Denoising OCT videos based on temporal redundancy.

The identification of eye diseases and their progression often relies on a clear visualization of the anatomy and on different metrics extracted from Optical Coherence Tomography (OCT) B-scans. However, speckle noise hinders the quality of rapid OCT imaging, hampering the extraction and reliability of biomarkers that require time series. By synchronizing the acquisition of OCT images with the timing of the cardiac pulse, we transform a low-quality OCT video into a clear version by phase-wrapping each frame to the heart pulsation and averaging frames that correspond to the same instant in the cardiac cycle. Here, we compare the performance of our one-cycle denoising strategy with a deep-learning architecture, Noise2Noise, as well as classical denoising methods such as BM3D and Non-Local Means (NLM). We systematically analyze different image quality descriptors as well as region-specific metrics to assess the denoising performance based on the anatomy of the eye. The one-cycle method achieves the highest denoising performance, increases image quality and preserves the high-resolution structures within the eye tissues. The proposed workflow can be readily implemented in a clinical setting.

Ocular rigidity and choroidal thickness changes in response to microgravity: A case study.

Purpose: To evaluate ocular rigidity and choroidal thickness changes in response to microgravity and the Valsalva maneuver in a private astronaut. Methods: Ophthalmological examination and Optical Coherence Tomography were performed before, during, and after space flight. Choroidal thickness was measured at all time points at rest and during the Valsalva maneuver. Ocular rigidity was obtained before and after flight using a non-invasive method enhanced with deep learning-based choroid segmentation. Results: Ocular rigidity decreased after space flight compared to baseline. There was an increase in average choroidal thickness during the Valsalva maneuver compared to the resting condition before, during, and after space flight, and such increase was greater when the Valsalva maneuver was performed during space flight. Conclusions and importance: The data indicates biomechanical changes to ocular tissues because of space flight and greater choroidal thickness increase. The findings could lead to a better understanding of space flight-associated neuro-ocular syndrome and may have repercussions for short duration missions in a nascent industry.

Quantification of Hypotony Maculopathy Using Spectral-Domain Optical Coherence Tomography.

PRCIS: We provide a free-to-use, open-source algorithm to quantify macular hypotony based on optical coherence tomography (OCT) images. This numerical approach calculates a metric that measures the deviations of Bruch's membrane from a smooth ideal retinal layer. PURPOSE: Hypotony maculopathy is a recurrent complication of glaucoma surgical interventions in which extremely low intraocular pressure triggers changes in the shape of retinal layers. Abnormal folds can often be observed in the retina using standard fundoscopy, but OCT is particularly important to appreciate the severity of symptoms at different depths. Despite the need for metrics that could be used for the informed clinical decision to evaluate the progression and resolution of macular hypotony, algorithms that quantify the retinal folds are not available in the literature or included in clinical imaging equipment. The purpose of this work is to introduce a simple algorithm that can be used to assess hypotony maculopathy from OCT B-Scans and volumes and a free, open-source implementation. METHODS: The pipeline we present is based on a straightforward segmentation of Bruch's membrane complex. The principal idea of quantification is to compute a smoothed version of this complex and analyze the deviations from an ideal interface. Such deviations are then measured and added to create a metric that characterizes each OCT B-Scan. A full OCT volume reconstruction is thus characterized by the average metric obtained from all planes. RESULTS: We tested the metric we proposed against the assessment of 3 experts and obtained a very good correspondence, with Pearson correlation coefficients higher than 0.8. Furthermore, agreement with automatic analysis seemed better than between experts. We describe the pipeline in detail and illustrate the results with a group of patients, comparing baseline images, severe hypotony maculopathy, and a variety of outcomes. CONCLUSION: The tool we introduce and openly provide fills a clinical gap to quantitatively grade hypotony maculopathy. It offers a metric of relatively simple interpretation that can be used to help clinicians in cases where the regression of symptoms is not obvious to the naked eye. Our pilot study demonstrates reliable results, and an open-source implementation facilitates easy improvements to our algorithm.

Ocular Rigidity and Current Therapy.

