Red-Free (Green) Filter-Enhanced Gonioscopy with Smartphone: A Pilot Study.

AIM: This pilot study aimed to demonstrate the usefulness of the red-free (green) filter as a novel modification for better iridocorneal angle visibility during routine gonioscopy. METHODS: As a pilot project, we observed 20 eyes of 10 patients aged 22 to 60 who attended the glaucoma department of a tertiary eye hospital in Bangladesh. All patients underwent a thorough ocular examination, from best-corrected visual acuity to the dilated fundus evaluation. Images and videos were obtained with a smartphone during gonioscopy with standard halogen light and the red-free (green) filter, subjectively analyzed by two glaucoma specialists. RESULTS: The mean age of the patients was 37 ± 13.42 years, of whom 70% were men. In this study, 40% of the patients had open-angle glaucoma, and 60% had open-angle without glaucoma. Without impairing the ability to see the iridocorneal angle structures in detail, the gonioscopy picture contrast was enhanced objectively for red-free filter images compared to standard light photos. The built-in warm filter of the slit-lamp also provided better visualization of the iridocorneal angle structures. CONCLUSION: Using the red-free (green) filter and a warm filter instead of the traditionally used standard light of the slit-lamp may significantly enhance the diagnostic capability during routine gonioscopy.

Evaluation of ciliary cleft changes after phacoemulsification using ultrasound biomicroscopy in dogs with cataracts.

Introduction: Glaucoma is one of the most serious complications that causes irreversible blindness after phacoemulsification in dogs; however, a clear mechanism has not been elucidated. This study aimed to analyse the possible anatomical factors associated with glaucoma after phacoemulsification using parameters that reflect the anatomical characteristics of dogs. Materials and methods: A total of 69 eyes of 48 dogs were included in this study. The patients were divided into three groups: normal eye (n = 18), cataract (n = 39), and post-phacoemulsification for at least 2 months after surgery (post-phaco, n = 12). For further analysis, the dogs were subdivided into two groups according to cataract stage: phacoemulsification non-candidate and candidate groups. Non-cataracts and incipient cataracts were categorized into the non-candidate group, whereas immature and mature cataracts were categorized into the candidate group. Measurements of the ciliary cleft parameters, including the area of the ciliary cleft (CCA), length of the ciliary cleft (CCL), width of the ciliary cleft (CCW), iridocorneal angle, and angle opening distance, were obtained using ultrasound biomicroscopy. Results: CCA, CCL, and CCW were significantly higher in the candidate group than in the non-candidate group. CCA, CCL, and CCW were significantly reduced in the post-phaco group compared to those in the cataract group. Based on these results, we found that the ciliary cleft expanded in cataract-affected eyes and narrowed after phacoemulsification. This may indicate that the space between the trabecular meshworks became narrower, potentially leading to an increase in the resistance of the aqueous humor. Conclusion: A narrowed ciliary cleft after phacoemulsification may be an anatomical factor associated with glaucoma.

Effect of the iridocorneal angle size on the diurnal pressure profile in a glaucoma suspect cohort and patients with glaucoma.

PURPOSE: To evaluate the impact of the iridocorneal angle size (ICAS) on the diurnal intraocular pressure (IOP) in patients with suspected glaucoma (SG). METHOD: Patients with any eye-pressure lowering medication or previous ocular surgery were excluded. In a retrospective study set, diurnal IOP profiles of 120 patients (205 eyes) within a 48-h period were analysed by regression analysis. Of those eyes, 44 were diagnosed to have glaucoma. The remaining eyes were used as healthy control group (HCG). RESULTS: The overall mean IOP was 15.63 mmHg ± 2.72 mmHg and mean ICAS was 23.92° ± 4.74°. In the glaucoma cohort, mean IOP was 18.77 ± 1.86 mmHg and mean ICAS was 25.02° ± 4.96°. In the HCG, mean IOP was 14.77 ± 2.25 mmHg and mean ICAS was 23.62° ± 4.64°. In the total cohort, as well as in the subgroups (HCG or glaucoma), regression analysis showed no significant impact even of the minimum ICAS, which was larger than 10°, on average (P = 0.89), maximum (P = 0.88), and range of IOP (P = 0.49) within 48 h. The difference between glaucoma cohort and HCG cohort was significant in terms of IOP (P < 0.001), but not for minimum ICAS (P = 0.07). Chi-square test showed no increase in prevalence of IOP peaks of  > 21 mmHg within 48 h in eyes with an angle between 10° and 20° (P = 0.18). CONCLUSION: An ICAS of larger than 10° in HCG or glaucoma patients with an open-angle does not influence the minimum, average, maximum or range of IOP. Additionally, an angle size larger than 10° does not allow the prediction of IOP changes in these two cohorts.

