일회용 써클소프트렌즈의 일일 초과착용 시 유발되는 건성안의자각적 불편감, 순목횟수, 중심안정 및 렌즈 광투과율의 변화

This study was assessed to investigate the change of subjective and/or objective symptoms and the lighttransmittance of lens caused by the use longer than recommended wearing time of daily disposable circle contactlenses (circle lens) in dry eyes. Methods: Three daily disposable circle lenses made of etafilcon A, hilafilcon B,and nelfilcon A were applied on 30 dry eyes with smaller tear volume than normal eyes in their twenties freefrom any eye diseases by when subjects complained any kind of discomfort. On the first and the last days of lenswearing, subjective discomfort, blinking rate, lens centration on corneal surface and visible light transmittance oflens were recorded at every case and compared. Results: The circle lens wearers complained subjectivediscomfort and quit the lens wearing when they wore the circle lens longer than 10 hours even though there weresome difference according to the lens materials of daily disposable circle lens. However, around 20% of dry eyescould wear the circle lens made of non-ionic materials longer than 40 hours. Dry eyes showed most sensitivefeeling of subjective discomfort against the circle lens made of etafilcon A among three different lens materials.
On the last day of lens wearing, the representative subjective discomforts were irritation, stiffness, dryness andtiredness. When the subjects wore circle lens more than the recommended time, blinking rate was significantlyincreased about 20~30% regardless of lens materials when it compared with the values right after lens wearing.
On the last day of lens wearing, the vertical direction of lens centration was shifted to pupil center however, itsdistribution in horizontal direction was wide compared with the distribution right after lens wearing. Especially,the centration of etafilcon A lens was unstable. Furthermore, the visible light transmittance of 3 different circlelenses in dry eyes has significantly been reduced around 15% averaged. Conclusions: From these results, it wasknown that the increase of dryness and stiffness caused by overusage of daily disposable circle lens inducedexcess irritation and decreased visible light transmittance and caused significant more blinking, which provokedlens decentration. It was also revealed that dry eyes showed sensitive reaction subjectively and objectively againstthe overusage of circle lens made of high water content/ionic lens material even there were some difference ofthe degree depending on the individual and the lens material. Thus, this research can be suggested as the basicreference for the education about some unexpected problems and the side effect caused by the wearing of circlelens in dry eyes.