Cost-Utility Analysis of Prophylactic Laser Peripheral Iridotomy for Primary Angle Closure Suspects.

PURPOSE: To assess the cost-utility of prophylactic laser peripheral iridotomy (LPI) for primary angle closure (PAC) suspects (PACS). DESIGN: Economic evaluation. METHODS: Our Markov model randomized PACS eyes to LPI or observation for 40 one-year cycles (100,000 iterations per strategy). Each cycle, an eye remained in its current health state, advanced linearly through PAC, mild, moderate, severe, and end-stage PAC glaucoma (PACG), or died. Transition rates were derived from the literature including the Zhongshan Angle Closure Prevention (ZAP) trial and the Singapore Asymptomatic Narrow Angles Laser Iridotomy Study (ANA-LIS). Eyes with acute-angle closure advanced to either PAC or directly to various PACG severities. A tracker monitored accumulated perimetric decibel reduction to progress PACG through increasing severities, with an annual probability of either stable or severity-dependent perimetry loss. We set a willingness to pay of an incremental cost-effectiveness ratio (ICER) <$50,000/quality-adjusted life-years. RESULTS: At age 50 years, LPI was cost-saving using ZAP data and cost-effective using ANA-LIS data. The ZAP iterations became cost-effective from the societal perspective when the model started at age 55 years and third-party perspective at age 70 years. LPI was no longer cost-effective from the societal perspective using ANA-LIS data at age 80 years or from the societal perspective using ZAP data or third-party perspective with ANA-LIS data at age 85. Probabilistic sensitivity analyses favored LPI until starting age 85. CONCLUSIONS: Prophylactic LPI for PACS is cost-effective across a spectrum of ages and should be considered from a public health perspective.

Practice Patterns and Sociodemographic Disparities in the Clinical Care of Anatomical Narrow Angles in the United States.

PURPOSE: To assess treatment and visit patterns among patients with newly diagnosed anatomical narrow angle (ANA) and identify sociodemographic factors associated with disparities in care. DESIGN: Retrospective practice pattern evaluation study. METHODS: A total of 263,422 patients diagnosed with ANA between 2007 and 2019 were identified in the Optum Clinformatics Data Mart. Inclusion was limited to newly diagnosed ANA, defined as (1) continuous enrollment during a 2-year lookback period and 1-year study period from first diagnosis; (2) diagnosis by an ophthalmologist or optometrist; and (3) no history of pseudophakia, ANA treatments, or prior primary angle closure glaucoma diagnosis. Outcome measures were treatment with laser peripheral iridotomy (LPI), cataract surgery, or intraocular pressure-lowering medications and number of eye care visits. Logistic and Poisson regression were performed to assess factors associated with treatment and eye care visits, respectively. RESULTS: Among 52,405 eligible cases, 27.7% received LPI, 13.9% received drops, and 15.1% received cataract surgery. Odds of LPI were higher in Asians and Hispanics (odds ratio [OR] ≥ 1.16, P < .001). Non-Whites had higher odds of drops (OR ≥ 1.19, P < .001), but Hispanics had lower odds of cataract surgery (OR = 0.79, P < .001). The mean number of eye care visits was 2.6±2.1 including the day of diagnosis. Older age and treatment were associated with higher rates of eye care visits (rate ratio > 1.15, P < .001). CONCLUSION: More than a quarter of patients with newly diagnosed ANA receive treatment with LPI. Racial minorities are more likely to receive ANA-specific treatments but less likely to receive cataract surgery. These differences may reflect racial differences in disease severity and the need for clearer practice guidelines in ANA care.

Assessment of the iridocorneal angle pigmentation and structures after the implantation of EVO+ Visian Implantable Collamer Lens.