Statistical agreement of gonioscopy performed as a puppy and as an adult in the Samoyed dog.

OBJECTIVE: To assess whether gonioscopy performed on Samoyed puppies (6-14 weeks of age) is a reliable predictor of their gonioscopy results as adults (>11 months of age). PROCEDURE: A retrospective medical record search was performed to identify Samoyed dogs that had undergone gonioscopy as a puppy (6-14 weeks of age). A second prospective gonioscopy examination was performed as an adult (>11 months of age) and the results were compared. Gonioscopy was assessed on two characteristics: percent of iridocorneal angle (ICA) unaffected by pectinate ligament abnormalities (PLA) and ICA width, with PLA results categorized into unaffected ( ≥ $$ \ge $$ 75% open), moderately affected (50%-74% open), and severely affected (<50% open) and the width categorized into wide, moderate, narrow, and closed groups. A multivariate model was created that considered factors such as PLA, angle width, sex, puppy age, neuter status, and time between examinations. RESULTS: The eyes of 77 Samoyed dogs (154 eyes) met inclusion criteria. When assessing PLA, 90% of dogs had the same categorization as a puppy and as an adult. When assessing ICA width, 53.2% of dogs had the same width classification as a puppy and as an adult. There is strong evidence that variation between puppy and adult results increases with time between examination (p = .03). CONCLUSION: Puppies unaffected by PLA and with a wide ICA angle, are likely to retain these features as adults. Selection of puppies with desirable gonioscopic traits may help breeders to choose dogs likely to retain these traits as adults for breeding. This may reduce the incidence of glaucoma in the breed. Puppy examinations should be performed in both eyes. Examination of adults prior to breeding remains prudent.

Short-term changes detected by corneal topography and optical coherence tomography after prophylactic laser iridotomy in primary angle closure suspect.

PURPOSE: To evaluate early changes in anterior segment parameters by Scheimpflug-Placido disc topography system and changes in retinal layers by optical coherence tomography in primary angle-closure suspects after laser peripheral iridotomy. METHODS: One eye of 26 patients with primary angle closure suspect and of 20 healthy subjects were included in this retrospective cross-sectional study. Anterior chamber depth/volume, iridocorneal angle and central corneal thickness were obtained by Scheimpflug-Placido disc topography system. Retinal thickness, retinal nerve fiber layer thickness and ganglion cell-inner plexiform layer thickness were acquired by optical coherence tomography. All the tests were repeated 1 week and 1 month after laser peripheral iridotomy. RESULTS: The mean ages of the patients and healthy controls were 64.8 ± 10.7 years and 64.5 ± 3.9 years, respectively (p = 0.990). Anterior chamber depth/volume and iridocorneal angle value were lower in the PACS group (p < 0.001, for all). Anterior chamber volume and iridocorneal angle increased significantly after laser peripheral iridotomy (p = 0.004, for both). While foveal thickness decreased significantly after laser peripheral iridotomy (p = 0.027), retinal nerve fiber layer thickness increased in superior and temporal quadrants (p = 0.038 and p = 0.016, respectively). CONCLUSION: Our results suggest that LPI in patients with PACS provides improved retinal thickness and RNFL thickness, as well as anterior chamber parameters.

Assessment by Optical Coherence Tomography of Short-Term Changes in IOP-Related Structures Caused by Wearing Scleral Lenses.

