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Study: Inexperienced operators effectively perform SD-OCT imaging
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OCT imaging may be appropriate for nonprofessional photographers to administer to undilated patients and in quantitative parameters for adequate screening in a community setting, according to researchers.
Researchers reported that patients with open angle glaucoma underwent OCT imaging with the Cirrus SD-OCT (Carl Zeiss Meditec Inc.) as part of their routine care on that day.
A clinical examination by a glaucoma specialist was also performed to rule out other conditions that could affect the optic disc or retinal nerve fiber layer (RNFL) and to confirm that the observed disc changes and field deficits were due to glaucoma, according to researchers.
A comparison group was included. These subjects were 18 years or older, with no diagnosed eye disease and a visual acuity of 20/25 or better with habitual correction.
A total of 112 individuals were enrolled, of which four participants were excluded due to inability to obtain iVue SD-OCT (Optovue) images. The remaining 108 individuals included 54 patients with OAG and 54 comparison individuals.
All iVue imaging was performed by nonprofessional photographers who had no experience in ophthalmic imaging before the study, aside from a single session on basic training.
The iVue imaging comprised: ganglion cell complex thickness, optic nerve head RNFL and optic nerve head 3D scan protocols in both eyes without dilation.
After iVue imaging, the OAG group had routine care including clinical examination and Cirrus SD-OCT by a professional photographer or technical staff member.
All analyzed iVue images were of sufficient quality for the auto-segmentation software to calculate quantitative scan parameters, according to researchers.
Researchers found that the iVue cup-to-disc ratio value was performed with a sensitivity of 0.96 at 90% specificity, and the area cup-to-disc ratio was almost equally sensitive and specific.
The iVue vertical cup-to-disc ratio and the Cirrus HD-OCT vertical cup-to-disc ratio were strongly correlated, and iVue and clinical cup-to-disc ratios observed by faculty ophthalmologists were also highly correlated, according to researchers.
Several RNFL parameters, such as the inferior quadrant thickness, also had impressive sensitivity and specificity.
“We have shown that a lay person with no prior experience may be trained in less than 30 minutes to competently and rapidly set-up and acquire images using the iVue,” researchers wrote. “This indicates the likely practicality of using this instrument with nonprofessional operators in the field, especially given its relatively small size and portability compared with other imaging modalities ...” – by Abigail Sutton
Perspective
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Brian Mahoney, OD, FAAO
Our understanding of OCT technology in glaucoma diagnosis and management is progressing rapidly but still lags behind its use in macular disease. Liu and colleagues investigate the potential application of OCT as a screening tool for glaucoma, particularly for minority and underserved populations.
The OCT images are interpreted by glaucoma specialists after acquisition by nonprofessional photographers who have undergone focused training on OCT imaging. This process is similar to screening for diabetic retinopathy by fundus photography as developed in the Veterans Health Administration.
The authors found a strong correlation regarding the sensitivity and specificity of vertical cup-to-disc ratio and inferior quadrant retinal nerve fiber layer parameters assessed by both Optovue iVue and Cirrus OCT (Carl Zeiss Meditec) instruments when compared to clinical dilated examination. The portability of the iVue instrument is highlighted as a significant advantage for use in glaucoma screenings in the community.
It’s heartening to learn that OCT technology is becoming more affordable and may play a role in community screenings by non-expert technicians. In our eye clinics, this study supports what we already know: OCT has become an important addition to other screening tools, including IOP measurement, visual field testing and optic nerve assessment.
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