ABSTRACT
Purpose: The aim of this study was to present an experimental optical coherence tomography (OCT)–guided anterior segment (AS) imaging chick embryo model. Through this model, we aimed to reveal similarities and differences between human cornea, AS tissues, and chick embryo tissues by quantitative image analysis. Methods: Ex vivo, the chick embryos' globes were determined by detailed AS camera of spectral-domain (SD)-OCT in 10 fertilized specific pathogen-free eggs on the 20th day. Quantitative image analysis of anterior chamber tissues was performed with SD-OCT in detail. After imaging, cross sections of the chick embryo globes containing cornea with anterior chamber were histologically examined and compared with human tissues. The similarities of our model with data in the human cornea and AS studies in the literature were compared. Results: SD-OCT imaging was able to successfully delineate the AS tissues of chick embryos such as the cornea, iris, lens, pupil, conjunctiva, ciliary body, anterior chamber, and lens. Quantitative semi-automated measurements showed the following: mean central corneal thickness: 213.4 ± 7.05 ?m (197–223 ?m), mean anterior chamber depth: 878.9 ± 41.74 (804–919 ?m), mean anterior chamber area: 2.43 ± 0.16 mm2 (2.17–2.73 mm2), mean corneoscleral junction (limbal) thickness: 322.8 ± 20.05 ?m (289–360 ?m), and mean iris thickness: 230.4 ± 13.27 ?m (203–245 ?m). In addition, detailed histological comparisons of the AS tissues with human tissues were evaluated to be very similar. Conclusion: In conclusion, this chick embryo model mimics human tissues and it can be considered as a platform for the study of teratogen-induced malformations and AS dysgenesis during gestation of AS tissues. In addition, this study demonstrates the feasibility of SD-OCT in the quantitative assessment of AS structures in chick embryo model.
ABSTRACT
Purpose: The purpose of this study is to evaluate anterior segment measurements obtained using CSO Sirius Topographer® (CSO, Firenze, Italy) and Nidek Axial Length (AL)-Scan® (Nidek CO., Gamagori, Japan). Methods: A total of 43 eyes of 43 patients were included in this prospective study. The central corneal thickness (CCT), anterior chamber depth (ACD), white-to-white distance (WTW), flat keratometry (K1), steep keratometry (K2), and mean keratometry (K) values were randomly measured three times with each device by the same examiner. The intraclass correlation coefficient of repeatability was analyzed. The compatibility of both devices was evaluated using the 95% limits of the agreement proposed by Bland and Altman. Results: Examiner achieved high repeatability for all parameters on each device except the WTW measured by Sirius. All measurements except WTW and K1 taken with the Sirius were higher than that taken with the Nidek AL-Scan®. The difference in CCT, ACD, and WTW values was statistically significant. Conclusion: High repeatability of the measurements was achieved on both devices. Although Km, K1, and K2 measurements of the Sirius and the AL-Scan® showed good agreement, WTW, CCT, and ACD measurements significantly differed between two devices. Thus, anterior segment measurements except for Km, K1, and K2 cannot be used interchangeably between Sirius and Nidek AL-Scan® devices.