• Journal of Korean Ophthalmic Optics Society
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• v.9 no.1
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• pp.81-91
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• 2004

The use of soft contact lenses for myopia correction is increasing in many countries. It is therefore important for contact lens practitioners to be properly educated in fitting these lenses. Before fitting lenses, it is important to consider the factors and procedures related to soft contact lens fitting, indications and contraindications of fitting soft contact lenses. In this article, the functions and activities involved in preliminary, fitting and delivery consultations will be presented.

• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.431-442
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• 2018

Purpose : The purpose of this study was to investigate subjective symptoms according to the wearing, purchase and fitting status of soft contact lens wearers, and consumer perception of base curve. Methods : A survey was conducted for those who visited optical shops and lens shops in Seoul from June to August 2018. A total of 98 answer sheets they submitted were used for the analysis. The chi-square test and Fisher's exact test were used to compare subjective symptoms (dryness, glare, uncomfortable fitting, and decreased vision) according to whether fitting condition is screened (case history and push-up test, ect relevant to wearing sensation), and the odds ratio (OR) was obtained by the logistic regression analysis. Results : When the contact lenses were purchased, the rate of which the visual acuity test was performed was 86.6% at optical shop and 64.7% at lens shop. When purchasing contact lens and the contact lens was not tested for fitting, they more experienced dryness (OR 4.41, 95% CI 1.25-15.62) and uncomfortable fitting (OR 2.68, 95% CI 1.08-6.64) than testing for fitting. In addition, it was investigated that 87.8% of contact lens wearers did not know about the term base curve, 92.9% did not listen to an explanation related to the base curve when purchasing contact lenses, and 96.9% did not experience with base curve test. Conclusion : It would be thought that satisfaction of the contact lens fitting of existing consumers should be improved by changing a proper base curve by confirming the fitting condition when prescribing soft contact lens.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.21-30
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• 2011

Purpose: The study was performed to compare the differences in lens rotation, lens movement by blinking and lens centration with alignment or steep fitting of soft contact lens in normal and dry eyes. Methods: Total 40 eyes (aged 20~30 years) were classified into the normal (n=20) or dry eye group (n=20) by the diagnosis methods for dry eyes and worn soft contact lens (polymacon material) with alignment fitting or steep fitting. Lens rotation, lens movement by blinking and lens centration were separately measured immediately after lens wearing and after stabilization of tear film and compared by fitting states of soft contact lenses. Results: With steep fitting of soft contact lens in dry eyes, averaged lens rotation immediately after lens wearing was not significantly different from that of the normal eye group with alignment fitting however, lens rotation after stabilization in dry eyes was significantly larger than that in normal eyes. Any significant difference in lens movement by blinking was not shown in normal eyes. However, lens movement by blinking in dry eyes was increased with steep fitting. The range of lens centration on cornea in normal eyes with alignment fitting was more vertically distributed. On the other hand, the range of lens centration on cornea in dry eyes with alignment fitting was more horizontally distributed. Lens centration was shown to be changed by stabilization of tear film. That is, lens centrations were somewhat vertically widespread immediately after lens wearing and restrictively distributed in horizontal direction, respectively, with steep fitting in dry eyes. Conclusions: These results suggested that lens movements and centration in dry eyes were different from those of normal eyes. Especially, those differences between normal and dry eyes were much bigger with steep fitting of soft contact lenses. Thus, those differences should be considered for the comfortable and safe fitting of soft contact lens in dry eyes.

• Journal of Korean Clinical Health Science
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• v.4 no.3
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• pp.652-661
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• 2016

The analysis of cornea morphology using corneal topographers is a clinical practice for the diagnosis of keratoconus in contact lens fitting. The recently technique has developed with the possibility of achieving a great number of measuring points of both anterior and posterior corneal surfaces in cornea. Also these data are used to extract a series of topographic valuation indices that permit to offer the most exact clinical diagnosis of keratoconus in contact lens fitting. This study describes the technologies in which current corneal topographers are based on the morphological characteristics that the keratoconus status observe on corneal surface. Therefore, this paper can provide that the analysis of corneal topographers applied for the diagnosis of keratoconus in contact lens fitting.

• Journal of Korean Clinical Health Science
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• v.4 no.4
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• pp.662-670
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• 2016

Purpose. Because of a recent increase in use of soft contact lens at younger ages, in the present study, the correlation between corneal eccentricity and radius of curvature and fitting types of contact lens was investigated. Methods. The study evaluated the fitting status of targets through lens centration, push-up test, dynamic lag test and static lag test of lenses usually worn by 49 men and women (98eyes) in their 20s to 30s who put on soft contact lenses. After evaluation, the subjects were classified into 3 categories by fitting status(steep, aligment and flat). The radius of corneal curvature in the naked eyes was measured by using keratometer. Moreover the corneal eccentricity in the nasal side, temporal side, superior side and inferior side was measured by using the device capable of measuring the corneal eccentricity. Results. The radius of corneal curvature and corneal eccentricity of soft lenses worn by subjects were higher in the order of steep fitting and flat fitting, and the higher average corneal curvature radius and corneal eccentricity is intend to be more steep fitting(p=0.051, p=0.052). The corneal eccentricity showed a tendency to nasal fitting type at the higher eccentricity and temporal fitting type at the smaller eccentricity, statistically significant difference was observed(p<0.05). The study showed there were low correlation that nasal and temporal side at steep fitting, superior side at normal fitting and 4side(nasal, temporal, superior, inferior) at flat fitting, therefore when the corneal eccentricity changed the radius of corneal curvature also changed. The corneal eccentricity and the radius of corneal curvature showed statistically significant difference at 4side and each fitting types(p<0.05). Conclusions. The results of this study, the fitting status, of wearer are based on radius of corneal curvature and corneal eccentricity, and if lens fitting would be done considering that, it seems to be useful in a soft contact lens prescription.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.4
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• pp.339-346
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• 2010

