Non-proliferative diabetic retinopathy
Microaneurysms are localized in the inner nuclear layer and belong to the first clinically determined disorders.
- gentle, rounded, red dots, which first appear temporally from the fovea. If they are surrounded by blood, they may not differ from point hemorrhages;
- assimilation of trypsin retina in diabetic retinopathy with periphovial microaneurysms:
- microaneurysms with a high cell content of cells;
- The PHAG reveals delicate hyperfluorescent points, which are non-corroborated microaneurysms, the number of which is usually greater than that of ophthalmoscopically visible ones. In the late phases, diffuse hyperfluorescence due to leakage of the liquid is visible.
Solid exudates are located in the outer plexiform layer.
- wax-shaped, yellow foci with relatively distinct edges, forming aggregations and / or rings in the posterior pole. In the center of the ring of solid exudate (annular exudate) microaneurysms are often determined. Over time, their number and size increase, which poses a threat to the fovea with possible involvement in the pathological process;
- The PHAG reveals the hypofluorescence caused by the blocking of the background fluorescence of the choroid.
Retinal edema is primarily localized between the outer plexiform and inner nuclear layers. Later, the inner plexiform layer and the layer of nerve fibers can be involved, up to the entire thickness of the retina. Further accumulation of fluid in the fovea leads to the formation of a cyst (cystic macular edema).
- Retinal edema is best determined by examining a slit lamp using a Goldmann lens;
- The PHAG reveals a late hyperfluorescence caused by leakage of the retinal capillaries.
- Intra-retinal hemorrhages appear from the venous ends of the capillaries and are located in the middle layers of the retina. These hemorrhages are pointlike, have a red color and an indefinite configuration;
- in the layer of retinal nerve fibers, hemorrhages arise from larger surface precapillary arterioles, which determines their shape in the form of "flame tongues".
Tactics of management of patients with non-proliferative diabetic retinopathy
Patients with nonproliferative diabetic retinopathy do not need treatment, however, an annual examination is necessary. In addition to optimal control over diabetes, it is necessary to take into account the accompanying factors (arterial hypertension, anemia and kidney pathology).
Pre-proliferative diabetic retinopathy
The appearance of signs of threatening proliferation with nonproliferative diabetic retinopathy indicates the development of pre-proliferative diabetic retinopathy. Clinical signs of pre-proliferative diabetic retinopathy indicate a progressive ischemia of the retina, which is detected in the FLG in the form of intensive areas of hypofluorescence of the unperfused retina ("capillary exclusion"). The risk of progression to proliferation is directly proportional to the number of focal changes.
Clinical features of pre-proliferative diabetic retinopathy
Cotton-like foci are local areas of infarcts in the layer of retinal nerve fibers caused by occlusion of precapillary arterioles. The interruption of the axoplasmatic current with subsequent accumulation of the transported material in the axons (axoplasmic stasis) gives the foci whitish shade.
- signs: small, whitish, cotton-like surface foci that cover lower lying blood vessels, clinically determined only in the post-equatorial zone of the retina, where the thickness of the layer of nerve fibers is sufficient for their visualization;
- The PHAG reveals local hypofluorescence caused by the blocking of the background fluorescence of the choroid, often accompanied by neighboring regions of unperfused capillaries.
Intra-retinal microvascular disorders are represented by shunts from the retinal arterioles to the veins that bypass the capillary bed, and are therefore often identified near the interruption sites of capillary blood flow.
- signs: tender red strips connecting arterioles and venules, which look like local parts of flat, newly formed retinal vessels. The main distinguishing feature of intra-retinal microvascular disorders is their location within the retina, the impossibility of crossing large vessels and the absence of sweating on the PHAG;
- The PHAG reveals local hyperfluorocenosis associated with adjacent areas of capillary blood flow interruption.
Venous disorders: enlargement, loops, segmentation in the form of "beads" or "beads".
Arterial disorders: constriction, a sign of "silver wire" and obliteration, which gives them a similarity to the occlusion of the branch of the central artery of the retina.
Dark spots of hemorrhages: hemorrhagic infarcts of the retina, located in its middle layers.
Tactics of management of patients with pre-proliferative diabetic retinopathy
With pre-proliferative diabetic retinopathy, special surveillance is required because of the risk of developing proliferative diabetic retinopathy. Photocoagulation is not usually indicated, except when it is impossible to observe in dynamics or the pair eye sight is already lost due to proliferative diabetic retinopathy.
The main cause of vision impairment in diabetics, especially in type 2 diabetes, is foveal edema, solid exudate deposition or ischemia (diabetic maculopathy).
Classification of diabetic maculopathy
Local exudative diabetic maculopathy
- signs: a clearly limited thickening of the retina, accompanied by a full or incomplete ring of perifovealnyh solid exudates;
- The PHAG reveals late local hyperfluorescence due to sweating and good macular perfusion.
Diffuse exudative diabetic maculopathy
- signs: diffuse thickening of the retina, which can be accompanied by cystic changes. Obliteration with pronounced edema sometimes makes it impossible to localize the fovea;
- The PHAG reveals multiple point hyperfluorescence of microaneurysms and late diffuse hyperfluorescence due to sweating, which is more pronounced compared with clinical examination. In the presence of cystic macular edema, a patch in the form of a "petal of a flower" is defined.
Ischemic diabetic maculopathy
- signs: decreased visual acuity with a relatively preserved fovea; is often associated with pre-proliferative diabetic retinopathy. Dark bleeding spots can be detected;
- The PHAG reveals the unperfused capillaries in the fovea, the severity of which does not always correspond to the degree of decrease in visual acuity.
