Ultrasound signs of diseases of the eye

Normal hemodynamic parameters are used for comparison with similar parameters in patients with various vascular, inflammatory, neoplastic and other diseases of the visual organ, both in the existing and in the newly formed vascular bed.

The greatest information content of Doppler methods was revealed in the following pathological processes:

• anterior ischemic optic neuropathy;
• hemodynamically significant stenosis or occlusion of the internal carotid artery, causing a change in the direction of blood flow in the ophthalmic artery basin;
• spasm or occlusion of the central retinal artery;
• thrombosis of the central retinal vein, superior ophthalmic vein and cavernous sinus;
• retinopathy of prematurity;
• pseudotumorous lesions of the fundus and orbit;
• tumors of the eye, its adnexa and orbit;
• retinal detachment against the background of fibrous changes in the vitreous body and the proliferative stage of diabetic angioretinopathy;
• aneurysm of the ophthalmic artery and varicose veins of the orbit;
• carotid-cavernous anastomosis.

Extraorbital vascular diseases, such as atherosclerosis of the vessels and hypertension, which cause an increase in the rigidity of the vascular wall, lead to flattening and rounding of the systolic peak of the Dopplerogram, its deviation, the appearance of an additional peak in systole, and pronounced spectral expansion.

When the ICA is occluded in the neck (if it does not close the mouth of the ophthalmic artery), retrograde blood flow is recorded through the ophthalmic artery; it becomes a kind of bridge through which the path of collateral blood flow to the brain is realized.

In case of stenosis of the internal carotid artery, the linear blood flow velocity (LBFV) decreases on the affected side both in the ophthalmic artery and in its branches. Against the background of glaucoma with increased intraocular pressure, the peripheral vascular resistance in the PCA and central retinal artery basin increases, and the velocities in the ophthalmic artery may decrease. A decrease in velocities in the central retinal artery and PCA occurs during the proliferative stage of diabetic angioretinopathy. Severe edema of the retrobulbar tissue and thickening of the extraocular muscles in autoimmune ophthalmopathy can cause difficulty in the outflow of venous blood from the orbit, and the LBFV in the ICA becomes below normal. Many pathological conditions developing in the vessels directly supplying the eye, if not treated in a timely manner, quickly lead to vision loss, and their early diagnosis is quite important. This group includes spasm or occlusion of the central retinal artery, thrombosis of the central retinal vein, and anterior ischemic optic neuropathy. In the latter condition, during the first day of the disease, depletion or absence of the vascular pattern around the optic nerve head is observed due to a sharp decrease in the velocity indices in the optic nerve head. Attempts to register the vascular pattern in them are not always successful. During treatment, usually during the first week, reperfusion occurs in the basin of these arteries with restoration of blood flow.

Spasm or occlusion of the central retinal artery is manifested by the absence of staining of this vessel in the area of the disk and the retrobulbar part of the optic nerve, the retina in the peripapillary area is edematous. If partial patency of the artery is maintained, the spectrogram becomes low-amplitude due to a decrease in the BFV.

Thrombosis of the central retinal vein leads to a significant change in intraocular hemodynamics. The blood flow in the vein is not recorded or a significant decrease in its speed is noted. Overflow of the venous bed of the retina with blood causes an increase in vascular resistance in the basin of the central retinal artery, the diastolic component of blood flow in the artery is poorly expressed or absent, the blood flow speed in the ophthalmic artery on the affected side decreases in compensation. Hemodynamic changes are accompanied by a characteristic picture in B-mode: the edematous optic disc and macular zone protrude, the inner membranes of the eye thicken.

Thrombosis of the cavernous sinus, sometimes in combination with thrombosis of the superior ophthalmic vein, causes an increase in the diameter of this vein; it is not stained during mapping; if there is no blood flow in it, the LSC is not recorded. With patency of part of the superior ophthalmic vein, the blood flow can be directed towards the facial veins, the venous type of the spectrum is preserved. In B-mode, edema of the retrobulbar fatty tissue, expansion of the perineural space in the orbit and prominence of the edematous optic disc are noted.

Pronounced hemodynamic changes in the eye and orbit occur with the formation of carotid-cavernous fistula (CCF). Considering that the classic triad of this disease (exophthalmos, pulsation of the eyeball and blowing noise in the temple and orbit on the affected side) is absent in approximately 25-30% of patients, the correct diagnosis in this group of patients is first established by ultrasound ophthalmological examination using Doppler techniques. When drawing parallels with the clinical triad of CCF, it is possible to identify the classic "ultrasound triad" of this disease:

• dilation, sometimes very significant, of the superior ophthalmic vein, which is visible in B-mode over a fairly large area as an additional curved anechoic tubular structure;
• retrograde blood flow in the superior ophthalmic vein in mapping mode (the color changes from blue to red-orange-yellow shades);
• arterialization of venous blood flow in the superior ophthalmic vein (linear velocities increase, retrograde direction of blood flow, sharp systolic peaks are formed on the Dopplerogram).

Overflow of the venous bed of the orbit with arterial blood affects hemodynamics in the retinal vessels and choroidal layer: disruption of venous outflow from intraocular structures leads to a significant increase in peripheral resistance in the basin of the central retinal artery and, to a lesser extent, in the PCA. In the central retinal artery, diastolic velocity can decrease to the point of occurrence of reverse flows with registration of a three-phase Dopplerogram; in the PCA, RI approaches unity. B-mode demonstrates edema of the retrobulbar tissue, optic disc, internal membranes of the eye, and expansion of the perineural space in the orbit.

