Preoperative Widefield Swept-Source Optical Coherence Tomography Versus Intraoperative Findings in Detecting Posterior Vitreous Detachment

Abstract

Purpose: To assess the accuracy of swept-source optical coherence tomography (SS-OCT) in detecting complete posterior vitreous detachment (PVD) in comparison with intraoperative findings.

Methods: The retrospective study included 145 eyes of 145 consecutive patients who underwent surgery for epiretinal membranes or macular holes. Within a week prior to surgery, PVD status was evaluated by SS-OCT with a depth of field of 3 mm and a capture window of 16 × 8 mm. Complete PVD was identified when the hyaloid condensation was visible clearly on any B-scan or when the vitreous cortex reflectivity was not visible on all 33 B-scans. Sensitivity, specificity, positive predictive value, and negative predictive value of SS-OCT for detection of complete PVD were then compared with those evaluated during a triamcinolone acetonide-assisted vitrectomy.

Results: Of the 101 eyes diagnosed as complete PVD by SS-OCT preoperatively, 97 eyes were found to have complete PVD and four eyes were found to have attached vitreous intraoperatively. Of the 44 eyes categorized as attached vitreous by SS-OCT preoperatively, 43 eyes were graded as attached vitreous and one eye was graded as complete PVD during surgery. The sensitivity of SS-OCT for detecting complete PVD was 99.0% and the specificity was 91.5%. The positive predictive value and the negative predictive value were 96.0% and 97.7%, respectively.

Conclusions: Widefield (16 × 8 mm) SS-OCT showed high accuracy for the diagnosis of complete PVD in patients with epiretinal membranes or macular holes.

Translational relevance: Widefield SS-OCT has great potential to evaluate PVD status preoperatively and explore the mechanisms of vitreoretinal diseases.

Figure 1.

A normal eye was imaged through a dilated pupil using SS-OCT coupled with a simultaneous SLO device. The SLO image (16 × 16 mm) and the OCT image were both centered on the foveola (the intersection of the two white lines). The 5.5-mm-diameter red circle is the macula. Thirty-three OCT horizontal line scans were acquired through a capture window of 16 × 8 mm (the field between the two green lines), covering both the macula and the optic nerve head. The retinal layers were positioned inferiorly to achieve maximum imaging depth into the vitreous. Built-in software allowed for optimizing the brightness of the OCT images to visualize the vitreous.

Figure 2.

PVD stages in four patients with epiretinal membranes (A–D) and in four patients with macular holes (E–H). The attached vitreous includes stages 0–2 (A, B, E, F) and stage 3 (C, G). Complete attached vitreous with premacular bursa is shown in a 31-year-old male with epiretinal membrane (A) and in an 8-year-old female with macular hole (E). Attached vitreous to both the macula and the optic nerve was observed in a 71-year-old male with epiretinal membrane (B) and a 58-year-old female with macular hole (F). Detached hyaloid in the whole premacular space and attached hyaloid to the optic nerve head were seen in a 67-year-old male with epiretinal membrane (C) and a 65-year-old male with macular hole (G). Vitreous cortex reflectivity was not visible on all 33 scans in a 54-year-old female with epiretinal membrane (D) and a 58-year-old female with macular hole (H), which were classified as stage 4 (complete PVD).

Figure 3.

Representative cases demonstrating PVD staging before and after brightness enhancement. Case 1 was classified as PVD stage 3 before enhancing the brightness, with the sign of vitreous attachment to the optic nerve head (A1). After the brightness was enhanced, Case 1 was categorized as stages 0–2 because the vitreous was attached to both the optic nerve head and the fovea (A2). Case 2 was graded as PVD stage 4 because of absence of vitreous cortex reflectivity on all 33 B-scans (B1). After the brightness was enhanced, Case 2 was graded as PVD stage 4 because the hyaloid condensation was clearly visible (B2).

Figure 4.

Representative images of a false-negative case (A1, A2) and a false-positive case (B1, B2). The false-negative case was a 69-year-old female diagnosed with epiretinal membrane, showing both obvious vitreous attachment (A1) and detached vitreous (A2) on SS-OCT B-scans. However, in this case, attached vitreous was not detected in the macular area or the optic nerve head during PPV surgery. The false-positive case was an 80-year-old male diagnosed with epiretinal membrane, showing complete PVD on SS-OCT B-scans (B1). However, attached vitreous was detected after TA staining intraoperatively (B2).