Use of preoperative swept-source optical coherence tomography in vitrectomy for advanced diabetic eye disease: a pilot study

Background: Swept-source optical coherence tomography (SS-OCT) is an OCT variant with longer wavelengths than other commonly used OCT devices. Our aim was to determine the benefit of pre-operative SS-OCT to detect occult retinal pathologies in patients with advanced diabetic eye disease (ADED). Methods: Fundus photos and SS-OCT were performed pre-operatively in all patients scheduled for vitrectomy for ADED. These were reviewed by two retina specialists. A modified BIO-score based on the Nussenblatt scale of vitreous haze was used to evaluate fundus clarity on fundus photos. Findings on fundus photos were compared with the findings on SS-OCT. Any disagreement between the retina specialists was resolved upon discussion. Results: We included 38 consecutive eyes of 35 patients. Various degrees of cataract was present in 22 eyes. In our sample, 84.2% of cases had a BIO score of 3 or more and 31.6% had a BIO score of 4 or 5. The most common diagnosis on fundus photos was vitreous haemorrhage (n = 23). Tractional retinal detachment (n = 20) was the most common diagnosis on SS-OCT. Only 3 cases had no view on SS-OCT. There was almost perfect (κ = 0.933, 95% CI: 0.887-0.979), substantial (κ = 0.734, 95% CI: 0.632-0.836) and moderate (κ = 0.593, 95% CI: 0.494-0.692) intergrader agreement for fundus photo diagnosis, SS-OCT diagnosis and BIO scores respectively. Conclusion: SS-OCT showed potential as an adjunct to clinical examinations, especially when hazy media opacities did not allow for a clear view of the fundus. However, it is important to recognise that OCT only serves as an adjunct and cannot be used as a definitive argument for assessing surgical feasibility.