PURPOSE: To evaluate the effect of EVO+ Visian Implantable Collamer Lens (ICL) implantation on the iridocorneal angle pigmentation and structures. METHODS: Myopic refractive surgery candidates who underwent posterior chamber EVO+ ICL implantation were evaluated preoperatively and 3 and 6 months postoperatively. High-resolution images of the iridocorneal angle (nasal, superior, temporal and inferior quadrants) were acquired during gonioscopy. A masked observer, blinded to study visits and patients' information, evaluated the angle width, apparent iris root insertion, iris configuration, and trabecular meshwork pigmentation according to the Spaeth scale in two different occasions. The intra-rater reliability was estimated using the weighted Gwet's Agreement Coefficient (AC2). Differences between visits were analyzed using the Cochran Q test or the Friedman test. RESULTS: Twenty-one patients (13 females and 8 males) aging 31.3 ± 6.3 years old were recruited. The intra-rater reliability of gonioscopy assessment was excellent for every parameter assessed (AC2 ≥ 0.97). No significant differences were found among the study visits for any quadrant in the angle width (p ≥ 0.74), apparent iris root insertion (p ≥ 0.22), iris configuration (p ≥ 0.21) and trabecular meshwork pigmentation (p ≥ 0.24). Mean pigmentation of trabecular meshwork for the four quadrants did not vary either among visits (p = 0.25). CONCLUSIONS: The EVO+ ICL implantation after uneventful procedures appears not to clinically affect the iridocorneal angle pigmentation and/or structures during a short-medium follow-up using gonioscopy assessment. The intra-rater reliability of glaucoma specialists assessing iridocorneal angle structures using gonioscopy images is very high.

Cost-effectiveness of Prophylactic Laser Peripheral Iridotomy in Primary Angle-Closure Suspects.

PURPOSE: To investigate the cost-effectiveness (CE) of prophylactic laser peripheral iridotomy (LPI) in primary angle-closure (PAC) suspects (PACSs). DESIGN: Cost-effectiveness analysis utilizing Markov models. SUBJECTS: Patients with narrow angles (PACSs). METHODS: Progression from PACSs through 4 states (PAC, PAC glaucoma, blindness, and death) was simulated using Markov cycles. The cohort entered at 50 years and received either LPI or no treatment. Transition probabilities were calculated from published models, and risk reduction of LPI was calculated from the Zhongshan Angle Closure Prevention trial. We estimated costs of Medicare rates, and previously published utility values were used to calculate quality-adjusted life year (QALY). Incremental CE ratios (ICER) were evaluated at $50 000. Probabilistic sensitivity analyses (PSAs) addressed uncertainty. MAIN OUTCOME MEASURES: Total cost, QALY, and ICER. RESULTS: Over 2 years, the ICER for the LPI cohort was > $50 000. At 6 years, the LPI cohort was less expensive with more accrued QALY. In PSA, the LPI arm was cost-effective in 24.65% of iterations over 2 years and 92.69% over 6 years. The most sensitive parameters were probability of progressing to PAC and cost and number of annual office visits. CONCLUSIONS: By 6 years, prophylactic LPI was cost-effective. The rate of progressing to PAC and differing practice patterns most impacted CE. With uncertainty of management of narrow angles, cost may be a decision management tool for providers. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any materials discussed in this article.

Assessment of Iris Trabecular Contact in Eyes with Gonioscopic Angle-Closure.

