Definition

Surgically treatable macular diseases are mainly represented by those forms of alteration of the macular region caused by mechanical phenomena. At the level of this region of the retina it is possible to form membranes at the area located in contact with the vitreous body. The vitreous body is surrounded by an outer film called the vitreous cortex. In correspondence of the macula there is a region in which due to specific anatomical particularities it is possible the formation of thin abnormal membranes originated sometimes from residues of the vitreous cortex, sometimes from the same retina. These membranes, called "epiretinal", contract relations with the macular retina, adhering to the inner retina.

The main macular diseases related to the presence of epiretinal membranes are:

1. The macularpucker (English term meaning: "wrinkling"), characterized by the presence of an epiretinal membrane attached to the macular region and contracted, therefore associated with image distortion and, in severe cases, the formation of central blind spots in vision (scotomes). Surgery can lead to a resolution, not always total, of visual diseases, and especially to a reduction in image deformation.
2. The vitreomacular traction, in which the vitreous cortex remains attached to the central portion of the macula, called the fovea. The resulting traction over such a small area can cause a noticeable visual lowering.
3. The macular hole, characterized by the formation of an opening in the central portion of the macular region, which mainly in eyes with high myopia can be associated with a posterior retinal detachment.

Symptomatology

If the cells that make up the membranes are not contractile in nature, they do not tend to exert traction on the points of contact and the visual disturbances caused by the epiretinal membranes are moderate. The disturbances in these cases are generally limited to image distortion, due to a modest wrinkling of the macular region subject to traction by the membrane.

If, on the other hand, the tractions are more marked, the retinal tissue suffers due to the strong deformation caused by the membrane and the visual lowering becomes more marked, being able to hesitate in severe reductions of vision if surgery is not performed.

Diagnostics

A key role in the therapy of these diseases affecting the macular region is played by Optical Coherence Tomography (OCT), which uses a low optical coherence light beam, not monochromatic, that “brushes” the macular region with a series of numerous parallel lines. The reflected light is then captured by a detector that analyzes it and establishes through a computer the optical density of each retinal point, reconstructing a three-dimensional map of the area of tissue analyzed. The result is high-resolution 3D images of the macular region and the vitreous in front of it, which make it possible to visualize the shape of the membranes, the relationships they have with the retina and the damage they are causing.

The OCT techniques have undergone a remarkable evolution over the years, from the "Time Domain" to the "Spectral Domain", to the last and most accurate system that is called "Swept Source", in which the precision is increased by the fact that the light source consists of a modulated laser, with a wavelength in the infrared field, allowing in addition to the production of extreme detail also a deeper penetration into the tissues, for which even the deepest structures are displayed.

Therapy

The most frequently used surgical technique is vitrectomy with removal of epiretinal membranes. In these cases it is a complex intervention because it involves an action on extremely delicate ocular structures, if we consider that the entire macular region is 1.5 mm large and consists of a tissue composed of high-density nerve cells with a critical disposition for the maintenance of visual acuity, and therefore it must be used only after an accurate morphological and functional evaluation of the patient that allows to establish if the benefit/risk ratio is favorable.

Vitrectomy surgery has also proved to be of great importance in the treatment of the most severe cases of retinopathy that occur in diabetic patients. Diabetes, in fact, in the most advanced cases, which currently thanks to the improvement of preventive care have become increasingly rare, can hesitate in intraocular hemorrhages and in retinal detachments with tractions also at the macular level. The intervention of vitrectomy, removing the hemorrhagic vitreous and the tractions that this exerts on the retina, allows the resolution of cases that in the past led to blindness.