by Joel Harrison
28. March 2011 14:25
An article in the latest Contact Lenses Today raises the issue of recognising whether a contact lens is inside out or not. The problem, according to the author of the text, Susan J. Gromacki, OD, MS, FAAO, is associated with the new materials and designs used to manufacture contact lenses.
Gromacki believes that the traditional method, which consists in looking at the edge of a lens on a person’s finger, is still effective in most cases. However, there are new ways of finding out if a contact lens is everted, as manufacturers put special indicators on the outside of the lens (numbers, symbols and/or letters). Those indicators can be read properly when viewed from underneath the lens, showing that the lens is not everted. In addition, the indicators help ophthalmologists check if the appropriate side of the lens touches the cornea, but that requires a biomicroscope.
The appearance of the indicator placed on Air Optix Night and Day (CIBA Vision) lenses (“OK”), according to Gromacki, requires additional explanation, as it can only be read correctly when it is at the 12 o’clock position. If the OK mark appears at the6 o’clock position, the lens is inside out.
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