Enhanced-depth optical coherence tomography for imaging horizontal rectus muscles in Graves' orbitopathy.

PURPOSE Graves' orbitopathy (GO) is an extraocular eye disease with symptoms ranging from minor discomfort from dry eyes to strabismus and visual loss. One of the hallmarks of active GO is visible hyperemia at the insertion of the extraocular muscles. The aim of the present study was to evaluate the use of enhanced-depth imaging spectral domain anterior segment optical coherence tomography (EDI SD AS-OCT) for detecting pathological changes in horizontal recti muscles of patients with GO. METHODS Prospective cross sectional study of 27 eyes. Only women were included. EDI AS-OCT was used to measure the thickness of the tendons of the horizontal recti muscles in a predefined area in patients with GO and healthy controls. RESULTS EDI AS-OCT was able to image the tendons of the horizontal recti muscles in both healthy controls and patients suffering from GO. The mean thickness of the medial rectus muscle (MR) tendon was 256.4 μm [±17.13 μm standard deviation (SD)] in the GO group and, therefore, significantly thicker (p = 0.046) than in the healthy group which had a mean thickness of 214.7 μm (±5.516 μm SD). There was no significant difference in the mean thickness of the tendon of the lateral recti muscles (LRs) between these groups. CONCLUSION This is the first report showing that EDI AS-OCT is suitable to detect swelling at the insertion site of the MR muscle in GO. MR tendon thickness may be a useful parameter to monitor activity in these patients

Detection of Relative Afferent Pupillary Defects Using Eye Tracking and a VR Headset.

PURPOSE The purpose of this study was to assess the feasibility of detecting relative afferent pupillary defects (RAPDs) using a commercial virtual reality headset equipped with an eye tracker. METHODS This is a cross-sectional study in which we compare the new computerized RAPD test with the traditional clinical standard using the swinging flashlight test. Eighty-two participants including 20 healthy volunteers aged 10 to 88 years were enrolled in this study. We present a bright/dark stimulus alternating between the eyes every 3 seconds using a virtual reality headset, and we simultaneously record changes in pupil size. To determine the presence of an RAPD, we developed an algorithm analyzing the pupil size differences. For the assessment of the performance of the automated and the manual measurement a post hoc impression based on all available data is created. The accuracy of the manual clinical evaluation and the computerized method is compared using confusion matrices and the gold standard of the post hoc impression. The latter is based on all available clinical information. RESULTS We found that the computerized method detected RAPD with a sensitivity of 90.2% and an accuracy of 84.4%, as compared to the post hoc impression. This was not significantly different from the clinical evaluation with a sensitivity of 89.1% and an accuracy of 88.3%. CONCLUSIONS The presented method offers an accurate, easy to use, and fast method to measure an RAPD. In contrast to today's clinical practice, the measures are quantitative and objective. TRANSLATIONAL RELEVANCE Computerized testing of Relative Afferent Pupillary Defects (RAPD) using a VR-headset and eye-tracking reaches non-inferior performance compared with senior neuro-ophthalmologists

Evaluation of the Reddesa Chart, a New Red Desaturation Testing Method, for Optic Neuritis Screening and Grading in Clinical Routine.

Background Optic neuritis usually leads to reduced color sensitivity. Most often, the change of red color, the so-called red desaturation, is tested in clinical routine. The aim of this study was to test the feasibility of the Reddesa chart, a new red desaturation test based on polarization, as a screening method for optic neuropathy. Methods A total of 20 patients with unilateral optic neuritis and 20 healthy controls were included in this prospective pilot study. Ophthalmological examination included assessment of best corrected visual acuity (BCVA), slit lamp examination, fundoscopy, testing of relative afferent pupillary defect (RAPD) and red desaturation with the red cup test and the Reddesa chart. Results The mean BCVA in the optic neuritis group was 0.76 ± 0.36 in the affected eye (95% of eyes with RAPD, 75% of eyes with difference in the Reddesa test) and 1.28 ± 0.24 in the healthy eye, whereas in the control group, BCVA was 1.14 ± 0.11 in the right eye and 1.15 ± 0.14 in the left eye (none of the eyes with RAPD or abnormal Reddesa test). In our study, the Reddesa test showed a positive predictive value of 100% and a negative predictive value of 80% for detecting optic neuritis. Conclusion The Reddesa chart allows to quantify red desaturation and has the potential to be implemented as a screening test in clinical routine

