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Updated: Jan 30, 2026

Doppler Optical Coherence Tomography of Retinal Circulation
Published on: September 18, 2012
Accuracy of swept-source optical coherence tomography based biometry for intraocular lens power calculation: a
Youngju An1, Eun-Kyoung Kang2, Hyojin Kim3
1Catholic Institute for Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
Background:
To evaluate the accuracy of biometric measurements by a swept-source optical coherence tomography (SS-OCT) based biometry for intraocular lens (IOL) power calculation.
Methods:
This retrospective observational study enrolled 431 patients undergoing cataract surgery. The charts were reviewed to investigate the failure rate of axial length (AL) measurement of the SS-OCT biometer, partial coherence interferometry (PCI), and A-scan ultrasonography (US) according to cataract type and severity. AL and keratometry in 164 eyes with the same IOL inserted were measured using the SS-OCT biometer, PCI, and A-scan US. The SRK/T formula was used to calculate IOL power. The mean absolute error (MAE) and percentage of eyes with a prediction error (PE) of ±0.50 D were compared.
Results:
The AL measurement failure rate was 0.00% for A-scan US, 2.32% for the SS-OCT biometer, and 15.31% for PCI. The number of eyes measured using three devices (SS-OCT biometer, PCI, and A-scan US) was 128 (Group A) and the number of eyes measured using two devices (SS-OCT biometer and A-scan US) was 36 (Group B). The score of posterior subcapsular opacity was significantly different between two groups (p < .001). The SS-OCT biometer and PCI showed significantly lower MAE compared to A-scan US in Group A (p = 0.027). Using SS-OCT biometer, MAE showed no significant difference between Group A (0.36 ± 0.27) and Group B (0.36 ± 0.31) (p = 0.785). Whereas, MAE of A-scan US was significantly higher than Group A (0.47 ± 0.39) in Group B (0.64 ± 0.36) (p = 0.023).
Conclusions:
Using biometry with advanced OCT is useful in clinical practice as it is more effective in obtaining biometric measurements in the eyes with PSC and provides accurate measurements for IOL power calculation regardless of cataract type and severity.
Trial Registration:
Retrospectively registered. Registration number: KC16RISI1020 . Registered 03 January 2018.
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Titration Calculations: Weak Acid - Strong Base
For the titration of 25.00 mL of 0.100 M CH3CO2H with 0.100 M NaOH, the reaction can be represented as:
Titration Calculations: Strong Acid - Strong Base
A titration is carried out for 25.00 mL of 0.100 M HCl (strong acid) with 0.100 M of a strong base NaOH. The pH at different volumes of added base solution can be calculated as follows:
(a) Titrant volume = 0 mL. The solution pH is due to the acid ionization of HCl. Because this is a strong acid, the ionization is complete and the hydronium ion molarity is 0.100 M. The pH of the solution is then:

