The Retinal Thickness Analyzer (RTA) is an ophthalmology (eye care) vision diagnostic system used to determine retinal thickness, visualize the optic nerve, and view the subretinal layers (tissue located beneath the retina). The system is used for early detection of glaucoma (glaucoma – increase in intraocular pressure with accompanying deterioration of vision) and macular degeneration (macula lutea – yellow spot – is the point of sharpest vision on the retina. A distinction is made between a common dry form and a rare wet form of age-related degeneration of the macula, both of which are associated with photoreceptor loss). Moreover, topographic imaging of the optic disc (exit site of the optic nerve from the eyeball) is also possible.
Indications (areas of application)
- Glaucoma – As a result of confirmation by clinical studies asking whether optic nerve damage exists in glaucoma patients temporally before possible visual field loss, the procedure is used in topographic imaging of the exit point of the optic nerve. Due to the possibility of visualization of the optic nerve, there is the option of detecting an excavation (hollowing) of the optic nerve, which is caused, for example, by increased internal pressure in the presence of glaucoma, so that the RTA as a device of early detection is of extremely important diagnostic significance.
- Diabetic retinopathy (diabetic retinopathy – a type 2 diabetes associated secondary disease that is clinically apparent as a reduction or loss of vision. Damage to the small blood vessels (microangiopathy) causes retinal damage so that visual field loss can result). – The RTA is performed here as a screening and control system.
- Macular degeneration (AMD) – In addition, the RTA is to be considered in screening examinations to control a present macular degeneration.
- Idiopathic damage to the retina or vitreoretinal layer – using the RTA, cystic intraretinal – located in the retina – tissue changes, as well as tissue thickening and age-independent macular degeneration can be detected.
- Uveitides – under the term “uvea” the vascular structures of the interior of the eye are summarized; these include the choroid (choroid), the iris (iris) and the ray body (ciliary body). Inflammation of these structures is called “uveitis“.
- Venous occlusion, postoperative edema of the macula.
The procedure
The principle of the Retinal Thickness Analyzer is based on the topographic imaging of the retina (retina) by projecting a laser beam onto the retina and analyzing the created fundus image (image of the fundus of the eye through the dilated pupil. The fundus is the inner wall of the eyeball visible through the transparent vitreous). On the procedure of RTA:
- Due to the exceedingly high resolution of the examination system, there is a need for mydriasis (dilation of the pupil) by parasympatholytics such as atropine (parasympatholytics cause pupil dilation).
- Following the pupil-dilating procedure, a procedure similar to slit-lamp microscopy (optical device that allows the examiner to view the magnified eye by emitting a beam of light) is performed – a laser beam is projected onto the eye under examination and the resulting image is viewed at an angle comparable to that of slit-lamp microscopy.
- The recorded images represent an optical retinal cross-section and are captured by a state-of-the-art special camera and then digitized.
- By calculating the distance between the vitreoretinal (= adjacent to the inner surface of the retina (retina), especially in the anterior section more compacted outer layer of the vitreous (corpus vitreum), built up from the basement membrane of the inner surface of the retina and a thin layer of vitreous fibrils) and the chorioretinal layers (= chorionic layer (choroidal layer), which is adjacent to the outer layer of the retina.) a determination of the thickness of the retinal layer is possible.
- By directing the laser beam to different regions of the retina, an area-specific measurement of retinal thickness is feasible.
Advantages of the Retinal Thickness Analyzer compared with the HRT (Heidelberg Retina Tomograph – ophthalmologic system for three-dimensional imaging of the optic disc and surrounding retinal regions) include the following:
- The RTA provides a higher-resolution image or video recording of the individual retinal regions.
- Using the RTA, a more comprehensive examination of the retina in terms of area is possible.
There are no known complications or conditions that prompt non-treatment when using the RTA. In its function as a screening method, the RTA procedure leads, among other things, to the earlier detection of glaucoma, so there is a chance to preserve the vision of a glaucoma patient. The presence of the RTA procedure in screening examinations for age-related macular degeneration (AMD) is also growing.