Purpose: Ocular rigidity (OR) is an important biomechanical parameter of the eye accounting for the material and geometrical properties of the corneoscleral shell.Methods: This study used a literature search to review the role of ocular rigidity and the application of potential therapies targeting this parameter in glaucoma and myopia.Conclusion: Biomechanical modeling and improved understanding of the biochemistry, and molecular arrangement of sclera and its constituents have yielded important insights. Recent developments, including that of a non-invasive and direct OR measurement method and improved ocular imaging techniques are helping to elucidate the role of OR in healthy and diseased eyes by facilitating large scale and longitudinal clinical studies. Improved understanding of OR at the initial stages of disease processes and its alterations with disease progression will undoubtedly propel research in the field. Furthermore, a better understanding of the determinants of OR is helping to refine novel therapeutic approaches which target and alter the biomechanical properties of the sclera in sight-threatening conditions such as glaucoma and myopia.

Ocular rigidity and neuroretinal damage in patients with vasospasticity: a pilot study.

OBJECTIVE: Evidence suggests that ocular blood flow dysregulation in patients with vasospasticity could occur in response to biomechanical stimuli, contributing to optic nerve head susceptibility in glaucoma. We evaluate the role of vasospasticity in the association between ocular rigidity (OR) and neuroretinal damage, hypothesizing that low OR correlates with greater glaucoma damage in patients with vasospasticity. DESIGN: Cross-sectional study. PARTICIPANTS: Patients with open-angle glaucoma (OAG), suspect discs, or no glaucoma. METHODS: OR was measured using a noninvasive, validated method developed by our group. Retinal nerve fibre layer (RNFL) and ganglion cell complex thicknesses were acquired using spectral domain optical coherence tomography. Vasospasticity was assessed by a standardized questionnaire that was based on existing validated questionnaires and adapted to our requirements. Atherosclerosis was evaluated based on Broadway and Drance's (1998) cardiovascular disease score. Correlations between OR and structural parameters were assessed in patients with vasospasticity and those with atherosclerosis. RESULTS: Of 118 patients with either OAG (n = 67), suspect discs (n = 26), or no glaucoma (n = 25) who were recruited consecutively, 10 were classified as having vasospasticity, and 37 as having atherosclerosis. In the vasospastic group, significant correlations were found between OR and the minimum ganglion cell complex thickness (rs = 0.681, p = 0.030), the average RNFL thickness (rs = 0.745, p = 0.013), and the RNFL in the temporal quadrant (rs = 0.772, p = 0.009), indicating more damage with lower OR. Similar trends were maintained when applying multiple testing correction; however, only the eighth RNFL clock hour corresponding to the inferior-temporal peripapillary region remained significantly correlated with OR in the vasospastic group (p = 0.015). In contrast, no correlation was found in the atherosclerotic group (p > 0.05). CONCLUSIONS: The findings of the current pilot study indicate a trend for more neuronal structural damage in less-rigid eyes of patients with vasospasticity, meaning that OR may play a greater role in glaucoma in vasospastic patients than in patients with atherosclerosis. Although these results provide interesting insight into the pathophysiology of OAG, further investigation is needed to confirm our observations.

Mapping Pulsatile Optic Nerve Head Deformation Using OCT.

Objective: To develop a noninvasive technique to quantitatively assess the pulsatile deformation due to cardiac contractions of the optic nerve head (ONH). Design: Evaluation of a diagnostic test or technology. Participants: Healthy subjects with no history of refractive surgery, divided into 2 cohorts on the basis of their axial length (AL). Methods: We present a noninvasive technique to quantitatively assess the pulsatile deformation of the ONH tissue by combining high-frequency OCT imaging and widely available image processing algorithms. We performed a thorough validation of the approach, numerically and experimentally, evaluating the sensitivity of the method to artificially induced deformation and its robustness to different noise levels. We performed deformation measurements in cohorts of healthy (n = 9) and myopic (n = 5) subjects in different physiological strain conditions by calculating the amplitude of tissue displacement in both the primary position and abduction. The head rotation was measured using a goniometer. During imaging in abduction, the head was rotated 40° ± 3°, and subjects were instructed to direct their gaze toward the OCT visual target. Main Outcome Measures: Pulsatile tissue displacement maps. Results: The robustness of the method was assessed using artificial deformations and increasing noise levels. The results show acceptable absolute errors before the noise simulations grossly exaggerate image degradation. For the group of subjects with AL of < 25 mm (n = 9), the median pulsatile displacement of the ONH was 7.8 ± 1.3 µm in the primary position and 8.9 ± 1.2 µm in abduction. The Wilcoxon test showed a significant difference (P ≤ 0.005) between the 2 paired measures. Reproducibility was tested in 2 different sessions in 5 different subjects with the same intraocular pressure, and an intraclass correlation coefficient of 0.99 was obtained (P < 0.005). Conclusions: The computational pipeline demonstrated good reproducibility and had the capacity to accurately map the pulsatile deformation of the optic nerve. In a clinical setting, we detected physiological changes in normal subjects supporting its translation potential as a novel biomarker for the diagnosis and progression of optic nerve diseases.

