Impact of the 2023 ACR/EULAR Antiphospholipid Syndrome Criteria on Retinal Vein Occlusion Patients

<b>Background/Objectives:</b> Retinal vein occlusion (RVO) represents a common ophthalmological disorder that, if untreated, often leads to severely impaired vision. The classic vascular risk factors, aging and glaucoma, represent the core pathogenic factors for RVO. However, antiphospholipid syndrome (APS) has been involved in a non-negligible number of patients with RVO. The main objective of the present study was to assess the performance of the new 2023 ACR/EULAR classification criteria for APS in a cohort of patients with RVO fulfilling the Sydney classification criteria. <b>Methods:</b> A prospective study of consecutive patients with RVO diagnosed with APS in a third-level university hospital. The new 2023 ACR/EULAR classification criteria for APS were applied to all patients. Vascular risk factors, the antiphospholipid antibody (aPL) profile, clinical management, and clinical outcomes were assessed and compared between those fulfilling the Sydney and the 2023 ACR/EULAR criteria. <b>Results:</b> Sixty-nine RVO-APS patients were included in the study. After applying the new classification criteria, 18 patients (26.1%) did not fulfill the new criteria for APS. Specifically, 17 (24.6%) were excluded due to the new Domain 8 (<i>p</i> < 0.001) as they presented only aPL IgM serology, and 1 patient (1.4%) was excluded due to having high venous thromboembolic risk (VTE) with a clinical domain score < 3. Interestingly enough, the presence of high arterial risk (45.1% vs. 50%; <i>p</i> = 0.72) was greater than the presence of high VTE (3.9% vs. 5.6%; <i>p</i> = 0.99); in both cases, the 51 RVO-APS patients were classified with the 2023 ACR/EULAR criteria, and the 18 cases were excluded according to the new classification criteria. Except for the expected differences in serological domains (Domain 7, <i>p</i> < 0.001, and Domain 8, <i>p</i> < 0.001), we did not find other significant differences in terms of prognosis or risk of recurrence between both groups of patients. <b>Conclusions:</b> The implementation of the new ACR/EULAR 2023 classification criteria for APS resulted in the exclusion of about one out of four previously diagnosed RVO-APS patients. The higher prevalence of manifestations of high arterial risk compared with high VTE among both newly classified and excluded APS patients highlights the importance of monitoring cardiovascular risk factors for both the prevention and the management of potential retinal and cardiovascular events.