Retinopathy of prematurity

Japanese: 未熟児網膜症 - みじゅくじもうまくしょう（英語表記）Retinopathy of prematurity

What is the disease?

This is a retinal vascular disorder that occurs in premature infants. In severe cases, Retinal detachment ( It's also easy to peel off ) Due to improvements in medical management of premature babies, the incidence of premature babies seems to be decreasing compared to the past.

What is the cause?

The underlying cause is the underdevelopment of retinal blood vessels. During development in the womb, retinal blood vessels extend from the optic nerve to the peripheral part of the fundus, and reach almost the entire periphery of the fundus at normal full-term birth.

However, in premature babies, the development of retinal blood vessels is only half complete and does not reach the periphery. When various conditions are added to this, the retinal blood vessels deviate from normal development and retinopathy develops.

Naturally, the lower the gestational age and birth weight, the more likely it is to occur. However, respiratory distress syndrome, oxygen therapy, Exchange transfusion ( Exchange ) These can also be factors in aggravating the condition.

How symptoms manifest

The area where the retinal blood vessels do not reach is called the avascular zone, and abnormal proliferation of blood vessels occurs at the border with the avascular zone. In many cases, this resolves naturally and the blood vessels grow back to the periphery. However, sometimes Fibrovascular proliferation ( Senbetsu kenkyuu zoo meal ) When it shrinks, it becomes the retina (especially Macular area ( Half-portion ) ) can be pulled or the condition can become serious, leading to retinal detachment.

Retinopathy of prematurity is in the active stage Scar stage ( Stamp ) The active stage is when fibrovascular proliferation occurs, and the scarring stage is when fibrovascular proliferation contracts, but each stage is classified according to its severity.

Testing and diagnosis

Babies born prematurely usually undergo regular eye examinations from around 29 weeks gestation or 3 weeks after birth until it is deemed that there is no longer any risk.

In the early stages, the extent of blood vessel extension (width of the avascular zone), Eruption ( Docho ) The degree of risk can be judged based on the degree of swelling. During the active stage, frequent fundus examinations are performed to determine the need for treatment and the timing of treatment.

Treatment methods

In the active stage, retinal photocoagulation is performed (column), Cryotherapy ( Art and Crafts ) Coagulation is targeted at the avascular zone. For retinal detachment in the scar stage, Vitreous surgery ( The art I want to present ) However, the treatment outcomes are not good and significant recovery of visual function cannot be expected.

Fundamentally, the ideal situation would be to improve childcare conditions and prevent the onset of retinopathy as much as possible. Although this is currently difficult, if we could faithfully recreate the environment inside the womb, retinopathy of prematurity would not occur.

What to do if you notice an illness

It is not a disease that the person himself or herself notices, nor is it something that those around him or her notice. It is a disease that must be monitored, managed, and treated by the medical community.

Shinichiro Kono

Retinopathy of prematurity
Retinopathy of prematurity
(Childhood illnesses)

What is the disease?

Retinopathy of prematurity (ROP) is a vascular proliferative disorder that occurs in immature developing retinal blood vessels. In severe cases, Retinal detachment ( It's also easy to peel off ) This results in severe vision impairment.

What is the cause?

It is said that the condition is based on the immaturity of the metabolic system of retinal blood vessels and tissue, and that various factors such as inappropriate oxygen administration, excess water, infection, intraventricular hemorrhage, and nutritional disorders are involved.

How symptoms manifest

In children born in a premature state, the peripheral retina has poor vascular development, and blood vessels grow after birth. According to the new clinical course classification (Table 2) by the Ministry of Health, Labor and Welfare research group, the progression of the most common type I ROP is reactive angiogenesis (stage 1), followed by the formation of a boundary between the angiogenesis and the avascular area (stage 2), and when it becomes more severe, Vitreous ( I want to ) Internal vascularization and bleeding occur (stage 3).

At this point, the condition often improves naturally, but in severe cases, it progresses to partial retinal detachment (stage 4) or total detachment (stage 5). There are also cases (type II) where the condition progresses rapidly and results in retinal detachment.

Please note that the New Clinical Course Classification and the International Classification use different methods for classifying stages.

Testing and diagnosis

Diagnosis is made by an ophthalmologist according to the new clinical course classification mentioned above. In cases where the birth weight is 1800g or less and the gestational age is 34 weeks or less, regular fundus examinations should be performed from 3 weeks after birth. If ROP develops, the intervals between examinations should be shortened and careful observation is required. In addition, children who have undergone high-concentration oxygen therapy or artificial ventilation are recommended to have an eye examination before being discharged from the hospital.

Treatment methods

Type I tends to heal naturally, but if it is in the middle stage of stage 3 and further progression is expected, treatment is required. Type II requires immediate treatment.

Treatment is with an argon laser Photocoagulation ( Hikari Industry ) However, depending on the condition, cryotherapy may also be performed, and in some severe cases, scleral buckling or vitreous surgery may also be performed. In addition, proper respiratory management (adequate oxygen administration, prevention of hypocapnia), fluid restriction, prevention of anemia, and other systemic management are also important.

