Diagnostic imaging of the ciliary body: Technologies, outcomes, and future perspectives

Abstract

The ciliary body (CB) is part of the uvea and is a complex, highly specialized structure with multiple functions and significant relationships with nearby structures. Its functions include the aqueous humor (AH) production in the ciliary processes, the regulation of the AH output through the uveoscleral pathway, and accommodation, which depends on the ciliary muscle. Also, the CB is an important determinant of angle width as it forms part of the ciliary sulcus. Until recently, knowledge of the CB was based on histological studies. However, this structure can currently be assessed in vivo using imaging techniques such as ultrasound biomicroscopy (UBM) and optical coherence tomography (OCT). Both techniques have shown good reproducibility of their measurements allowing for quantification of CB dimensions and their localization. In effect, studies have shown a larger CB in myopia and its diminishing size with age. Swept-source OCT devices offer fast, non-invasive high-resolution imaging allowing the identification of multiple structures. UBM requires contact and is uncomfortable for the patient. However, this technique offers deeper imaging and therefore remains the gold standard for assessing the posterior chamber, ciliary processes, or zonula. The clinical utility of CB imaging includes its assessment in different types of glaucoma such as angle-closure, malignant or plateau iris. Diagnostic CB imaging is also invaluable for the assessment of ciliochoroidal detachment when suspected, the position after the implantation of a pre-crystalline or sulcus-sutured lenses, diagnosis or monitoring of cysts or tumors, sclerotomies after retinal surgery, intermediate uveitis, or accommodation.

Characteristics of the Ciliary Body in Healthy Chinese Subjects Evaluated by Radial and Transverse Imaging of Ultrasound Biometric Microscopy

“…UBM can be used to measure any quadrant on living subjects, as it is unaffected by shrinkage. Since its inception, UBM has been used in many clinical and preclinical studies associated with CB-related disease, and it is irreplaceable for the study of the posterior chamber and the innermost structures of the iridociliary region compared to AS-OCT [4,[18][19][20]. To the best of our knowledge, this is the first report that demonstrated the morphology parameters of the CB from both radial and transverse scans in four different quadrants in vivo of Chinese people and the correlations between them with systemic and ocular parameters.…”

“…Ultrasound biometric microscopy (UBM) has been widely used to analyze anterior chamber structures, especially the structure behind the iris, such as the CB [3,4]. The UBM imaging and analysis of the CB, based on the radial scan, is valuable in many potential clinical applications, such as analyzing the pathogenesis of different types of angle-closure glaucoma [5][6][7][8]; describing the effects of pharmacologic agents on CB [9][10][11]; revealing the relationship between CBT and refractive error [12]; and assessing the development of uveitis, tumors, and cysts [13][14][15].…”

Iris Morphological and Biomechanical Factors Influencing Angle Closure During Pupil Dilation

“…During distance accommodation, ciliary muscle contraction pushes the ciliary body centrally and anteriorly to increase lens curvature and increases the lens vault. [40][41][42][43] This in turn pushes the iris anteriorly during near vision. During light accommodation, the iris dilator muscle constricts when light intensity decreases to increase pupil size, pushing the anterior border layer closer to the cornea.…”

Iridociliary measurements using the Anterion swept-source optical coherence tomography

“…[ 4 ] The scleral spur can be located manually and is identified from the point of inward protrusion of the sclera at the interface between the less reflective ciliary muscle and the more reflective corneoscleral junction at the inner corneal margin. [ 5 ] The ciliary body is an area of interest for studying and treatment of presbyopia, myopia, and glaucoma and in diseases like intermediate uveitis and in surgical procedures of intravitreal injections and sclerotomies. [ 5 ] The ciliary body and the iridociliary sulcus, that is, the space between the posterior surface of the iris and the anterior face of the ciliary body measurements, have not been incorporated in Anterion.…”

“…[ 5 ] The ciliary body is an area of interest for studying and treatment of presbyopia, myopia, and glaucoma and in diseases like intermediate uveitis and in surgical procedures of intravitreal injections and sclerotomies. [ 5 ] The ciliary body and the iridociliary sulcus, that is, the space between the posterior surface of the iris and the anterior face of the ciliary body measurements, have not been incorporated in Anterion. Is this space important to the clinician?…”