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Background: Ultrasound biomicroscopy (UBM) is a high?resolution ultrasound technique, which allows noninvasive, in vivo imaging of the ocular anterior segment structures. Purpose: This video gives a description of the identification of the iridocorneal angle structures in the cross?sectional view in a radial scan through a typical ciliary process and a guide toward measuring the angle parameters. Synopsis: UBM provides two?dimensional, grayscale images of the iridocorneal angle. The real?time image is displayed on a video monitor and can be recorded for qualitative and quantitative analysis. The angle parameters can be measured by in?built calipers in the machine software and manipulated by the examiner. Highlights: This video demonstrates UBM caliper positions as displayed on the monitor and marked by the examiner for the measurement of various anterior segment parameters of the eye.
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Purpose: To correlate and analyze the pattern of the visual field (VF) defects by perimetry and anterior chamber angle parameters by AS-OCT in primary angle-closure glaucoma (PACG) across varied severity levels on presentation to a tertiary eye care center. Methods: This was a cross-sectional study, which included 323 eyes of clinically diagnosed cases of PACG. Glaucoma severity was categorized according to mean deviation (MD) as mild (-6.00 dB or more), moderate (-6.01 to -12.00 dB), and severe (-12.01 to -30.00 dB). AS-OCT measured the nasal (N) and temporal (T) angle opening distance at 500 ?m (AOD 500) and 750 ?m (AOD 750), anterior chamber angle (ACA), lens vault (LV), and anterior chamber width (ACW). The VF severity was then correlated with the AS-OCT parameters using statistical analysis. Results: The mean age ± standard deviation (SD) of the patients included in the study was 56.03 ± 8.6 years, with a 1:1.2 gender ratio. The number of eyes with mild, moderate, and severe VFs were 140 (43.3%), 88 (27.24%), and 95 (29.41%), respectively. There was no statistically significant correlation in the mean anterior chamber angle parameters (AOD 500, AOD 750, ACA 500, ACA 750, LV, ACW, and axial length (AL)) among the groups. However, the correlation between AOD 500 and LV thickness was found to be significant (P = 0.0000) with a negative Spearman’s rank correlation coefficient (r = -0.3329). Conclusion: The ACA parameters obtained by AS-OCT along the horizontal axis after elimination of pupillary block by laser peripheral iridotomy do not correlate and cannot be used to assess the disease severity of PACG
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Purpose: To determine the comparability of anterior chamber biometric measurements in primary angle closure disease (PACD) patients using two commercially available anterior segment optical coherence tomography machines (ASOCT): Visante and Casia. Methods: This was a cross-sectional observational study, which included clinically, diagnosed cases of PACD. Anterior segment biometric measurements were done using Casia and Visante ASOCT. Parameters studied were central corneal thickness (CCT), anterior chamber depth (ACD), nasal (N) and temporal (T) angle opening distance at 500 ?m (AOD500) and 750 ?m (AOD750), and N and T trabecular iris space area at 500 ?m (TISA500) and 750 ?m (TISA750). Results: Total 36 PACD patients (72 eyes) with average age of 59.48 ± 7.95 years were recruited, out of which 25 were females (69.44%) and 11 males (30.56%). The mean measurements of CCT, ACD, AOD500, and TISA on Casia and Visante machines were 522.5 ± 34.75 ?m and 539.55 ± 29.56 ?m (P = 0.00); ACD- 2.144 ± 0.38 mm and 2.133 ± 0.39 mm (P = 0.487); AOD500-0.27 ± 0.16 ?m and 0.21 ± 0.10 ?m (P = 0.04); and TISA500-0.100 ± 0.07 ?m and 0.063 ± 0.03 ?m (P = 0.00), respectively. A statistically significant difference was noted in CCT, N and T AOD, and TISA. A good corelation for ACD and CCT (ACD = 0.9816 and CCT = 0.772) only were noted between the two machines. The Bland-Altman plot analysis of different parameters between two machines has revealed good agreement of measurement of ACD and CCT but poor agreement for rest of the parameters. Conclusion: It is advisable not use the two machines interchangeably because of the wide limits of agreement and poor correlation of angle measurement values of Casia and Visante ASOCT.
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PURPOSE: To assess the accuracy of intraocular lens (IOL) power prediction for cataract surgery with open angle glaucoma (OAG) and to identify preoperative angle parameters correlated with postoperative unpredicted refractive errors. MATERIALS AND METHODS: This study comprised 45 eyes from 45 OAG subjects and 63 eyes from 63 non-glaucomatous cataract subjects (controls). We investigated differences in preoperative predicted refractive errors and postoperative refractive errors for each group. Preoperative predicted refractive errors were obtained by biometry (IOL-master) and compared to postoperative refractive errors measured by auto-refractometer 2 months postoperatively. Anterior angle parameters were determined using swept source optical coherence tomography. We investigated correlations between preoperative angle parameters [angle open distance (AOD); trabecular iris surface area (TISA); angle recess area (ARA); trabecular iris angle (TIA)] and postoperative unpredicted refractive errors. RESULTS: In patients with OAG, significant differences were noted between preoperative predicted and postoperative real refractive errors, with more myopia than predicted. No significant differences were recorded in controls. Angle parameters (AOD, ARA, TISA, and TIA) at the superior and inferior quadrant were significantly correlated with differences between predicted and postoperative refractive errors in OAG patients (-0.321 to -0.408, p<0.05). Superior quadrant AOD 500 was significantly correlated with postoperative refractive differences in multivariate linear regression analysis (β=-2.925, R²=0.404). CONCLUSION: Clinically unpredicted refractive errors after cataract surgery were more common in OAG than in controls. Certain preoperative angle parameters, especially AOD 500 at the superior quadrant, were significantly correlated with these unpredicted errors.