BACKGROUND: The mechanism that could increase intraocular pressure (IOP) during scleral lens (SL) wear is not fully understood, although it may be related to compression of the landing zone on structures involved in aqueous humor drainage. METHODS: Thirty healthy subjects were fitted with two SLs of different sizes (L1 = 15.8 mm, L2 = 16.8 mm) for 2 h in the right eye and left eye as a control. Central corneal thickness (CCT), parameters of iridocorneal angle (ICA), Schlemm's canal (SC), and optic nerve head were measured before and after wearing both SLs. IOP was measured with a Perkins applanation tonometer before and after lens removal and with a transpalpebral tonometer before, during (0 h, 1 h, and 2 h), and after lens wear. RESULTS: CCT increased after wearing L1 (8.10 ± 4.21 µm; p < 0.01) and L2 (9.17 ± 4.41 µm; p < 0.01). After L1 removal, the ICA parameters decreased significantly (p < 0.05). With L2 removal, nasal and temporal SC area and length were reduced (p < 0.05). An increased IOP with transpalpebral tonometry was observed at 2 h of wearing L1 (2.55 ± 2.04 mmHg; p < 0.01) and L2 (2.53 ± 2.22 mmHg; p < 0.01), as well as an increased IOP with Perkins applanation tonometry after wearing L1 (0.43 ± 1.07 mmHg; p = 0.02). CONCLUSIONS: In the short term, SL resulted in a slight increase in IOP in addition to small changes in ICA and SC parameters, although it did not seem to be clinically relevant in healthy subjects.

Evaluation of peripheral anterior synechia formation following gonioscopy-assisted transluminal trabeculotomy surgery.

PURPOSE: To quantitatively assess the development of peripheral anterior synechia (PAS) formation rate and PAS locations on gonioscopic examination following gonioscopy-assisted transluminal trabeculotomy (GATT) surgery and investigate the surgical outcomes. METHODS: A total of 35 eyes from 31 patients with open angle glaucoma who underwent GATT or combined GATT and phacoemulsification surgery were analyzed. Presence of PAS was assessed on gonioscopy in nasal, temporal, superior and inferior quadrants at months 1, 3 and 6 following surgery. Surgical outcomes were also noted. RESULTS: Frequencies of PAS formation were 38.3%, 25.3%, 17.0% and 19.1% at postoperative 1 month, 34.0%, 26.4%, 17% and 22.6% at postoperative 3 months and 32.3%, 25.8%, 16.1% and 25.8% at postoperative 6 months, in nasal, temporal, superior and inferior quadrants, respectively. The highest amount of PAS involvement was 3 clock hours in the study which was identified only in nasal and inferior quadrants. Frequency of PAS formation did not significantly differ between nasal, temporal, superior and inferior quadrants at all time points (p > 0.05). No significant differences of mean IOP levels were observed between patients who developed PAS and who did not develop PAS at postoperative 1 month (p = 0.72), 3 months (p = 0.21) and 6 months (p = 0.59). The mean IOP and mean number of antiglaucoma medications decreased from 31.5 ± 7.2 mmHg and 3.6 ± 0.6 at baseline to 13.8 ± 3.1 mmHg and 1.6 ± 1.3 at postoperative 6 months, respectively (p < 0.001, for both). Cumulative success rate (95% confidence interval) was 74.3% (69.9-78.6%) at the end of the study. Mild to moderate degrees of hyphema occurred in all cases postoperatively. CONCLUSION: Although PAS formation was observed to be relatively higher in nasal quadrant, PAS frequency was not statistically different between the angle quadrants.

Evaluation of changes in anterior segment morphology using Sirius Scheimpflug-Placido disk topographer following laser peripheral iridotomy in primary angle-closure disease.

Purpose: To assess the morphological changes in the anterior segment following laser peripheral iridotomy (LPI) in primary angle-closure disease (PACD) using Sirius Scheimpflug-Placido disk corneal topographer. Methods: This was a prospective observational study. A total of 52 eyes of 27 patients with PACD who underwent LPI were analyzed for iridocorneal angle (ICA), anterior chamber depth (ACD), anterior chamber volume (ACV), horizontal visible iris diameter (HVID), corneal volume (CV), central corneal thickness (CCT), and horizontal anterior chamber diameter (HACD) 1 week following LPI, using Sirius Scheimpflug-Placido disk corneal topographer. Data analysis was done using Statistical Package for the Social Sciences (SPSS) software version 19.0, and paired t-test was used to assess the statistical significance. Results: Laser peripheral iridotomy was performed in 43 eyes with primary angle-closure suspect (PACS), six eyes with primary angle closure (PAC), and three eyes with primary angle-closure glaucoma (PACG). The analysis of the data showed statistically significant changes in anterior segment parameters of ICA, ACD, and ACV. Post-laser increase in ICA from 34.13° ± 2.64° to 34.75° ± 2.84° (P < 0.041), mean ACD increase from 2.21 ± 0.25 to 2.35 ± 0.27 mm (P = 0.01), and mean ACV increase from 98.19 ± 12.13 to 104.15 ± 11.16 mm3 (P = 0.001) were noted. Conclusion: Significantly quantifiable short-term changes in the anterior chamber parameters of ICA, ACD, and AC volume were seen after LPI in patients with PACD on Sirius Scheimpflug-Placido disc corneal topographer.

