Analysis of the natural course of quiescent choroidal neovascularization with optical coherence tomography angiography

PURPOSE: Assessing the potential progression of quiescent choroidal neovascularization cases by evaluating changes in morphological and quantitative data in optical coherence tomography angiography parameters over the natural course. MATERIALS AND METHODS: The data of cases that were diagnosed with quiescent choroidal neovascularization and had been followed for at least six months in the Department of Ophthalmology, Retina Unit, Manisa Celal Bayar University Hospital, between November 2019 and May 2023, were retrospectively reviewed. A total of 28 patients meeting the study criteria were included, encompassing 30 eyes. Information such as age, gender, systemic diseases, laterality, diagnosis, number of visits, presence and date of activation, duration of follow-up, best-corrected visual acuity, fundus findings, and other ocular characteristics were recorded from the patients' medical records. Using structural OCTA function from OCT and OCTA images obtained during the follow-ups, the CNV total and flow area size were calculated. In en-face images, previously described CNV morphological data (lesion shape; circular or irregular, presence of trunk, margin; small or large loop, presence of hyporeflective halo) were categorized. Data related to neovascular activity with OCT biomarkers were collected, including intraretinal fluid and subretinal fluid. Central macular thickness (CMT) was calculated as the average retinal thickness in the central 1000 μm area, which was automatically measured by the device. Subfoveal choroidal thickness (SFCT) was defined as the vertical distance between the basal membrane and the chorioscleral interface at the fovea. The changes in morphological and quantitative data during the follow-up were assessed for potential progression. RESULTS: The mean age of the patients was 69.70 ± 7.63 years (ranging from 54 to 85 years). Of the patients, 53.3% were male, and 43.3% had the condition in their right eye. Twenty-one patients were diagnosed with AMD, while nine patients had PNV. The prevalence of quiescent CNV was 2.08% in AMD patients, while it was 13.63% in PNV patients. The mean follow-up duration was 18.9 months, ranging from 6 to 50 months. During the follow-up, the mean number of visits was 5.57 ± 2.80. The BCVA of the patients was observed to be 0.82 ± 0.18 at the first visit and 0.78 ± 0.22 at the last visit. This change was not statistically significant (p=0,068). Fundus examination revealed RPE changes in 11 eyes, drusen in 17 eyes, and geographic atrophy in 2 eyes. In patients, 46.66% had foveal localization of CNV, while 53.33% had an extrafoveal location. In quiescent CNVs, at the first visit, a hyporeflective halo was observed in 30% (9 cases), trunks in 16.6% (5 cases), large loops in 30% (9 cases), and irregularities in 63.3% (19 cases). In the last visit, a hyporeflective halo was observed in 40% (12 cases), trunks in 26.6% (8 cases), large loops in 43.3% (13 cases), and irregularities in 76.6% (23 cases). However, these morphological changes were not statistically significant (p>0.05). During the follow-up, exudation developed in 4 patients. In the last visit of the patients with exudation, 2 eyes had a hyporeflective halo, 1 eye had a trunk, and 2 eyes had a large loop. No significant changes in morphology were observed in patients with exudation. At the first visit, the mean CMT of the patients was 240.8 ± 32.61 µm, while at the last visit, it was 236.57 ± 35.43 µm. The mean SFCT was 212.63 ± 83.47 µm at the first visit and 227.10 ± 82.92 µm at the last visit. No statistically significant changes were observed in CMT and SFCT (p=0,407; p=0,161). The mean CNV area was 1.799 ± 2.84 mm² at the first visit and 2,12 ± 2,89 mm2 at the last visit. The mean CNV flow area was 1.055 ± 1.58 µm² at the first visit and 1,300 ± 1,77 µm² at the last visit. Statistically significant changes were observed in CNV area and flow between the first and last visits (p=0.043, p=0.018).No significant correlation was found between BCVA and CNV and flow area during follow-up (p=0.103; p=0,191). WWhen the final visit was compared to the baseline, it was observed that there was no morphological change in 14 (46.6%) cases. When the groups with and without morphological changes were examined, the CNV area changes were 0.42 and 0.21 mm2, respectively. No correlation was detected between morphological change and CNV area change (p=0,934). CONCLUSION: Quiescent CNV is important for diagnosis and monitoring due to being a precursor lesion of exudative CNV. There is currently no established algorithm in the literature for the follow-up and treatment of quiescent CNV. In this study, changes in morphological and quantitative data in OCTA parameters during the natural course of quiescent CNV cases were evaluated. It was observed that the quantitative data changes were in line with and supportive of the literature. We believe that our study will contribute to the future development of an algorithm for the follow-up and treatment of quiescent CNV. Early diagnosis and monitoring of exudative CNV are expected to positively impact visual prognosis. Keywords: Morphological changes, Natural course analysis,non-exudative choroidal vascularization, optical coherence tomography angiography, quiescent choroidal vascularization.