OCT of Retinal and Choroidal Tumors

Abstract

OCT is an important imaging technique to have cross sectional images of eye tissues with good details without the need for taking specimens. Visualization of the deeper layers of the choroid and sclera by conventional OCT is limited by light scattering from pigmented tissue i.e. the RPE and choroid. New imaging modalities, such as EDI-OCT & SS-OCT offer improvements in the diagnosis, treatment planning and monitoring response in patients with ophthalmic tumors. Furthermore, these technologies continue to evolve and become more readily available through ophthalmology practices. SS-OCT is extremely fast scan and can produce 101,000 A scans per second.It can image both the retina and choroid excellent with good deep penetration into the choroid due to the longer wavelength. EDI-OCT is based on placing the zero-delay line further posteriorly to obtain a clearer image at the inner sclera and choroid. Cross sectional images can also be acquired with this new non-invasive modality that is able to image choroidal tumors distinctly from the normal choroid especially those undetectable by ultrasonography i.e. < 1mm in height and < 9 mm in diameter. It can give more detailed information about the intraocular tumors for example • Choroidal nevus is characterized by Gentle contour and dom shaped elevation with deep choroidal shadowing according to pigmentation. • Small choroidal melanoma is characterized by Shaggy photoreceptors, intraretinal odema, photoreceptor loss, loss of ELM, loss of IS/OS, irregularity of IPL & GCL and deep choroidal shadowing in all cases. • Choroidal metastasis is characterized by Lumpy-bumpy contour with dom shaped elevation of the neurosensory retina. • Choroidal lymphoma is characterized by Placid, rippled, or seasick contourwith loss of choriocapillaris. . • CHRPE is characterized by Flat contour and subretinal cleft in the third of cases. • Retinoblastoma is characterized by disorganized neurosensory retina. • Choroidal hemangiomas which can be difficult to see clinically and on ultrasound, could be readily identified in most cases with EDI-OCT with characteristic smooth gentle slopping anterior choroidal contour and gradual choroidal expansion without choriocapillaris compression. • Choroidal osteoma shows hyper-reflective horizontal lamellar lines mostly representing bone lamellae. • Vasoproliferative retinal tumor shows disorganized inner retina. • Retinal capillary haemangioma is characterized by optically dense mass with disorganized inner rtina. • Retinal cavernous haemangioma is characterized by optically clear spaces with lobulated hyper-reflective inner retina and mostly epiretinal membrane. • Retinal lymphoid tumor shows dom shaped RPE irregularity. • Retinal astrocytoma shows inner retinal disorganization & thickening. • Combined hamartoma of retina and retinal pigment epithelium shows anatomic disorganization with loss of retina layers identification. No doubt we are still in the early days, months and years of learning what EDI-OCT and other imaging modalities can teach us about tumors of the choroid and other intraocular structures. We look forward for more information on this subject.