Age-related Macular Degeneration (AMD)
Age-related Macular Degeneration is the leading cause of blindness in the industrialized world. Early and intermediate AMD is characterized by fundus changes in the posterior pole such as drusen (white/yellowish deposits of lipids and proteins between the retinal pigment epithelium RPE and the Bruch’s membrane) and RPE abnormalities such as hyper and hypo pigmentations. In the advanced stages of AMD either a complete atrophy of the RPE, a so called geographic atrophy develops and/or a neovascular complex nAMD either originating from the choroid or from the retina (choroidal neovascularisation CNV or retinal angiomatous proliferation RAP respectively) arises. Currently advanced stages of AMD are in the main focus of clinical research, in the last decade the development of anti-vascular endothelial growth factor therapies (Anti-VEGF) revolutionized the way we treat and the way we examine nAMD patients. Another huge development to better understand this disease was the development of the optical coherence tomography (OCT) technology. In recent years research gained momentum in the field of dry AMD therapy, especially in case of advanced dry AMD with geographic atrophy.
Diabetic retinopathy is one of the leading causes of visual impairment in the working-age population. With the increasing number of patients with diabetes mellitus, diabetic retinopathy (with a prevalence of approximately 35% for adults (40+ years) with diabetes) is about to be a major healthcare issue. The key point in the pathophysiology of diabetic retinopathy is the development capillary endothelial dysfunction. Although the cause is still unclear, this leads to capillary nonperfusion, outpouching of the capillary walls (micro-aneurysm), and increased vascular permeability. Clinical sings of diabetic retinopathy (nonproliferative diabetic retinopathy NPDR) are microaneurysms, intraretinal hemorrhages, and in more advanced NPDR forms cotton wool spots, intraretinal microvascular abnormalities (IRMA) and venous abnormalities such as beadings and loop formation. An even more advanced stage of the disease is proliferative diabetic retinopathy (PDR) is characterized by the formation of neovascularisations (NV) on the surface of the retina, that can cause severe visual decrease by causing vitreous hemorrhages or retinal detachments. Another vision threatening sequel of DR is fluid accumulation in the fovea (diabetic macular edema DME) caused by increased vascular permeability. In the formation of NVs and DME increased secretion of VEGF plays a pivotal role, and current studies have shown, that anti-VEGF therapy is not only effective in the treatment of sequels like DME and NVs, but also has a beneficial effect on the severity of diabetic retinopathy.
Retinal Vein Occlusion (RVO)
Retinal vein occlusions are common retinal diseases. The most widely accepted theory of the pathogenesis of thrombotic occlusion in retinal veins is due to hemodynamic disturbances caused by compression by rigid retinal arteries due to arteriosclerotic changes. These hemodynamic disturbances cause endothelial damage, and thrombus formation. Due to the reduced blood outflow the intraluminal pressure rises, and causes widespread capillary endothelial damage. Depending on the location of the occlusion RVOs are divided in two distinct forms: if the occlusion occurs in the optic nerve head it is called central retinal vein occlusion (CRVO), if the occlusion occurs more distal in a vein branch, than it is called branch vein occlusion (BRVO), in some cases due to anatomic variations only the upper or lower central vein trunk is occluded, these cases are called hemi-CRVO. In general the less retinal area is affected by the occlusion the better the prognosis of the disease is. Macular edema due to increased vascular permeability can occur both in BRVO and in CRVO, and can be treated with anti-VEGF therapy or intravitreal corticosteroids. The most feared complication of RVO is widespread retina ischemia due to permanent capillary destruction, that may lead to neovascularisation formation (NV) both in the posterior and the anterior segment of the eye, later resulting in secondary elevated intraocular pressure.
Retinopathy of Prematurity (ROP)
Retinopathy of prematurity is a vasoproliferative disease affecting extremely premature infants, where the normal development of the retinal vasculature is still incomplete, and is vulnerable to exposure to hyperoxia. Low birth weight and young gestation age and accompanying diseases are the associated risk factors. Disease severity is scored based on the location of the demarcation line/ridge between vascularised and nonvascularised retina (zones I-III), the stage of the demarcation line/ridge (stage I (only a demarcation line) to stage V (total retinal detachment)), and the presence of plus disease (dilatation and tortuosity of the vessels on the posterior pole). ROP may regress spontaneously, but more advanced stages require treatment in order to reduce the risk of progression to advanced stages. Traditionally the treatment of ROP was laser photocoagulation of the nonvascularised retina. Recent studies show increasing evidence that anti-VEGF therapy may be an effective therapy of the disease.
Macular Telangiectasia (Mac Tel)
First described by Gass in the 1960’s, macular telangiectasia (Mac Tel) is characterized by an abnormal change of capillaries at the central area of the macula, associated with a loss of the outer nuclear layers and the ellipsoid zone. Patients often complain of metamorphopsia or scotoma. Visual acuity also gradually reduces. Mac Tel is divided sub-types, although type 2 is most common. Mac Tel type 2 shows a bilateral, acquired manifestation, which mostly affect elder people. Due to a high prevalence of hypertension and diabetes mellitus in patients with Mac Tel type 2, neurodegenerative processes may be used to explain the etiology of the disease. Diagnostic methods involve fluorescein angiography, optical coherence tomography (angiography) and an ophthalmic examination. Management and prognosis of patients with Mac Tel type 2 depend on the secondary complications and have to be evaluated individually.