Optical coherence tomography and Scheimpflug imaging of the iridocorneal angle following intravitreal injection of different medications: A longitudinal analysis.

PURPOSE: Intravitreal injection of medications induces a sudden increase in posterior segment volume and pushes iris plane anteriorly to narrow iridocorneal angle. The aim of this study to follow and define longitudinal course of these changes following intravitreal injection of 3 different anti-vascular endothelial growth factor (VEGF) medications or dexamethasone implant. MATERIALS AND METHODS: This prospective, longitudinal study included 89 eyes of 89 patients that had an intravitreal injection of bevacizumab (n = 20) or ranibizumab (n = 26) or aflibercept (n = 22) or dexamethasone implant (n = 21). All the participants had a detailed ophthalmological examination including anterior segment optical coherence tomography (AS-OCT) and Scheimpflug imaging of the iridocorneal angle, evaluation of anterior chamber depth (ACD), axial length with optical biometry and endothelial cell counts with specular microscopy just before the injection, at post-injection day 1, and post-injection 1st month. RESULTS: Iridocorneal angle became significantly wider following intravitreal injection of dexamethasone implant at nasal and temporal quadrants at the post-injection 1st month both in AS-OCT (p = 0.006, p = 0.002, respectively) and Scheimpflug imaging (p = 0.003, p = 0.004, respectively). Small changes were observed in iridocorneal angle following anti-VEGF injections but these small could not be confirmed in both imaging techniques. There were also no changes in ACD, axial length and endothelial counts in all groups. CONCLUSION: Dexamethasone implants induced widening of iridocorneal angle that persisted at the post-injection 1st month both at nasal and temporal quadrants. However, intravitreal injection of anti-VEGF agents did not have a comparable effect on iridocorneal angle.

Equine pectinate ligament descemetization is associated with age.

PURPOSE: To evaluate the correlation between equine pectinate ligament descemetization and ocular disease. METHODS: The pathology database of the North Carolina State University Veterinary Medical Center was searched from 2010-2021 for all equine globes. Disease status was then assigned as affected by glaucoma, uveitis, or "other" based upon clinical records. The iridocorneal angles (ICA) of each globe were evaluated for the presence of pectinate ligament descemetization, the length of descemetization, as well as for the degree of angle collapse and the extent of cellular infiltrate or proteinaceous debris. One slide from each eye was evaluated by two separate, blinded investigators (HW & TS). RESULTS: A total of 66 eyes from 61 horses were identified, with a total of 124 sections of ICA of sufficient quality to review. 16 horses were affected by uveitis, 8 by glaucoma, 7 by both glaucoma and uveitis, and 30 horses by other ocular disease, most commonly ocular surface disease or neoplasia, which served as controls. Pectinate ligament descemetization was most prevalent in the control group compared to the glaucoma and uveitis groups. Pectinate ligament descemetization length was positively correlated with age, with an increase of 13.5 µm per year of age (p = .016). Infiltrate scores and angle closure scores were higher in both the glaucoma and uveitis group compared to the control group (p < .001). CONCLUSIONS: Equine pectinate ligament descemetization appears to be correlated with increased age and should not be used as a histologic marker for the presence of glaucoma.

A Prospective Observational Study on Changes in Intraocular Pressure and Iridocorneal Angle Following the Use of Escitalopram and Amitriptyline.

Background: Depression has emerged as one of the prime morbidities affecting professional and personal lives worldwide. Antidepressants are one of the mainstays of management of depressive episodes. Although antidepressants are considered a safe class of drugs, the studies examining the effects of antidepressant prescription on intraocular pressure (IOP) have shown a propensity to increase IOP, but not consistently. This study aimed to compare the changes in IOP and iridocorneal angle in drug-naïve patients with depressive episodes prescribed escitalopram or amitriptyline. Methods: Overall, 109 patients were recruited, of which 53 were prescribed amitriptyline and 56, escitalopram. A comparison of IOP and the iridocorneal angle at weeks 0, 4, and 8 was done using a two-way repeated-measures analysis of variance (two-way RM analysis of variance). Results: Patients initiated on escitalopram tended to show a higher rise in the IOP (left eye-[F = 3.27; P = 0.04]; right eye [F = 2.47; P = 0.08]). No difference was found in the iridocorneal angles in any of the four quadrants across both eyes. Conclusions: Escitalopram use had an association with an increase in IOP. While initiating patients on antidepressants, clinicians should be aware of this possibility, which can lead to ocular emergencies, and obtain a proper history of ocular morbidities.

