• Journal of The Korean Ophthalmological Society
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• v.59 no.12
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• pp.1122-1128
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• 2018

Purpose: To compare the measurements of the rebound tonometer (RT), Goldmann applanation tonometer (GAT) and noncontact tonometer (NCT) in patients who underwent penetrating keratoplasty (PKP), and to evaluate the reproducibility of the RT measurements. Methods: This study included 19 PKP eyes and 28 normal eyes. We compared the intraocular pressure (IOP) measurements of the GAT and NCT with the RT in both groups using Spearman's correlation analysis and the Wilcoxon signed-rank test. The IOP, as measured with an RT in each group, was assessed with respect to reproducibility using the intraclass correlation coefficient (ICC). Results: In normal eyes, there was no significant difference in the measurements obtained with the RT, GAT, and NCT (p > 0.050). In the patient group, the RT measurements were not significantly different from those of the GAT (p = 0.872), but they were significantly lower than those obtained with the NCT (p = 0.011). However, the RT measurements showed a relatively high correlation with those of the GAT and NCT (r = 0.770 and 0.879, respectively). The ICC of the RT was 0.986 for the PKP eye group and 0.961 for the normal eye group, both of which were highly reproducible. Conclusions: In PKP eyes, the measurements obtained with the RT showed a relatively high correlation with those of the GAT and NCT, and the repeatability of the RT measurements was high and similar to those for normal eyes. The RT can therefore be considered a useful method for measuring the IOP in PKP eyes.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.9
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• pp.17-22
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• 2007

• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.589-596
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• 2018

Purpose : We compared intraocular pressure (IOP) values measured by two types of tonometers in condition of normotensive and glaucomatous rat model. We tried to determine which of tonometer can more easily and accurately measure the IOP of animal model. Methods : Glaucomatous eyes were induced by intracameral injections of hyaluronic acid in right eyes of six-week-old male Spargue-Dawley (SD) rats. Normotensive contralateral eyes were left eyes of the SD rats. IOP was measured using a rebound tonometer (Tonolab) and a immersive tonometer ($Tonopen^{(R)}$ XL) about 3:00 pm. Results : The mean IOP values of normotensive control eyes were $10.80{\pm}1.03mmHg$ by Tonopen, and $15.10{\pm}0.73mmHg$ by Tonolab. They were statistically insignificant (p = .1). The mean IOP values of glaucomatous experimental eyes were $30.20{\pm}2.67mmHg$ by Tonopen, and $37.90{\pm}2.73mmHg$ by Tonolab. They were statistically insignificant (p = .95). High IOP values of glaucomatous eyes by two types of tonometers had strong positive correlation each other (r = .904, p < .01). Conclusion : This is the first study to compare IOP values using two types of tonometers between normotensive and glaucomatous model made by intracameral injection of hyaluronic acid. Tonopen should be used carefully when the IOP is within normal range, and both Tonopen and Tonolab can be used reliably when the IOP is high.

• Journal of Yeungnam Medical Science
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• v.11 no.2
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• pp.277-283
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• 1994

We studied the change in intraocular pressure (IOP) in 15 consecutive cataract patients who underwent extracapsular cataract extraction and posterior chamber lens implantation between Feb. 1993 and Apr. 1993 to evaluate the effect of this surgery on postoperative IOP. To evaluate the clinical usefulness of non-contact tonometer, the intraocular pressures were measured with Kowa non-contact tonometer (TM-2000, Japan) as well as Goldmann applanation tonometer. There was a decrease in IOP of $3.4{\pm}2.9$mmHg (p<0.00l) 3 months after this surgery and the intraocular pressure differences between pseudophakic eyes and contralateral phakic eyes at 3 months postoperatively were $2.4{\pm}3.8$mmHg (p<0.05). The correlation coefficient between non-contact tonometer and Goldmann tonometer was 0.8876 (p=0.001) in the postoperative 76 eyes. Therefore, our results suggest that extracapsular cataract extracion and posterior chamber lens implantation alone can be a useful surgical method in cataract patient with ocular hypertension, and non-contact tonometer was relatively accurate in measuring the postoperative intraocular pressure.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.131-135
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• 2008

