Optical coherence tomography-based misdiagnosis and morphological distinction in pachychoroid neovasculopathy vs. polypoidal choroidal vasculopathy

Abstract

Purpose: To evaluate the rate of misdiagnosis of aneurysmatic pachychoroid type 1 choroidal neovascularization/polypoidal choroidal vasculopathy (PAT1/PCV) among cases diagnosed as non-aneurysmatic pachychoroid neovasculopathy (PNV) and to define optical coherence tomography (OCT) features facilitating their distinction.

Methods: The database of the Department of Ophthalmology, Ludwig-Maximilians University Munich, was screened for patients diagnosed with PNV. Multimodal imaging was screened for the presence of choroidal neovascularization (CNV) and aneurysms/polyps. Imaging features facilitating the diagnosis of PAT1/PCV were analysed.

Results: In total, 49 eyes of 44 patients with a clinical PNV diagnosis were included, of which 42 (85.7%) had PNV and 7 (14.3%) represented misdiagnosed PAT1/PCV. SFCT was comparable (PNV: 377 ± 92 vs. PAT1/PCV: 400 ± 83 µm; p = 0.39). Whereas no difference was detected in total pigment epithelium detachment (PED) diameter (p = 0.46), maximum PED height was significantly higher in the PAT1/PCV group (199 ± 31 vs. 82 ± 46, p < 0.00001). In a receiver operating characteristic (ROC) analysis, the optimum cutoff for defining "peaking PED" was 158 µm with an area under the curve of 0.969, a sensitivity of 1.0 (95% CI: 0.59-1.0), and a specificity of 0.95 (95% CI: 0.84-0.99). Sub-retinal hyperreflective material (SHRM; p = 0.04), sub-retinal ring-like structures (SRRLS; p < 0.00001), and sub-RPE fluid (p = 0.04) were significantly more frequent in eyes with PAT1/PCV.

Conclusion: A relevant percentage of eyes diagnosed with PNV might instead suffer from PAT1/PCV. The detection of a maximum PED height ("peaking PED") exceeding approximately 150 µm, SHRM, SRRLS, and sub-RPE fluid might greatly aid in the production of a more accurate diagnosis.

Fig. 1. Comparison of two cases PNV and two cases of PAT1/PCV.

In patients 1 and 2 with PNV, OCT (A + D) demonstrates a flat irregular PED (alternatively double layer sign) and subretinal fluid. Note that the flat irregular PED has a wide horizontal diameter (green horizontal arrow) and low height. Whereas FA (B + E) shows unspecific hyperfluorescence, ICG (C + F) shows a type 1 choroidal neovascularization without evidence of aneurysmal/polypoidal lesions. In patients 3 and 4 with PAT1/PCV, OCT (G + J) shows a peaking PED (red vertical arrow) with greater height having an adjacent double layer sign (diameter demonstrated with a green horizontal arrow). FA (H + K) shows a more focal hyperfluorescence, and ICG (I + L) clearly demonstrates the presence of aneurysms/polyps.

Fig. 2. OCT scans of all seven cases of PAT1/PCV primarily misdiagnosed as PNV.

All eyes (A–G) clearly show a peaking PED adjacent to a double layer sign. Note the presence of SHRM above the peaking PED in cases (B, C, F, and G). The eye in A also exhibits SHRM below the demonstrated B-scan, indicating a SHRM prevalence of 71.4 % in PAT1/PCV eyes, a value that is significantly more frequent than in PNV (28.6%, p = 0.04). Also note the sub-retinal ring-like structures within the peaking PED in (A, B, and D). All demonstrate peaking PEDs exceeded a height of 150 µm. Eyes (A–D) present with one peaking PED/aneurysm on ICG, whereas eyes (E), (F) demonstrate 2, and eye G has 3 peaking PEDs/aneurysms on OCT and ICG.

Fig. 3. Receiver operating characteristic (ROC) analysis of PED height and diameter.

The optimum cutoff used to define “peaking PED” was 158 µm with an area under the curve (AUC) of 0.969 (sensitivity 1.0 (95% confidence interval (CI): 0.59–1.0); specificity 0.93 (95 CI: 0.81–0.99)). For a PED diameter as a parameter of distinction, ROC analysis yielded markedly worse results with an AUC of 0.601 (optimum cutoff: 1598 µm); sensitivity 0.86 (95% CI: 0.42–1.0); specificity: 0.46 (95 CI: 0.31–0.63).