Purpose: The study was performed to compare the difference of non-invasive tear break-up time (NIBUT) with alignment or steep fitting of soft contact lens in normal and dry eyes. Methods: Total 40 eyes (aged 20~30 years) were classified to the normal (n=20) or dry eye group (n=20) by the diagnosis methods for dry eyes and worn soft contact lens (polymacon material) with alignment or steep fitting. NIBUTs of lens wearers were separately measured at the points of before wearing, immediately after wearing and after stabilization of tear film. Results: With alignment fitting, averaged NIBUT in the dry eye group after stabilization of tear film was not significantly different from that of the normal eye group. However, averaged NIBUTs in the normal and dry eyes had significant difference when measured immediately after lens wearing. However, the number of eyes having NIBUT less than 4.0 second was 30% higher compared to the number of normal eyes with steep fitting when measured immediately after wearing. Some shorten NIBUT in dry eyes with steep fitting was also shown after stabilization of tear film. Conclusions: These results suggest that wearing soft contact lens in dry eyes differently affect tear film compared to normal eyes. Thus, dry eyes need more advertent fitting for contact lens wearing because of unstable tear film.

• 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.5 no.2
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• pp.65-72
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• 2000

The study investigated the effects of base curve radius art the fit of thin, mid-water contact lenses. It was found that central corneal curvature(as measured with the keratometer) was not predictive of the best fitting base curve. Proper lens fit may be the single most important factor that ultimately determines the success of contact lens wear. Comfort, vision, and physiological response are all dependent on the fit of the lens. The percent of optimal fits was highest with the 8.4 mm base curve lens for all three ranges of keratometry values. When fit with the 8.4 mm lens. For most eyes, fitting a flatter lens led to greater decentration, decreased comfort, and no increase in lens movement. The 8.4 mm lens was found to provide on "optimal" fit in over 60% of eyes tested and a fit of "good" or "better" in nearly 90% of eyes tested. Comparisons of different manufactures' lens found that similiar lenses do not always fit in the same way due to subtle design and production differences. Therefore, different products may require different base curve radii to fit the same patient. This is even true when water content, center thickness, and diameter are approximately the same. A praditioner fitting a new patient in this lenses should begin with the 8.4 mm base curve radius.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.255-264
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• 2011

Purpose: To study the effect of hyaluronic acid(HA), which was widely used in artificial tears, multi-purpose solution(MPS), cosmetics, and drug acting on the musculo-skeletal system, in wettability and comfort of contact lens, we compared HA including lens(+HA) with HA excluding lens(-HA) by clinical evaluation. Methods: During four weeks, the selected 28 university student volunteers who did not have any eye disease wore +HA contact lens on their right eyes, and -HA contact lens on their left eyes, and then compared right eyes to left eyes as control. After prescribing by spherical equivalent calculation, over-refraction by auto-refractometer, and contact lens wearing for two weeks and four weeks, tear evaluation, the anterior of eyes examination, fitting convenience evaluation, surface wetting test, surveys were checked up. Results: Compared with the control group (-HA contact lens), +HA contact lens provided better wetting properties. The amount of released tear in -HA contact lens group became less in four weeks than before, but that in +HA contact lens group showed no significant difference from the initial one. In terms of the redness in eye, there was no significant difference between +HA and -HA contact lens groups. Fitting of +HA contact lens on eye was much easier than the control, -HA contact lens. From the results of survey, comfort, wettability, ease of cleaning, and dryness of eye in +HA contact lens group were generally better than those of -HA group, but redness and contact lens handling showed little difference. Conclusions: The addition of HA in soft contact lens(+HA) may enhance the wettability of lens during lens wearing, resulted in the better comfortable wearing of lens eventually.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.107-116
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• 2011

Purpose: The review article was written to establish an excel program that could calculate minimal Dk of contact lens without $O^2$ deficiency and actual $O^2$ concentration on cornea when contact lens were being fitted by changing lens-related factors. Methods: An excel program was formulated to calculate the thickness of post-lens lacrimal layer, Dk of contact lens and $O^2$ concentration on cornea. Results: With the excel program established, minimal $O^2$ concentration needed on cornea could be calculated when the thickness of post-lens lacrimal layer was changed by varying lens-related factors. A different route in the excel program was needed to choose based on the shape of lacrimal layer. The thickness of lacrimal layer was determined by the shape of meniscus made of tear between lens edge and cornea with flat fit. Thus, the $O^2$ concentration showing negative number in calculation decreased on peripheral cornea with flatter fitting and actual $O^2$ concentration would be zero on cornea. With tight fitting, the thickness of post-lens lacrimal layer is much thicker than lens itself thus negative number in calculation by the excel program is shown indicating zero oxygen on cornea. It can cause $O^2$ deficiency regardless of Dk of contact lens. Conclusions: The calculation of thickness of post-lens lacrimal layer and $O^2$ concentration on cornea by the established excel program is suggested to avoid $O^2$ deficiency when fitting state is varied by changing lens-related factors.