The retina is a light-sensitive inner layer of the eye, which contains the photoreceptors (cones and rods). A light stimulus reaches the photoreceptors and is converted into a nerve stimulus, with the involvement of the dipole and ganglion cells of the retina and is perceived as an image by the brain.
The choroid is located between the retina and the sclera and, together with the iris and ciliary body, forms the uvea.
The choroid belongs to the most vascularized tissues of the human body.
The vitreous body makes up about 80% of the eye’s volume and is made up of collagen, soluble proteins, hyaluronic acid and water molecules. It naturally adheres to its base at the boundaries of the optic disc and perifoveal.
With age, the vitreous gel undergoes changes such as liquefaction (synchysis) and syneresis, often leading to posterior vitreous detachment, which often causes symptoms such as”floaters” “spiders”, “threads”, photopsia etc.
Η ωχρά κηλίδα είναι μία στρογγυλή περιοχή του οπίσθιου πόλου, υπεύθυνη για την κεντρική όραση.
OCT plays a key role in modern ophthalmic multimodal imaging. It is a non-invasive method without radiation and non-contactimaging technique, which allows the capture of many high-definition images in real time. With the OCT we can obtain information about both the anterior and posterior segments of the eye by examining the tissues of the eye with thin sections. The advent of OCT revolutionizedthe diagnosis and monitoring of macular diseases e.g. age-related degeneration, diabetic maculopathy, epiretinal membrane, etc.
OCT-A, which is based on OCT technology, depicts in a non-invasive way the flow in the blood vessels of the eye, without the need to inject a contrast medium.
This is achieved through changes in the OCT signal, which are caused by the movement of red blood cells.
For example, OCT-A has applications in the diagnosis of choroidal neovascular membrane and its follow-up after treatment, as well as in diabetic retinopathy.
Ultrasonography uses high-frequency sound waves, which are reflected back to the transmitter as they hit the interfaces between the tissues of the eye. This forms an image of the inside of the eye.
B-scan ultrasonography is a key tool in diagnosing retinal detachment in cases of opaque refractive media, e.g. in case of hypermature cataracts or vitreous hemorrhage.
Also, b-scan ultrasonography is necessary in the evaluation of intraocular masses, e.g. choroidal nevus, choroidal melanoma, etc.
