Retinopathy of Prematurity

RETNOPATHY OF PREMATURITY
( Retrolental Fibroplasia, ROP )

It is Retinal disorder of premature children and may progress to retinal detachment and blindness.

Who can develop it

Child less than 1500 gm birth weight.

Less or equal to 34 weeks of gestational age.

Exposed to oxygen for more than 30 days.

Premature children less than 37 weeks and/or less than 2000 grams should be screened.

If there is multiple births and those surviving septicaemia, multiple blood transfusions, respiratory distress syndrome, multiple apnoeic episodes and intraventricular haemorrhage.

What happens

There is poor blood vessels development in eye leading to poor oxygen supply to eye . This results in formation of new vessels on pupil ( Plus stage ) and on retina which may lead to fibrosis and scar formation. When severe it is seen as white reflex through pupil.

Classification

All the findings should be well documented according to the international classification of ROP recommendations specifying the severity of disease, location, with or without plus component and the extent of clock hours.

Stages of the disease ( severity )

Stage 1
Should be done preferably in 4-6 hours, earlier the better.

Stage 2
Demarcation ridge ( Thickened demarcation line ).

Stage 3
Demarcation ridge with extraretinal fibrovascular proliferation.

Stage 4
(a) Subtotal retinal detachment not involving macula.

(b) and involving macula.

Stage 5
Total retinal detachment.

The location of disease (zones )

Zone 1
Area centered on the optic disc and extending from the disc to twice the distance between disc and fovea.

Zone 2
Nasal edge of Zone 1 to ora on nasal side and up to equator on the temporal side.

Zone 3
The remaining temporal retina.

Plus disease

Dilatation and tortuosity of retinal blood vessels, iris vascular engorgement, pupillary rigidity and vitreous haze.

Rush disease

It is zone 1 ROP with Plus disease. In Rush disease progression of ROP is rapid and fulminant and needs urgent treatment.

Extent of the disease

The eye is divided into twelve sectors similar to a clock. The extent of ROP is defined by how many clock hours of the eye's circumference is diseased. The extent can vary from 1 to 12 clock hours.

Classification

The retinopathy of prematurity has been classified on the basis of location on retina, degree of proliferation and extent of proliferation in circumferential manner.

1. Prethreshold disease:

   (a) Any extent of ROP in zone 1 with / without plus disease.
   (b) Zone 2 stage 2 with Plus disease.
   (c) Zone 2 or zone3 stage 3 in less than 5 contiguous or 8 non contiguous clock hours with plus disease.

2. Threshold disease:

   Stage 3 in more than 5 contiguous or 8 non contiguous clock hours with plus disease.

When to screen

3 -4 weeks after birth or 32 - 34 weeks after conception , whichever is earlier. Infants weighing less than 1200 grams at birth and those born at 24 - 30 weeks gestational age are screened within 2 - 3 weeks.

Follow up

It depends on initial fundus findings:

If retina is fully mature ( defined as retinal vessels seen upto nasal ora serrata ) no further evaluation for ROP required.

If retina immature ( retinal vessels not seen up to nasal ora serrata ) then baby should be screened every 2 weeks till the retina is mature.

In eyes with retinal vessels seen only up to zone 1 area at initial visit, weekly evaluation is needed.

If early signs of ROP weekly check up for any progression or regression.