Purpose: To measure and quantify the factors of intraocular pressure (IOP) variation for normal Korean youth. Methods: The IOP of normal youth 805 persons (male: 367, female: 438) were measured as a function of time and quantity for fixation, reclining posture, hard blinking, drinking water, drinking hard liquor, tobacco and coffee by using non-contact tonometer (AT555, Reichert Co.). In the case of fixation, reclining posture and hard blinking, the intraocular pressure of right and left eye were measured for 6 males and 6 females every 10 minutes during 30 minute. In the case of water, liquor, tobacco and coffee, the measurement for 4 or 5 groups (6 persons/ group) having similar IOP were done for the IOP variation of right eye. Results: The mean IOP was 15.2 mmHg for males and 15.8 mmHg for females (slightly higher than male's), respectively and the 99% of those were in the range of the normal IOP. The measured IOP was increased by fixation, reclining posture and hard blinking with males and females. The gradient of increasing slope was 0.15/0.13/0.07/0.08, 0.09/0.08/0.08/0.08 and 0.19/0.08/0.26/0.31, respectively. The IOP variation was elevated by drinking water (especially in the case of 1000 ml) and lowered in proportion to the amount of drinking by hard liquor. Cigarette smoking was associated with rise in intra ocular pressure, but was not shown a definite relation. And coffee had virtually no effect. Conclusions: Fixation, reclining posture, hard blinking and Tobacco caused a transient increase in IOP, but alcohol elicited a slight reduction in IOP overall.

• Journal of the Korea Convergence Society
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• v.11 no.8
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• pp.317-321
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• 2020

This study researched the correlation between myopic refractive errors and intraocular pressure. The study population comprised 39 adults(17 of males, 22 of females). We measured the intraocular pressure using a Non-Contact Tonometer(NCT) and the correlation between myopic refractive errors was analyzed by dividing into three groups: mild, moderate, high myopia. The gender of subjects showed no statistically difference between the intraocular pressure and refractive errors, but as the refractive errors increased, the intraocular pressure incereased, which showed a statistically significant difference. In addition, the higher intraocular pressure in moderate and high myopia than mild myopia can cause glaucoma, that can develop at a young age. it is need to sufficient recognition and understanding correlation between intraocular pressure and myopic refractive errors in the middle-aged high myopia.

• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.543-551
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• 2018

Purpose : The purposes of this study were to evaluate the changes of intraocular pressure according to corneal ablation amount after corneal refractive surgery and the changes of intraocular pressure according to refractive errors before corneal refractive surgery. Methods : The mean age of adults who underwent LASIK corneal refractive surgery were $37.34{\pm}7.42years$, and 108 adults(48 males, 60 females) were participated in this study. Refractive errors, intraocular pressure, and corneal ablation amount were measured using an autorefractor, a noncontact tonometer, and an excimer laser. All test values were considered statistically significant when p<0.05. Results : The mean intraocular pressure before corneal refractive surgery was $15.08{\pm}2.60mmHg$ in males and $14.16{\pm}2.67mmHg$ in females. The decrease of intraocular pressure after corneal refractive surgery were 4.22mmHg in males and 3.61mmHg in females. Spherical equivalent power were $-3.89{\pm}2.17D$ in males and $-4.45{\pm}2.92D$ in females before corneal refractive surgery, and $-0.10{\pm}0.46D$ in males and $-0.04{\pm}0.46D$ in females after corneal refractive surgery. The corneal ablation amount after corneal refractive surgery were statistically significant, with $53.95{\mu}m$ in males and $61.26{\mu}m$ in females. There was significant correlation between corneal ablation amount and decrease of intaocluar pressure(r=0.2299, p<0.001). As the growth of corneal ablation amount in males, the decrease of intraocular pressure was significantly increased. As the growth of refractive error, the amount of decrease in intraocular pressure was also significant. The decrease of intraocualr pressure were $3.04{\pm}2.18mmHg$ in low refractive error, $4.10{\pm}2.16mmHg$ in middle refractive error, and $4.65{\pm}3.29mmHg$ in high refractive error. Conclusion : We found that intraocular pressure decreased after corneal refractive surgery by noncontact tonometer and the change of intraocular pressure which is an important index for glaucoma diagnosis, may affect the judgment of eye disease. We think that a preliminary questionnaire whether corneal refractive surgery is necessary for the measurement of intraocular pressure.

