• Journal of Yeungnam Medical Science
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• v.17 no.1
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• pp.55-65
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• 2000

Purpose: To compare the efficacy, predictability, stability and safety of excimer laser photorefracive keratectomy(PRK) for myopia and photoastigmatic refractive keratectomy(PARK) for compound myopic astigmatism. Methods: Two-hundred and three eyes(l18 eyes < -7D spherical equivalent, 85 eyes ${\geq}$ -7D spherical equivalent) received excimer laser correction for compound myopic astigmatism and 152 eyes(116 eyes < -7D, 36 eyes ${\geq}$ -7D) for simple myopia. A VISX 20/20B $VisionKey^{TM}$ excimer laser was used to perform either PARK or PRK. Visual acuity with and without correction, refraction, IOP, corneal haze, and topography were evaluated at 1, 3, 6, and 12 months postoperatively. All patients were followed up for more than 12 months. Results: Postoperative refraction were generally stable after 3 months without significant early overcorrection. At 12 months, 110(94.8%) eyes that underwent PRK and 104(88.1%) eyes that underwent PARK achieved UCVA of 20/30 or better in the group who had lower than -7D correction. For eyes treated with -7D or more, these figures were 31(86.1%) eyes after PRK and 57(67.1%) eyes after PARK. The incidences of within 1D of plano refraction at 1 year follow-up were 97.4% after PRK and 93.2% after PARK in the group who had lower than -7D correction. For eyes treated with -7D or more, these figures were 80.6% after PRK and 70.6% after PARK. Conclusions Myopia with or without astigmatism was successfully treated in most of the eyes using PRK or PARK with VISX 20/20B $VisionKey^{TM}$ excimer laser. The predictability and stability of the postoperative refraction during the first 12 months seem to be quite reliable. Further improvement of excimer laser system and software should increase the clinical outcomes and safety of refractive procedures.

• Journal of Veterinary Clinics
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• v.22 no.1
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• pp.16-20
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• 2005

The purpose of this study was to compare the antiangiogenic effects of As₄O/sub 6/ to those of As₂O₃ on the rat corneal micropocket model induced by VEGF. 20 ng VEGF impregnated pellets were used for angiogenic inducer on the rat cornea micropocket assay in this study. After ophthalmoscopic examination, Sprague-Dawley rats with normal cornea were implanted VEGF pellet. Total 60 eyes were used in this study. Control group only received VEGF pellet, As₂O₃ group followed oral administration of As₂O₃ at a dose of 50 mg/kg per day after VEGF pellet implantation and As₄O/sub 6/ group followed oral administration of As₄O/sub 6/ at a dose of 50 mg/kg per day after VEGF pellet implantation were classified. The eyes were examined under a surgical microscope daily on postoperative from day 3 to day 9 after pellet implantation. The number, length, clock hour of vascularization, and area of vessels in As₄O/sub 6/ group were significantly less evident than those of control group and As₂O₃ group (P < 0.05). In conclusion, As₄O/sub 6/ had better antiangiogenic effects on the new vessel induced by VEGF in the rat cornea.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.247-253
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• 2015

Purpose: The purpose of this study was to compare and analyze the ocular surface and the palpebral conjunctiva of categorized subjects, which were divided into normal eye group and dry eye group, by using a thermal camera. Methods: Subjects were 144 eyes of 72 normal university students, who didn't have any corneal disease, abnormal lacrimal ducts, medical records regarding ocular surgeries, or experience of using contact lens. Subjects were divided into two groups, which were normal eye group and dry eye group, based on the results of TBUT, Schirmer I test, and McMonnies test. After categorizing the subjects, the temperature of the subjects' ocular surface and the palpebral conjunctiva were measured and analyzed by using a thermal camera (Cox CX series, Answer co., Korea). Results: In the normal eye group's Central Ar.1, Nasal Ar.2, Temporal Ar.3, Superior Ar.4, Inferior Ar.5, the measured amount of temperature change on each area was $-0.13{\pm}0.08$, $-0.14{\pm}0.08$, $-0.12{\pm}0.08$, $-0.14{\pm}0.08$, $-0.10{\pm}0.09(^{\circ}C/sec)$. The dry eye group's results were $-0.17{\pm}0.08$, $-0.16{\pm}0.07$, $-0.16{\pm}0.08$, $-0.17{\pm}0.09$, $-0.15{\pm}0.08(^{\circ}C/sec)$. When compared with the normal eye group, the values of Ar.1, Ar.3, Ar.5 were significantly different in the dry eye group(p<0.05). The amount of temperature change, which was observed on the palpebral conjunctiva(Ar.1:central, Ar.2: nasal, Ar.3: temporal) of the normal eyes, measured by thermography, was $34.36{\pm}1.12$, $34.17{\pm}1.10$, $34.07{\pm}1.12^{\circ}C$ on each area. Same values taken from the dry eye group was $33.55{\pm}0.94$, $33.43{\pm}0.97$, $33.51{\pm}1.06^{\circ}C$ on each area. The values of Ar.1, taken from the dry eye group, had a significant difference, compared to the values of the normal eye group(p=0.05). Conclusion: The temperature of the ocular surface decreased faster on the dry eyes, compared to the normal eyes. The temperature measured on the palpebral conjunctiva of the dry eyes were also lower than the normal eyes. The temperature changes on the ocular surface, observed with a thermal camera, were objective values to assess the stability of tear films, and might provide useful data for studies related to dry eye syndrome.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.51-58
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• 2008