The Clinical Approach to Canine Glaucoma.

This article provides a simplified approach to diagnosis and clinical decision making in cases of canine glaucoma for the general practitioner. An overview of the anatomy, physiology, and pathophysiology related to canine glaucoma is provided as a foundation. Classifications of glaucoma based on cause are described as congenital, primary, and secondary, and a discussion of key clinical examination findings is provided to guide appropriate therapy and prognostication. Finally, a discussion of emergency and maintenance therapy is provided.

Changes in anterior chamber dimensions following small incision lenticule extraction (SMILE).

PURPOSE: To evaluate the changes in anterior chamber dimensions including horizontal anterior chamber diameter (HACD), anterior chamber depth (ACD), and iridocorneal angle (ICA) following small incision lenticule extraction (SMILE) using Scheimpflug-Placido disk tomographer (Sirius). METHODS: The records of the 73 eyes of 47 patients who received SMILE for myopia and myopic astigmatism were retrospectively reviewed. Preoperative and 6-month postoperative measurements of central corneal thickness (CCT), HACD, ACD, ICA, nasal anterior chamber angle (nACA), and temporal anterior chamber angle (tACA) were obtained by tomography, and compared with paired t-tests. Pearson's correlation and linear regression tests were used to evaluate the relationship between these parameters. RESULTS: The CCT, HACD, and ACD values decreased significantly at 6-month postoperatively (p < 0.05 for all). ICA, nACA, and tACA showed no statistically significant difference postoperatively (p = 0.54, p = 0.118, and p = 0.255, respectively). Pearson's correlation analysis confirms negative relationship between Δ-HACD and Δ-tACA (r = -0.475, p < 0.01), and a loose negative relationship between change in ACD and change in ICA (r = -0.282, p = 0.016). Age and Δ-tACA were found as predictive parameters for Δ-HACD and, Δ-ICA was a predictor for Δ-ACD. CONCLUSION: While HACD and ACD decreased significantly, there was no significant change in ICA, nACA and tACA. Changes in HACD and ACD should be considered in terms of subsequent surgeries after SMILE.

Morphological changes in the iridocorneal angle and their relationship with intraocular pressure after infantile cataract surgery.

AIM: To evaluate morphological changes in the iridocorneal angle after pediatric cataract surgery. METHODS: Children who underwent primary infantile cataract surgery were included and 64 eyes from 41 children, including 18 with unilateral cataracts (18 eyes) and 23 with bilateral cataracts (46 eyes) were examined. All patients underwent two gonioscopic examinations to evaluate the iridocorneal angle, before the primary lens removal and before the secondary intraocular lens implantation. The anatomical changes in the iridocorneal angle and the relationship between intraocular pressure (IOP) and iridocorneal angle changes were also analyzed. RESULTS: The iridocorneal angle was wide in 64 eyes before and after surgery. The trabecular meshwork pigmentation, number of iris processes in every quadrant of the iridocorneal angle, and the width of the ciliary body band in the superior and inferior quadrants at the second gonioscopic examination were significantly increased compared to those at the first examination (P<0.001, P<0.05, P<0.05, and P<0.05, respectively). IOP gradually increased at 1mo after operation, and returned to the preoperative level at 3mo. However, IOP still increased significantly at 6 and 12mo. CONCLUSION: The main changes after pediatric cataract surgery include an increase in trabecular meshwork pigmentation and number of iris processes, IOP gradually increase and has positive correlation with trabecular meshwork pigmentation and anterior insertion of iris process.

Increased Intraocular Pressure During Hemodialysis: Ocular Dialysis Disequilibrium.

A man in his early 70s presented with a 1-month history of headache, left-sided photophobia, periorbital pain, and redness occurring during hemodialysis. He had a history of ESKD secondary to diabetic nephropathy and of proliferative diabetic retinopathy. We observed elevated intraocular pressure during dialysis. A diagnosis of neovascular glaucoma with a compromised iridocorneal angle was made. Medical management of glaucoma and modifications to the hemodialysis regimen were initiated but were insufficient. The resolution of symptoms required surgical management, including cataract extraction with intraocular lens placement, pars plana vitrectomy, and peripheral retina endolaser, and placement of an Ahmed glaucoma drainage valve. This case illustrates the importance of attention to intraocular pressure and risk factors for glaucoma in patients treated with hemodialysis. Clinicians caring for patients treated by hemodialysis should consider hemodialysis-related elevation in intraocular pressure as a possible etiology for headache, visual changes, or ocular symptoms during dialysis and should pursue ophthalmic evaluation.