The incidence rate of ROP varies depending on the report, but it is said that the incidence rate of extremely low birth weight infants (birth weight less than 1000g) is around 80%, and the treatment rate is around 40%. The earlier the gestational age and the lighter the birth weight, the higher the possibility of ROP.

What to do if you notice an illness

Medical examination and overall management by an ophthalmologist and neonatologist are required.

Masaki Wada

Table 2. New Ministry of Health, Labour and Welfare Clinical Course Classification (active stage) and International Classification of ROP
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Table 2. New Ministry of Health, Labour and Welfare Clinical Course Classification of ROP (active…

Source: Houken “Sixth Edition Family Medicine Encyclopedia” Information about the Sixth Edition Family Medicine Encyclopedia

Japanese:

どんな病気か

　未熟児に起こる網膜血管病変です。重症例では、網膜剥離(もうまくはくり)を起こして失明に至ることもあります。未熟児の医学的管理が向上したため、一時期に比べれば減少しているようです。

原因は何か

　根本的な原因は、網膜血管の未発達性にあります。網膜の血管は、胎内での発達期に視神経から眼底周辺部へと延びていき、正常な満期産の出生時にはほぼ眼底周辺部に達します。

　しかし、未熟児で生まれると、網膜血管の発達は道半ばで周辺までは達していません。それにさまざまな条件が加わることにより、網膜血管が正常な発達を逸脱して網膜症が発症します。

　在胎週数、出生体重が少ないほど起こりやすいのは当然ですが、呼吸窮迫(こきゅうきゅうはく)症候群、酸素投与、交換輸血(こうかんゆけつ)なども重症化の要因になります。

症状の現れ方

　網膜血管が達していない部分を無血管帯といいますが、無血管帯との境目に血管の異常な増殖が起こります。多くの場合、それは自然に解消して再び血管は周辺部へと延びていきます。しかし、時には線維血管増殖(せんいけっかんぞうしょく)へと発展し、やがてそれが収縮すると網膜（とくに黄斑部(おうはんぶ)）が引っ張られたり、網膜剥離になったりして重症化します。

　未熟児網膜症は活動期と瘢痕期(はんこんき)に分けられます。線維血管増殖が起こるまでが活動期、それが収縮したあとが瘢痕期ですが、それぞれ程度に応じて分類されています。

検査と診断

　未熟児で生まれると、普通は眼底検査を定期的に行います。期間は在胎週数に換算して29週ないし生後3週ころから、もう危険がないと判断されるまでです。

　初期には、血管の延び具合（無血管帯の広さ）、怒張(どちょう)（ふくれる）の程度などで、危険の度合いが判断できます。活動期には頻繁に眼底検査を行い、治療の要否、治療のタイミングを計ります。

治療の方法

　活動期には網膜光凝固術(もうまくひかりぎょうこじゅつ)（コラム）、冷凍凝固術(れいとうぎょうこじゅつ)が行われます。凝固は無血管帯が標的になります。瘢痕期の網膜剥離に対しては硝子体手術(しょうしたいしゅじゅつ)が行われますが、治療成績は良好とはいえず、視機能の大きな回復は望めません。

　根本的には保育条件を向上させ、網膜症の発症を極力抑えることが理想です。今のところ困難ですが、胎内の環境を忠実に再現できれば未熟児網膜症は起こらないわけです。

病気に気づいたらどうする

　本人はもちろん、周囲の人が気づく病気ではありません。医療側が監視、管理、治療すべき病気です。

河野　眞一郎

未熟児網膜症
みじゅくじもうまくしょう
Retinopathy of prematurity
(子どもの病気)

どんな病気か

　未熟児網膜症（ROP）は発達中の未熟な網膜血管に起こる血管増殖性病変で、重症例では網膜剥離(もうまくはくり)となり重度の視力障害を生じます。

原因は何か

　網膜血管および網膜組織の代謝系が未熟であることを基盤とし、不適切な酸素投与、過剰な水分、感染、脳室内出血、栄養障害などのさまざまな因子が関係しているといわれています。

症状の現れ方

　未熟な状態で出生した子どもの網膜周辺部は血管の発育が悪く、出生したあとに血管が伸びていきます。厚生省研究班による新臨床経過分類（表2）によると、最も多いⅠ型のROPの進行は反応性の血管造成（1期）後、それらと無血管域の間に境界線が形成され（2期）、さらに高度になると硝子体(しょうしたい)内部への血管造成や出血が起こります（3期）。

　この時点で自然によくなっていく場合が多いのですが、重症例では部分的網膜剥離（4期）、全剥離（5期）となります。また、急速に進行し網膜剥離となる症例（Ⅱ型）もあります。

　なお、新臨床経過分類と国際分類はstageの分類の仕方が異なっているため、注意が必要です。

検査と診断

　診断は前述の新臨床経過分類に従い、眼科医により行われます。出生体重1800g以下、在胎週数34週以下の症例では、生後3週以降から定期的に眼底検査を行う必要があります。ROPが発症した場合には診察の間隔を短くし、注意深い観察が必要です。また、高濃度酸素療法や人工換気療法を行った子どもでは、退院前に眼の診察を受けることがすすめられます。