Retinopathy of prematurity

Over the past decade, scientists have come to a common opinion about the multifactorial nature of the occurrence of the disease (that is, the presence of many risk factors), have developed a unified classification of the disease and have proven the effectiveness of preventive laser and cryosurgical treatment. Surgery is still under development in the active and scar stages of the disease. At this stage of development of ophthalmology, it is considered indisputable that the development of retinopathy of prematurity occurs in an immature infant, as a violation of the normal formation of retinal vessels (which ends by the 40th week of intrauterine development, that is, by the time of birth of the full-term baby). It is known that up to 16 weeks of intrauterine development, the retina of the fetus has no blood vessels. Their growth in the retina begins from the exit of the optic nerve in the direction of the periphery. By week 34, the formation of the vascular network in the retinal nasal part is completed (the optic nerve head, from which the vessels grow, is closer to the nasal side). In the temporal part of the growth of blood vessels lasts up to 40 weeks. The earlier a child is born, the smaller the area of ​​the retina covered with vessels, that is, during an ophthalmologic examination, more extensive areas without vessels or avascular zones are detected. If the child was born before 34 weeks, then avascular retinal zones are detected on the periphery from the temporal and nasal sides.

The main risk factors for retinopathy of prematurity are the following. :

• small period of gestation (that is, the birth of a child ahead of time - up to 38-40 weeks) and immaturity (the child may be immature and at birth at term)
• low birth weight
• intensity and duration of mechanical ventilation and oxygen therapy (stay in the incubator )
• concomitant fetal abnormality
• the presence of the mother of chronic inflammatory gynecological diseases during pregnancy , bleeding during childbirth.

After birth in a premature baby, the process of vascular formation is affected by various pathological factors - the external environment, light, and oxygen, which can lead to the development of retinopathy of prematurity. The main manifestation of retinopathy of prematurity is the arrest of the normal formation of vessels, their germination directly inside the eye into the vitreous body. The growth of the vascular and, after it, the young connective tissue causes tension and retinal detachment. As mentioned earlier, the presence of avascular zones in the periphery of the fundus is not a disease, this is only evidence of retinal vasculature development, and, accordingly, the possibility of retinopathy in the future.

In the development of retinopathy of prematurity there are 3 periods. :

1. Active (up to 6 months of age), including changes in retinal vessels (changes in arteries, varicose veins, vascular tortuosity, clouding of the vitreous, hemorrhages in the vitreous, formation of traction retinal detachment, rarely tears and retinal tears (rhematogenous retinal detachment), or combinations thereof .
2. The period of reverse development (from 6 months of age to 1 year). Possible in the early stages of the active period to changes in the vitreous body.
3. Cicatricial period (after 1 year of life). May be accompanied by the formation of medium and high degree myopia , tears and retinal detachment, the development of lens opacities , increased intraocular pressure, a decrease in eyeballs (subatrophy).

In some cases, the lens and the iris can be shifted anteriorly, with a decrease in the anterior chamber of the eye, the development of corneal dystrophy and its subsequent opacification. In some cases, the reverse development of symptoms of the disease occurs, with partial or complete regression. In the case of partial regression, a symptom is a “comet” symptom, which is a traction maculopathy, that is, a central retinal displacement under the action of cicatricial tension in the temporal side, with a characteristic view of narrow vessels in the form of a “comet tail” of the main vessels extending from the optic nerve disk.

Starting at 34 weeks of development (or 3 weeks of life), the child needs to be examined by an ophthalmologist who has special equipment for examining the retina of young children. Such control is necessary for all children born to 35 weeks and weighing less than 2000 grams at birth. If signs of retinopathy of prematurity are detected, examinations are carried out every week (with the so-called “plus” disease - every 3 days) until the threshold stage develops ( At this stage, the question of conducting prophylactic surgical treatment) or complete regression of the disease is being resolved. When the pathological process regresses, an examination can be carried out 1 time per 2 weeks. Inspection is carried out with the mandatory expansion of the pupil, with the use of special children's eyelids (so as not to exert finger pressure on the eye). Most often, the threshold stage of retinopathy of prematurity develops at 36-42 weeks of development (1-4 months of life), therefore parents of a premature baby should know that during this period it should be examined by a specialist (oculist with special equipment and aware of signs of active retinopathy) .

