid eyestrain, if it is not for fashion. Eyestrain is an eye muscle business, helped by the proper glasses, if an ophthalmologist so directs-but not by dark glasses. Keep dark glasses for the glare situations already described, and don’t use them otherwise in the daytime or for night driving, unless a doctor specialising in eye diseases prescribes them. Cheap dark glasses of ordinary coloured glass or celluloid should not be worn, for ‘they can be dangerous. The pupils enlarge, and unprotective tinted glasses or celluloid let in, therefore, more irritating sun rays. Dark glasses need to be as accurately ground and as correct scientifically as colourless spectacles-so wear them only in glare, never daily, unless prescribed by an ophthalmologist.