• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.189-199
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• 1998

The system for optical tolerances of completion spectacles was made to sum of the accumulated error - the circumstances on composing prescription, the visual-distance, the tilting angle, the losing of a temple, the vertex distance, the axis of toric lens and the sloping of lens etc. It was given by the relation of allowed values size(T) and power(D), $T=T_0e^{-aD}$. Here, $T_0$ is the size of allowed values of plane-lens with power is 0 and ${\alpha}$ is the factor of allowed values. In case of being adopted to new form s tolerance corresponding to RAL 915, for the tolerance is large direction, the factor of allowed values ${\alpha}$ is $0.166(T_0=5.90)$ and for the tolerance is small direction, the factor of allowed values ${\alpha}$ is $0.166(T_0=2.95)$.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.213-217
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• 2010

Purpose: To emphasize the necessity of post-fitting by follow-up test, the mis-alignment was analyzed after initial wearing of toric soft contact lenses (TSCL). Methods: After trial contact lenses were worn to 87 eyes with myopic astigmatism for 1 week, we observed the alignment of axis mark on trial contact lenses using slit lamp and corrected the rotated axis by method of LARS. After final fitting, rotation ratio, rotation degree and rotation position were analyzed compared to initial prescription divided to amount of cylinderical and spherical powers. Results: Rotation ratio of TSCL's axis was increased as increment of both cylinderical powers and (-)spherical powers. An average of rotation degree was $10^{\circ}{\sim}13^{\circ}$ which was not related to amount of their powers. Rotation position of TSCL's axis was more to temporal than to nasal. Conclusions: Because mis-alignment of axis after TSCL wearing induce the poor sight, adjustment of axial alignment as a result of follow-up must be performed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.04a
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• pp.1-6
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• 2003

In injection molding of an optical disk, a toric lens, etc., their performance depends on the transcription preciseness of fine surface structure of a mold. However, transcription behavior has not been made clear yet, because transcription is made in very short time and the structure is very small. In this paper, transcription properties have been examined, by using V-grooves of various sizes. machined on mold surfaces, and the following results are obtained. (1) Transcription properties have been made clear experimentally and it was found that the mold temperature $T_D$ makes great influence on the transcription property and that compression applying time $t_c$ should be taken more than 2.0s for fine transcription. (2) A mechanical model of transcription process, in consideration with strain recovery due to viscoelastic property of polymer. is proposed. (3) Simulation results agree with experimental ones fairly well. It means that the transcription model is useful for estimation of transcription property in advance of an actual. injection molding.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.143-148
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• 2013

Purpose: The aim of this study was to investigate the distribution of age and gender, types of intraocular lens (IOL), and refractive errors in subjects who had cataract surgery. Methods: 2,217 subjects who had cataract surgery were surveyed at an optometry clinic in Chungbuk from 2010 to 2012. Information about IOL was obtained from case history, reflective and retroillumination images IOL by auto refracto-keratometer. Refractive errors were determined by objective and subjective refraction. Results: The mean age of the subjects was $71.74{\pm}10.62$ years. The number of cataract surgeries increased from 524 persons in 2010 to 888 persons in 2012. Of the subjects surveyed, 52 persons (2.3%) were under the 40 years of age, 144 persons (6.5%) were in 50s, 404 persons (18.2%) were in 60s, 1,132 persons (51.1%) were in 70s, 485 persons (21.9%) were in above 80s. Cataract surgery was significantly prevalent in more female (1,338 persons, 60.4%) than in male (879 persons, 39.6%). Types of IOL were 2,141 persons (96.6%) for monofocal lens, special IOLs such as multifocal, accommodative and toric lens were 76 persons (3.4%). The distribution of refractive errors after cataract operation were 1,588 eyes (38.5%) for simple myopic astigmatism, 327 eyes (7.9%) for simple hyperopic astigmatism, 601 eyes (14.6%) for mixed astigmatism, 1,240 eyes (30.0%) for myopia, 136 eyes (3.3%) for hyperopia, and 234 eyes (5.7%) for emmetropia. The uncorrected and best corrected visual acuity of the subjects were $0.55{\pm}0.25$ and $0.80{\pm}0.23$, respectively. Conclusions: The prevalence of cataract surgery increased with age until 70s years of age, it was more prevalent in men than women over 60s, and frequency of special types of IOL were low. Most cataract surgeries left residual refractive errors. Therefore even after cataract surgery it may need spectacles for better vision at either distance or near.