Strabismus measurements with novel video goggles

PURPOSE: To assess the validity of a novel, simplified, noninvasive test for strabismus using video goggles. DESIGN: Cross-sectional method comparison study in which the new test, the strabismus video goggles, is compared with the existing reference standard, the Hess screen test. PARTICIPANTS: We studied 41 adult and child patients aged ≥6 years with ocular misalignment owing to congenital or acquired paralytic or comitant strabismus and 17 healthy volunteers. METHODS: All participants were tested with binocular infrared video goggles with built-in laser target projection and liquid crystal display shutters for alternate occlusion of the eyes and the conventional Hess screen test. In both tests, ocular deviations were measured on a 9-point target grid located at 0±15° horizontal and vertical eccentricity. MAIN OUTCOME MEASURES: Horizontal and vertical ocular deviations at 9 different gaze positions of each eye were measured by the strabismus video goggles and the Hess screen test. Agreement was quantified as the intraclass correlation coefficient. Secondary outcomes were the utility of the goggles in patients with visual suppression and in children. RESULTS: There was good agreement between the strabismus video goggles and the Hess screen test in the measurements of horizontal and vertical deviation (intraclass correlation coefficient horizontal 0.83, 95% confidence interval [0.77, 0.88], vertical 0.76, 95% confidence interval [0.68, 0.82]). Both methods reproduced the characteristic strabismus patterns in the 9-point grid. In contrast to Hess screen testing, strabismus video goggle measurements were even possible in patients with comitant strabismus and visual suppression. CONCLUSIONS The new device is simple and is fast and accurate in measuring ocular deviations, and the results are closely correlated with those obtained using the conventional Hess screen test. It can even be used in patients with visual suppression who are not suitable for the Hess screen test. The device can be applied in children as young as 6 years of age

Hess screen testing shows an exodeviation shift compared to the Harms screen test

Manifest ocular deviation (tropia) is present in strabismus patients while latent ocular deviation (phoria) is common in normal subjects. Besides the prism cover test for near and far, Hess and/or Harms screen testing are often performed to objectively assess the amount of ocular misalignment. This study investigates the differences of the results from Harms and Hess screen test, and the prism cover test

Adaptation to New Onset Incomitance (.pdf)

Incomitance is characterized by gaze dependent deviations of ocular alignment. The physiological mechanisms that maintain equal horizontal ocular alignment in all gaze directions (concomitance) in healthy individuals are poorly explored. We investigate adaptive processes in the vergence system that are induced by horizontal incomitant vergence stimuli (stimuli that require a gaze dependent vergence response in order to re-establish binocular single vision)

Imaging artifacts in fluorescence lifetime imaging ophthalmoscopy

Purpose: To investigate and quantify the influence of imaging artifacts on retinal fluorescence lifetime (FLIO) values and to provide helpful hints and tricks to avoid imaging artifacts and to improve FLIO image acquisition quality. Methods: A systematic analysis of potential parameters influencing FLIO quality and/or fluorescence lifetime values was performed in a prospective systematic experimental imaging study in five eyes of five healthy subjects. For image acquisition, a fluorescence lifetime imaging ophthalmoscope (Heidelberg Engineering) was used. Quantitative analysis of FLIO lifetime changes due to imaging artifacts was performed. Results: Imaging artifacts with significant influence on fluorescence lifetimes included too short image acquisition time, insufficient illumination, ocular surface problems, and image defocus. Prior use of systemic or topical fluorescein makes analysis of retinal fluorescence lifetimes impossible. Conclusion: Awareness of possible sources of imaging artifacts is important for FLIO image acquisition and analysis. Therefore, standardized imaging and analysis procedure in FLIO is crucial for high-quality image acquisition and the possibility for systematic quantitative fluorescence lifetime analysis

Gaze-dependent phoria and vergence adaptation

Incomitance is a condition with gaze-dependent deviations of ocular alignment and is common in strabismus patients. The physiological mechanisms that maintain equal horizontal ocular alignment in all gaze directions (concomitance) in healthy individuals are poorly explored. We investigate adaptive processes in the vergence system that are induced by horizontal incomitant vergence stimuli (stimuli that require a gaze-dependent vergence response in order to re-establish binocular single vision). We measured horizontal vergence responses elicited after healthy subjects shifted their gaze from a position that required no vergence to a position that required convergence. Repetitive saccades into a position with a convergence stimulus rapidly decreased phoria (defined as the deviation of ocular alignment in the absence of a binocular stimulus). This change of phoria was present in all viewing directions (from 0° to 0.86° ± 0.40°, p < 0.001) but was more pronounced in the gaze direction with a convergence stimulus (from 0.26° ± 0.13° to 1.39° ± 0.33°, p < 0.001). We also found that vergence velocity rapidly increased (p = 0.015) and vergence latency promptly decreased (p < 0.001). We found gaze-dependent modulation of phoria in combined saccade-vergence eye movements and also in pursuit-vergence eye movements. Thus, acute horizontal, gaze-dependent changes of vergence, such as may be encountered in new onset strabismus due to paralysis, can rapidly increase vergence velocity and decrease latency. Gaze-specific (concomitant) and gaze-independent (incomitant) phoria levels will adapt. These early adaptive processes increase the efficacy of binocular vision and maintain good ocular alignment in all directions of gaze