Comparison of refractive outcomes using five devices for the assessment of preoperative corneal power

Whang, Woong‐,Joo,Byun, Yong‐,Soo,Joo, Choun‐,Ki Blackwell Publishing Asia 2012 Clinical & experimental ophthalmology Vol.40 No.5

<P><B>A<SMALL>bstract</SMALL></B></P><P><B>Background: </B> To compare keratometric values obtained with a manual keratometer (Topcon), an automated keratometer (Canon), an Orbscan II (Bausch & Lomb), the IOLMaster keratometer (Carl‐Zeiss) and the Pentacam rotating Scheimpflug camera (Oculus) in cataract surgery, and to characterize the refractive outcomes generated using each device.</P><P><B>Design: </B> Retrospective study conducted at a tertiary university hospital.</P><P><B>Participants: </B> Sixty‐nine eyes of 69 patients were analysed.</P><P><B>Methods: </B> The keratometric values obtained with different devices (manual keratometer, automated keratometer, corneal topography, IOLMaster keratometer and Scheimpflug camera) were employed for intraocular lens power calculation. Multiple comparisons of averaged keratometric value were conducted, and the averaged keratometric value was used to calculate the predicted refraction. The absolute values of corneal astigmatism were calculated and also compared.</P><P><B>Main Outcome Measures: </B> Mean keratometric value, absolute value of astigmatism, mean error and mean absolute error from each device.</P><P><B>Results: </B> The mean keratometric values generated by manual keratometer, automated keratometry, corneal topography, IOLMaster keratometer and the Pentacam Scheimpflug system were 43.95 ± 1.39, 43.91 ± 1.39, 44.67 ± 1.53, 44.03 ± 1.41 and 42.96 ± 1.39 diopter, respectively. The absolute value of astigmatism determined via manual keratometer, automated keratometer, corneal topography, IOLMaster keratometer and the Pentacam Scheimpflug system were 0.95 ± 0.60, 0.99 ± 0.69, 1.14 ± 0.74, 1.11 ± 0.65 and 1.03 ± 0.73 diopter, respectively. The corneal topography showed statistically significant differences with other devices and produced the greater value in mean absolute errors (all <I>P</I> < 0.05).</P><P><B>Conclusion: </B> Keratometric values with standard devices are a good choice for cataract surgery, whereas the corneal topography is not an appropriate method for the assessment of preoperative keratometric values.</P>

Comparison of postoperative refractive outcomes: IOLMaster? versus immersion ultrasound.

Whang, Woong-Joo,Jung, Byung-Ju,Oh, Tae-Hoon,Byun, Yong-Soo,Joo, Choun-Ki Slack 2012 Ophthalmic surgery, lasers & imaging Vol.43 No.6

<P>To compare the postoperative refractive outcomes between IOLMaster biometry (Carl Zeiss Meditec, Inc., Dublin, CA) and immersion ultrasound biometry for axial length measurements.</P>

Zernike 다항식을 통한 수차와 콘택트렌즈

황웅주(Woong-Joo Whang) 대한검안학회 2021 Annals of optometry and contact lens Vol.20 No.2

Aberration refers to a phase difference in light caused by a variation in the refractive power. Zernike polynomials, the most widely used method for analyzing aberrations in the human eye, consist of various polynomials configured according to the radial order and angular frequency. Among them, aberrations with an angular frequency of zero are suppressed by pupil and retinal sensitivity. Contact lenses for correcting presbyopia have mechanisms that induce vertical coma or spherical aberration. Positive spherical aberration is induced after wearing Ortho-k lenses.

백내장 수술 시 3가지 각막 곡률 검사기의 비교

황웅주(Woong-Joo Whang),주천기(Choun-Ki Joo) 대한검안학회 2012 Annals of optometry and contact lens Vol.11 No.1

