thy of Pre Maturity

8/3/2019 thy of Pre Maturity

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Retinopathy of Prematurity

Mr Farrukh Ali

Department of Ophthalmology

Arrowe Park Hospital, Wirral UK


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Introduction

Retinopathy of prematurity (ROP) is an abnormal growth of blood vesselsin the retina at the back of a premature babys eye. It primarily affectspremature infants weighing about 1500 grams or less and are born before

32 weeks of gestation (A full-term pregnancy has a gestation of 3842weeks).

Today, with advances in neonatal care, smaller and more premature

infants are being saved. These infants are at a much higher risk for ROP.Not all babies who are premature develop ROP. The disease improves

and leaves no permanent damage in milder cases of ROP. About 90percent of all infants with ROP are in the milder category and do not needtreatment. However, infants with more severe disease can developimpaired vision or even blindness.

ROP was first diagnosed in 1942.


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Cause of ROP

ROP occurs when abnormal blood vessels grow and spreadthroughout the retina, the tissue that lines the back of the eye.

These abnormal blood vessels are fragile and can leak, scarringthe retina and pulling it out of position. This causes retinaldetachment. Retinal detachment is the main cause of visual

impairment and blindness in ROP

Division of retina in zones to classify ROP


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Several complex factors may be responsible for the development of ROP.

The eye starts to develop at about 16 weeks of pregnancy, when the

blood vessels of the retina begin to form at the optic nerve in the back ofthe eye. The blood vessels grow gradually toward the edges of thedeveloping retina, supplying oxygen and nutrients. During the last 12

weeks of a pregnancy, the eye develops rapidly. When a baby is born full-term, the retinal blood vessel growth is mostly complete (The retina

usually finishes growing a few weeks to a month after birth). But if a babyis born prematurely, before these blood vessels have reached the edges

of the retina, normal vessel growth may stop. The edges of the retinatheperipherymay not get enough oxygen and nutrients


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Risk factors for ROPIn addition to birth weight and how early a baby is born, other factors

contributing to the risk of ROP include anaemia, blood transfusions,respiratory distress, heart anomalies, breathing difficulties, and theoverall health of the infant.

Scientists believe that the periphery of the retina then sends out signalsto other areas of the retina for nourishment. As a result, new abnormal

vessels begin to grow. These new blood vessels are fragile and weakand can bleed, leading to retinal scarring. When these scars shrink,they pull on the retina, causing it to detach from the back of the eye.


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Stages of ROP

ROP is classified in five stages, ranging from mild (stage I) tosevere (stage V):

Stage I The outer aspect of the retina is affected by thediminished blood supply and is shown by a cleardemarcation line. About 80% of babies born more than 10

weeks early will suffer some degree of Stage 1 retinopathy.This usually resolves spontaneously without any significant

effect on vision.

Demarcation line as shown above


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Stage II

In stage 2 demarcation line becomes thickened and ridged.

Ridge


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Stage III

In stage 3 abnormal blood vessels develop on the ridge. Theseabnormal vessels can loose there elasticity and begin to contract leading

to retinal detachment. Some infants who develop stage III improve withno treatment and eventually develop normal vision. However, when

infants have a certain degree of Stage III and "plus disease, treatment isconsidered. "Plus disease" means that the blood vessels of the retinahave become enlarged and twisted, indicating a worsening of thedisease. Treatment at this point has a good chance of preventing retinal

detachment.

Plus

Disease

Ridge with abnormal vessels


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Stage IV

Partially detached retina. Traction from the scar produced by bleeding,

abnormal vessels pulls the retina away from the wall of the eye

Stage V

Completely detached retina and the end stage of the disease. If the eyeis left alone at this stage, the baby can have severe visual impairment

and even blindness.


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What are the symptoms of retinopathy of prematurity

There are no symptoms of retinopathy, therefore all small babiesborn less than 32 weeks gestation are screened by specialist doctor

( Ophthalmologist ). Usually the screening begins when the baby iseither six weeks old or is 33 weeks gestation and usually takes place

fortnightly until the blood vessels in babys retina are mature.

Why is screening so important?

Screening is important for two reasons.

1. The seriousness of the condition is not apparent unless the retina isexamined. The baby can still see up to and including stage 3 disease.It is only when stage 4 or 5 has occurred and when there is retinaldetachment, that the baby stops being able to see.

2. Treatment is only successful at stage 3 disease.

Therefore, it is very important for the baby to attend regular check ups

by the ophthalmologist. ROP is a very progressive disease and evenone week can make a difference.


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What happens during the screening checks?

