• Journal of Korean Ophthalmic Optics Society
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• v.17 no.1
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• pp.27-35
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• 2012

Purpose: The present study was conducted to compare any difference caused by pigmentation in the centrations and movement patterns on the cornea between circle and soft contact lens with identical material and parameters during lens wearing. Methods: Soft and circle contact lenses with identical material and parameters were applied to twenty eyes with normal tear volume for 3 hrs a day during a total of 5 days and then their lens centrations, the moving distances and rotations by repeat blinking were compared. Results: The lens centration beyond the fitting criteria was shown in initial wears of both soft contact lens and circle contact lens. However, the centration of soft contact lens was changed to the pupil center for being suitable to the fitting criteria with longer wearing time. On the other hand, the decentration of circle contact lens in the horizontal direction was still presented even with longer wearing time. The moving distances of soft contact lens and circle contact lens decreased with the expand of lens wearing but were not significantly different between total wearing period and daily wearing time. The rotation of circle contact lens by repeat blinking was significantly different from that of soft contact lens even when the wearing period was extended. Conclusions: We revealed that the lens centration and movement of circle contact lens on cornea were different from those of regular soft contact lens resulting in bigger difference with the expand of wearing period in the study.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.147-157
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• 2011

Purpose: The present study was conducted to investigate the actual condition of circle lens wear and the differences caused by the pigmentation in blinking rate, non-invasive tear break-up time (NIBUT), and lens surface between circle and soft contact lens wear during clinical application. Methods: Eighty subjects were surveyed to know the actual condition of wearing circle lens. Blink rate, NIBUT of 20 subjects in twenties were measured after separately wearing soft contact lens and circle lens for 5 days. Their lens surfaces were also observed by scanning electron microscope. Results: Fifty percent of circle lens wearers answered that major reason for changing circle lens was discomfort and 67% of answerers wore circle lens more than 6 hours a day. The tendency of increased blink rates in both wearers of circle and soft contact lens at 30 minutes later when tear film stabilized and 3 hour after lens wearing was shown on the 1st, 3rd and 5th day with expanding wearing time. Especially at 3 hours after lens wearing on the 3rd and 5th day, the difference of blink rates was statistically different in circle lens wear and soft contact lens wear. The NIBUTs of soft contact lens wearers and circle lens wearers were 6.0 and 3.7 secs, respectively, at 30 min later on 1st day and were significantly different. NIBUTs of soft contact lens wearers and circle lens wearers were also statistically different 3 hrs after lens wearing on the 1st day and the similar pattern of NIBUTs was shown on the 3rd and 5th day. The roughness of both surfaces in soft contact lens and front surface in circle lens was same. However, pigmented front surface of circle lens was rougher and uneven. Conclusions: As the results, the circle lens wearers might feel discomfort in clinical application since the difference in lens surface of circle lens would change lens wettability during wearing. The difference by tinting contact lens was shown from the result, which could help better wearing circle lens.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.125-131
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• 2015

Purpose: The effect of pigmentation in circle contact lens on lens wearers' tear film stability was investigated in this study. Methods: Non-invasive tear film break-up times of 54 normal eyes before and after lens wearing in twenties and the portion of first tear breakup were measured. The frontal and back surface roughness of circle contact lens was further observed with a scanning electron microscope. The clear lens which was made of hilafilcon B and circle contact lenses which were made of hilafilcon B, polymacon and copolymer of HEMA NVP were tested. Results: Non-invasive tear film breakup time was significantly reduced compared with it before lens wearing. In some case, statistically significant difference in tear film breakup time was also observed between circle contact lenses. The tear file break-up was usually early started in lower than upper portion, and in temporal than nasal portion although there was variation in the lens material. The tear film break-up of circle contact lenses made of hilafilcon B was more commonly observed in peripheral portion(pigmented area) compared with clear contact lens made of same material. Conclusions: The present study revealed that the stability of tear film was affected by wearing circle contact lens and the result seems to be used as the basis for the problem solving that can occur due to the pigmentation when wearing circle contact lens.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.1
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• pp.19-25
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• 2013

Purpose: The degree of the pupil covered with tinted region of circle soft contact lens was determined according to the illuminant conditions in everyday life and the change of visual acuity by its covering was further investigated. Methods: The circle contact lens having the non-tinted area of 6.2 mm in the center of the lens was applied on 82 eyes in their 20s and their minimum separable visual acuity and minimum legible visual acuity were determined under the luminances of 50 and 370 lux. Results: The covering of pupil was not found when wearing circle contact lens under 370 lux, however, some pupil covering ranged from 0.40 to 1.70 mm was observed in all subjects under 50 lux. The minimum separable visual acuity and minimum legible visual acuity were significantly decreased by the wearing of circle contact lens under 50 lux and the correlation between the larger pupil size of subjects and more decrease of visual acuity was observed. Furthermore, the decrease of minimum separable visual acuity was larger than the case of minimum legible visual acuity indicating that minimum separable visual acuity was largely affected by the covering of pupil. Conclusions: The consideration is necessary for the lens wearers and the manufacturers since the wearing circle contact lens in low-light indoor or nighttime activities may affect directly visual acuity.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.171-177
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• 2014