Correlation of ocular rigidity with intraocular pressure spike after intravitreal injection of bevacizumab in exudative retinal disease.

BACKGROUND/AIMS: To evaluate the non-invasive measurement of ocular rigidity (OR), an important biomechanical property of the eye, as a predictor of intraocular pressure (IOP) elevation after anti-vascular endothelial growth factor (anti-VEGF) intravitreal injection (IVI). METHODS: Subjects requiring IVI of anti-VEGF for a pre-existing retinal condition were enrolled in this prospective cross-sectional study. OR was assessed in 18 eyes of 18 participants by measurement of pulsatile choroidal volume change using video-rate optical coherence tomography, and pulsatile IOP change using dynamic contour tonometry. IOP was measured using Tono-Pen XL before and immediately following the injection and was correlated with OR. RESULTS: The average increase in IOP following IVI was 19±9 mm Hg, with a range of 7-33 mm Hg. The Spearman correlation coefficient between OR and IOP elevation following IVI was 0.796 (p<0.001), showing higher IOP elevation in more rigid eyes. A regression line was also calculated to predict the IOP spike based on the OR coefficient, such that IOP spike=664.17 mm Hg·µL×OR + 4.59 mm Hg. CONCLUSION: This study shows a strong positive correlation between OR and acute IOP elevation following IVI. These findings indicate that the non-invasive measurement of OR could be an effective tool in identifying patients at risk of IOP spikes following IVI.

The Association Between Ocular Rigidity and Neuroretinal Damage in Glaucoma.

Purpose: Ocular rigidity (OR) is an important biomechanical property, thought to be relevant in the pathophysiology of open-angle glaucoma (OAG). This study aims to evaluate the relationship between OR and neuroretinal damage caused by glaucoma. Methods: One hundred eight subjects (22 with healthy eyes, 23 with suspect discs, and 63 with OAG) were included in this study. OR was measured using a noninvasive optical coherence tomography (OCT)-based method developed by our group. We also measured central corneal thickness (CCT), corneal hysteresis (CH), and corneal resistance factor (CRF). Pearson and partial correlations were performed to evaluate the relationship between OR and glaucomatous damage represented by ganglion cell complex (GCC), retinal nerve fiber layer (RNFL) thicknesses, and neuroretinal rim area. Results: Significant positive correlations were found between OR and minimum GCC thickness (r = 0.325, P = 0.001), average GCC thickness (r = 0.320, P = 0.002), rim area (r = 0.344, P < 0.001), and RNFL thickness in the superior (r = 0.225, P = 0.023), and inferior (r = 0.281, P = 0.004) quadrants. These correlations were generally greater than those found for CCT, CH, and CRF. Furthermore, no correlation was found between OR and corneal biomechanical parameters. After adjusting for age, sex, and ethnicity, significant correlations were found between OR and minimum and average GCC thickness (r = 0.357, P = 0.001 and r = 0.344, P = 0.001, respectively), rim area (r = 0.327, P = 0.001), average RNFL thickness (r = 0.331, P = 0.001), and RNFL thickness in the superior (r = 0.296, P = 0.003) and inferior (r = 0.317, P = 0.001) quadrants. Conclusions: In this study, we found a positive correlation between structural OCT-based parameters and OR, indicating more neuroretinal damage in eyes with lower OR. These findings could provide insight into the pathophysiology of OAG.

Non-invasive in vivo measurement of ocular rigidity: Clinical validation, repeatability and method improvement.

