• Journal of Korean Ophthalmic Optics Society
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• v.18 no.4
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• pp.503-507
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• 2013

Purpose: This study was to design wide angle mobile camera corrected optical distortion for peripheral area, which were reduced optical distortion and TV distortion by using 4 aspherical lenses. Methods: The optical design was satisfied with ${\pm}1%$ optical distortion in viewing angle of $95^{\circ}$ and total length of optical system was less than 4.5 mm which was considering a thickness of mobile camera. 1/3.2 inch (5M) CCD sensor was used in the optical system and set design condition to satisfy MTF which was over than 20% in 140 lp/mm. Results: Optimized wide angle mobile camera showed ${\pm}1%$ optical distortion in full field of $95^{\circ}$ viewing angle and TV distortion was 0.46% so that distortion of peripheral area was reduce. MTF showed over than 20% in every field. Ray aberration and astigmatism were small amount so that it showed stable performance. Conclusions: Obtain wider and clearer view which is reduced image distortion of surrounding area via optical method in wide angle mobile camera which has wider view angle than current mobile camera. And it was able to fix a demerit when it occurred via software correction. It is able to apply to study of camera which is related to spectacles.

• 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.20 no.3
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• pp.333-339
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• 2015

Purpose: The aim of this study was to evaluate clinical characteristics of subjective accommodative lags determined by fused cross-cylinder (subjective method), and an open-field autorefractor (objective method) under uncorrected and corrected conditions. Methods: Thirty three healthy subjects (26 males and 7 females aged $23.73{\pm}1.35$ years from 22 to 27 years) participated. Four methods were used to determine accommodative lag: (1) a subjective method with the fused cross-cylinder (FCC) under +2.00 D fogging lenses condition, (2) an objective method with the autorefractor under uncorrected condition (3) a corrected method (effective accommodative lag) using equations presented by Gwiazda et al. in objective methods, and (4) a corrected method using equations presented by Mutti et al. in objective methods. Results: The mean accommodative lags were 0.72 D for subjective method, 0.82 D for uncorrected objective method, 0.88 D for corrected method with Gwiazda's equations, and 0.78 D for corrected method with Mutti's equations. There were significant differences between the objective accommodative lags, but no significant differences between the objective and subjective accommodative lags. The effective accommodative lags showed significant correlations between phorias and refractive errors. The effective accommodative lag by Mutti's equations had a high correlation with uncorrected accommodative lags (r=0.99, p<0.001). Conclusions: The objective accommodative lag correlated with phorias and refractive errors. Especially, The effective accommodative lag using Mutti's equations may be considered for clinical availability and qualitative evaluation associated with symptoms.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.1
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• pp.27-34
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• 2005

Photochromic lens is the color changing lens from colorlessness to colorness when exposed to UV light. It can protect eyes from UV-B light which cause the cataract and can be used as sunglass in the summer since it can cut off 70~80% of sun light. Surface coating technique was used to develop lens which has 70% light transmittance and of which fading time of color change is within 5 min. Various color lenses were developed so that these had various color such as blue, green, brown, violet, yellow and red etc. Lens has an excellent physical properties, 100% adhesion and 4~5H hardness. The chemical and the scratch resistance of this lens were the greatest and the thermal stability was also higher. The clinical trial of developed lens were applied to 65 patients who had photophobia by various reasons at ophthalmology of Soonchunhyang University Hospital. Results showed that glaring was significantly reduced and the visual health were remarkably improved. Especially, anti-glaring effect in the night was great for the patient who had the LASIK operation. Protection of UV-B and blue light also can prevent the patient from cataract and the yellowish crystalline lens at old ages. Through the result of clinical. trial, we know that photochromic lens could be a new technique for both cure and precaution of photophobia.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.297-304
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• 2013

Purpose: To investigate blue light rejection and the percentage of blue light in the visible light of blue light blocking lens according to light source, and to study prescriptions for blue light blocking lens Methods: UV-VIS spectrophotometer was used for blue light rejection and the percentage of blue light in the visible light according to light source, and the percentage of blue light in solar light was used to evaluate the prescription for blue light blocking lens. Results: The blue light rejection and the percentage of blue light in the visible light of each lens were depending on light sources. Through the way to compare the percentages of blue light in the visible light passing through the lens with that in solar light, blue light blocking lenses suitable to each light source could been selected. Conclusions: In the prescription for blue light blocking lens, inquiry for user's display must be preceded. And then the percentages of blue light in the visible light passing through the lens based on that in solar light may be useful as a method of evaluating the prescription for blue light blocking lens.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.271-277
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• 2013

Purpose: The purpose was to study the corneal refractive power changes associated with the wearing of everted silicone hydrogel soft lenses. Methods: The corneal refractive power and corneal astigmatism were measured using corneal topographer (CT-1000, Shin-nippon Co., Japan) for checking change of corneal refractive power and objective refractive error was measured by auto-refractometer (Natural vision-K 5001, Shin-nippon Co., Japan). We measured at baseline and 1 week after lens wearing. Results: The correcting of corneal refractive power could be effective in low myopia. It's more effective to the higher power of greatest meridian of cornea and the more corneal astigmatism. 73% of subjects' refractive error was decrease less than 1 D and 17% of the subjects had an reverse effect (increase) occurs. The reduction of objective refractive error was more effective when cornea refractive power was great or corneal astigmatism was much. Conclusions: Pressure which the everted silicone hydrogel lens to the cornea could be caused. It occurred as the degrees of corneal power, corneal astigmatism and objective refractive error differences. Selection of an appropriate subject is important considering difficulty of changing the parameters of the lens.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.4
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• pp.487-492
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• 2014