PURPOSE: To investigate the extent of iris trabecular contact (ITC) measured by anterior segment OCT (AS-OCT) and its association with primary angle-closure (PAC) and PAC glaucoma (PACG) in eyes with gonioscopic angle-closure and to determine the diagnostic performance of ITC for detection of gonioscopic angle-closure. DESIGN: Multicenter, prospective study. PARTICIPANTS: A total of 119 healthy participants with gonioscopic open-angle and 170 patients with gonioscopic angle-closure (94 with PAC suspect and 76 with PAC/PACG) were included. METHODS: One eye of each subject was randomly selected for AS-OCT imaging. Angle-opening distance (AOD500) and trabecular iris space area (TISA500) were measured every 10° for 360°. Two criteria of ITC500 were examined: (1) AOD500 = 0 mm and (2) TISA500 = 0 mm2. The association between the extent of ITC500 and PAC/PACG in eyes with gonioscopic angle-closure was analyzed with logistic regression analysis. MAIN OUTCOME MEASURES: Sensitivity and specificity of ITC500 for detection of gonioscopic angle-closure; odds ratio (OR) of PAC/PACG. RESULTS: The sensitivity of ITC500 ≥ 10° for detection of gonioscopic angle-closure ranged from 82.4% (AOD500 = 0 mm) to 84.7% (TISA500 = 0 mm2), and the specificity was 85.7% (for both AOD500 = 0 mm and TISA500 = 0 mm2). The extent of ITC500 determined by AS-OCT, not cumulative gonioscopy score (i.e., the sum of the modified Shaffer grades over 4 quadrants), was associated with the odds of PAC/PACG in eyes with gonioscopic angle-closure; the odds of PAC/PACG increased by 5% for every 10° increase in ITC500 (OR, 1.051, 95% confidence interval [CI], 1.022-1.080 for AOD500 = 0 mm; OR, 1.049, 95% CI, 1.022-1.078 for TISA500 = 0 mm2). Axial length and anterior chamber depth were not associated with PAC/PACG in eyes with gonioscopic angle-closure (P ≥ 0.574). CONCLUSIONS: A greater extent of ITC measured by AS-OCT, not angle-closure determined by gonioscopy, was associated with a greater odds of PAC/PACG in eyes with gonioscopic angle-closure.

Early Assessment of Circumferential Anterior Segment Structures Following Implantable Collamer Lens V4c Implantation Via SS-OCT.

Purpose: To explore early changes in circumferential anterior segment structures following Implantable Collamer Lens (ICL) V4c implantation via swept-source optical coherence tomography (SS-OCT). Methods: In 103 eyes of 56 myopic patients undergoing ICL V4c surgery, anterior segments were measured via SS-OCT to compute local anterior chamber angle (ACA) parameters on the nasal-temporal (0°-180°), superior-inferior (90°-270°), and superior nasal-inferior temporal (80°-260°) meridians, including angle-opening distance at 500 µm (AOD500), trabecular-iris space area at 500 µm (TISA500), trabecular-iris angle at 500 µm (TIA500), and circumferential ACA parameters, including AOD area at 500 µm (AODA500), trabecular-iris circumference volume at 500 µm (TICV500), and the index and area of iris-trabecular contact (ITC). ACA parameters were compared preoperatively and at 1 week, 1 month, and 3 months postoperatively and compared among quadrants. Mixed-effects model was used to evaluate the parameters correlated with the post-ITC parameters. Results: The mean AOD500, TISA500, TIA500, AODA500, and TICV500 were decreased by 65.4% to 71%, 64.1% to 69.3%, 53.8% to 61.5%, 69.9%, and 69.2%, respectively, at 1 week postoperatively. The ITC index and area values rose from 1.436% ± 4.427% and 0.070 ± 0.254 mm2 to 12.343% ± 13.216% and 0.903 ± 1.304 mm2 (all P < 0.05). No further decreases in ACA parameters were observed beyond 1 week postoperatively (all P > 0.05). Significant differences were observed among quadrants, with the narrowest in the superior-nasal quadrant, followed by the superior quadrant. The 3-month vault was significantly correlated with the ITC index and area at 3 months postoperatively. Conclusions: Anterior segment structures were significantly shallow at 1 week with no further decreases thereafter. In light of anatomical variability, we recommend circumferential meridian scan to assess angle status, with special attention to the superior-nasal and superior quadrants. Translational Relevance: We investigated the early changes in circumferential anterior segment structures following ICL V4c implantation, thus providing a better perspective for understanding anterior segment structural characteristics after ICL V4c surgery.

In vivo biomechanical assessment of iridial deformations and muscle contractions in human eyes.