Ocular rigidity (OR) is thought to play a role in the pathogenesis of glaucoma, but the lack of reliable non-invasive measurements has been a major technical challenge. We recently developed a clinical method using optical coherence tomography time-lapse imaging and automated choroidal segmentation to measure the pulsatile choroidal volume change (ΔV) and calculate OR using Friedenwald's equation. Here we assess the validity and repeatability of this non-invasive technique. We also propose an improved mathematical model of choroidal thickness to extrapolate ΔV from the pulsatile submacular choroidal thickness change more accurately. The new mathematical model uses anatomical data accounting for the choroid thickness near the equator. The validity of the technique was tested by comparing OR coefficients obtained using our non-invasive method (OROCT) and those obtained with an invasive procedure involving intravitreal injections of Bevacizumab (ORIVI) in 12 eyes. Intrasession and intersession repeatability was assessed for 72 and 8 eyes respectively with two consecutive measurements of OR. Using the new mathematical model, we obtained OR values which are closer to those obtained using the invasive procedure and previously reported techniques. A regression line was calculated to predict the ORIVI based on OROCT, such that ORIVI = 0.655 × OROCT. A strong correlation between OROCT and ORIVI was found, with a Spearman coefficient of 0.853 (p < 0.001). The intraclass correlation coefficient for intrasession and intersession repeatability was 0.925, 95% CI [0.881, 0.953] and 0.950, 95% CI [0.763, 0.990] respectively. This confirms the validity and good repeatability of OR measurements using our non-invasive clinical method.

The effects of anti-VEGF and kinin B1 receptor blockade on retinal inflammation in laser-induced choroidal neovascularization.

BACKGROUND AND PURPOSE: Age-related macular degeneration (AMD) is a complex neurodegenerative disease treated by anti-VEGF intravitreal injections. As inflammation is potentially involved in retinal degeneration, the pro-inflammatory kallikrein-kinin system is a possible alternative pharmacological target. Here, we investigated the effects of anti-VEGF and anti-B1 receptor treatments on the inflammatory mechanisms in a rat model of choroidal neovascularization (CNV). EXPERIMENTAL APPROACH: Immediately after laser-induced CNV, Long-Evans rats were treated by eye-drop application of a B1 receptor antagonist (R-954) or by intravitreal injection of B1 receptor siRNA or anti-VEGF antibodies. Effects of treatments on gene expression of inflammatory mediators, CNV lesion regression and integrity of the blood-retinal barrier was measured 10 days later in the retina. B1 receptor and VEGF-R2 cellular localization was assessed. KEY RESULTS: The three treatments significantly inhibited the CNV-induced retinal changes. Anti-VEGF and R-954 decreased CNV-induced up-regulation of B1 and B2 receptors, TNF-α, and ICAM-1. Anti-VEGF additionally reversed up-regulation of VEGF-A, VEGF-R2, HIF-1α, CCL2 and VCAM-1, whereas R-954 inhibited gene expression of IL-1ß and COX-2. Enhanced retinal vascular permeability was abolished by anti-VEGF and reduced by R-954 and B1 receptor siRNA treatments. Leukocyte adhesion was impaired by anti-VEGF and B1 receptor inhibition. B1 receptors were found on astrocytes and endothelial cells. CONCLUSION AND IMPLICATIONS: B1 receptor and VEGF pathways were both involved in retinal inflammation and damage in laser-induced CNV. The non-invasive, self-administration of B1 receptor antagonists on the surface of the cornea by eye drops might be an important asset for the treatment of AMD.

Patch graft using collagen matrix (Ologen) for glaucoma drainage device exposure in a patient with Boston Keratoprosthesis type 1.

PURPOSE: To report the first successfully treated case of recurrent tube exposure in a patient with the Boston Keratoprosthesis type 1 with a collagen matrix patch graft (Ologen). OBSERVATIONS: A 50 year-old female with a Boston Keratoprosthesis type 1 and a history of Axenfeld-Reiger syndrome presents to our department with recurrent glaucoma drainage device exposure in her left eye. After failed spontaneous closure with topical antibiotics and lubricants, she undergoes tube exposure repair using an Ologen patch graft. Surgery was successful and the patient did not have any recurrence up to last follow-up two years post-operatively. CONCLUSION: Collagen matrix patch graft seems to be advantageous in treating glaucoma tube exposure in the Boston KPro eye, which is often a more challenging entity to treat. IMPORTANCE: Collagen matrix patch graft could be considered as a primary patch graft in treating tube exposure in eyes with the Boston KPro.

