Ciliary body naevus

An update on ophthalmological perspectives in oculodermal melanocytosis (Nevus of Ota)

PURPOSE

To provide a review of the literature on oculodermal melanocytosis (ODM) with a focus on the diagnostic and therapeutic implications of multimodal imaging techniques in the management of ophthalmic complications.

METHODS

The authors carried out a literature search on PubMed, Medline, and Scopus of English language articles published on ODM through August 2021. This review presents traditional and novel diagnostic methods in the diagnosis and follow-up of patients with particular emphasis on addressing the role of imaging in the management of the ophthalmic complications of the condition towards improving current practice patterns.

RESULTS

ODM is a rare, prevalently unilateral, congenital condition that presents with brown or blue/gray flat asymptomatic lesions of the skin, mucosae, episclera/sclera, and uvea localized within the territory of distribution of the ophthalmic and mandibular branches of the trigeminal nerve. Glaucoma and predisposition to uveal melanoma are the main ophthalmic complications. Diagnosis and management are through comprehensive opthalmological examination and traditional imaging methods such as ultrasonography and fluorescein/indocyanine green angiography as pigmentation of the fundus can conceal subtle retinal and choroidal alterations. Anterior segment optical coherence tomography and ultrasound biomicroscopy are used to evaluate the anterior segment and the ciliary body in the presence of glaucoma or melanoma of the anterior uveal tract. Fundus autofluorescence and retinal pigment epithelium (RPE) alterations are of aid in the differential diagnosis between choroidal nevi and melanoma. Enhanced depth imaging spectral domain optical coherence tomography offers outstanding in vivo evaluation of the dimensions and details of tumors or nevi and surrounding choroidal tissues and small choroidal melanomas may show distortions of the retinal and sub-retinal profile, presence of intra and sub-retinal fluid, abnormalities of the RPE, and compression of the choriocapillaris.

CONCLUSIONS

Novel multimodal imaging techniques are significant in the diagnosis and management of the ophthalmic complications of ODM. Fundus autofluorescence and enhanced depth spectral domain optical coherence tomography have adjunctive value in the detection of early-stage melanoma and differential diagnosis between nevi and melanoma. Awareness of current and emerging imaging techniques can propagate improved standardized definition and assessment of the complications of ODM.

Imaging of the Ciliary Body: A Major Review

PURPOSE

We conducted a systematic search of literature to understand the various methods of imaging of the ciliary body.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Semiautomatic extraction algorithm for images of the ciliary muscle

PURPOSE

To develop and evaluate a semiautomatic algorithm for segmentation and morphological assessment of the dimensions of the ciliary muscle in Visante Anterior Segment Optical Coherence Tomography images.

METHODS

Geometric distortions in Visante images analyzed as binary files were assessed by imaging an optical flat and human donor tissue. The appropriate pixel/mm conversion factor to use for air (n = 1) was estimated by imaging calibration spheres. A semiautomatic algorithm was developed to extract the dimensions of the ciliary muscle from Visante images. Measurements were also made manually using Visante software calipers. Interclass correlation coefficients and Bland-Altman analyses were used to compare the methods. A multilevel model was fitted to estimate the variance of algorithm measurements that was due to differences within- and between-examiners in scleral spur selection vs. biological variability.

RESULTS

The optical flat and the human donor tissue were imaged and appeared without geometric distortions in binary file format. Bland-Altman analyses revealed that caliper measurements tended to underestimate ciliary muscle thickness at 3 mm posterior to the scleral spur in subjects with the thickest ciliary muscles (t = 3.6, p < 0.001). The percent variance due to within- or between-examiner differences in scleral spur selection was found to be small (6%) when compared with the variance because of biological difference across subjects (80%). Using the mean of measurements from three images, achieved an estimated interclass correlation coefficient of 0.85.

CONCLUSIONS

The semiautomatic algorithm successfully segmented the ciliary muscle for further measurement. Using the algorithm to follow the scleral curvature to locate more posterior measurements is critical to avoid underestimating thickness measurements. This semiautomatic algorithm will allow for repeatable, efficient, and masked ciliary muscle measurements in large datasets.