Eye hypotension is a syndrome, the pathognomonic sign of which is a decrease in intraocular pressure below 15 mmHg. The main clinical manifestations are “flies” and “floating opacities” in front of the eyes, increased visual fatigue, visual impairment, headache. Tonometry, electronic tonography, visometry, ophthalmoscopy, biomicroscopy, gonioscopy, ultrasound, Seidel filtration test are used for diagnostics. Conservative therapy is reduced to the appointment of vasodilators, cycloplegic mydriatics, antioxidants and glucocorticosteroids. Surgical treatment is based on plastic surgery of the filtering area.
H44.4 Eye hypotension
Eye hypotension is a widespread pathology in clinical ophthalmology. According to statistics, a decrease in ophthalmotonus is observed in 40.6% of cases after concussion, in 55.3% – after penetrating corneal-scleral injury. In 75% of patients, the IOP level is below 12 mmHg. Most often, this syndrome develops at the age of 20 to 45 years. Signs of hypotension are diagnosed mainly in men, which is due to more frequent injuries and contusions of the eyes in males. In childhood, the symptoms of the disease in 81.4% develop against the background of severe injuries. Pathology is found everywhere.
A decrease in ophthalmotonus may occur with direct damage to the structures of the eye or be one of the manifestations of systemic diseases. Intraocular pressure (IOP) below the reference values is observed in diabetic and uremic coma, dehydration, collaptoid conditions, low intracranial pressure. The main etiological factors of eyeball hypotension include:
- Penetrating wounds of the eye. During perforation of the ocular membranes, IOP progressively decreases due to the release of watery moisture outside the eye. The larger the size of the wound defect, the faster hypotension will increase. In severe cases of mechanical injuries, along with intraocular fluid (IOFs), the vitreous body also falls out of the eye cavity.
- Formation of fistulas. Small fistulas cause chronic hypotension. As a rule, they are formed when the edges of the wound are incorrectly brought together during surgery. Less often, minor injuries are the trigger factors.
- Violation of the production of intraocular fluids. The synthesis of watery moisture decreases with age-related changes in the ciliary body. A similar dysfunction is also detected when the ciliary muscle is damaged. At the same time, its contractility decreases and, accordingly, the synthesis of IOFs.
- Contusion of the eyeball. With a severe degree of contusion of the eye, a subconjunctival rupture of the sclera is observed. Most often, ruptures are localized under the external muscles of the eye, because at this point the thickness of the fibrous membrane is only 0.3 mm, or in the projection area of the Schlemm canal.
- Retinal or choroid detachment. With retinal detachment, acute hypotension of the eye is noted with a high risk of massive bleeding from the vessels. At the same time, intraocular pressure remains lowered even in the long-term postoperative period.
- Surgical interventions. Hypotension is a frequent complication of anti–glaucomatous operations. The risk of a decrease in ophthalmotonus increases significantly with intraoperative use of cytostatics, as well as with a large size of the trepanation opening. A decrease in the volume of the vitreous body may occur when it is partially removed during endovitreal surgery.
With eye hypotension, the intensity of IOFs production decreases. This is caused by a shortage of blood supply, which leads to trophic disorders and ischemia of surrounding tissues. Subsequently, destructive changes of the ciliary body develop with its further dysfunction. Hydrodynamic shifts play an important role in the pathogenesis of posttraumatic hypotension. With a puncture wound, persistent ophthalmohypertension after damage to the membranes of the eye is replaced by severe hypotension. In some cases, the tone of the eye block is low due to the increased outflow of chamber moisture. Similar pathological changes are observed with the detachment or flat detachment of the ciliary body.
With a slight decrease in IOP, the appearance of “floating opacities” and “flies” in front of the eyes is traced. The long course of the disease leads to the development of headache, which in most cases is localized in the occipital region. Patients note increased fatigue when performing visual work (reading, watching TV). With severe hypotension, a decrease in visual acuity is detected. Patients complain of discomfort with the movements of the eyeballs and deterioration of peripheral vision. A pronounced pain syndrome indicates the traumatic nature of the pathology. When the disease occurs against the background of infection, there is an injection of conjunctival vessels, increased lacrimation.
Most often, massive hemorrhages develop in violation of intraocular hydrodynamics and low ophthalmotonus. It is important to note that with acute hypotension of the eye, the pressure in the anterior chamber also drops. This leads to dislocation of the vitreous body and ruptures of hyaloid-angioretinal adhesions, followed by damage to retinal vessels. The development of such severe consequences as expulsive hemorrhage and detachment of the vascular membrane is traced. Intraoperative ophthalmohypotonia can cause vitreous prolapse or the development of cyst-like macular edema. However, the most formidable complication of hypotension is considered to be atrophy of the eyeball.