Purpose: This study relates to the development of the 3X scope, whose objective part is configured with a doublet + a meniscus lens. Methods: By the initial condition of the objective part having a configuration of a doublet + a singlet, we could optimize the optical system of scope in order to minimize the finite ray aberrations of the objective part and the whole optical system of scope, and so we could develope a new type 3X scope. Results: On the condition of the objective part having a configuration of a doublet + a singlet, when the optical system of scope was optimized in order to minimize the finite ray aberrations, we could find that the singlet became the meniscus type lens having the concave shape to the direction of the doublet, and the longer the distance between the doublet and the meniscus lens is, the more the finite ray aberrations are minimized. Conclusions: In this study, we could develope a new type 3X scope of which finite ray aberrations can be reduced to 1/14 than the existing scope by adopting the objective part of the 3X scope having a configuration of three lenses composed of a doublet + a singlet. We could confirm that this reduction of aberrations can be a means to increase the effective aperture than the existing scope and to shorten the length of the optical system.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.445-454
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• 2015

Purpose: The present study was aimed to investigate the effect of tear volume on a change of axial rotation according to wearing time of toric soft contact lens and gaze directions. Method: Toric soft contact lenses with double thin zone design applied on 62 eyes. Then, changes in non invasive tear film break-up time and the rotational direction/amount of lens when changing gaze direction were respectively measured after 15 minutes and 6 hours of lens wear. Results: Lens rotation to temporal direction was more found when changing gaze direction after lens wear. However, its rotation was varied according to wearing time and the subjects' tear volume. Furthermore, the frequency of lens rotation to temporal direction was higher in dry eyes compared with normal eyes at nearly all gaze directions after 15 minutes and 6 hour of lens wear. The rotational amount of lens was generally greater in dry eyes after 15 minutes of lens wear. However, its difference between normal eyes and dry eyes was not great after 6 hours of lens wear. Conclusion: The present study revealed that axial rotation of toric soft contact lens was varied according to the wearer's tear volume and lens rotational patterns at the initial, and extending periods of lens wear were different. The change in rotational pattern of toric soft contact lens from these results means the possibility of visual change after extending lens wear, and the identification of its correlation with tear volume suggests the necessity of considering factors for choosing appropriate toric soft contact lens.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.3
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• pp.17-27
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• 2009

Purpose: This review article was written to determine the effects of parameters characterizing a hard contact lens (RGP included), such as BCs, diameters, edge angles, on the time interval for tight fitted lens to return to the equilibrium when it was decentered from blinking. Methods: A mathematical formulation was established to relate or calculate the restoring forces and thickness of lacrimal layer beneath the cornea with the various lens parameters when the tight fitted lens was decentered from blinking. Based on this formulation the differential equations and their numerical solution program were set up to describe the time dependence of the lens on the position and to estimate the time for the lens's return to the equilibrium after blink. Results: It is found that the time interval for the tight fitted lens to return to the equilibrium decreases as either the BC decreases or the diameter increases because both the reduction in BC and increase in diameter result in the increase in the lacrimal layer thickness between the lens and cornea increase which yielded the lowering of the viscous friction in the lens motion. As the edge angle of tight fitted lens increases the time for recentering decreases due to the increase in restoring force without change in lacrimal thickness beneath the lens. In the case of flat fitted hard lens (RGP included), the lacrimal layer thickness under the lens increases as either BC or diameter increases which results in reduction in viscous friction so that the time for the lens's return to the equilibrium were to decrease. The edge angle of flat fitted lens does not affect the lens motion. Conclusions: The effect of BCs on the lens motion (time to approach the equilibrium) was concluded to be significant with both tight and flat fitted lens where its results are contrary with each other. The edge angle of lens only affects the motion in tight fitted lenses.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.65-71
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• 2008

Purpose: This paper studied the effect of eyes on the comparison between the distance optical centers problem of dispensing reading glasses made by optician and finished reading glasses in the current market. Methods: The method of this study has been measured by eleven different categories from +1.00D to +4.00D. This study also separated into three groups by their optical frame size and measured optical center point (O.C) and optical center height (O.H) with 200 peoples of man and females over 40 years old without ocular disease living in Gwang-san gu, Gwang-Ju city. Results: As a result, optical center point ranged from 57 mm to 80 mm and it turned to be most common range is from 61 mm to 65 mm (64.6%). Moreover, the optical center height ranged from 1 mm to 8mm and most common ranged (23%) were 4 mm. In other words, finished reading glasses have irregular optical ranges. After observing 200 people who are over 40 years old men and women, result shows that more than 75.5% (151 people) currently use finished reading glasses. Survey of 151 people, most common error between the finished reading glasses's O.C and the wearers P.D were 4 mm (45%). Furthermore, the most common error between the finished reading glassses's O.H and the wearers O.H ranged from 3 mm to 4 mm. Astonishingly, the entire 151 people who wear finished reading glasses appeal that they feel tiredness on their eyes when they wear finished reading glasses. 53 people (35%) claimed that they feel tiredness on their eyes after 10 to 20 minutes wearing finished reading glasses. Base on the research, We conducted more experiment to find the value of prism of optical centers err because it will tell us whether the finished reading glasses are good enough to wear or not. We multiplied diopter by the difference between finished reading glasses's O.C. and wearer's P.D. Consequently, We found out that the finished reading glasses counter to the German RAL-RG 915 policy. And We also found that it is relative to the diopter of lenses. In conclusion, based on the researched that wearing finished reading glasses have a dangerous factor for our vision. Therefore optician must need to recommend correctly made dispensing reading glasses based on the optical center point.