Preparation of a Single Cell Suspension from the Murine Iridocorneal Angle.

Single cell RNA sequencing is a powerful tool that can be used to identify distinct cell types and transcriptomic differences within complex tissues. It has proven to be especially useful in tissues of the eye, where investigators have identified novel cell types within the retina, anterior chamber, and iridocorneal angle and explored transcriptomic contribution to disease phenotypes in age-related macular degeneration. However, to obtain high quality results, the technique requires isolation of healthy single cells from the tissue of interest, seeking complete tissue digestion while minimizing stress and transcriptomic changes in the isolated cells prior to library preparation. Here, we present a protocol developed in our laboratory for isolation of live single cells from the murine iridocorneal angle, which includes Schlemm's canal and the trabecular meshwork, suitable for single cell RNA sequencing, flow cytometry, or other downstream analysis. Graphical abstract.

The iridocorneal angle and related anterior segment structures in pediatric anisohyperopic amblyopic eyes.

Objectives: We aimed at investigating the iridocorneal angle, anterior segment structural differences, and their relationship in pediatric anisohyperopic amblyopic eyes. Methods: This study was designed as an observational case-control study. We prospectively evaluated the pediatric patients who were newly diagnosed with hyperopic anisometropic amblyopia. Iridocorrneal angle in four sectors, axial length, and anterior segment structures were compared to emmetropic fellow and control eyes using Pentacam and IOLMaster 700 devices. The anisohyperopia and iridocorneal angle related factors were determined in hyperopic anisometropic amblyopic eyes. Results: Forty-three hyperopic anisometropic amblyopic eyes, 43 fellow eyes, and 44 control eyes were included. The mean axial length, anterior chamber volume, and anterior chamber depth were significantly reduced in the study eyes compared to the fellow (p < 0.001, p = 0.021, and p = 0.045, respectively) and control eyes (p < 0.001, p = 0.001, and p = 0.009, respectively). The average iridocorneal angle was significantly lower in the study eyes than in the fellow and control eyes (p < 0.001 and p = 0.018, respectively). The iridocorneal angle correlated with anterior chamber depth (r = 0.49, p = 0.013), anterior chamber volume (r = 0.42, p = 0.038), the anterior radius of curvature (r =-0.54, p = 0.005), the posterior radius of curvature (r =-0.58, p = 0.002), and lens thickness (Rho =-0.41, p = 0.033) in the study eyes. Anisohyperopia was related to the interocular difference in axial length (Rho = 0.53, p = 0.005), anterior chamber depth (Rho = 0.53, p = 0.005), and anterior chamber volume (Rho = 0.42, p = 0.031). Conclusion: Pentacam and IOLMaster 700 are suitable for non-contact imaging of iridocorneal angle and anterior segment structures in the pediatric age. These biometric differences and their relationship should be kept in mind whenever anterior or posterior segment surgery is planned for pediatric anisohyperopic amblyopic eyes.

Comparison of iridocorneal angle parameters measured by spectral domain optical coherence tomography and ultrasound biomicroscopy in dogs.

OBJECTIVE: To compare the measurements of iridocorneal angle parameters between spectral domain optical coherence tomography (SD-OCT) and ultrasound biomicroscopy (UBM) in dogs. ANIMALS STUDIED AND PROCEDURES: A total of 47 eyes of dogs were scanned at the temporal limbus using SD-OCT and UBM. Iridocorneal angle (ICA) and angle opening distance (AOD) were measured from the obtained images accordingly. The intra-observer and inter-observer reproducibility were evaluated using the intraclass correlation coefficient. To evaluate intra-observer reproducibility, measurements of the first and second grading from the first examiner were compared. To evaluate inter-observer reproducibility, measurements between the two examiners were compared. Agreement between ICA and AOD for SD-OCT and UBM was evaluated using Bland-Altman plots. RESULTS: In the first grading, the mean ICA and AOD for SD-OCT were 31.4 ± 6.4° and 641.4 ± 270.8 µm, respectively. The mean ICA and AOD for UBM were 32.0 ± 4.8° and 700.4 ± 238.8 µm, respectively. For ICA and AOD measurements, intra-observer reproducibility was excellent for both devices, whereas inter-observer reproducibility was excellent for SD-OCT and good for UBM. The mean difference in ICA between SD-OCT and UBM was 0.6° with a limit of agreement (LoA) span of 18.9°. The mean difference in AOD between SD-OCT and UBM was 58.9 µm with a LoA span of 804.4 µm. CONCLUSIONS: Spectral domain optical coherence tomography is an effective non-contact imaging modality for the evaluation of canine iridocorneal angle parameters in a clinical setting. Reproducibility of measurements obtained is comparable or superior to UBM, but values obtained by SD-OCT and UBM for AOD are not interchangeable between devices.

