Shao Yilei, Tao Aizhu, Jiang Hong, Shen Meixiao, Zhu Dexi, Lu Fan, Karp Carol L, Ye Yufeng, Wang Jianhua
1Bascom Palmer Eye Institute, University of Miami, Miami, FL USA.
2School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang China.
Eye Vis (Lond). 2018 Jul 9;5:16. doi: 10.1186/s40662-018-0111-4. eCollection 2018.
Spectral domain optical coherence tomography (SD-OCT) was a useful tool to study accommodation in human eye, but the maximum image depth is limited due to the decreased signal-to-noise ratio (SNR). In this study, improving optical resolutions, speeds and the SNR were achieved by custom built SD-OCT, and the evaluation of the impact of the improvement during accommodation was investigated.
Three systems with different spectrometer designs, including two Charge Coupled Device (CCD) cameras and one Complementary Metal-Oxide-Semiconductor Transistor (CMOS) camera, were tested. We measured the point spread functions of a mirror at different positions to obtain the axial resolution and the SNR of three OCT systems powered with a light source with a 50 nm bandwidth, centered at a wavelength of 840 nm. Two normal subjects, aged 26 and 47, respectively, and one 75-year-old patient with an intraocular lens implanted were imaged.
The results indicated that spectrometers using cameras with 4096 camera pixels optimized the axial resolutions, due to the use of the full spectrum provided by the light source. The CCD camera system with 4096 pixels had the highest SNR and the best image quality. The system with the CMOS camera with 4096 pixels had the highest speed but had a compromised SNR compared to the CCD camera with 4096 pixels.
Using these three OCT systems, we imaged the anterior segment of the human eye before and after accommodation, which showed similar results among the different systems. The system using the CMOS camera with an ultra-long scan depth, high resolution and high scan speed exhibited the best overall performance and therefore was recommended for imaging real-time accommodation.
光谱域光学相干断层扫描（SD-OCT）是研究人眼调节的一种有用工具，但由于信噪比（SNR）降低，其最大图像深度受到限制。在本研究中，通过定制的SD-OCT提高了光学分辨率、速度和信噪比，并研究了调节过程中这些改进的影响。
测试了三种具有不同光谱仪设计的系统，包括两台电荷耦合器件（CCD）相机和一台互补金属氧化物半导体晶体管（CMOS）相机。我们测量了镜子在不同位置的点扩散函数，以获得由中心波长为840nm、带宽为50nm的光源供电的三个OCT系统的轴向分辨率和信噪比。对两名分别为26岁和47岁的正常受试者以及一名植入人工晶状体的75岁患者进行了成像。
结果表明，使用具有4096个相机像素的相机的光谱仪优化了轴向分辨率，这是由于利用了光源提供的全光谱。具有4096像素的CCD相机系统具有最高的信噪比和最佳的图像质量。具有4096像素的CMOS相机系统速度最高，但与具有4096像素的CCD相机相比，其信噪比有所降低。
使用这三个OCT系统，我们对人眼调节前后的眼前节进行了成像，不同系统之间的结果相似。使用具有超长扫描深度、高分辨率和高扫描速度的CMOS相机的系统表现出最佳的整体性能，因此推荐用于实时调节成像。