• Journal of Veterinary Clinics
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• v.30 no.2
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• pp.95-99
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• 2013

This study was performed to evaluate the seasonal variation of intraocular pressure (IOP) values in normal Sapsaree dogs. Sapsaree dogs (n = 474) clinically free from ophthalmic disease were included in this study, and both eyes were examined in each dog. An applanation tonometer (Tonopen$^{(R)}$ XL) was used to measure IOP values in both eyes. Data obtained from both eyes were stratified by factors thought to affect IOP values including age, gender, hair coat type as well as season of measurement. The IOP results were compared by ANCOVA to verify the effect each factor had on IOP, and an ANOVA test followed by a Bonferroni post hoc test was used for further analysis. The overall mean ${\pm}$ SD IOP value was $19.1{\pm}3.7$ mmHg (range: 8 to 28 mmHg) in the present study. Only seasonal variation showed a significant effect (P < 0.001), on IOP values. IOP values measured in winter ($20.4{\pm}3.4$ mmHg) and summer ($17.1{\pm}3.6$ mmHg) were significantly higher and lower, respectively, than those measured in other seasons. These results suggest a seasonal variation has a significant effect on the IOP of normal dogs. This may prompt further research and possible modification of current veterinary ophthalmic references.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.41-45
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• 2003

The researchers have studied on the effect of three main morphological types(nuclear, cortical, and subcapsular cataract) of age related cataract on refractive error. We also identified that spherical and cylinderical shift in each type of morphological cataract accoding to their locations and effect of intraocular pressure before and after cataract surgery. Nuclear cataract showed myopic shift while cortical cataract showed hyperopic shift, and subcapsular cataract showed not significant changes on both direction. Age related cataract subjects(120 eyes) only were recruited from sun-cheon area. We use optic section of slit lamp biomicroscope to identify the anatomical location of cataract, and optimal refractive correction determined by objective(retinoscope) and subjective refraction then spherical changes were calculated from the spherical eqivalent value. Intra-ocular pressure were measured by auto-tonometer before and 7 days after cataract has been replaced by IOL. The change in cylindrical power, usually A-P diameter decreased according to increases of age, A-P diameter increased because intra-ocular pressure rises by progression of cataract and this convertion with the rule astigmatism to against the rule astigmatism and this increases more by intra-ocular pressure.

• Journal of IKEEE
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• v.18 no.2
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• pp.240-247
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• 2014

Intraocular pressure is measured after a cornea air puff by observing biomechanical properties such as thickness or displacement of the cornea. In this paper, we deal with a frequency domain analysis of corneal deformation in the air puff tonometry that is used to diagnose glaucoma or lasik. We distinguish the patient from the normal by measuring the oscillation frequency in the neighborhood of the central cornea section. A binary image was obtained from the video images, and cornea vertical oscillation profile was extracted from the difference between the vertical displacement data and the curve fitting. In terms of Fourier transform, a vibration frequency of 479.2Hz for the patient was obtained as well as more higher 702.8Hz for the normal due to stiffness. Hilbert-Huang transform's empirical mode decomposition generally describes local, nonlinear, and nonstationary data. After the data were decomposed into intrinsic mode functions, a spectrum and power were analysed. Finally, we confirm that the patient has 6 times more higher power ratio for the specific intrinsic mode function between the patient and the normal.