Active retinopathy is a staged pathological process that can end in regression with the complete disappearance of manifestations of the disease or cicatricial changes. According to the international classification, active retinopathy is divided into stages of the process, its localization and length.

• Stage 1: the appearance of a dividing whitish line on the border of the vascular and avascular retina. At revealing stage 1, prophylactic treatment with corticosteroids should be prescribed and if the child receives additional oxygen therapy with antioxidants . From this point on, the observation should be carried out weekly to correct the treatment if the disease progresses or until the disease is fully regressed (if the child is discharged from the hospital, see the eye specialist by follow-up). If retinopathy of stage 1 does not progress after 38 weeks and the child’s somatic condition is stable, then the frequency of examinations can be increased to 2 weeks.
• Stage 2: the appearance of the shaft in place of the line. An increase in the dosage of corticosteroids is carried out, the use of drugs that dilate the vessels is limited, and, if possible, the concentration of supplemental oxygen gradually decreases.
• Stage 3: characterized by the appearance in the shaft of the gray tissue, consolidation of the vitreous body above the shaft with retinal vessels retracting into the vitreous and the development of retinal tension with a tendency to detach it.
• Stage 4: partial retinal detachment (A - central, macular region, B - macular region - exfoliated).
• Stage 5: complete retinal detachment.

Separately, “plus” disease and posterior malignant form are distinguished as the most unfavorable forms of active retinopathy. The disease begins earlier than classical retinopathy, has no clearly defined stages, progresses rapidly and leads to retinal detachment not reaching the threshold stage. The pathological process is characterized by a dramatic expansion of the retinal vessels, marked vitreous edema, hemorrhages along the vessels, dilation of the vessels of the iris, often with the impossibility of dilating the pupil. The effectiveness of treatment for malignant forms of retinopathy of prematurity remains low. In case of “plus” disease, the examination is carried out 1 time in 3 days. After 1 year of life, children with cicatricial retinopathy of prematurity are observed by an oculist for life.

If the active process has reached 3 or more stages in its development, then after its completion (with or without preventive treatment), cicatricial changes of varying severity form on the fundus of the eye.

• 1 degree: minimal changes in the periphery of the fundus
• 2 degree: dystrophic changes in the center and on the periphery, remnants of scar tissue
• Grade 3: deformation of the optic nerve head, with displacement of the central parts of the retina
• Grade 4: the presence of retinal folds, combined with changes characteristic of the 3rd stage
• 5 degree: complete, often funnel-shaped, retinal detachment.

With the first and second degrees, a sufficiently high visual acuity can be maintained, with the development of a third or more degrees, a sharp, often irretrievable decrease in visual acuity occurs.

Treatment for retinopathy depends on the stage of the process. There are 2 main directions. :

1. Conservative - instillation of drops prescribed by an ophthalmologist. Most often it is vitamin and hormone preparations. Efficiency is mild.
2. Surgical The choice of surgical method depends on the stage of the process.
   • As a rule, laser or cryosurgical ( liquid nitrogen ) coagulation of the retina is performed. Coagulation of the retina (preferably laser coagulation, due to less pronounced long-term adverse effects) helps to prevent retinal detachment.
   • Another method of surgical treatment carried out during the development of retinal detachment is vitrectomy (removal of the vitreous body) by experienced ophthalmological surgeons in specialized medical institutions. Half of the patients have a tragic discrepancy between a successful surgical solution of the problem (that is, a technically successful operation) and the lack of vision of the operated patient. Many causes and factors lead to such unsatisfactory results. These include underdevelopment of retinal photoreceptors and their damage (both during retinopathy itself and during surgical treatment), the presence of severe concomitant CNS pathology, congenital damage to the visual pathways and subcortical centers.
3. Transcranial magnetotherapy - determining the effectiveness of this method requires further research.