Surgical Outcome of Replacing a Failed Ahmed Glaucoma Valve by a Baerveldt Glaucoma Implant in the Same Quadrant in Refractory Glaucoma.

PURPOSE: The purpose of this study was to describe the surgical technique and outcomes in eyes that underwent surgery to replace a failed Ahmed valve by a Baerveldt glaucoma implant in the same quadrant. METHODS: This study was a retrospective case series of 9 patients. Parameters analyzed include age, glaucoma type, prior surgery, complications, intraocular pressure (IOP), visual acuity, and number of glaucoma medications before and after the surgery. Surgical success was defined as having either an IOP below 21 mm Hg or a 20% IOP reduction, with or without hypotensive agent. RESULTS: The mean follow-up duration was 47 months. After surgery, at the time of final follow-up, the mean IOP decreased from 29.9 mm Hg to 16.7 mm Hg (36% of mean IOP reduction; P=0.008). There was a significant reduction of hypotensive agents from a mean of 4.33 to 2.22 (P=0.02). The visual acuity did not have a significant deterioration (P=0.07). In the final visit, 5 of 9 patients met total success criteria and 2 patients were qualified successes. Two cases failed totally after 69 and 125 months of follow-up. The cumulative probability of total success after 6 months was 76% and this rate remained stable until the sixth year. One patient had bullous keratopathy. Two patients had early postoperative pressure spikes: the first patient was treated by trabeculectomy, and the second by vitrectomy. CONCLUSIONS: A replacement of the failed Ahmed glaucoma valve by a new Baerveldt glaucoma implant in the same quadrant can be a reasonable choice to control refractory glaucoma.

Small-Gauge Endoscopy-Guided Pneumatic Anterior Hyaloid Detachment: A New Surgical Technique for Combined Pars Plana Vitrectomy and Pars Plana Glaucoma Drainage Implant.

BACKGROUND AND OBJECTIVE: Pars plana glaucoma drainage implant (GDI) occlusion is mainly related to entrapment of residual anterior vitreous gel in the implant. The aim of the present report is to describe a new surgical technique to induce pneumatic anterior hyaloid detachment in eyes with GDI. PATIENTS AND METHODS: This is a description of the surgical technique used to induce pneumatic anterior hyaloid detachment. RESULTS: The technique was used in two cases. The first patient had secondary Ahmed valve (New World Medical, Rancho Cucamonga, CA) obstruction secondary to anterior vitreous entrapment; the second patient had neovascular glaucoma secondary to proliferative diabetic retinopathy and underwent pars plana GDI implantation. CONCLUSION: Endoscopy-assisted anterior hyaloid detachment allows for complete removal of anterior hyaloid and decreases the risk of secondary implant obstruction. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:48-50.].

Pilot study of the pulsatile neuro-peripapillary retinal deformation in glaucoma and its relationship with glaucoma risk factors.

PURPOSE: To perform a pilot study of the neuro-peripapillary retinal tissue deformation during the cardiac cycle among healthy eyes, ocular hypertensive (OHT), open angle glaucoma suspect (OAG-S), and early open angle glaucoma (EOAG) patients using video rate optical coherence tomography (OCT) image series. METHODS: OCT line scan sequences of the same region of the optic nerve head (ONH) were obtained from 15 EOAG, 6 OHT, 10 OAG-S, and 10 healthy age-matched eyes. One eye per patient was studied. Changes in the axial distance between the inferotemporal peripapillary retina and the prelaminar tissue, in time, were determined using an automated custom made algorithm. Linear correlations between this neuro-peripapillary retinal (N-PP) deformation and variables measured during the full ophthalmic examination are analyzed. RESULTS: Healthy eyes showed larger N-PP deformation (4.8 ± 1 µm) than the OHT (3.5 ± 0.3 µm, p = 0.015), OAG-S (3.8 ± 0.8 µm, p = 0.045), and EOAG (3.2 ± 0.7 µm, p < 0.001) groups. Eyes with lower ocular pulse amplitude, thinner RNFL's, or worse visual fields showed smaller N-PP deformation, depending on the diagnosis. A linear model to explain deformation within the EOAG group with intraocular pressure and systolic perfusion pressure as predictors was found to be significant (R2 = 0.767, p < 0.001). CONCLUSIONS: Smaller mean N-PP deformation was observed in the EOAG, OAG-S, and OHT groups compared to healthy eyes in this pilot study. The measured deformation correlated with risk factors for the glaucomatous optic neuropathy, but these correlations varied depending on the diagnosis. The role of pulsatile neuro-peripapillary retinal deformation in the pathophysiology of OAG remains to be determined.

