A retrospective study assessing the factors associated with visual outcome in retinal vein occlusion patients after anti-VEGF therapy

Background Retinal vein occlusion (RVO) is one of the most frequent retinal vascular diseases. In this study, we aimed to investigate the predictive factors of visual outcome for RVO patients who underwent anti-vascular endothelial growth factor (VEGF) therapy. Methods RVO patients who underwent anti-VEGF treatment were recruited in this study from January 2018 to June 2020. Clinical data and optical coherence tomography (OCT) parameters were retrospectively reviewed. Best-corrected visual acuity (BCVA) was examined at baseline and after anti-VEGF therapy. Predictive factors associated with visual outcome were assessed by logistic regression model. Treatment-related adverse events were also recorded. Results The average logMAR BCVA was 0.91 at baseline and 0.70 at final examination (P = 0.003). Among 75 patients, 41 experienced visual improvement were categorized as group A, the remaining 34 patients without improved vision were categorized as group B. Patients in group A demonstrated better visual outcomes, including decreased logMAR BCVA (average logMAR BCVA: 0.53 in group A vs. 0.91 in group B, P < 0.001) and central retinal thickness (CRT) (average CRT: 230.88 µm in group A vs. 404.97 µm in group B, P < 0.001) after anti-VEGF treatment. Multivariable analysis showed that injection frequency (odds ratio [OR], 2.623; 95% confidence interval [CI], [1.282–5.366]), hypertension (odds ratio [OR], 0.189; 95% CI [0.044–0.811]), hyperlipemia (odds ratio [OR], 0.195; 95% CI [0.040–0.941]) and external limiting membrane (ELM) disruption (odds ratio [OR], 0.148; 95% CI [0.032–0.691]) were all significantly associated with the visual outcome of RVO patients who underwent anti-VEGF treatment. In general, anti-VEGF therapy was feasible for all RVO patients, though the response to anti-VEGF was suboptimal in certain patients. Prognostic factors including injection frequency, hypertension, hyperlipemia and ELM disruption may all be useful to provide predictive information of visual outcome of RVO patients in response to anti-VEGF treatment

An Autocollimator Axial Measurement Method Based on the Strapdown Inertial Navigation System

Autocollimators are widely used optical axis-measuring tools, but their measurement errors increase significantly when measuring under non-leveled conditions and they have a limited measurement range due to the limitations of the measurement principle. To realize axis measurement under non-leveled conditions, this paper proposes an autocollimator axis measurement method based on the strapdown inertial navigation system (SINS). First, the measurement model of the system was established. This model applies the SINS to measure the change in attitude of the autocollimator. The autocollimator was then applied to measure the angular relationship between the measured axis and its own axis, based on which the angular relationship of the axis was measured via computation through signal processing and data fusion in a multi-sensor system. After analyzing the measurement errors of the system model, the Monte Carlo method was applied to carry out a simulation analysis. This showed that the majority of the measurement errors were within ±0.002° and the overall measurement accuracy was within ±0.006°. Tests using equipment with the same parameters as those used in the simulation analysis showed that the majority of the measurement errors were within ±0.004° and the overall error was within ±0.006°, which is consistent with the simulation results. This analysis proves that this method solves the problem of the autocollimator being unable to measure the axis under non-leveled conditions and meets the needs of axis measurement with the application of autocollimators under a moving base