It should be emphasized that in 70-80% of cases with 1-2 stages of retinopathy of prematurity, a spontaneous cure of the disease is possible with minimal residual changes in the fundus. When the growth of tissue and vessels inside the eye has spread to a fairly large area, such a condition is considered to be the threshold stage of retinopathy of prematurity, then the process of its progression becomes practically irreversible and requires urgent prophylactic treatment. At this stage, not only corticosteroids , but also vascular growth blockers (Avastin, Lucentis) have recently been used in the world. The child should be observed in the neonatal ward, in which prophylactic treatment can be carried out. Despite the far advanced process, with a small length of the shaft with tissue and vessels, as well as in the first two stages of active retinopathy of prematurity, spontaneous regression is possible, however, the residual changes are more pronounced.

The effectiveness of prophylactic laser and cryocoagulation of the avascular retina ranges from 50-80%. Timely treatment can significantly reduce the number of adverse outcomes of the disease. If the operation is not performed within 1-2 days after the diagnosis of the threshold stage of retinopathy, the risk of retinal detachment increases sharply. With the development of retinal detachment conducting cryo, laser coagulation is not possible. Further prognosis for the development of vision in such an eye is extremely unfavorable. The operation is more often carried out under general anesthesia (less commonly, local anesthesia is used) in order to avoid eye-heart and eye-lung reactions. Evaluation of the results of treatment is carried out in a few days to resolve the issue of repeating the procedure. The effectiveness of prophylactic treatment can be judged in 2-3 weeks after the formation of scars at the site of the shaft. If the treatment was not carried out or the effect was not achieved after the treatment (severe retinopathy of prematurity), terminal stages develop.

Thus, at the 4th stage, the issue of conducting early vitrectomy for the prevention of the development of total retinal detachment is resolved. The particular importance of timely diagnosis of the 4th stage of retinopathy is determined by the need for early surgical treatment for the initial retinal detachment. The earlier vitreosurgical intervention will be performed, the better the functional effect will be achieved with the development of vision in a premature baby. A feature of early surgery at 4 stages of retinopathy is the possibility of using high-tech techniques and tools that allow manipulations on the vitreous body and the retina while maintaining the lens through microdioces with a diameter of less than 0.5 mm. This improves the rehabilitation of vision in the postoperative period and significantly reduces the length of stay in the hospital, as well as the drug load on the child. With total high local retinal detachment (in 4A and 4B stages), especially volcanic-shaped ones, the lens cannot be preserved, and the use of modern microtechnologies is not technically feasible. The functional results of such surgery will be much worse.

If the retina has detached over the entire surface, then the development of objective vision is no longer possible - irreversible damage occurs to the pigment epithelium and sensory cells ( rods and cones ). In this stage, surgical treatment is carried out depending on the degree of vascular activity in the fundus , the duration of the detachment, and the physical condition of the child. When the process has reached stage 5, it is also necessary to conduct a whole range of therapeutic and surgical measures aimed at preventing severe cicatricial changes of the retina and eyeball. Surgical treatment (Lensvitrectomy) is carried out with the help of microsurgical computer systems, which allow long-term manipulation in the eye cavity, maintaining intraocular pressure.

The indications for surgical treatment of the cicatricial stages of retinopathy of prematurity are strictly individual, determined by the degree and localization of retinal detachment, as well as the general somatic condition of the child. In any case, the functional and anatomical efficiency of operations is palpable only up to 1 year of life, when it is possible to obtain an increase in visual acuity and the creation of conditions for eye growth.

Upon reaching the 5th stage of retinopathy of prematurity, the pathological process can continue and lead to the development of complications in the form of corneal opacities and secondary glaucoma . Therefore, with the development of contact of the cornea and iris, urgent surgical treatment is necessary to preserve the eye (in this case, it is not about improving visual acuity). It is believed that if a child has suffered even mild stages of active retinopathy of prematurity, or has unexpressed cicatricial changes, then it does not form a full-fledged retina. In the future, these children have a high risk of developing myopia , dystrophy, and secondary retinal detachment ^[3] .

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