Purpose: The present study was conducted to investigate whether the elution of the dyes from the circle contact lenses existed or not when rubbed with cotton swab. Methods: The change of lens surface was observed by scanning electron microscope when a total of seven kinds of circle contact lens were rubbed with cotton swab, and the dye elution was further compared when the lenses were soaked in multi-purpose solution in $20^{\circ}C$ and $36.5^{\circ}C$ for a week. Results: Five of a total of 7 circle contact lenses showed the dye elution from the front or the back surface of the lens when rubbed with cotton swabs, and existence of dye elution was varied depending on the type of contact lenses and different at the front and back surface even in the same lens. The tear-off of the pigmented portion by the rubbing was found through scanning electron microscopic observation when the dye elution existed. However, the dye was not eluted when the circle contact lenses was soaked in a multi-purpose solution in $20^{\circ}C$ or $36.5^{\circ}C$ for a week. Ingredient of colorant was not provided by the manufacturers in more than 50% of the circle contact lenses investigated for this study and the basic information such as the pigmentation method was provided inappropriately. Conclusions: In this study, the result was the dye elution from circle contact lenses was obtained when a physical force is applied thus, it may appear to contribute the development of circle contact lenses and safety of lens wear.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.153-162
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• 2014

Purpose: This study was assessed to investigate the change of subjective and/or objective symptoms and the light transmittance of lens caused by the use longer than recommended wearing time of daily disposable circle contact lenses (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 free from any eye diseases by when subjects complained any kind of discomfort. On the first and the last days of lens wearing, subjective discomfort, blinking rate, lens centration on corneal surface and visible light transmittance of lens were recorded at every case and compared. Results: The circle lens wearers complained subjective discomfort and quit the lens wearing when they wore the circle lens longer than 10 hours even though there were some difference according to the lens materials of daily disposable circle lens. However, around 20% of dry eyes could wear the circle lens made of non-ionic materials longer than 40 hours. Dry eyes showed most sensitive feeling 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 and tiredness. When the subjects wore circle lens more than the recommended time, blinking rate was significantly increased 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, its distribution 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 circle lenses in dry eyes has significantly been reduced around 15% averaged. Conclusions: From these results, it was known that the increase of dryness and stiffness caused by overusage of daily disposable circle lens induced excess irritation and decreased visible light transmittance and caused significant more blinking, which provoked lens decentration. It was also revealed that dry eyes showed sensitive reaction subjectively and objectively against the overusage of circle lens made of high water content/ionic lens material even there were some difference of the degree depending on the individual and the lens material. Thus, this research can be suggested as the basic reference for the education about some unexpected problems and the side effect caused by the wearing of circle lens in dry eyes.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.3
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• pp.277-284
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• 2015

Purpose: The study aimed to evaluate the effect of circle contact lens wearing on visual quality of the eyes after a refractive surgery. Methods: The objective visual quality was evaluated for 40 eyes who did not get refractive surgery and 30 eyes who got a refractive surgery after applying plano circle contact lenses on their eyes, respectively. Modulation transfer function (MTF), objective scatter index (OSI) and the focusing ratio on retina (Strehl ratio) were measured by using optical quality analysis system (OQAS) and the correlation between pupil size and objective visual quality was analyzed by measuring the pupil size. Results: When wearing circle contact lens on the eyes after refractive surgery, MTF and Strehl ratio were reduced and OSI was increased compared with the eyes without refractive surgery. The eyes after a refractive surgery showed more significant difference changes in MTF, OSI and Strehl ratio according to the pupil size compared with those without refractive surgery. Conclusions: The results showed that wearing of circle contact lens after the refractive surgery has deteriorated the objective visual quality based on the quality of focused image on the retina. Therefore, we suggest that sufficient understanding and consideration about the deterioration of visual quality is necessary in the case of circle contact lens wearing after refractive surgery.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.4
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• pp.429-439
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• 2013

