The correlational structure of stride-to-stride fluctuations differs between healthy and pathological gait. Uncorrelated and anti-persistent stride-to-stride fluctuations are believed to indicate pathology whereas persistence represents healthy functioning. However, this reading can be questioned because the correlational structure changes with task constraints, like acoustic pacing, signifying the tightness of control over particular gait parameters. We tested this “tightness-of-control interpretation” by varying the maneuverability range during treadmill walking (small, intermediate, and large walking areas), with and without acoustic pacing. Stride-speed fluctuations exhibited anti-persistence, suggesting that stride speeds were tightly controlled, with a stronger degree of anti-persistence for smaller walking areas. Constant-speed goal-equivalent-manifold decompositions revealed simultaneous control of stride times and stride lengths, especially for smaller walking areas to limit stride-speed fluctuations. With acoustic pacing, participants followed both constant-speed and constant-stride-time task goals. This was reflected by a strong degree of anti-persistence around the stride-time by stride-length point that uniquely satisfied both goals. Our results strongly support the notion that anti-persistence in stride-to-stride fluctuations reflect the tightness of control over the associated gait parameter, while not tightly regulated gait parameters exhibit statistical persistence. We extend the existing body of knowledge by showing quantitative changes in anti-persistence of already tightly regulated stride-speed fluctuations.

Purpose: To report a series of 21 patients with perifoveal exudative vascular anomalous complex (PEVAC) and to investigate the anatomical changes over time. Methods: We conducted a retrospective study. Clinical data of consecutive patients, presenting at the Rotterdam Eye Hospital between 2014 and 2019, were analyzed. The data collected included best-corrected visual acuity, fundus photography, optical coherence tomography (OCT), OCT-angiography, fluorescence angiography, and indocyanine green angiography. Results: We included 21 patients with a PEVAC lesion with a mean follow-up of 24.3 ± 13.8 months (range, 9–46 months). Patients with PEVAC were on average 75.3 ± 11.1 years (range, 53–90 years). The large perifoveal vascular aneurysmal abnormality was associated with small retinal hemorrhages in six patients and hard exudates in three patients. The PEVAC lesion was associated with intraretinal cystic spaces on OCT in 15 patients. Twelve of 21 patients showed no changes in cystic spaces on OCT during follow-up: 9 patients had stable cystic spaces and 3 patients had no cystic spaces. In contrast, in 9 of 21 patients, we observed changes in cystic spaces on OCT during follow-up. In two patients, cystic spaces appeared during follow-up, and in seven patients, there was a spontaneous resolution of cystic spaces. In three of these seven patients, the PEVAC lesion completely disappeared. Two patients, with stable intraretinal cystic spaces on OCT, were treated with intravitreal injections of anti–vascular endothelial growth factor without improvement. Conclusion: Perifoveal exudative vascular anomalous complex is an idiopathic perifoveal retinal vascular abnormality that is associated with intraretinal cystic spaces. These intraretinal cystic spaces associated with a PEVAC lesion, and even the PEVAC lesion itself, can have a spontaneous resolution over time.

PURPOSE. To compare quantitative optical coherence tomography angiography (OCT-A) measurements of the parafoveal microvasculature in retinal capillary plexuses among Behҫet uveitis (BU) patients, non-ocular Behҫet's disease (NOBD) patients, and healthy volunteers (HVs). METHODS. Sixty-eight subjects were enrolled in this prospective observational crosssectional study. OCT-A imaging was performed using the Heidelberg Engineering Spectralis OCT. A custom algorithm was developed to calculate the vessel density (VD) in three retinal vascular layers: deep capillary plexus, intermediate capillary plexus, and superficial vascular plexus. The foveal avascular zone (FAZ) and acircularity index were calculated for the whole retinal vascular complex. RESULTS. We analyzed one eye from 21 BU patients (age, 51 ± 10 years), 23 NOBD patients (age, 48 ± 14 years), and 22 HVs (age, 44 ± 13 years). One-way multivariate analysis of covariance showed a statistically significant difference in VD among the three groups when combining the layers after controlling for scan quality (P < 0.001). The VD was lowest in the BU group and highest in the HV group in all layers. The FAZ area was also statistically significant different among the groups (P < 0.005), with the largest FAZ areas in BU patients and smallest FAZ areas in the HV group. However, no statistically significant difference was found for the acircularity index. CONCLUSIONS. The parafoveal microvasculature is affected not only in BU patients but also in NOBD patients. Most deviations in the retinal microcirculation in Behҫet patients were found in the deeper layers of the retina by using the quantitative VD measurement.

Purpose Perifoveal exudative vascular anomalous complex (PEVAC) was initially described as an isolated aneurysmal lesion in healthy eyes. Similar aneurysmal abnormalities may occur in association with retinal vascular diseases such as diabetic retinopathy or retinal vein occlusions (PEVAC‐resembling). The aim of this study was to compare several imaging characteristics of PEVAC and PEVAC‐resembling lesions. Methods Ten eyes with a PEVAC and 27 eyes with a PEVAC‐resembling lesion were included in this cross‐sectional study. They were all imaged with optical coherence tomography (OCT), OCT angiography (OCT‐A) and colour fundus photography (CFP). Several clinical, morphological and vascular characteristics were assessed and compared between both PEVAC types. Results All PEVAC lesions were unilateral, while PEVAC‐resembling lesions appeared bilateral in 23% of patients (p > 0.05). Unilateral multifocal PEVAC‐resembling lesions were more frequently observed (56%) than unilateral multifocal PEVAC lesions (10%, p < 0.01). Furthermore, 90% of the PEVAC lesions were located within 500 µm from the centre of the fovea, while this was only true for 56% of the PEVAC‐resembling lesions (p > 0.05). No notable differences were observed in other studied characteristics. Conclusions The clinical, morphological and vascular features of PEVAC and PEVAC‐resembling lesions are similar based on multimodal imaging. Given the bilaterality and multifocality seen in PEVAC‐resembling lesions, an underlying retinal vascular disease may stimulate the quantity of aneurysmal abnormalities. Due to the similarities with PEVAC‐resembling lesions, PEVAC may also be considered a microangiopathy but with an unknown origin.

Purpose Only an endophytic growth pattern in juxtapapillary retinal hemangioblastoma (JRH) is an indication for surgical treatment, but classification of growth types is difficult using conventional imaging techniques. This case report describes the use of optical coherence tomography angiography (OCT-A) features for classification and treatment follow-up in a case with JRH. Observations The JRH of this patient was easily detected with two different OCT-A methods in both en-face and cross-sectional B-scan images, and was classified as a sessile growth type. This growth type excluded the treatment option of vitreoretinal surgery with excision of the lesion or ligation of the feeder vessels. The patient was treated multiple times with intravitreal bevacizumab. Treatment follow-up with OCT-A initially revealed a stable extent of the JRH, with some slight flow deviations in en-face visualization, followed by a period of progressive growth of the lesion. Conclusions OCT-A revealed the depth localization of the JRH and seems to be a valuable tool for JRH classification. Detailed classification may be useful when surgery is considered as a treatment strategy. Furthermore, treatment follow-up is possible with OCT-A, although imaging artifacts should be taken into account.