Dopplerography has a differential diagnostic character when detecting, against the background of pronounced opacities in the vitreous body and fibrous strands of detached retina and vascular membranes, a functioning vitreous artery in children with cicatricial stages of retinopathy of prematurity.

Since funnel-shaped retinal detachment can be simulated by V-shaped membranous structures of the vitreous body, it is necessary to detect a retinal vessel in this structure to confirm it. It is easier to do this near the place where the retina attaches to the optic nerve head. Signals during mapping can be weakly expressed, traced on individual fragments of the retina when a large branch of the central retinal artery falls into the scanning area. The LSC in retinal vessels is low-amplitude, the velocities are lower than in the central retinal artery, sometimes - 2 times.

In the projection of the bubble-like detached choroid, arterial blood flow is well recorded, the velocities exceed those in the retinal vessels, and most of the “bubbles” are stained during mapping.

In children with retinopathy of prematurity, a rough or poorly defined cord is often found, fixed by one edge in the area of the optic nerve head, by the other - in the area of the posterior capsule of the lens and the retrolental fibrovascular tissue, which is quite common in such children. With such an ultrasound picture, the impression of a T-shaped retinal detachment is created. However, the mapping mode allows you to see a usually well-defined arterial flow in the projection of the cord, the velocity characteristics of which are often much higher than in the retinal vessels, the blood flow signals are clearer.

The color duplex scanning method is of particular importance when examining patients with suspected ophthalmic oncology. In a pediatric oncology clinic, detection and assessment of the neovascular bed allows differential diagnostics between retinoblastoma, tumor-like deposits of hard exudate in the subretinal space and in the retinal layers in Coats disease, and fibrovascular growths in the vitreous body in cicatricial stages of retinopathy of prematurity.

The absolute majority of intraocular malignant neoplasms in children are represented by retinoblastoma. Color duplex scanning allows detecting tumor vessels in the lesion even in the presence of massive petrification areas.

In cicatricial stages of retinopathy of prematurity, developing fibrovascular structures create an acoustic “plus tissue” effect, but unlike retinoblastoma, signals from blood flow through small vessels in its projection are quite weak, and blood flow is difficult to register due to its low speed.

Hard exudate deposits on the fundus of children with Coats disease are virtually identical to retinoblastoma on B-mode ultrasound. The correct diagnosis is established by a combination of sonographic criteria, one of which is the avascularity of the lesions and the recording of only the retinal vessel on the surface of the formation, the signals from the blood flow in which are most often unstable, as a result of which the blood flow cannot be recorded.

In adults, the most important task is to differentiate choroidal melanoma, which accounts for up to 80% of all malignant intraocular tumors, from the pseudotumor phase of central involutional retinal dystrophy, subretinal and subchoroidal hemorrhages, metastasis, and hemangioma of the choroid. A combination of sonographic features, including Dopplerographic ones, allows us to successfully cope with this task.

Choroidal melanomas are characterized by the development of a predominantly arterial network in the lesion, one or more feeding vessels are clearly distinguished on the periphery of the formation, the degree of vascularization varies from scanty to very pronounced. The distribution of newly formed arteries in the tumor also changes in different patients. Due to imperfect neoplastic angiogenesis, some components of the vessel wall are missing, which is why Dopplerograms show deviations of some blood flow parameters from the norm.

In terms of vascular characteristics, choroidal metastases, which are the second most common malignant intraocular neoplasms in adults, are similar to melanomas, and the diagnosis is made based on a combination of ultrasound criteria. A large feeding arterial vessel is much less often identified in a metastatic tumor, the degree of vascularization is usually moderate, and a diffuse, multicentric growth pattern predominates.

Over time, choroidal hemangiomas acquire a developed vascular network with signs of arteriovenous shunting in the angio-bed and high echogenicity in B-mode.

Tumor-like protruding foci on the fundus that arise with subretinal and subchoroidal hemorrhages, pseudotumor phase of central involutional retinal dystrophy, etc., are avascular in the mapping mode, which, in combination with other parameters, allows for differential diagnostics in an oncology clinic.

With an accurately established diagnosis of an intraocular tumor, Doppler characteristics (the degree and nature of neovascularization, hemodynamic parameters in tumor vessels) are an important criterion for the success of organ-preserving treatment. Along with a decrease in the volume of the neoplasm, positive criteria include desolation of the vascular bed in it, a decrease in the LSC, an increase in resistance in the tumor basin, which was assessed as vascular obstruction due to post-radiation necrotic changes in the lesion, the effects of polychemotherapy, laser destruction, etc.

CDS helps in differential diagnostics of space-occupying lesions of the orbit and adnexa of the eye, since a number of pathological conditions, such as dacryoadenitis, inflammatory granuloma, hematoma, etc., are difficult to distinguish from a neoplastic process in B-mode. At the same time, the nature of tumor vascularization helps to determine their species. Thus, neurogenic tumors - glioma and meningioma - have different degrees of blood supply (in meningioma, the vascular network is well developed). In small lymphosarcoma localized in the conjunctiva of the eyelids - the eyeball, the vessels are single, visible at the surface of the foci. In some cases in adults, in hemangiomas located retrobulbarly, against the background of caverns, a few signals are also recorded. At the same time, in children, mixed hemangiomas in the eyelid area and rhabdomyosarcomas have a well-developed vascular network.

Thus, at present, a certain range of pathological conditions of the eye, its adnexa and orbit require the mandatory use of the entire arsenal of Doppler techniques for timely and correct diagnostics, on which not only the quality of life of a patient with preserved vision, but also life itself often depends. In some cases, Dopplerography in combination with B-scanning helps to avoid more expensive, sometimes invasive interventions, such as X-ray angiography and CT, MRI, and in some diseases surpasses them in information content.