Abstract
Purpose: :
The objective of the investigation was to evaluate the effect of contact lens edge designs on the circumlimbal conjunctiva to develop a photographic grading scale of staining with lissamine green.
Design: :
the rounded edge designs showed the least amount of staining, whereas lenses with a chisel edge or knife point design showed the most. The differences observed ranged from 0.4 point to 1.9 points on the 5-point scale.iii. The staining observed was not related to subjective comfort.
Methods: :
Twenty-seven successful contact lens wearers constituted the study population. The investigation was a bilateral, double masked, randomised, cross-over investigation; five contact lenses with different lens edge designs were tested: four silicone hydrogel lenses (Acuvue Oasys, Biofinity, AirOptix, PureVision) and one conventional hydrogel lens (Acuvue 2). Each contact lens type was worn for a period of 10 (±2) days. At the baseline and follow-up visits, conjunctival staining was rated subjectively and photographed; from the digital photographs, the extent of true staining was measured to produce an objective measurement of of circumlimbal conjunctival lissamine green staining. At the follow-up visits, the lens edge was photographed and classified based upon its shape.Results:The results obtained showed that:i. A significant increase (p<0.001) in circumlimbal conjunctival staining was observed with all five contact lens types; the average increase ranged from 0.5 point to 2.5 points on the 5-point scale.ii. The staining observed at the follow-up visit was statistically significantly (p<0.001) different between contact lens types and dependent upon the contact lens edge
Conclusions: :
Soft contact lens wear of any type induces circumlimbal staining, the level of staining being influenced by the contact lens edge design. However, high level of circumlimbal staining is not associated with decreased comfort. The scale developed based upon objective measurements is intended to facilitate rating of circumlimbal staining in routine practice and clinical investigations.
Clinical Trial: :
www.clinicaltrials.gov NCT00940459
Keywords: contact lens • conjunctiva