• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.229-235
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• 2011

Purpose: The present study was performed to evaluate the safety of ophthalmic lenses in domestic market since eyeglasses wearers could be exposed to the negligent accident by damaged ophthalmic lenses. Method: Totally, 160 ophthalmic lenses (NK55, ${n_{d}}$ = 1.56) with the refractive powers of -3D, -6D, +3D, +6D manufactured by 4 companies in domestic market were evaluated using drop ball test. In accordance with FDA standard, steel ball (~16 g) was freely dropped on these ophthalmic lenses from 127 cm high and the surfaces of lenses were observed. Results: From the study, center thicknesses of NK55 ophthalmic lenses manufactured by 4 different companies showed somewhat different numbers even though the lenses had the same refractive index and powers. All convex lenses of +3D, +6D were evaluated as the safe lenses since there was no damage such as crack and broken found on the lens surfaces after drop ball testing. However, some noticeable broken was shown on the surfaces of concave lenses with relatively thinner center thickness. Especially, 59(73.8%) of total 80 concave lenses with the refractive power of -3D and -6D classified as unacceptable lenses to FDA standard. Conclusions: From the results, the negligent accident by damaged ophthalmic lenses should be considered as well as the correction of visual acuity, design and price when customers purchase eyeglasses. Thus, the enforcement regulation like drop ball testing of uncut ophthalmic lens could be suggested to guarantee the safety of ophthalmic lenses in domestic market.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.43-48
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• 2008

Purpose: This study is to evaluate reliability of geometrical optics properties of spectacle lenses by using ISO and the medical instrument standard of KFDA, which are being sold in Korea. Methods: We used samples of three hundred and ninety eight spectacle lenses of eight company in total. Refractive indices of each samples which were used in experiment were classified into three groups of medium index (1.55~1.56), high index (1.60~1.61) and extra high index (1.67). Results: Conformity of refractive power was 81.61% in total spectacle lenses. The results showed that thickness conformity 90%, appearance conformity 85.18%, size conformity 96.23% and optical center point conformity 99.50% in total. Conclusions: We found that they deviated from the permitting value in many spectacle lenses on refractive power. The results of errors on prism power, surface inspection and optical center point showed small values in total products. In experiment of lens size and thickness, the bulk of indication rates and conformities of samples deviated from the permitting errors.

• Journal of Korean Ophthalmic Optics Society
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• v.1 no.1
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• pp.73-84
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• 1996

Satisfactory for children's spectacles fitting can only be achieved with the resonable selection and assortment of frames of different pad shapes, size, materials, the general property of sample frame are flexibility for the temple. Loughness for bridge and variety for the length of temple, a selection of the lens is chosen usually by the characteristic of the power, safty, size and so on, it will be comport fit of frame controlled the hight and width of pad and angle of pad between the nose side, frontal angle of pad will be determinded that whether a frame may be capable of providing a comport fit. An important part of the fitting of spectacles is the final adjustment before the wearer takes them away, and also their continued adjustment to maintain the optimum comport and lens efficiency. It is suggested that spectacle adjustment is essentially a practical art that can only be acquired by continual practice.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.2
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• pp.1-12
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• 2007

Object of this research is to estimate the effect of myopia correction and safety on reverse geometry contact lens fitting in school children. This research include 53(106eyes) schoolchildren among 7 to 18 years who has low to moderate myopia(-1.00D~-5.00D) and prescribed reverse geometry contact lens for purpose on orthokeratology between January to July 2004 and had 3months full follow up examination. They were tested for slit lamp examinations, BUT(Break up time), direct ophthalmoscopy, retinoscopy, uncorrected visual acuity, best corrected visual acuity, autorefraction, autokeratometry and corneal topography in each examination(1day, 1week, 2weeks, 1, 2, and 3months) of before-and-after lens wearing to find out the effect of myopic correction and side effect. The results came out as follow. The average of uncorrected visual acuity was $0.0938{\pm}0.378$ before lens wear and $0.3136{\pm}0.283$ after 1day lens wear, and there was fast improvement after 1week($0.7925{\pm}0.301$) and little improvement after 2weeks period but still they shows better uncorrected visual acuity(p<0.01). The result of this study, the reverse geometry lens is very useful to correct refractive error and control the progression of myopia temporally among low to moderate myopic patient. The side effects were relatively rare but further study should be necessary with long term lens wear effect on eye health. For the lens prescription, the clinical fitting process had higher rate of success with consideration of eccentricity and corneal topography.