Purpose: This study was assessed to investigate the change of subjective and/or objective symptoms and the light transmissibility of lens caused by over-usage of daily disposable circle contact lenses (circle lens). Methods: Three daily disposable circle lenses made of etafilcon A, hilafilcon B, and nelfilcon A were applied on 20 normal eyes free from any eye diseases by when subjects complained any kind of discomfort. On the first and the last days of lens wearing, subjective discomfort, blinking rate, non-invasive break-up time, lens centration on corneal surface and visible light transmissibility of lens were recorded at every case and compared. Results: The circle lens wearers complained discomfort when they wore the circle lens more than 15 hours, in excess of 8 hours being the recommended wearing time and the most circle lens wearers quit the lens wearing when they wore more than 30 hours. On the last day of lens wearing, the representative subjective discomforts were stiffness, dryness and tiredness. When the subjects wore circle lens more than the recommended time, a tendency of increased blinking rate and decreased NIBUT was observed when it compared with the values right after lens wearing. On the last day of lens wearing, the lens centration was shown to be decentrated from the pupil center compared with the centration right after the wearing. These changes in lens centration and blinking rate were consistently shown in all cases of lens wearing however, the difference in the degree of subjective and/or objective change was present depending on lens materials and subjects. The visible light transmissibility of circle lens has largely been changed. Conclusions: From these results, it was thought that the decreased NIBUT induced dryness and stiffness and decreased visible light transmissibility caused more blinking when daily disposable circle lens was exceedingly used, which provoked lens decentration and subjective discomfort. However, the difference of subjective and/or objective change was largely varied in accordance with the lens material types and individuality and thus it may occur some unexpected problems by the individual base. Therefore, the education about the necessity to comply with the recommended wearing time and the problem will be essential.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.2
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• pp.109-117
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• 2016

Purpose: The study was aimed to figure out the effect of materials and pigmentation of soft contact lens on the adherence of Staphylococcus aureus upon soft contact lenses deposited with tear components. Methods: The number of adherent S. aureus on clear and circle soft contact lenses made of etafilcon A, hilafilcon B, nelfilcon A was measured before and after incubation in artificial tear. Furthermore, the denaturalization level of tear protein with time after incubation in artificial tear was estimated by electrophoresis. Results: The adherence of S. aureus was significantly different according to the lens materials. The pattern of bacterial adherence on clear and circle contact lenses was different. That is, the adherent amount of S. aureus was somewhat larger on circle lens made of etafilcon A however, amount on circle lenses made of hilafilcon B and nelfilcon A was 89.3% and 71.3% of the number on clear lenses. When the tear protein was deposited on contact lenses, the number of adherent bacteria decreased and its degree was varied according to the lens material. The degree of decrease was the biggest in clear soft lens made of etafilcon A. Anti-bacterial effect of tear protein decreased with time after deposition of tear protein on soft contact lens and the amount of lysozyme also decreased. The reduction of anti-bacterial effect and quantity of lysozyme was different according to contact lens materials and pigmentation. Conclusions: It was revealed that the adherence of S. aureus depends on contact lens materials and pigmentation, and the specification of lens material affects more on adherence of S.aureus than pigmentation. It was further figured out the denaturalization level of anti-bacterial protein on soft contact lens varies according to lens materials and pigmentation, which produces an effect on the quantity of bacterial adherence.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.1
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• pp.11-21
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• 2016

Purpose: The aim of this study was to analyze the difference in tear film stability according to the wearing time when wearing clear and circle soft contact lens(circle lens) made of same material. Methods: The clear and circle contact lenses of hilafilcon B and nelfilcon A materials were respectively applied on the subjects classified as normal and dry eyes depending on their tear volume, and their tear film stability was investigated by measuring the non-invasive tear film break-up times, lens centration and the first appearing area of tear breakup after 30 mins and 6 hrs of lens wearing. Results: Non-invasive tear film breakup time significantly reduced with increase of the wearing time for normal and dry eyes when wearing clear and circle contact lenses. The starting ratio of tear film break-up was higher at the peripheral area of clear and circle lenses in all two different materials, and higher at the peripheral area of dry eyes than normal eyes. Starting ratio of tear film break-up was higher at the peripheral area of nelfilcon A lenses compared with hilafilcon B lenses, however, its change with the increase of wearing time showed a different aspect. The number of tear film break-up per unit area when wearing circle lenses of nelfilcon A increased at the central area with the wearing time while its number was higher at the peripheral area when wearing circle lenses of hilafilcon B. The centration of clear lenses made of two materials was closer to pupil compared to circle lenses with the increase of wearing time, however, a larger decentration was shown in dry eyes compared with normal eyes. Conclusions: The research revealed that an effect on tear film stability may be changed by clear lenses as well as circle lenses with coloring process according to the increase of wearing time, and the factors affecting on tear film stability may also vary depending on lens materials. Thus, the appropriate lenses should be selected by the consideration of lens material as well as coloring method/dyes according to the wearers' habit such as daily wearing time and wearing period when trying to wear clear and circle lenses.