Maladaptive coping strategies and glaucoma progression.

The identification of modifiable risk factors for glaucoma progression is needed. Our objective was to determine whether maladaptive coping styles are associated with recent glaucoma progression or worse visual field mean deviation.A hospital-based case-control study was conducted in the Glaucoma Service of Maisonneuve-Rosemont Hospital in Montreal, Canada. Patients with primary open angle glaucoma or normal tension glaucoma with ≥4 years of follow-up and ≥5 Humphrey visual fields were included. Cases had recent visual field progression as defined according to the Early Manifest Glaucoma Trial pattern change probability maps. Controls had stable visual fields. The Brief Cope questionnaire, a 28-item questionnaire about 14 different ways of coping with the stress of a chronic disease, was asked. Questions were also asked about demographic and medical factors, and the medical chart was examined. Outcomes included glaucoma progression (yes, no) and visual field mean deviation. Logistic and linear regressions were used.A total of 180 patients were included (82 progressors and 98 nonprogressors). Although none of the 14 coping scales were associated with glaucoma progression (P > 0.05), higher denial was correlated with worse visual field mean deviation (r = -0.173, P = 0.024). In a linear regression model including age, sex, education, depression, intraocular pressure, and family history of glaucoma, greater levels of denial (ß = -1.37, 95% confidence interval [CI] -2.32, -0.41), Haitian ethnicity (ß = -7.78, 95% CI -12.52, -3.04), and the number of glaucoma medications (ß = -1.20, 95% CI -2.00, -0.38) were statistically significantly associated with visual field mean deviation.The maladaptive coping mechanism of denial was a risk factor for worse visual field mean deviation. Further prospective research will be required to verify the pathways by which denial may exert an effect on glaucomatous visual field loss.

Neuroretinal Rim Area Change in Glaucoma Patients With Visual Field Progression Endpoints and Intraocular Pressure Reduction. The Canadian Glaucoma Study: 4.

PURPOSE: To compare rim area rates in patients with and without the visual field (VF) progression endpoint in the Canadian Glaucoma Study and determine whether intraocular pressure (IOP) reduction following the endpoint altered rim area rate. DESIGN: Prospective multicenter cohort study. METHODS: setting: University hospitals. PATIENT POPULATION: Two hundred and six patients with open-angle glaucoma were examined at 4-month intervals with standard automated perimetry and confocal scanning laser tomography. INTERVENTION: After the endpoint, IOP was reduced by ≥20%. OUTCOME MEASURES: Univariate analysis for change in rim area rate and multivariable analysis to adjust for independent covariates (eg, age, sex, and IOP). RESULTS: Patients with an endpoint (n = 59) had a worse rim area rate prior to the endpoint compared to those without (n = 147; median [interquartile range]: -14 [-32, 11] × 10(-3) mm(2)/y and -5 [-14, 5] × 10(-3) mm(2)/y, respectively, P = .02). In univariate analysis, there was no difference in rim area rate before and after the endpoint (median difference [95% CI], 8 (-10, 24) × 10(-3) mm(2)/y), but the muItivariate analysis showed that IOP reduction >2 mm Hg after the endpoint was strongly linked to a reduction in rim area rate decline (8 × 10(-3) mm(2)/y for each additional 1 mm Hg reduction). CONCLUSIONS: Patients with a VF endpoint had a median rim area rate that was nearly 3 times worse than those without an endpoint. Lower mean follow-up IOP was independently associated with a slower decline in rim area.

Impact of a Brief Educational Intervention on Glaucoma Persistence: A Randomized Controlled Clinical Trial.