목적: 수동 각막 곡률 검사기와 IOLMaster 자동 각막 곡률 검사기, Pentacam을 통해 측정된 각막 곡률값을 비교하고, 백내장 수술 시에 효용성이 있는 기구를 찾고자 하였다. 대상과 방법: 백내장 수술을 시행한 71안(71명)을 대상으로, 술 전 수동 각막 곡률 검사기와 IOLMaster, Pentacam (true net power)을 통해 각막 곡률을 측정하고, 비교하였다. 술 후 3개월에 굴절값을 측정하여, 예측 오차와 예측 오차의 절대값을 비교하였다. 안축장의 길이 측정에는 IOLMaster를 이용하였으며, 예측값 계산에는 A-상수를 후향적으로 보정한 SRK-T공식을 사용하였다. 결과: 수동 각막 곡률 검사기와 IOLMaster, Pentacam true net power상의 각막 곡률은 43.93±1.39, 44.02±1.40, 42.93±1.43D였다. 예측 오차는 0.000±0.53, 0.000±0.51D, 0.000±0.57D였으며, 예측 오차의 절대값은 0.43±0.31, 0.42±0.29, 0.47±0.33D였다. 결론: IOLMaster 자동 각막 곡률 검사기를 통해 측정한 각막 곡률이 백내장 수술 시 상대적으로 유용했다. Purpose: To compare keratometric values obtained with a manual keratometer, the IOLMaster automated keratometer (Carl Zeiss), and the Pentacam rotating Scheimpflug camera (Oculus) in cataract surgery, and to characterize the refractive outcomes generated using each device. Methods: In this retrospective study, 71 eyes of 71 patients were analyzed. The keratometric values obtained with different devices (manual keratometer, the IOLMaster automated keratometer and Pentacam scheimpflug camera) were employed for IOL power calculation. Axial length was measured by the IOLMaster partial coherence interferometry. The predicted refraction was evaluated using the SRK-T formula and optimization was conducted. Multiple comparisons of averaged corneal powers were conducted and the averaged corneal power was used to calculate the predicted refraction. The absolute values of corneal astigmatism were calculated using the corneal powers for the flat and steep meridians ([Ks-Kf]), and those were also compared. After cataract surgery, mean errors and mean absolute errors were compared. Results: The mean keratometric values generated by manual keratometer, the IOLMaster automated keratometer, and the Pentacam Scheimpflug system (true net power) were 43.93±1.39, 44.02±1.40 and 42.93±1.43 diopter. The standard deviation of the mean errors from manual keratometer, IOLMaster optical biometer and Pentacam Scheimpflug system were 0.53D, 0.51D and 0.57D. The mean absolute values from manual keratometer, IOLMaster optical biometer and the Pentacam Scheimpflug system were 0.43±0.31, 0.42±0.29 and 0.47±0.33 diopter. Conclusions: Corneal power measurements with the IOLMaster optical biometer are a good choice for application to cataract surgery.

시설 수박의 터널피복재 보온효과 구명

주선종(Joo Seon-Jong),정재현(Jeong Jae-Hyun),이경희(Lee Kyong-Hee),황선웅(Whang Seon-Woong) 한국생물환경조절학회 1999 한국생물환경조절학회 학술발표논문집 Vol.8 No.1

The Effects of Electrode Configuration on the Luminance and Luminous Efficacy of Mercury-Free Flat Fluorescent Lamp

Byung Joo Oh,Ohyung Kwon,Jae-Chul Jung,In Woo Seo,Ki-Woong Whang IEEE 2011 IEEE transactions on plasma science Vol.39 No.10

<P>To obtain highly efficient and stable discharges in mercury-free flat fluorescent lamps (MFFLs), the effects of the main electrode configuration on the electro-optical characteristics such as the operating voltage margin, luminance, and luminous efficacy are investigated. The spatiotemporal characteristic of the infrared emission from discharges in different electrode configurations (conventional coplanar, counter, and combination discharges) is also studied with an intensified charge-coupled device camera to see the differences with the electrode configuration variation. The MFFL having the combination electrode configuration with Ne-30% Xe gas mixture and a total pressure of 13.3 kPa showed high luminance from 3102 to 22 067 cd/m<SUP>2</SUP> and high luminous efficacy from 49 to 93.5 lm/W for the warm white daylight with a color coordinate of (0.36, 0.36).</P>

Original Articles : Accuracy of Intraocular Lens Power Calculation Formulas in Primary Angle Closure Glaucoma

( Jong Soo Joo ),( Woong Ju Whang ),( Tae Hoon Oh ),( Kyu Dong Kang ),( Hyun Seung Kim ),( Jung Il Moon ) 대한안과학회 2011 Korean Journal of Ophthalmology Vol.25 No.6

