Enhanced depth imaging OCT (EDI-OCT) appears to offer superior sensitivity, specificity, and accuracy in diagnosing optic disc drusen (ODD) compared to traditional imaging modalities.
Study design
This cross-sectional study compared ultrasonography (US), fundus photography, fundus autofluorescence (FAF), and EDI-OCT in 105 patients (255 eyes) referred for suspected ODD. According to the reference standard—the attending neuro-ophthalmologists' clinical judgment based on the entire medical record—roughly half of the eyes had ODD while the other half did not. The images were independently reviewed by three masked neuro-ophthalmologists to determine the presence or absence of ODD and evaluate the sensitivity, specificity, and accuracy of each imaging modality.
Outcomes
All 4 imaging modalities had high specificity, ranging from 97–100%. However, EDI-OCT was the most sensitive and accurate at detecting ODD (95% and 97%, respectively) compared with FAF (84%, 92%), US (74%, 86%), and fundus photography (38%, 66%). Reviewers were confident in their assessment with EDI-OCT 96% of the time compared to 88% of the time with other imaging modalities.
Limitations
The reference standard for the presence or absence of ODD was based on the clinical judgment of two attending neuro-ophthalmologists. Both doctors were included in the blinded analysis of the imaging modalities, which could have influenced their assessment. In addition, the study evaluated EDI-OCT but did not provide the sensitivity of OCT without EDI. The study also did not include fluorescein angiogram as a modality for ODD detection. Interestingly, Chang and colleagues1 found fluorescein angiogram to be the most sensitive modality for ODD, but this was in a pediatric population in which ODD are often buried and non-calcified. In the current study, only 8% of the patients were pediatric (<12 years old) and, therefore, the sensitivity of EDI-OCT for small non-calcified ODD was not adequately assessed.
Clinical significance
This study demonstrated that EDI-OCT is more sensitive and accurate than other imaging options, including US, thus providing a strong push toward EDI-OCT becoming the modality of choice for ODD. I also have found EDI-OCT to be very sensitive for ODD detection in adults, though it may have less sensitivity in young children. An additional drawback of OCT is that it requires a trained eye to differentiate ODD from other structures, such as vessels and peripapillary hyperreflective ovoid mass-like structures (PHOMS). While I agree that FAF is less sensitive than EDI-OCT, it is often easier for an untrained eye to differentiate a positive and negative result using FAF. Therefore, FAF should remain in the armamentarium for the identification of ODD. Lastly, although US remains a good imaging modality for ODD and is helpful for identifying deeply buried ODD, it can be limited by its availability and the expertise of the ultrasonographer.
In summary, this is an excellent study that provides further support that EDI-OCT is a sensitive and accurate imaging modality for the detection of ODD. However, in difficult borderline cases, multimodal imaging should still be considered. Future studies comparing fluorescein angiogram and EDI-OCT are warranted, especially in a pediatric cohort.
Financial Disclosures: Dr. John J. Chen discloses financial relationships with Horizon Therapeutics (Consultant/Advisor); UCB (Consultant/Advisor).
Reference
1 Chang MY, Velez FG, Demer JL, et al. Accuracy of diagnostic imaging modalities for classifying pediatric eyes as papilledema versus pseudopapilledema. Ophthalmology. 2017(124):1839-48.