PURPOSE: To determine whether two sessions of a glaucoma educational intervention resulted in better persistence to glaucoma eye drop therapy compared to normal care. METHODS: A total of 165 patients newly diagnosed with glaucoma who required eye drop therapy were recruited into a randomized clinical trial from the glaucoma clinic at Maisonneuve-Rosemont Hospital in Montreal, Canada. Patients were randomized to either an immediate intervention or normal care. The intervention consisted of two 60-90 minute sessions of education on glaucoma and its management, given in a small group format by a non-practicing ophthalmologist. Persistence to glaucoma medication was examined for 1 year by the use of Hospital medical records and by pharmacy claims records from the Régie de l'assurance maladie du Québec (Quebec Health Insurance Program). A questionnaire was administered, and medication possession ratio calculated. The primary outcome was persistence, defined as having medication available at least 75% of the time. Secondary outcomes included eye drop instillation technique and perception of the importance of eye drop therapy. RESULTS: The intervention group achieved better persistence to eye drop therapy, as 77% of controls and 89% of people receiving the intervention were persistent (p = 0.049). The intervention also resulted in better eye drop instillation technique (p < 0.001) and greater perception of the importance of eye drop therapy (p < 0.001). CONCLUSIONS: Brief instructional sessions offered to newly diagnosed glaucoma patients can result in better persistence rates over 1-year follow-up. Strategies to permanently offer these types of initiatives should be considered.

Automatic segmentation of the optic nerve head for deformation measurements in video rate optical coherence tomography.

Optical coherence tomography (OCT) imaging has become a standard diagnostic tool in ophthalmology, providing essential information associated with various eye diseases. In order to investigate the dynamics of the ocular fundus, we present a simple and accurate automated algorithm to segment the inner limiting membrane in video-rate optic nerve head spectral domain (SD) OCT images. The method is based on morphological operations including a two-step contrast enhancement technique, proving to be very robust when dealing with low signal-to-noise ratio images and pathological eyes. An analysis algorithm was also developed to measure neuroretinal tissue deformation from the segmented retinal profiles. The performance of the algorithm is demonstrated, and deformation results are presented for healthy and glaucomatous eyes.

Gonioscopic findings associated with a positive dark-room provocative test in narrow angles after laser iridotomy.

PURPOSE: To determine clinical factors and ultrasound biomicroscopic (UBM) findings associated with a positive prone dark-room provocative test (DRPT) in patients with narrow angles after laser peripheral iridotomy (LPI). PATIENTS AND METHODS: Seventeen eyes with a positive DRPT and 18 eyes with a negative DRPT were included in this comparative case series, based on chart review of patients diagnosed with narrow angles persisting after LPI who had undergone clinical evaluation with a 45-minute DRPT and UBM imaging. Subjects with a positive DRPT [an increase of intraocular pressure (IOP) of 6 mm Hg or more] were compared with a negative DRPT control group. Charts were reviewed for age, refraction and gonioscopic examination. UBM measurements obtained included the anterior chamber depth, angle opening distance at 500 µm, angle recess area, anterior chamber angle, trabecular-ciliary process distance, iris thickness, iris-ciliary process distance, height of plateau, and distance of iris-cornea contact. RESULTS: Mean increase in IOP was 11.1±3.5 mm Hg in the positive DRPT group (group A) and 0.9±0.1 mm Hg in the negative DRPT (group B). On indentation gonioscopy, patients in group A had significantly more synechial angle closure of 180 degrees or more (35% vs. 0%, P=0.008), more frequent double-hump sign (59% vs. 11%, P=0.005), and significantly more patients in this group had at least one of these findings, (13/16 vs. 2/15, P=<0.001). Mean age did not differ between groups (P=0.88). There were significantly more women in group B (58% men in group A and 83% women in group B, P=0.01). Mean refraction was +3.41±2.27 D in group A and +2.60±2.06 D in group B (P=0.32). There were no statistically significant differences in any of the UBM parameters between the 2 groups. CONCLUSIONS: A positive DRPT was found in patients presenting a more compromised drainage angle after LPI, due to anterior synechiae and/or an anteriorly positioned ciliary body as shown by the presence of a double-hump sign. DRPT may help identify patients at higher risk of intermittent increases in IOP among those presenting persistent narrow angles after LPI, and indentation gonioscopy remains an important step in evaluating these patients.