The iris is a muscular organ whose deformations can cause primary angle-closure glaucoma (PACG), a leading cause of blindness. PACG risk assessment does not consider iridial biomechanical factors, despite their expected influence on iris deformations. Here, we exploited an existing biometric dataset consisting of near-infrared movies acquired during the pupillary light reflex (PLR) as a unique resource to study iris biomechanics. The PLR caused significant (greater than 100%) and essentially spatially uniform radial strains in the iris in vivo, consistent with previous findings. Inverse finite-element modelling showed that sphincter muscle tractions were ca fivefold greater than iridial stroma stiffness (range 4- to 13-fold, depending on sphincter muscle size). This muscle traction is greater than has been previously estimated, which may be due to methodological differences and/or to different patient populations in our study (European descent) versus previous studies (Asian); the latter possibility is of particular interest due to differential incidence rates of PACG in these populations. Our methodology is fast and inexpensive and may be a useful tool in understanding biomechanical factors contributing to PACG.

Assessment of iris vasculature abnormalities in dogs with diabetes mellitus.

OBJECTIVE: To identify and characterize abnormalities of iris vasculature in dogs with diabetes mellitus, compared to clinically normal, age-matched control dogs, by means of anterior segment angiography. ANIMALS: 10 dogs with naturally occurring diabetes mellitus and 10 age-matched control dogs with no ocular or systemic disease. PROCEDURES: The day before iris vasculature abnormality (IVA) assessment, all dogs underwent complete physical and ophthalmic examinations and baseline clinicopathologic analyses. For diabetic dogs, serum fructosamine concentration and a 12-hour blood glucose concentration curve were generated. The next day, all dogs were sedated and anterior segment angiography (following IV injection of indocyanine green [1 mg/kg] and subsequently sodium fluorescein [20 mg/kg]) was performed with a full-spectrum camera and camera adapter system. Group findings were compared, and multiple linear regression analysis was performed to identify potential factor associations with IVAs. RESULTS: During anterior segment angiography, the arterial, capillary, and venous phases were identified in all dogs. Times to onset of all phases in diabetic dogs were significantly less than those in control dogs. Vascular disruptions within the peripupillary region (evident following sodium fluorescein administration) were common in diabetic dogs. Severity of dye leakage into the iris stroma and aqueous humor was significantly greater in diabetic dogs than in control dogs. Duration of disease, mean blood glucose concentration, and serum fructosamine concentration were significantly associated with IVAs. CONCLUSIONS AND CLINICAL RELEVANCE: In diabetic dogs, anterior segment angiography revealed IVAs that were not evident in control dogs. The severity of those changes appeared to be associated with disease duration and blood glucose regulation.

A Deep Learning System for Automatic Assessment of Anterior Chamber Angle in Ultrasound Biomicroscopy Images.

Purpose: To develop and assess a deep learning system that automatically detects angle closure and quantitatively measures angle parameters from ultrasound biomicroscopy (UBM) images using a deep learning algorithm. Methods: A total of 3788 UBM images (2146 open angle and 1642 angle closure) from 1483 patients were collected. We developed a convolutional neural network (CNN) based on the InceptionV3 network for automatic classification of angle closure and open angle. For nonclosed images, we developed a CNN based on the EfficienttNetB3 network for the automatic localization of the scleral spur and the angle recess; then, the Unet network was used to segment the anterior chamber angle (ACA) tissue automatically. Based on the results of the latter two processes, we developed an algorithm to automatically measure the trabecular-iris angle (TIA500 and TIA750), angle-opening distance (AOD500 and AOD750), and angle recess area (ARA500 and ARA750) for quantitative evaluation of angle width. Results: Using manual labeling as the reference standard, the ACA classification network's accuracy reached 98.18%, and the sensitivity and specificity for angle closure reached 98.74% and 97.44%, respectively. The deep learning system realized the automatic measurement of the angle parameters, and the mean of differences was generally small between automatic measurement and manual measurement. The coefficients of variation of TIA500, TIA750, AOD500, AOD750, ARA500, and ARA750 measured by the deep learning system were 5.77%, 4.67%, 10.76%, 7.71%, 16.77%, and 12.70%, respectively. The within-subject standard deviations of TIA500, TIA750, AOD500, AOD750, ARA500, and ARA750 were 5.77 degrees, 4.56 degrees, 155.92 µm, 147.51 µm, 0.10 mm2, and 0.12 mm2, respectively. The intraclass correlation coefficients of all the angle parameters were greater than 0.935. Conclusions: The deep learning system can effectively and accurately evaluate the ACA automatically based on fully automated analysis of a UBM image. Translational Relevance: The present work suggests that the deep learning system described here could automatically detect angle closure and quantitatively measure angle parameters from UBM images and enhancing the intelligent diagnosis and management of primary angle-closure glaucoma.