Drops will be put into babys eyes to enlarge ( dilate ) pupils, this is

necessary for the doctor to see babys retina. Once pupils are dilated,anaesthetic drops will be put into the eyes so that baby does not feel any

pain during examination. The doctor will hold babys eyelids open, either byhand or with a small instrument, and look closely at the back of the eye witha special light. The doctor may need to gently press around babys eyes witha special probe, in order to get a better look. The examination only takes a

few minutes. The baby will not like the examination but should only feel slightpressure, but no pain.

Your babys nurse will keep you fully informed about the state of babys

retina and let you know if treatment is needed and the course of thetreatment will be discussed with you by the ophthalmologist.


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How is retinopathy of prematurity treated?

Stage 1 & 2:

Most babies who develop ROP stages I or II regresses without major

complications, as shown in the picture.


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Stage 3:

If the baby has stage 3 retinopathy and fulfils the criteria fortreatment ( 5 contiguous or 8 non contiguous clock hours of stage 3

with plus disease in zone I or II. ), laser treatment will be given. Laseris a special piece of equipment that emits a very bright and fine beamof light. This laser light destroys non vascularised retina leading to

resolution of abnormal blood vessels causing haemorrhage, scarringfollowed by retinal detachment. Laser treatment involves baby havinga general anaesthetic and usually takes 2-3 hours. Normally only onelaser treatment session is necessary, but the doctors will continue to

check babys eyes on a regular basis. Laser treatment can causebabys eyes to become a little red and inflamed but this settle down

in a few days.


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In the later stages of ROP ( stage 4 & 5 ), other treatment options include:

Scleral buckle. This involves placing a silicone band around the eye andtightening it. This keeps the vitreous gel from pulling on the scar tissue and allows

the retina to flatten back down onto the wall of the eye. Infants who have had asclera buckle need to have the band removed months or years later, since the eye

continues to grow; otherwise they will become nearsighted. Scleral buckles areusually performed on infants with stage IV or V.

Vitrectomy. Vitrectomy involves removing the vitreous and replacing it with a

saline solution. After the vitreous has been removed, the scar tissue on the retina

can be peeled back or cut away, allowing the retina to relax and lay back downagainst the eye wall. Vitrectomy is performed only at stage V.

The results of retinal surgery have been very disappointing. Regrettably,few, if any regain any useful sight.

Is this the end?No. There is much that can be done to help both you and your baby come to

terms with poor vision or blindness. There are all sorts of special services andteachers available to help blind children. Your doctor would be happy to discuss

this with you.


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What is the long term outlook for babies with retinopathy?

Currently 80% of babies with stage 3 retinopathy do well and have good vision,

but will be regularly checked. Even with treatment, a small number of babieswith stage 3 retinopathy will have significant visual loss.

Most babies have an increased risk of developing eye problems as they grow

older. These problems may include:

Amblyopia ( Lazy eye ):

This can occur if the vision in one eye is better than in the other. The brain

learns to ignore the vision it receives from the weak eye, causing varyingdegrees of visual loss in that eye. Occlusion therapy ( Patching ) will be started

this involves your child wearing a patch over the strong eye to improvevision in the weak one.

Strabismus ( Squint ):

A squint ( eye turn ) may develop as a result of a lazy eye. Treatment of squintwill depend upon its severity and surgery may be required.


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Myopia ( Short sightedness )

This is when the rays of light passing through the cornea are unable to focus

onto the retina, causing distant object to become blurry. This is usually

corrected by wearing appropriate glasses.

Glaucoma ( raised pressure within the eye )

Fluid in the eye is unable to drain away causing a build up of pressure. Thisincreased pressure can eventually cause some degree of visual loss. Often it

can be controlled with medicine and eye drops but, in some infants, mayrequire surgery.

All of these conditions, if they arise, will be discussed in much greater detailby babys eye doctor.


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RISK OF EYE PROBLEMS IN PREMATURE VS TERM INFANTS

Myopia 6% vs. 2%

Amblyopia 4% vs. 0.1%

Strabismus 10% vs. 2%

Anisometropia (markedly different amount of nearsightedness orfarsightedness in the right and left eyes) 6% vs. 1.5%

Nystagmus (rapid "shaking" of the eyes) 2.5% vs. 0.1%


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If you would like to know further and discuss your babys eyecondition, please contact me or the consultant on following

phone numbers:

Mrs P Pennefather: 0151 6785111 ext 2705

Mr F Ali: 0151 6785111 ext 2705

You may like to visit Royal College of Ophthalmologist website

( www. rcophth.ac.uk ) or other related websites for detailedinformation.

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