Purpose: To compare the accuracy of intraocular lens (IOL) power calculation formulas in eyes with primary angle closure glaucoma (ACG). Methods: This retrospective study compared the refractive outcomes of 63 eyes with primary ACG with the results of 93 eyes with normal open angles undergoing uneventful cataract surgery. Anterior segment biometry including anterior chamber depth, axial length, and anterior chamber depth to axial length ratio were compared by the IOL Master. Third generation formulas (Hoffer Q and SRK/T) and a fourth generation formula (Haigis) were used to predict IOL powers in both groups. The predictive accuracy of the formulas was analyzed by comparison of the mean error and the mean absolute error (MAE). Results: In ACG patients, anterior chamber depth and the anterior chamber depth to axial length ratio were smaller than normal controls (all p < 0.05). The MAEs from the ACG group were larger than that from the control group in the Haigis formula. The mean absolute error from the Haigis formula was the largest and the mean absolute error from the Hoffer Q formula was the smallest. Conclusions: IOL power prediction may be inaccurate in ACG patients. The Haigis formula produced more inaccurate results in ACG patients, and it is more appropriate to use the Hoffer Q formula to predict IOL powers in eyes with primary ACG.

Corneal Astigmatism in Patients After Cataract Surgery: A 10-Year Follow-up Study

Kim, Hyojin,Whang, Woong-Joo,Joo, Choun-Ki SLACK INCORPORATED 2016 Journal of refractive surgery Vol.32 No.6

<P>PURPOSE: To report the long-term outcomes of corneal astigmatism after cataract surgery. METHODS: The study included 55 eyes of 46 patients who underwent cataract surgery with temporal 3-mm clear corneal incisions from January 2001 to December 2003. All patients underwent complete ophthalmological examination including keratometry at the preoperative visit and at 2 months and 10 years after surgery. Only those eyes that underwent a follow-up of 10 years or longer from the time of cataract surgery were enrolled. Arithmetic and vector analyses were performed to obtain the change in corneal astigmatism with advancing age. RESULTS: The mean age of the patients was 59.11 +/- 12.33 years (range: 18 to 75 years), and 58.7% of the patients were women. The mean follow-up period was 131.28 +/- 14.36 months. The average magnitudes of surgically induced astigmatism and long-term astigmatism change were 0.66 +/- 0.42 and 0.57 +/- 0.47 diopters (D), respectively. The vector difference was 0.56 +/- 0.55 D at 90 degrees +/- 0 degrees between the preoperative and 2-month visits. However, there was no difference in vector values between postoperative 2 months and 10 years (0.00 +/- 0.74 D at 0 degrees +/- 0 degrees). CONCLUSIONS: Patients with corneal astigmatism who underwent cataract surgery did not show a long-term against-the-rule change in corneal astigmatism during a 10-year follow-up. These results provide useful information when planning toric intraocular lens implantation in patients with corneal astigmatism.</P>

건성 골수천자의 임상적 고찰

김진민,김주항,한지숙,고윤웅 大韓血液學會 1981 大韓血液學會誌 Vol.16 No.1

Comparison of Accuracy of Six Modern Intraocular Lens Power Calculation Formulas

Ji Hyun Yoon,Woong-Joo Whang 대한안과학회 2023 Korean Journal of Ophthalmology Vol.37 No.5

Purpose: To compare the accuracy of modern intraocular lens (IOL) power calculation formulas in predicting refractive outcomes after standard cataract surgery. Methods: The medical records of 203 eyes from 203 patients that received phacoemulsification and IOL implantation were retrospectively reviewed. Partial coherence interferometry was used to obtain the biometric values. The refractive outcomes of Barrett Universal II (BUII), Emmetropia Verifying Optical (EVO) 2.0, Hill-RBF 3.0, Hoffer QST, Kane, and PEARL-DGS formulas were evaluated. Axial length (AL) subgroup analysis was done separately. The correlations between the prediction error calculated by each formula and AL and corneal power were also analyzed. Results: Overall, there was no significant difference between the absolute prediction errors predicted by the six formulas after adjusting the mean prediction error (p = 0.058). AL subgroup analysis of absolute error also showed that there is no significant difference between the formulas. The BUII and Hill-RBF 3.0 formulas showed a higher percentage of eyes with prediction error within ±0.50 diopters compared to the Hoffer QST formula (p = 0.022 and p = 0.035, respectively). However, there was no significant difference after Bonferroni correction was applied. The BUII formula showed the highest IOL Formula Performance Index and therefore the highest accuracy, followed by PEARL-DGS, EVO 2.0, Kane, Hill-RBF 3.0, and Hoffer QST formulas. Out of the six formulas, the prediction error calculated by the Hoffer QST was significantly correlated with the AL (p = 0.011). None of the prediction errors calculated by the six formulas showed correlation to the corneal power. Conclusions: Analysis of the prediction error showed that the six modern IOL power calculation formulas have comparable accuracy overall and across different ranges of AL.