Comparison of optical biometry and conventional acoustic biometry in the axial length measurement in silicone oil-filled eyes

Purpose: To compare the axial length (AL) obtained by A-scan biometry (PAC SCAN 300AP; Sonomed Escalon, USA) and LENSTAR-LS 900 (Haag-Streit, Koeniz, Switzerland) in silicone oil (SiO)-filled eyes. Methods: AL measurements were taken in 50 SiO-filled eyes using A-scan and LENSTAR-LS 900 before SiO removal and 1 month following SiO removal. In the subset of patients requiring intraocular lens (IOL) insertion, the predicted refraction and the refraction obtained were compared. IOL power in these patients was calculated using SRK-T formula and the AL obtained by LENSTAR. Results: In SiO-filled eyes, a significant difference was noted between the AL values obtained using the two methods (P = 0.0002). No significant difference was noted after SiO removal (P = 0.634). In the subset of patients needing IOL insertion, no significant difference (P = 0.07) was seen between target refractive error and postoperative refractive error (mean deviation from the target being 0.176 diopter). AL of an SiO-filled eye is more accurately measured using optical low coherence reflectometry (OLCR)-based biometry (LENSTAR) than with conventional acoustic biometry (A-scan). Conclusion: We conclude that LENSTAR gives more accurate biometry in an SiO-filled eye. The AL obtained after SiO removal was comparable and showed no significant difference

Comparison of Ocular Biometry Using Low-Coherence Reflectometry with Other Devices for Intraocular Lens Power Calculation

PURPOSE: To compare axial length (AL) and keratometry (K) using optical low-coherence reflectometry (OLCR, Lenstar LS900(R), Haag-Streit, Bern, Switzerland) with current ocular biometry devices and evaluate the accuracy of intraocular lens (IOL) power calculation. METHODS: In this prospective, comparative observational study of eyes with cataracts, AL and K were measured using an OLCR device (Lenstar LS900(R), Haag-Streit), partial coherence interferometry (PCI, IOL Master(R), Carl Zeiss, Jena, Germany), A-scan (Eyecubed) and automated keratometry (KR-7100, Topcon, Tokyo, Japan). IOL power calculation was performed using the Sanders-Retzlaff-Kraff (SRK/T) formula. The IOL prediction error (PE) was calculated by subtracting the predicted IOL power from the postoperative (PO) IOL power (PO 4 weeks, PO 12 weeks). RESULTS: A total of 50 eyes of 39 patients with cataracts (mean age 67.12 +/- 8.51 years) were evaluated in this study. AL and K were not significantly different between the OLCR device and other devices (analysis of variance [ANOVA], p = 0.946, 0.062, respectively). The mean PE in IOL power calculation was -0.22 +/- 0.50D with the OLCR device, 0.08 +/- 0.45D with the PCI device and -0.01 +/- 0.48D with A-scan and automated keratometry (ANOVA, p = 0.006). The highest percentage of eyes with PE smaller than +/- 0.5D was IOL Master(R) followed by Eyecubed and then Lenstar LS900(R). The mean absolute PE was not statistically significant among the 3 devices (ANOVA, p = 0.684). CONCLUSIONS: Ocular biometry measurements were comparable between the OLCR device and the PCI ultrasound device. However, the IOL power prediction showed significant differences among the 3 devices. Therefore, the differences in application of these devices should be considered.

Comparison of Anterior Segment Measurements Using Scanning-Slit Topography and Optical Low-Coherence Reflectometry (OLCR) Biometry

PURPOSE: To compare the results of anterior segment biometry including white-to-white (WTW) between scanning-slit topography (ORBscan IIz(R), Bausch & Lomb), optical low-coherence reflectometry (OLCR) biometry (Lenstar(R), Haag-Streit), and Castroviejo calipers. METHODS: Measurements on 72 eyes of 36 patients that underwent refractive surgery were measured using ORBscan(R), Lenstar(R), and calipers and compared. Ocular biometry parameters used in this study included the WTW, central corneal thickness, anterior chamber depth (ACD), keratometry, and pupil size. RESULTS: The WTW measurements using ORBscan(R) and calipers (11.57 +/- 0.35 mm and 11.58 +/- 0.34 mm, respectively) were statistically similar. However, the measurement using Lenstar(R) (12.05 +/- 0.40 mm) was significantly greater than with the other methods (p < 0.001). Central corneal thickness and keratometry measurements using ORBscan(R) were greater than when using Lenstar(R) (p = 0.01 for both). ACD and pupil size measurement using Lenstar(R) were greater than when using ORBscan(R) (p < 0.001 for both). CONCLUSIONS: Because WTW and ACD measurements using Lenstar(R) were greater than when using ORBscan(R) and calipers, unexpected high-vaulting may be observed due to the selection of a larger-sized posterior chamber phakic intraocular lens. Therefore, the differences in measurements obtained when using these methods should be considered.

Comparison of Anterior Segment Measurements Using Scanning-Slit Topography and Optical Low-Coherence Reflectometry (OLCR) Biometry

PURPOSE: To compare the results of anterior segment biometry including white-to-white (WTW) between scanning-slit topography (ORBscan IIz(R), Bausch & Lomb), optical low-coherence reflectometry (OLCR) biometry (Lenstar(R), Haag-Streit), and Castroviejo calipers. METHODS: Measurements on 72 eyes of 36 patients that underwent refractive surgery were measured using ORBscan(R), Lenstar(R), and calipers and compared. Ocular biometry parameters used in this study included the WTW, central corneal thickness, anterior chamber depth (ACD), keratometry, and pupil size. RESULTS: The WTW measurements using ORBscan(R) and calipers (11.57 +/- 0.35 mm and 11.58 +/- 0.34 mm, respectively) were statistically similar. However, the measurement using Lenstar(R) (12.05 +/- 0.40 mm) was significantly greater than with the other methods (p < 0.001). Central corneal thickness and keratometry measurements using ORBscan(R) were greater than when using Lenstar(R) (p = 0.01 for both). ACD and pupil size measurement using Lenstar(R) were greater than when using ORBscan(R) (p < 0.001 for both). CONCLUSIONS: Because WTW and ACD measurements using Lenstar(R) were greater than when using ORBscan(R) and calipers, unexpected high-vaulting may be observed due to the selection of a larger-sized posterior chamber phakic intraocular lens. Therefore, the differences in measurements obtained when using these methods should be considered.