Purpose: This study was assessed to investigate adverse effect induced by overuse of disposable soft contact lenses (CL). Methods: Three disposable lenses (etafilcon A, hilabilcon A, and nelfilcon A) were applied to 19 normal subjects free from any eye diseases for either a single day or variable periods by when subjects complained any discomforts. On the first and last days, localizations of lens' center on corneal surface and blink rates were recorded at every case. Results: Among CL wearers, 10.5% and 47.4% of total subjects quit wearing on the second day and third day, respectively. The case of stopping disposable lens wear was continuously increased with extended hour of lens application. On fourth day, 70.2% of CL wearers reported severe discomforts such as redness, dryness, irritation, pain and blurred vision. When subjects stopped CL wear, decentration of lens from the center of cornea was observed when it compared to the case of single usage of disposable CL. Also about 80% of total subjects showed increased blink rate when CL were worn for more than 2 days. These changes in lens centration and blink rate were consistantly shown regardless of lens types. Conclusions: Blurred vision and acute/chronic discomforts could occur to CL wearers by decentration of lens and increased blink rate when CL were overused more than 2 days even the numbers of two parameters measured in this study were variable by each subject or lens types. Therefore, consideration of individual characteristics and lens types is critical to prevent adverse effects may induced by overusage of disposable lens.

• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.497-504
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• 2018

Purpose : The purpose of this study was to investigate the temperature changes of the ocular surface before and after cataract surgery using thermography of a thermal imaging camera. Methods : The study included 75 patients (75 eyes) aged from 50 to 79 years who underwent cataract surgery. In the past, those who underwent corneal-related surgery, wearing contact lens, disorder of tear secretion and taking medication for systemic disease were excluded from this study. The temperature changes of the eyeball surface were measured using a thermal imager (Cox CX series, Answer, Korea) following Tear Break Up Time (TBUT) test, Mcmonnies questionnaire and Schirmer's Test in real time, Results : While the temperature of preoperative ocular surface was $35.20{\pm}0.54^{\circ}C$ and that of postoperative temperature was $35.30{\pm}0.53^{\circ}C$, the difference was not significant. The temperature changes in the ocular surface were statistically significant at $-0.12{\pm}0.08{\Delta}$ ($^{\circ}C/sec$) before the surgery and $-0.18{\pm}0.07{\Delta}$ ($^{\circ}C/sec$) after the surgery. In comparison of the age groups, it was shown that the changes in the surface temperature before the surgery were from $-0.19{\pm}0.05{\Delta}$ ($^{\circ}C/sec$) to $-0.14{\pm}0.09{\Delta}$ ($^{\circ}C/sec$) in the 50s group, and from $-0.12{\pm}0.08{\Delta}$ ($^{\circ}C/sec$) to $-0.15{\pm}0.07{\Delta}$ ($^{\circ}C/sec$) in 60s group, and $-0.18{\pm}0.07{\Delta}$ ($^{\circ}C$) to $-0.12{\pm}0.08{\Delta}/sec$) in the 70s group, showing significant changes in the ocular surface temperature at all ages. Conclusion : Following the cataract surgery, all the indicators of dry eye syndrome were decreased, and eye surface temperature changes were significant. The thermography technique of the ocular surface would be expected to be useful for the evaluation of various dry eye syndromes because it is easy to evaluate dry eye syndrome noninvasively and can be quantified.

• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.443-451
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• 2018

Purpose : To find out the reliability of autorefractometer after laser refractive surgery Methods : We measured and compared spherical and cylinder powers of those undergone LASEK surgery with 1.0 of naked vision after at least 3 months of the surgery with an autorefractometer(CANON Full Auto Ref-Keratometer RK-F1, Japan) and a retinoscope(Streak Retinoscope 18200, WelchAllyn, USA), and also applied spherical equivalent powers. The refractive status before surgery was divided into high, medium, and low myopia according to the results measured using an autorefractometer, and then analyzed again the reliability of the autorefractometer after surgery according to the preoperative refractive status. The agreement of two methods was identified using Bland-Altman(Bland-Altman limits of agreement(LoA)). Results : After the surgery, when comparing spherical, cylinder and equivalent powers in the whole data measured by autorefractometry and retinoscopy significant differences were found(p<0.01). According to the degree of refractive errors, all sort of refractive errors was shown significantly different(p<0.01) except for cylinder power of the medium myopia. In general, the refractive errors especially spherical and spherical equivalent powers by autorefractometry were shown a myopic trend from -0.38 D to -0.53 D. On the other hand, it was shown a hyperopic trend of approximately +0.30 D using retinoscopy. In comparison of two objective refractions, it was shown a myopic trend as $-0.51{\pm}0.45D$(LoA +0.36 D ~ -1.39 D) and compatible. Conclusion : Even though it would be positive in terms of compatibility of the methods, it is necessary that the glasses should be prescribed by subjective refraction since autorefractometry is shown myopic in those undergone the surgery and suffering from myopic regression.

• Journal of Preventive Medicine and Public Health
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• v.25 no.3 s.39
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• pp.247-268
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• 1992

This study was conducted to evaluate the effect of VDT work on eyes and vision among workers in a TV manufacturing plant. The study subjects consisted of 264 screen workers and 74 non-screen workers who were less than 40 years old male and had no history of opthalmic diseases such as corneal opacities, trauma, keratitis, etc and whose visual acuity on pre-employment health examination by Han's test chart was 1.0 or above. The screen workers were divided into two groups by actual time for screen work in a day : Group I, 60 workers, lesser than 4 hours a day and group II, 204 workers, more than 4 hours a day. From July to October 1992 a questionnaire was administered to all the study subjects for the general charateristics and subjective eye symptoms after which the opthalmologic tests such as visual acuity, spherical equivalent, lacrimal function, ocular pressure, slit lamp test, fundoscopy were conducted by one opthalmologist. The proportion of workers whose present visual acuity was decreased more than 0.15 in comparison with that on the pre-employment health examination by Han's test chart was 20.6% in Group II. 15.0% in Group I and 14.9% in non-screen workers. However, the differences in proportion were not statistically significant. The proportion of workers with decreased visual acuity was not associated with the age, working duration, use of magnifying glass and type of shift work (independent variables) in all of the three groups. However, screen workers working under poor illumination had a higher proportion of persons with decreased visual acuity than those working under adequate illumination (P<0.05) . The proportion of workers whose near vision was decreased was 27.5% in Group II, 18.3% in Group I, and 28.4% in non-screen workers and these differences in proportion were not statistically significant. Changes of near vision were not associated with 4 independent variables in all of the three groups. Six out of seven subjective eye symptoms except tearing were more common in Group I than in non-screen workers and more common in Group II than in Group I (P<0.01). Mean of the total scores for seven subjective symptoms of each worker(2 points for always, 1 point for sometimes, 0 point for never) was not significantly different between workers with decreased visual acuity and workers with no vision change. However, mean of the total scores for Group II was higher than those for the Group I and non-screen workers (P<0.01). Total eye symptom scores were significantly correlated with the grade of screen work, use of magnifying glass, and type of shift work. There was no independent variable which was correlated with the difference in visual acuity between the pre-employment health examination and the present state, the difference between far and near visions, lacrimal function, ocular pressure, and spherical equivalent. Multiple linear regression analysis for the subjective eye symptom scores revealed a positive linear relationship with actual time for screen work and shift work(P<0.01). In this study it was not observed that the VDT work decreased visual acuity but it induces subjective eye symptoms such as eye fatigue, blurred vision, ocular discomfort, etc. Maintenance of adequate illumination in the work place and control of excessive VDT work are recommended to prevent such eye symptoms.