The diagnosis is based on anamnestic information, the results of a physical examination and specific research methods. During the initial examination of the patient, the decrease in ophthalmotonus can be determined palpationally and compared with the opposite eye. In order to establish the etiology of the disease, it is necessary to use the following diagnostic methods:
- Measurement of intraocular pressure. A specific diagnostic criterion for eye hypotension is considered to be a drop in the tonometric IOP to 15 mmHg and below. At the same time, the true IOP does not exceed 8 mmHg. In case of eye injuries, the use of non-contact tonometry is recommended.
- Electronic tonography. The study allows you to measure the IOP, as well as to study the nature of the hydrodynamics of the eye. During the study, the volume of intraocular fluid, its outflow coefficient, as well as the rate of production of chamber moisture are calculated. With severe hypotension, it is impossible to perform electronic tonography.
- Visometry. With severe eye damage, central vision is absent in 55.3% of patients. Visual functions remain at a high level only in 5.3% of patients (0.3-0.7 dptr). In 39.4%, visual acuity indicators are in the range of 0.1-0.3 dptr.
- Gonioscopy. The pathology in question is accompanied by a deepening of the angle of the anterior chamber of the eye. With traumatic genesis, gonioscopy reveals a blood accumulation (hyphema), and with systemic diseases – inflammatory exudate. Increased pigmentation of the anterior chamber angle is determined, which leads to a violation of the circulation of IOFs.
- Examination of the anterior segment of the eye. With biomicroscopy of the eyeball, it is possible to visualize swelling and opacity of the cornea. With perforating wounds, defects on the surface of the cornea are often observed. The passage of light rays is difficult due to turbidity of watery moisture or vitreous.
- Ophthalmoscopy. A decrease in tonometric indicators leads to edema of the central area of the retina. Prolonged hypotension causes the progression of dystrophic changes. According to ophthalmoscopy, maculopathy is manifested by swelling of the retina and its radial folding. Retinal vessels are dilated.
- Ultrasound examination of the eye. All patients with low ophthalmotonus are shown an ultrasound of the eye with measurement of the anteroposterior size of the eyeball and subsequent comparison with the parameters of a healthy eye. If the difference in sagittal size is more than 3.0 mm, this corresponds to severe hypotension.
- Seidel filtration sample. Instillation of sodium fluorescein solution is performed for the study. With a perforated corneal wound, it is eroded due to the filtration of the moisture of the anterior chamber. However, in case of micro-injuries, the sample is not informative enough.
Etiotropic therapy with reduced ophthalmotonus is aimed not only at increasing IOP, but also at improving the blood supply to the membranes of the eyes, which increases the activity of metabolic processes in its structures. To do this, plasma substitutes and angioprotectors are injected intravenously. In hypotension caused by a violation of IOFs production, it is advisable to prescribe cycloplegic mydriatics and vasodilators. Alternate use of antioxidants (methylethylpyridinol) and synthetic glucocorticosteroids (dexamethasone phosphate) is recommended. However, these methods can increase intraocular pressure only for a short period of time.
Laser stimulation of the ciliary body is considered to be an effective way to influence the synthesis of IOFs. To restore ophthalmotonus in persons with previously performed anti-glaucomatous surgery, plastic surgery of the filter zone is indicated. To do this, a solution of volumetrically structured collagen gel is injected into the cavity of the filtration pad. A revision of the surgical intervention zone is being performed. Tissue plasty is carried out by applying additional sutures to the trepanation hole and the scleral flap.
To reduce the outflow of watery moisture, such methods of physical influence as diathermy, laser therapy and cryoaplication are used. In case of penetrating eye injury, it is necessary to reduce the edges of the wound in order to achieve complete sealing. In the case of a pronounced decrease in the size of the vitreous body, intravitreal administration of silicone, isotonic sodium chloride solution or hyalon is recommended.
Prognosis and prevention
The outcome directly depends on the etiology of the disease. With hypotension caused by severe damage to the eyeball, in 74.3% of cases, it is not possible to normalize hydrodynamic parameters and restore visual acuity in full. The achievement of high visual acuity can be traced only in 13.7% of patients. In 2% of patients, visual functions can be maintained at the level of 0.1-0.3 dptr. Specific preventive measures have not been developed. Non-specific prevention is aimed at preventing eye injury. To do this, it is recommended to use personal protective equipment (glasses, masks) with a high risk of injury.