Iridocorneal angle assessment in children with spontaneously regressed retinopathy of prematurity.

PURPOSE: To assess anterior segment anatomic parameters in school-aged children with spontaneously regressed retinopathy of prematurity (sr-ROP) and in children born preterm without ROP history (preT). METHODS: sr-ROP and preT children were compared with healthy, born at term children (control group). Biometric characteristics were measured with the IOLMaster. Iridocorneal angle structure was evaluated using Visante AS-OCT, and angle opening distance, trabecular iris space area and scleral spur angle were calculated. Best-corrected visual acuity (BCVA) was measured with the ETDRS chart. RESULTS: We examined 22 eyes of 11 children with sr-ROP, 26 eyes of 13 preT children and 24 eyes of 12 healthy controls, with a median age of 8 years. sr-ROP children exhibited worse mean BCVA and reduced AL compared to controls (p = 0.001 and p = 0.007, respectively). A narrower iridocorneal angle was found in sr-ROP compared to the preT and the control groups. Preterm children were found to have similar anterior chamber angle metrics compared to the full-term control group. CONCLUSION: In this study, school-aged children with a history of sr-ROP had narrower angles compared to preterm- and term-born children. AS-OCT demonstrated structural differences of the iridocorneal angle in sr-ROP, possibly reflecting a mild developmental arrest of the anterior segment.

Assessment of Generative Adversarial Networks for Synthetic Anterior Segment Optical Coherence Tomography Images in Closed-Angle Detection.

Purpose: To develop generative adversarial networks (GANs) that synthesize realistic anterior segment optical coherence tomography (AS-OCT) images and evaluate deep learning (DL) models that are trained on real and synthetic datasets for detecting angle closure. Methods: The GAN architecture was adopted and trained on the dataset with AS-OCT images collected from the Joint Shantou International Eye Center of Shantou University and the Chinese University of Hong Kong, synthesizing open- and closed-angle AS-OCT images. A visual Turing test with two glaucoma specialists was performed to assess the image quality of real and synthetic images. DL models, trained on either real or synthetic datasets, were developed. Using the clinicians' grading of the AS-OCT images as the reference standard, we compared the diagnostic performance of open-angle vs. closed-angle detection of DL models and the AS-OCT parameter, defined as a trabecular-iris space area 750 µm anterior to the scleral spur (TISA750), in a small independent validation dataset. Results: The GAN training included 28,643 AS-OCT anterior chamber angle (ACA) images. The real and synthetic datasets for DL model training have an equal distribution of open- and closed-angle images (all with 10,000 images each). The independent validation dataset included 238 open-angle and 243 closed-angle AS-OCT ACA images. The image quality of real versus synthetic AS-OCT images was similar, as assessed by the two glaucoma specialists, except for the scleral spur visibility. For the independent validation dataset, both DL models achieved higher areas under the curve compared with TISA750. Two DL models had areas under the curve of 0.97 (95% confidence interval, 0.96-0.99) and 0.94 (95% confidence interval, 0.92-0.96). Conclusions: The GAN synthetic AS-OCT images appeared to be of good quality, according to the glaucoma specialists. The DL models, trained on all-synthetic AS-OCT images, can achieve high diagnostic performance. Translational Relevance: The GANs can generate realistic AS-OCT images, which can also be used to train DL models.

