- Objective: To investigate the natural history and risk factors for exudative conversion in treatment-naive nonexudative polypoidal choroidal vasculopathy (PCV).
- Methods:
- Retrospective cohort study of 42 eyes from 40 patients with nonexudative PCV diagnosed using indocyanine green angiography (ICGA) and optical coherence tomography (OCT).
- Patients were followed for a mean of 54.3 ± 35.5 months.
- Exudative conversion was defined as the development of subretinal fluid or hemorrhage.
- Risk factors for exudative conversion were analyzed using OCT and ICGA imaging.
- Results:
- Exudative Conversion: 54.8% (23/42 eyes) developed exudation after a mean of 42.2 ± 28.3 months.
- Exudation-Free Survival: 53.6% at 5 years.
- Risk Factors:
- Sequentially increased protrusion of retinal pigment epithelium (RPE) in the polyp area was a significant predictor of exudation (OR = 10.16; 95% CI, 1.78–57.81; \( P = 0.01 \)).
- Heterogeneous hyporeflectivity within the RPE protrusion was also associated with exudation but not significant in multivariate analysis.
- Visual Acuity: Final visual acuity was worse in the conversion group compared to the stable group (LogMAR 0.13 ± 0.29 vs. 0.04 ± 0.18, \( P = 0.03 \)).
- Discussion:
- Nonexudative PCV has a high risk of exudative conversion, with over half of the cases developing exudation within 5 years.
- Increased RPE protrusion height on OCT is a reliable biomarker for predicting exudative conversion.
- The study highlights the importance of long-term monitoring for patients with nonexudative PCV, especially those with progressive RPE protrusion.
- Prophylactic treatments for nonexudative PCV, such as anti-VEGF injections or photodynamic therapy, were not evaluated but may warrant further investigation.
- Conclusion:
- Increased RPE protrusion height in the polyp area is a significant predictor of exudative conversion in nonexudative PCV.
- Clinicians should closely monitor patients with nonexudative PCV, particularly those with progressive RPE changes, to detect and manage exudative conversion early.
Fig. 1: ICGA and OCT B-scans of the asymptomatic right eye from an 82-year-old male patient with nonexudative polypoidal choroidal vasculopathy followed up for 19 months in which exudation developed after 11 months from baseline.
(A) Baseline ICGA with branching neovascular network and polypoidal lesions (number 1–3). OCT B-scan images at baseline (sections A-1, A-2, and A-3; white dotted lines) show the subfoveal double layer sign and maximal height of RPE protrusions corresponding to polypoidal lesions number 1 to 3 (maximal height of RPE protrusions at baseline: 164 mm [polypoidal lesion 1], 147 mm [polypoidal lesion 2], and 90 mm [polypoidal lesion 3]).
(B) Infrared reflectance fundus imaging after 6 months. OCT B-scan images at 6 months (sections B-1, B-2, and B-3) showing an increased maximal height of RPE protrusion (at polypoidal lesion 3) from the maximal baseline height of RPE protrusion (maximal height of RPE protrusions at 6 months: 147 mm [polypoidal lesion 1], 140 mm [polypoidal lesion 2], and 167 mm [polypoidal lesion 3]).
(C) OCT scan images (sections C-1, C-2, and C-3) after 11 months of observation show further increased maximal height of RPE protrusion (polypoidal lesion 3) with surrounding subretinal fluid and heterogeneous hyporeflectivity changes within the RPE protrusion (maximal height of RPE protrusions at 11 months: 155 mm [polypoidal lesion 1], 143 mm [polypoidal lesion 2], and 255 mm [polypoidal lesion 3]). ICGA taken at that time shows the enlarged size of the polypoidal lesion number 3.
Conclusion: Exudative conversion occurs in nearly half of nonexudative polypoidal choroidal vasculopathy (PCV) cases within 5 years. Increased height of retinal pigment epithelium (RPE) protrusion in the polyp area is a significant biomarker for predicting exudative conversion, suggesting that close monitoring is essential for patients with progressive RPE changes.