Other areas of non-perfusionable capillaries are often present in the posterior pole and on the periphery.
Mixed diabetic maculopathy is characterized by signs of both ischemia and exudation.
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Clinically significant edema of the macula
Clinically significant edema of the macula is characterized by the following:
- Retinal edema within 500 μm from the central fovea.
- Solid exudates within 500 μm from the central fovea if they are accompanied by a thickening of the retina around it (which may extend beyond 500 μm).
- Retinal edema within 1 DD (1500 μm) or more, i.е. Any zone of edema should fall within 1 DD from the central fovea.
Clinically significant edema of the macula requires laser photocoagulation regardless of visual acuity, since treatment reduces the risk of vision loss by 50%. Improvement of visual functions is rare, so treatment is indicated for prophylactic purposes. It is necessary to conduct PHAG before treatment in order to determine the areas and sizes of sweating. Detection of unperfused capillaries in fovea (ischemic maculopathy), which is a poor prognostic sign and contraindication to treatment.
Argon laser coagulation
Local laser coagulation involves applying laser coagulants to microaneurysms and microvascular disorders in the center of the rings of solid exudates localized within 500-3000 microns from the central fovea. The size of the coagulum is 50-100 μm with a duration of 0.10 sec and sufficient power to provide gentle discoloration or darkening of the microaneurysm. Treatment of foci up to 300 μm from the central fovea is indicated with persisting clinically significant edema of the macula, despite earlier treatment and visual acuity below 6/12. In such cases, it is recommended that the exposure time be shortened to 0.05 seconds; b) Lattice laser coagulation is used in the presence of sites of diffuse thickening of the retina localized at a distance of more than 500 μm from the central fovea and 500 μm from the temporal margin of the optic nerve disc. The size of the coagulates is 100-200 microns, the exposure time is 0.1 sec. They should have a very light color, they are imposed at a distance corresponding to the diameter of 1 coagulate.
Results. Approximately 70% of cases it is possible to achieve stabilization of visual functions, in 15% - there is an improvement and in 15% of cases - the subsequent deterioration. The resolution of edema occurs within 4 months, so repeated treatment during this period is not indicated.
Factors for unfavorable prognosis
Solid exudates covering the fovea.
- Diffuse edema of the macula.
- Cystic edema of the macula.
- Mixed exudative ischemic maculopathy.
- Severe retinopathy at the time of examination.
The pars plana vitrectomy may be indicated for macular edema associated with tangential traction, which extends from a thickened and compacted posterior hyaloid membrane. In such cases, laser treatment is ineffective in contrast to the surgical removal of macular tract.
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Proliferative diabetic retinopathy
It occurs in 5-10% of patients with diabetes. In type 1 diabetes, the risk is particularly high: the incidence rate is 60% after 30 years. Contributing factors are carotid occlusion, posterior vitreous detachment, high degree myopia and optic nerve atrophy.
Clinical features of proliferative diabetic retinopathy
Signs of proliferative diabetic retinopathy. Neovascularization is an indicator of proliferative diabetic retinopathy. Proliferation of the newly formed vessels can occur at a distance of up to 1 DD from the optic nerve disk (neovascularization in the region of the disc) or along the main vascular (neovascularization outside the disc). Both options are possible. It has been established that the development of proliferative diabetic retinopathy is preceded by non-perfusion of more than a quarter of the retina. The absence of an internal border membrane around the optic disc partly explains the propensity for neoplasm in this area. New vessels appear as endothelial proliferation, most often from veins; then they cross the defects of the inner border membrane, they lie in the potential plane between the retina and the back surface of the vitreous that supports them.
PHAG. For diagnostics it is not necessary, but reveals neovascularization in the early phases of angiogram and shows hyperfluorescence in the late phases caused by active sweating of the dye from neovascular tissue.
Symptoms of proliferative diabetic retinopathy
The severity of proliferative diabetic retinopathy is determined by comparing the area occupied by the newly formed vessels to the area of the optic nerve disk:
Neovascularization in the region of the disk
- Moderate - sizes less than 1/3 of the DD.
- Expressed - the size is more than 1/3 of the DD.
Neovascularization outside the disc
- Moderate - the size is less than 1/2 DD.
- Expressed - the size is more than 1/2 DD.
Elevated newly formed vessels are less amenable to laser treatment than flat ones.
Fibrosis associated with neovascularization is of interest in that, with significant fibrotic proliferation, despite the low probability of bleeding, there is a high risk of traction retinal detachment.
Hemorrhages, which may be preretinal (subgialoid) and / or inside the vitreous humor, are an important risk factor for reducing visual acuity.
Characteristics of an increased risk of significant vision loss during the first 2 years in the absence of treatment are as follows:
- Moderate neovascularization in the area of the disk with hemorrhages is 26% of the risk, which is reduced to 4% after treatment.
- Expressed neovascularization in the area of the disk without hemorrhage is 26% of the risk, which after treatment is reduced to 9%.
Expressed neovascularization of the optic disc with elevation
- Expressed neovascularization in the area of the disk with hemorrhages is 37% of the risk, which after treatment is reduced to 20%.
- Expressed neovascularization outside the disk with hemorrhages is 30% risk, which after treatment is reduced to 7%.
If these criteria are not met, it is recommended to refrain from photocoagulation and examine the patient every 3 months. However, in fact, most ophthalmologists have resorted to laser photocoagulation already at the first signs of neovascularization.