Purpose
To compare the full-depth visualization of vitreoretino-choroidal structures in the macula between CDI technique on Heidelberg Spectralis and Topcon DRI SS-OCT.
Methods
Two foveal scans using CDI-OCT on Heidelberg Spectralis and SS-OCT using Topcon DRI were obtained in 40 normal eyes, 40 eyes with AMD, and 40 eyes with glaucoma. CDI-OCT images were obtained enhancing the vitreoretinal interface first and then the choroid, while averaging 100 separate OCT scans. SS-OCT images were obtained averaging 96 scans. Two independent masked physicians graded visualization of the inner border of the vitreal pocket, of the interdigitation zone line, and of the outer border of the choroid, as well as sharpness of choroidal structures. In case of disagreement, a third physician was consulted.
Results
The agreement between observers was high (k, 0.71; P<.001). A full-depth image of vitreoretino-choroidal structures was successfully achieved with CDI-OCT in 118 cases (98.3%) and with SS-OCT in 45 cases (37.5%, p<.001). CDI-OCT was superior to SS-OCT in visualizing the anterior border of the vitreal pocket in 109 eyes (90.8%, p<.001), while the 2 machines were equivalent for the remaining eyes. SS-OCT was equivalent to CDI-OCT in visualizing the posterior border of the choroid in 108 eyes (90%), while in 7 eyes it was superior to CDI-OCT (5.8%, p=0.564). The visualization of the interdigitation zone line was identical between the 2 machines (p=1.000). In subgroups analysis, the visualization of the anterior border of vitreal pocket was consistently better using CDI-OCT than SS-OCT (p<.001), while the visualization of the posterior choroidal border was equivalent between the 2 machines (p=0.564 for normal eyes, p=0.564 for eyes with macular diseases, and p=0.414 for eyes with glaucoma). The sharpness of the choroidal structures was greater with SS-OCT than with CDI-OCT (p<.001).
Conclusions
The manual technique of CDI-OCT on Spectralis OCT is superior to SS-OCT in visualizing macular structures into a single full-depth image. Details of the preretinal vitreous are better imaged using the shorter wavelength of the spectral domain OCT. For clinical purpose of visualizing choroidal borders for choroidal thickness measurement the 2 machines are equivalent, however the sharpness of the choroidal structures is better using higher scanning speed of the SS-OCT.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)