Ultrasound biomicroscopy (UBM) is an invaluable investigation for imaging anterior segment structures. Although it is operator-dependent and time consuming, unlike optical-based imaging techniques, it is able to image structures posterior to the iris, such as the zonules, ciliary body and part of the pars plana. It is especially useful in advanced cataracts, traumatic cataracts, subluxed lenses, posterior polar cataracts, and congenital and developmental anomalies affecting the anterior segment. It provides diagnostic information in eyes with complex cataracts or intraocular lens (IOL)-related pathology, and aids in surgical planning in order to minimise complications. In this review, we describe the UBM features of various lenticular pathologies and demonstrate its application in the diagnosis and surgical management of lens and IOL-related pathologies.

UNASSIGNED: We conducted a systematic search of literature to understand the various methods of imaging of the ciliary body.
UNASSIGNED: PubMed, Science Direct, Cochrane Library and Google Scholar were searched comprehensively and systematically to find studies related to the various modalities of ciliary body imaging.
UNASSIGNED: The various ciliary body parameters that have been described are Ciliary body thickness, Ciliary body length, ciliary muscle thickness, ciliary process length, ciliary muscle length, ciliary muscle anterior length, trabecular ciliary process distance and Iris ciliary process distance. The various angles which have been measured, which mostly have a significance in Primary angle closure glaucoma (PACG) are Iris ciliary angle, Trabecular ciliary angle, scleral ciliary process angle. Various authors have defined them in various ways with subtle differences. Plateau iris and PACG mechanisms, not forgetting malignant glaucoma are better understood with imaging of the ciliary body using the ultrasound biomicroscopy (UBM). The anterior segment optical coherence tomography (ASOCT) imaging of the ciliary body has been described albeit with its own disadvantages. A few other fields dependant on the importance of ciliary body imaging are intravitreal injections, pars plana vitrectomy, measurements for implantable collamer lens (ICL) and of utmost importance, the differentiating features of ciliary body masses.
UNASSIGNED: The UBM is still preferred over the ASOCT for imaging of the ciliary body. A lot of lacunae of knowledge still exists and consensus has to be reached on defining all the parameters universally. Future studies will be able to shed more light on the role of the ciliary body in the many ocular disorders mentioned in this review.

Efficient ocular drug delivery is a challenging clinical problem with various therapeutic options but no clearly preferred methodology. Given the ubiquity of ultrasound as a diagnostic technique, the safety profile of ultrasound in an ocular context, and the prospect of custom-made ultrasound-sensitive contrast agents, ultrasound presents an attractive ocular drug delivery modality. In this review, we evaluate our present understanding of ultrasound as it relates to ocular drug delivery and significant knowledge gaps in the field. In doing so, we hope to call attention to a potentially novel drug delivery pathway that could be manipulated to treat or cure ocular diseases.

OBJECTIVE: Primary congenital glaucoma (PCG) is a form of childhood glaucoma caused by maldevelopment of the anterior chamber. Disease severity differs greatly amongst patients. Ultrasound biomicroscopy (UBM) is a non-invasive technique that can visualize the anterior segment in infants in vivo. The purpose of this narrative review is to make an overview of the UBM data in PCG and study the applicability of UBM in characterizing the disease.
METHODS: An online search was performed on PubMed in December 2020. After a critical appraisal of the included articles, study and patient characteristics were summarized. The UBM measurements of the anterior segment in PCG of the different studies were analysed.
RESULTS: Six studies were included in this review. All were cross-sectional prospective studies. A total of 221 PCG eyes were examined. PCG eyes showed a larger trabecular iris angle, decreased iris thickness, narrower or absent Schlemm\'s canal and an increased zonular length compared to controls. Abnormal tissue membrane covering the trabecular meshwork and abnormal insertion of the iris and ciliary process were frequently found. The success rate of glaucoma surgery depended on the severity of anterior segment malformations found with UBM.
CONCLUSIONS: Malformations of the anterior segment in PCG can be demonstrated by UBM in vivo. This imaging can help to characterize disease severity and might support surgical treatment decisions.

Pars plana vitrectomy is currently the most common technique used in retinal surgery. Although primarily involving the posterior segment of the eye it also affects the anterior segment. As this is a less published topic, the aim of this paper was to review the literature on changes in the anterior segment after uncomplicated pars plana vitrectomy using data based literature search. The conclusions are that even in otherwise ophthalmologically healthy patients, complications may occur in the anterior segment. Surgeons need to pay utmost attention in glaucoma patients and in those with endothelial insufficiency who are at highest risk of complications. He/she must also correctly plan a potential cataract surgery if not already done earlier. From the literature, most of the changes in the anterior segment after uncomplicated PPV are found to be temporary.

BACKGROUND: Pigment dispersion syndrome (PDS) is a condition where anomalous iridozonular contact leads to pigment dispersion throughout the anterior segment and the released pigment is abnormally deposited on various ocular structures.
METHODS: The clinical presentation of PDS is defined by the presence of pigmented cells on the corneal endothelium, an increase of pigmentation of the trabecular meshwork, and mid-periphery transillumination defects of the iris. This syndrome, more common in myopes, is usually bilateral and can be associated with ocular hypertension or glaucoma. Secondary open-angle pigmentary glaucoma (PG) can develop due to reduction of the outflow of aqueous humour and consequent increase in intraocular pressure leading to glaucomatous optic neuropathy. Diagnosis of PG is commonly between 40 and 50 years of age, occurring more frequently in men. The advent of ultrasound biomicroscopy and anterior segment optical coherence tomography has contributed to enhancing our knowledge on the condition. Typical alterations of the anterior segment are the posterior insertion of the iris and iris concavity. Treatment of PG should be initiated early to hinder disease progression, glaucomatous damage, and vision loss. Management is based on medical therapy, laser iridotomy, selective laser trabeculoplasty, and filtration procedures.
CONCLUSIONS: The differential diagnosis of PDS with other disorders can be challenging and awareness of the condition together with meticulous ophthalmologic examination allows early diagnosis followed by appropriate management strategies. The present review is a comprehensive report on the clinical characteristics, pathogenesis, current management, and status quo of PDS and PG.

The visualization capabilities of various ocular imaging instruments can generally be categorized into photographic (e.g. gonioscopy, Pentacam, RetCam) and optical tomographic (e.g. optical coherence tomography (OCT), photoacoustic (PA) imaging, ultrasound biomicriscopy (UBM)) methods. These imaging instruments allow vision researchers and clinicians to visualize the iridocorneal angle, and are essential in the diagnosis and management of glaucoma. Each of these imaging modalities has particular benefits and associated drawbacks in obtaining repeatable and reliable measurement in the evaluation of the angle. This review article in this context summarized recent progresses in anterior chamber imaging techniques in glaucoma diagnosis and follow-up procedures.

Ultrasound biomicroscopy is a non-invasive imaging technique, which allows high-resolution evaluation of the anatomical features of the anterior segment of the eye regardless of optical media transparency. This technique provides diagnostically significant information in vivo for the cornea, anterior chamber, chamber angle, iris, posterior chamber, zonules, ciliary body, and lens, and is of great value in assessment of the mechanisms of glaucoma onset. The purpose of this paper is to review the use of ultrasound biomicroscopy in the diagnosis and management of rare diseases of the anterior segment such as mesodermal dysgenesis of the neural crest, iridocorneal endothelial syndrome, phakomatoses, and metabolic disorders.