Circumferential Assessment of Changes in Anterior Segment Characteristics and Baseline Predictors of Angle Widening After Laser Iridotomy in Caucasian Eyes.

PRCIS: Laser peripheral iridotomy (LPI) widened the iridocorneal angle and flattened the iris circumferentially in Caucasian eyes and baseline refractive error, lens vault, and iris volume play a significant role in the angle widening. PURPOSE: The purpose of this study was to investigate circumferential angle widening and iris changes after LPI using swept-source optical coherence tomography (SS-OCT) in Caucasian eyes with the use of novel anterior segment parameters. MATERIALS AND METHODS: A total of 130 eyes (68 primary angle-closure suspect, 34 primary angle closure, and 28 primary angle-closure glaucoma eyes) of 66 subjects underwent 360-degree SS-OCT (SS-1000 CASIA) angle imaging and gonioscopy in the dark before and 7, 30, 90 days after LPI. For each eye, 16 frames (11.25 degree apart) were selected for analysis from 128 cross-sectional images, and novel 2-dimensional and 3-dimensional anterior segment parameters namely angle opening distance area (AODA) and the trabecular-iris space volume (TISV) 750 µm from the scleral spur, as well as iris parameters such as iris thickness (IT750 and IT2000), iris curvature, and iris curvature area were measured for each image. RESULTS: AODA and TISV were significantly increased and the iris curvature and iris curvature area were significantly decreased at days 7, 30, and 90 after LPI when compared with their baseline (all P<0.001) but there was no significant change in the IT750 and IT2000 (all P>0.05). The multivariable linear regression model showed a significant association of ΔAODA with refractive error (ß=-0.23, P=0.013), lens vault (ß=2.8, P=0.007), and iris volume (ß=-0.11, P=0.027) after adjusting for age and sex. CONCLUSIONS: LPI widened the iridocorneal angle and flattened the iris circumferentially in Caucasian eyes in this study. Baseline refractive error, lens vault, and iris volume play a significant role in the circumferential angle widening by LPI.

Angle-closure assessment in anterior segment OCT images via deep learning.

Precise characterization and analysis of anterior chamber angle (ACA) are of great importance in facilitating clinical examination and diagnosis of angle-closure disease. Currently, the gold standard for diagnostic angle assessment is observation of ACA by gonioscopy. However, gonioscopy requires direct contact between the gonioscope and patients' eye, which is uncomfortable for patients and may deform the ACA, leading to false results. To this end, in this paper, we explore a potential way for grading ACAs into open-, appositional- and synechial angles by Anterior Segment Optical Coherence Tomography (AS-OCT), rather than the conventional gonioscopic examination. The proposed classification schema can be beneficial to clinicians who seek to better understand the progression of the spectrum of angle-closure disease types, so as to further assist the assessment and required treatment at different stages of angle-closure disease. To be more specific, we first use an image alignment method to generate sequences of AS-OCT images. The ACA region is then localized automatically by segmenting an important biomarker - the iris - as this is a primary structural cue in identifying angle-closure disease. Finally, the AS-OCT images acquired in both dark and bright illumination conditions are fed into our Multi-Sequence Deep Network (MSDN) architecture, in which a convolutional neural network (CNN) module is applied to extract feature representations, and a novel ConvLSTM-TC module is employed to study the spatial state of these representations. In addition, a novel time-weighted cross-entropy loss (TC) is proposed to optimize the output of the ConvLSTM, and the extracted features are further aggregated for the purposes of classification. The proposed method is evaluated across 66 eyes, which include 1584 AS-OCT sequences, and a total of 16,896 images. The experimental results show that the proposed method outperforms existing state-of-the-art methods in applicability, effectiveness, and accuracy.

Optical Coherence Tomography and ImageJ Software for objective assessment of optical density of anterior chamber iris cyst.

