Peering into the eye: A comprehensive look at ultrasound biomicroscopy (UBM) and its diagnostic value in anterior segment disorders.

Background: Ultrasound biomicroscopy (UBM) is a noninvasive imaging modality that enables in-vivo visualization of the structures of the anterior segment of the eye. Unlike routine ophthalmic diagnostic ultrasound which uses frequencies of 5-10 MHz, UBM utilizes ultrasound frequencies in the range of 50-100 MHz. The high-frequency probes in UBM allows for higher resolution and better visualization of subsurface ocular structures, even in the presence of anatomic or pathological obscuration. UBM has qualitative as well as quantitative applications in various disorders affecting the anterior segment of the eye. Despite its huge importance, many clinicians lack in knowledge about the technique and its clinical usefulness. The current educational video aims to address this gap in knowledge by highlighting the technique and various clinical indications of UBM. Purpose: The purpose of this video is to demonstrate the technique of UBM and showcase its quantitative and qualitative implications and importance through various clinical cases. Synopsis: UBM is an imaging technique that assesses the depth of tissue structures by measuring the time delay of the returning ultrasound signal. This modality is capable of measuring the size of various structures within the eye, such as the cornea, iris, ciliary body, sclera, and the depth of the anterior and posterior chamber. To perform a UBM, a transducer is inserted into a specially designed eye cup filled with distilled water, creating a water bath environment. Axial and longitudinal scans can be performed in a similar fashion as in routine diagnostic B-scan ultrasound. Quantitative indications for UBM depicted in this video include measurements of corneal thickness, depth of the anterior chamber, and the width of the angle. The video also showcases how UBM can aid in the diagnosis and management of various anterior segment disorders like angle-closure glaucoma, plateau iris configuration, secondary glaucoma, and anterior uveitis with complicated cataract. Qualitative indications for UBM highlighted in this video include its role in intermediate uveitis, ocular hypotony, ocular surface tumors, cystic lesions of iris, and identifying the location and type of intraocular foreign bodies in the anterior segment based on the type of artifact seen. Additionally, the video shows the applications of UBM in scleral and episcleral pathologies. Highlights: This video will educate clinicians about the technique of UBM and showcase a bouquet of UBM findings in various case scenarios, helping one to better understand the potential of this modality in clinical practice. Video link: https://youtu.be/F626TMbJXoU.

Ocular structural changes in patients with Duane retraction syndrome: Does a correlation exist?

PURPOSE: The purpose of this study was to investigate the structural changes (axial length, central macular thickness (CMT), subfoveal choroidal thickness, and keratometry) in subjects with unilateral Duane retraction syndrome (DRS) as compared with the normal fellow eye. METHODS: In this prospective study, we included 34 subjects with unilateral DRS from January 2016 to December 2016 seen at our institute. Data was collected for axial length, keratometry using partial coherence interferometry, CMT, subfoveal choroidal thickness using the enhanced depth imaging-optical coherence tomography (EDI-OCT). All these measurements were compared between the affected and fellow eye. RESULTS: During this period, we included 34 subjects with unilateral DRS (22 Type I, 1 Type II, and 11 Type III). The mean age (±SD) of subjects was 14 ± 8 years (range: 5-28 years). There were 15 males and 19 females. Eyes with DRS were significantly shorter (median axial length 22.4 mm, interquartile range (IQR): 21.56 - 23.17) as compared to fellow eye (median axial length 22.7 mm, IQR: 22.35-23.55), P = 0.04. Choroidal thickness, CMT, and average keratometry were similar in DRS and fellow eyes (P = 0.39, 0.06, and 0.11, respectively). A significant difference in axial length was found only between Type I and Type III DRS (P = 0.03). CONCLUSION: This study suggests that in subjects with DRS, the affected eye has shorter median axial length when compared with the fellow eye. Prevalence of refractive error in eye with DRS was higher compared to fellow eye. But, there was no difference in magnitude of refractive error found between eye with DRS and normal fellow eye.

SHORT-TERM SAFETY OF 2 MG INTRAVITREAL ZIV-AFLIBERCEPT.

PURPOSE: To evaluate the safety of single intravitreal 2 mg ziv-aflibercept (0.08 mL) injections for the treatment of choroidal neovascular membranes (CNVM). METHODS: Eyes with choroidal neovascular membranes because of several conditions each received single intravitreal injections of 2 mg ziv-aflibercept (0.08 mL). Comprehensive ophthalmic examinations and detailed systemic evaluations were performed at baseline and Days 1, 7, and 30 after injections. Standard electroretinography was performed at baseline and Day 30. Primary outcome measures consisted of safety assessments (signs of clinical toxicity and electroretinographic abnormalities). Secondary outcome measures included changes in best-corrected visual acuity (BCVA) and central subfield thickness (CST) of the macula. RESULTS: Twenty-one eyes of 20 patients (12 males) received injections. Etiologies responsible for the choroidal neovascular membranes included age-related macular degeneration (14), polypoidal choroidal vasculopathy (PCV) (3), myopia (2), and idiopathic juxtafoveal telangiectasia (2). None of the patients complained of worsening vision or pain after the intravitreal injections and no intraocular inflammation was seen. No significant changes in the electroretinographic b/a ratio from baseline to 1 month were measured (scotopic: P = 0.89; photopic: P = 0.13) and mean intraocular pressures were unchanged (14.2 ± 3.6 vs. 13.7 ± 3.0 mmHg; P = 0.62). Mean best-corrected visual acuity did not change significantly from baseline to 1 month (0.66 ± 0.37 logMAR [Snellen equivalent: 20/100] vs. 0.61 ± 0.35 logMAR [Snellen equivalent: 20/80]; P = 0.72) but significant improvements in central subfield thickness were seen (343 ± 177 vs. 210 ± 133 µm; P = 0.01). CONCLUSION: Single intravitreal injections of 2 mg ziv-aflibercept (0.08 mL) appear to be safe through 1 month.