Statistics from Altmetric.com
Editor,—Behçet’s disease (BD) is an immune system related obstructive vasculitis characterised by recurrent inflammation that affects multiple systems. Posterior uveitis and retinal vasculitis are the common features of ocular involvement.1-3 Colour Doppler imaging (CDI) is a non-invasive ultrasonographic method which permits simultaneous grey scale imaging of structure and colour coded imaging of blood velocity. CDI has successfully demonstrated changes in orbital haemodynamics associated with a variety of pathological conditions.4-7In the present study the haemodynamic changes in ophthalmic (OA), central retinal (CRA), and posterior ciliary arteries (PCA) of the patients with BD were investigated by using CDI.
The study group consisted of 26 patients with BD (five females, 21 males), aged between 22 and 58 (mean 32.19 (SD 8.27)). Diagnosis was made according to the criteria recommended by International Study Group for Behçet’s disease.8 Control group consisted of 20 males, six females, aged between 21 and 58 (31.49 (8.60)), who had no ocular or systemic pathology other than presbyopia.
After performing full ophthalmological evaluation, transocular CDI was performed in all the patients and controls with a colour Doppler sonographic unit (General Electric Sonochrome 625L, Les Moulineaux, France) with a 7.5 MHz linear transducer. CDI was performed to both eyes of Behçet’s patients and left eyes of the controls. Activity status of the patients was evaluated according to the ocular findings. During CDI, eyes of Behçet’s patients who had cells in anterior chamber, cells in the vitreous, macular oedema, papillary oedema, retinal vasculitis, and exudation in pars plana or retina were encountered as active, and the ones without any activity but with permanent damage were encountered as inactive. Peak systolic velocity (PSV), end diastolic velocity (EDV), and average flow velocities (AFV) were calculated by using flow spectrums. Resistivity (RI) and pulsatility indexes (PI) were calculated by using flow velocities. Statistical analysis was performed in three stages by using Mann–Whitney U test for independent groups and Wilcoxon signed rank sum test for paired data. p Values were taken from Mann–Whitney U test.
During CDI 21 eyes were active and 30 eyes were inactive. The left eye of a single patient was phthisical and it was encountered as inactive. Results were analysed in three stages. In the first stage, the flow velocities and indexes in right and left eyes of the patients were compared regarding the activity status during CDI. No statistically significant difference was detected in the flow velocities and indexes of three arteries in any of the groups. In stage two, only flow velocities and indexes of OA, CRA, and PCA in left eyes of the patients were compared with the controls. There was a statistically significant reduction in PSV, EDV, and AFV of PCA in both inactive and active eyes compared with controls. However, the increase in RI and PI of PCA in patients compared with controls was short of statistical significance. In the third stage flow velocities and indexes of three arteries in all left eyes and right eyes of the patients were compared with control eyes irrespective of the activity status (Tables 1 and 2). In all patients there was a statistically significant reduction in EDV and AFV, and a significant increase in RI and PI of CRA than controls. Also the reduction of flow velocities of PCA in patients was statistically significant. The increase in RI and PI of PCA in left eyes was significant; however, in right eyes it was fell short of significance.
In the present study, no significant difference in between the flow velocities of active and inactive eyes of Behçet’s patients was detected; however, there was a significant reduction in EDV and AFV of PCA and CRA in eyes of Behçet’s patients regardless of the activation, than the controls. This shows that haemodynamic changes occur in BD which are not always correlated with clinical presentation. It could be postulated that CRA involvement plays an important role in the pathogenesis of BD, as it is shown that inner retinal layers are the main region affected in BD. However, the results of our study showed that choroidal circulation is also affected by vasculitis although it is rarely detected clinically. In a previous study carried out in Behçet’s patients, PSV and EDV of PCA of the patients with ocular involvement was found to be significantly reduced compared with those without ocular involvement and the controls.9 A preliminary report on CDI in BD revealed that PSV of CRA and CRV were significantly lower in patients with ocular involvement irrespective of the activation compared with the cases without ocular involvement. This might be the result of occlusive vasculitis seen in retinal vessels in BD. However, no difference was detected in flow velocities in PCA between the patients and controls, which is not in accordance with our findings.10 The insignificant difference in the flow velocities of OA between the patients and the controls might be due to the predilection of the inflammatory process for small arteries in BD.
In conclusion, CDI is a useful technique in evaluating orbital haemodynamic changes in BD non-invasively, and the quantitative findings could help to determine the ultimate degree of ocular damage and visual outcome; however, the clinical significance of our findings are yet to be determined.
The authors wish to thank Professor Refik Burgut for advice on the statistical methods and assistance with the data analysis.