Aim: To report the optical characteristics of the fluid in an anterior chamber iris cyst. Method: A 26-year-old male presented with blurring of vision in his right eye for two months, without any other associated ocular complaints. His visual acuity was 6/ 9 on Snellen's chart. On slit lamp examination, a small translucent pigmented cyst was noted inferiorly in the anterior chamber, struck on to the cornea at 6 o'clock periphery, without any feeder vessel. Anterior segment optical coherence tomography (OCT) revealed a cystic lesion with hyperreflective walls and hypo reflective lumen attached to the cornea, compressing the endothelium. Results: The optical density (OD) of the cyst fluid was determined using ImageJ, an open code Java-based image processing software. The OD of cyst fluid was found comparable to the anterior chamber fluid. Conclusion: Ultrasound biomicroscopy (UBM) and OCT are useful tools for the diagnosis of cystic lesions of the anterior segment. The innovative use of an OCT image and the ImageJ software to determine the optical density of the iris cyst may aid in the diagnosis and follow-up of such cases.

Iris melanoma with ciliary body infiltration presenting as a presumed chronic unilateral inflammatory glaucoma. The challenges of iris tumor biopsy assessment.

Uveal melanoma is the most common primary malignancy of the eye in adults. It may involve the choroid and ciliary body, and in only 2-3% of cases it involves the iris. We present a case of a 56-year-old patient with a 6-year history of unilateral, inflammatory, refractory glaucoma of the right eye. Due to acquired heterochromia and heterogeneous thickness of the iris, iris melanoma was suspected, but the incisional biopsy did not confirm the diagnosis. In the next months, the lesion enlarged and the eye globe was enucleated. Histopathological examination revealed an iridociliary melanoma with annular growth pattern.

Iridocorneal Angle Assessment After Laser Iridotomy With Swept-source Optical Coherence Tomography.

AIM: To investigate the reliability of anterior chamber angle (ACA) measurements in narrow angles and assess the effect of laser peripheral iridotomy (LPI) on these measurements using novel swept-source optical coherence tomography (SS-OCT) technology. MATERIALS AND METHODS: In this prospective observational study, patients with gonioscopically narrow angles were enrolled and scheduled for prophylactic LPI. Twelve ACA sections were obtained in each eye using SS-OCT (ANTERION, Heidelberg Engineering, Germany) before and after Nd:YAG LPI. A built-in algorithm calculated ACA measurements after manual identification of the scleral spur and ACA recess. Eight ACA parameters were evaluated: ACA (ACA 500, ACA 750); scleral spur angle (SSA 500, SSA 750); angle opening distance (AOD 500, AOD 750); and trabecular iris space area (TISA 500, TISA 750). The effect of LPI was assessed for each parameter, both nasally and temporally. RESULTS: Ten patients (18 eyes) were enrolled (mean age, 61.8±13.6 y; 60.0% female individuals). On average, the ACA was wider nasally than temporally (P=0.004). LPI significantly widened the ACA (range, 26.7-29.4%; P<0.05). ACA 500 increased by 29.4% (P<0.001), ACA 750 by 29.2% (P=0.002), SSA 500 by 27.3% (P=0.003), SSA 750 by 28.1% (P=0.001), AOD 500 by 28.6% (P=0.009), AOD 750 by 28.6% (P=0.003), TISA 500 by 27.3% (P=0.004), and TISA 750 by 26.7% (P=0.200). CONCLUSIONS: SS-OCT ANTERION imaging can be used to reliably measure ACA before and after LPI. ACA, AOD, SSA, and TISA are all valid ACA measurement methods.

Assessment of anterior segment measurements using a high-resolution imaging device.