Accurate Identification of the Trabecular Meshwork under Gonioscopic View in Real Time Using Deep Learning.

PURPOSE: Accurate identification of iridocorneal structures on gonioscopy is difficult to master, and errors can lead to grave surgical complications. This study aimed to develop and train convolutional neural networks (CNNs) to accurately identify the trabecular meshwork (TM) in gonioscopic videos in real time for eventual clinical integrations. DESIGN: Cross-sectional study. PARTICIPANTS: Adult patients with open angle were identified in academic glaucoma clinics in both Taipei, Taiwan, and Irvine, California. METHODS: Neural Encoder-Decoder CNNs (U-nets) were trained to predict a curve marking the TM using an expert-annotated data set of 378 gonioscopy images. The model was trained and evaluated with stratified cross-validation grouped by patients to ensure uncorrelated training and testing sets, as well as on a separate test set and 3 intraoperative gonioscopic videos of ab interno trabeculotomy with Trabectome (totaling 90 seconds long, 30 frames per second). We also evaluated our model's performance by comparing its accuracy against ophthalmologists. MAIN OUTCOME MEASURES: Successful development of real-time-capable CNNs that are accurate in predicting and marking the TM's position in video frames of gonioscopic views. Models were evaluated in comparison with human expert annotations of static images and video data. RESULTS: The best CNN model produced test set predictions with a median deviation of 0.8% of the video frame's height (15.25 µm) from the human experts' annotations. This error is less than the average vertical height of the TM. The worst test frame prediction of this model had an average deviation of 4% of the frame height (76.28 µm), which is still considered a successful prediction. When challenged with unseen images, the CNN model scored greater than 2 standard deviations above the mean performance of the surveyed general ophthalmologists. CONCLUSIONS: Our CNN model can identify the TM in gonioscopy videos in real time with remarkable accuracy, allowing it to be used in connection with a video camera intraoperatively. This model can have applications in surgical training, automated screenings, and intraoperative guidance. The dataset developed in this study is one of the first publicly available gonioscopy image banks (https://lin.hs.uci.edu/research), which may encourage future investigations in this topic.

Anterior chamber changes assessment by Scheimpflug analysis after intravitreal dexamethasone implantation.

PURPOSE: To evaluate structural changes in the anterior chamber and intraocular pressure (IOP) changes following intravitreal dexamethasone implantation. METHODS: Forty-two eyes of 42 patients that received intravitreal dexamethasone implant for the management of macular edema secondary to diabetic retinopathy or branch retinal vein occlusion (BRVO) were included in the study. IOP was measured by Goldmann applanation tonometry. Anterior chamber depth (ACD) and iridocorneal angle (ICA) was measured by a Scheimflug camera (Sirius, CSO, Italy) the day before the injection of the dexamethasone implant and on postoperative day 1, first week, and first month. RESULTS: Mean IOP was 15.14 ± 2.77 mmHg before the procedure and, 15.67 ± 3.70 mmHg, 15.86 ± 3.11 mmHg, 16.21 ± 2.75 mmHg on day 1, first week, and first month following intravitreal dexamethasone implantation, respectively. Mean ICA and ACD were significantly higher in pseudophakic eyes compared to phakic eyes. However, there was no statistically significant change in ICA before and after the procedure (on postoperative day 1, first week, and first month) among both phakic and pseudophakic patients (p = 0.783). Similarly, ACD remained unchanged after the procedure (on postoperative day 1, first week, and first month) compared to the initial measurement (p = 0.802). CONCLUSION: This study confirmed that there was an increase in IOP. However, these changes were not accompanied with a change in ACD or ICA.