PURPOSE: To assess the repeatability of several anterior segment parameters obtained with swept-source optical coherence tomography (SS-OCT). METHODS: We measured 5-times consequently several parameters in 69 eyes using the ANTERION SS-OCT. White-to-white (WTW), angle-to-angle (ATA), spur-to-spur (STS), and lens vault distances were measured in the horizontal- and vertical-meridian. Anterior-chamber-angle (ACA), scleral-spur-angle (SSA), angle-opening-distance (AOD), and trabecular-iris-space-area (TISA) were measured at 500 and 750 µm for the superior-, nasal-,inferior-, and temporal-quadrants. Intrasubject standard deviation (Sw),coefficient of variation (CoV), coefficient of repeatability (CoR), and intraclass-correlation-coefficient (ICC) were calculated for each parameter. Bland-Altman analysis was done. RESULTS: We have not found statistically significant differences between repeated measurements (p > 0.05). Repeatability was good for the different parameters evaluated. Sw values in distances and areas were low and ranged from 0.01 to 0.07. CoR values showed a similar pattern being larger for those metrics measuring angles. The same happened with CoV values, being very small for WTW,ATA, and STS distances (0.16-0.57%). ICC values for all parameters analyzed were > 0.97. Bland-Altman plots evidenced the narrow limits of agreement for all parameters. CONCLUSIONS: The ANTERION SS-OCT demonstrated high repeatability measuring different distances, angles, and areas of the anterior segment of the eye.

In vitro optical quality assessment of a monofocal IOL sutured to an artificial iris.

PURPOSE: To assess whether the combined implantation of a monofocal IOL and an artificial iris had an effect on the IOL's optical performance. SETTING: David J. Apple International Laboratory for Ocular Pathology, Heidelberg, Germany. DESIGN: In vitro laboratory study. METHODS: IOL optical quality was assessed using an OptiSpheric IOL Pro II to measure the IOL's modulation transfer function (MTF) at 3.0 mm pupil size and spatial frequency of 100 lp/mm. Three ASPIRA-aAY IOLs with different base powers, 10.0 diopter (D) (IOL A), 20.0 D (IOL B), and 30.0 D (IOL C) were measured before and after suturing the IOL to an ArtificialIris (AI). The degree of IOL decentration about the center of the AI was also evaluated. RESULTS: The mean MTF values prior to suturing were 0.57, 0.65, and 0.63 for IOLs A, B, and C, respectively. After suturing to the AI, the mean MTF values were 0.52, 0.54, and 0.55 for IOLs A, B, and C, respectively. The decentration values in vertical direction were 0.20 mm, 0.00 mm, and 0.02 mm for IOLs A, B, and C, respectively. In horizontal direction, the decentration values were 0.42 mm, 0.10 mm, and 0.03 mm for IOLs A, B, and C, respectively. CONCLUSIONS: The MTF decreased slightly in all 3 IOLs after they were sutured to the AI. The small differences, however, should be clinically irrelevant. This laboratory assessment showed that suturing of the IOL to the AI can be performed in a reliable and reproducible manner without deteriorating optical quality.

Chemical eye injury: pathophysiology, assessment and management.

Chemical eye injury (CEI) is an acute emergency which can threaten sight and life. These commonly occur at home or the workplace with the former being generally mild and the latter more severe and bilateral. Major workplace accidents involve other parts of the body and can be associated with inhalation or ingestion of the chemical. Alkali injuries cause damage by saponification of tissue and deeper penetration as a consequence. Acid injuries cause rapid coagulation of tissue, which impedes penetration and limits damage. Irritants such as alcohols, cause superficial epithelial denudation. Severe chemical insult can affect all anterior segment structures causing iris, pupil and lens abnormalities. Eye pressure is variably affected and can be low or high or start as one and rapidly change to the other. Chorioretinal changes in the form of vasculopathy are seen and ascribed to be secondary to anterior segment inflammation rather than due to the direct effect of CEI. Final outcome related to structure and function is determined by the injurious agent, duration of exposure, nature of treatment and the rapidity with which it is instituted. Prevention of further damage by profuse and prolonged eye wash, after ascertaining pH of both eyes, together with exploration and removal of all particulate matter, is the key. Other management principles include a complete and thorough assessment, control of inflammation, facilitation of healing and prevention and management of sequelae and complications. Intraocular pressure is often forgotten and must be assessed and managed. Management often requires a multidisciplinary approach.