Retinopathy of=20 Prematurity (ROP) Screening =96 Practical aspects

Dr Satyen Deka MS, = DNB

Department of=20 Vitreoretina

Sri Sankaradeva = Nethralaya,=20 Guwahati

&nbs= p; =20

&nbs= p; = ; = &= nbsp; &n= bsp; =20 Present=20 Knowledge

= Retinopathy Of = Prematurity=20 (ROP) is a disorder of = prematurely born,=20 low birth weight infants featuring abnormal proliferation of developing = retinal=20 blood vessels at the junction of vascularized and avascular = retina.=20

At 16 weeks = of=20 gestation mesenchyme grows out of optic disc, which are the precursors = of=20 retinal capillary network. This tissue grows centrifugally reaching = nasal ora by=20 36weeks of gestation & temporal ora by 40 weeks of =

gestation and the = edge of=20 the tissue has a

delicate network of = capillaries. An=20 inco-

mpletely = vascularized=20 retinal periphery is

one of the = important factors=20 for ROP

development.=20

Theodore = Terry⁴=20 first described the condition

in 1942. Campbell⁶ = first=20 noticed the relation-

ship between = intensive=20 oxygen therapy in

infants and = subsequent=20 development of ROP.

Kinsey⁵ established = that, the=20 incidence of ROP is inversely proportional to the birth weight.=20

Two=20 theories on development of ROP are-

1) = Theories = Hypoxia, and=20

2)=20 Spindle cell hypothesis.

As with the advent = of=20 sophisticated neonatal care system there is an increased survival rate = of=20 premature babies, concurrently incidence of ROP is also raised. Western=20 literatures have reported the incidence of ROP in premature babies to = vary from=20 21 to 65.8% ^7,8. Indian studies have reported the incidence = of ROP in=20 premature infants is as high as 38-47%^1,2in sample = populations. ROP=20 may regress completely and spontaneously or may progress to total = retinal=20 detachment. 42.10% patients with stage 3 ROP progressed to threshold ROP = in the=20 study by Rohit C et al.² The ICROP³ has made it = convenient=20 to classify ROP and has enabled setting up of guidelines to decide on = treatment=20 of ROP.

Classification of=20 ROP

To diagnose and = treat ROP at=20 its earliest, in 1984 International classification³ has = provided a=20 standard framework, which focuses on location, extent &stages of the = disease.

1. = Location:=20

a) = Zone = 1: Bounded by the = imaginary=20 circle whose radius is twice the distance from the disc to=20 macula

b) =20 Zone = 2: Extends from the = edge of=20 zone 1 to a point tangential to the nasal ora serrata and round to an = area near=20 the temporal equator.

c) = Zone 3: Residual = temporal crescent=20 anterior to zone 2

2. = Extent: Determined by = the number=20 of clock hours involved.

3. = = Stages:

a) = Stage 1 = (demarcation=20 line):

the first pathognomonic sign of =

active ROP is the=20 development of

a thin, tortuous, grey-white = line,=20

which runs roughly = parallel=20 with

the ora serrata = separate=20 the

avascular periphery retina from = the

vascularized posterior retina.=20

= b) Stage 2 = (ridge):=20 if the ROP progresses, the demarcation line develops into a ridge of = tissue that=20 extends out of the plane of the retina. It represents a mesenchymal shunt = that=20 joins venules with arterioles.

= c) Stage 3 (ridge = with extra=20

retinal fibro = vascular=20 proliferation):

the ridge becomes pink as a=20 result

of the development of FVP along =

the surface of = retina and=20 into the

vitreous.

d) Stage 4 = (sub-total=20 retinal detachment): progression of = FVP gives=20 rise to TRD that starts in the extreme periphery and spreads=20 centrally.

e) = Stage = 5 is characterized = by=20 total retinal detachment. =

Plus = disease is characterized = by=20 dilatation of the venules and tortuosity of the arterioles in the = posterior=20 fundus.

Threshold=20 ROP is=20 defined as stage 3 ROP involving 5 or more contiguous or 8 or more = cumulative=20 clock hours in the presence of plus disease

Examination=20 procedures:

Informed consent = will be=20 taken from the parents for frequent and early eye examination.=20

Eligibility=20 criteria

=20 All premature babies having-

=B7 =20 Birth weight=20 <2000gm

=B7 =20 Gestational = age<36=20 weeks

=B7 =20 Associated = systemic=20 complications

Examination Schedule

=B7 =20 Initial=20 examination: Within 4-6 weeks = of birth=20 when the baby is stable enough. Babies fulfilling the criteria will be = examined=20 on a specific day of the week in the Neonatal Care units under care of = the=20 Neonatologist

Follow up:=20

Subsequent follow = up will be=20 done in eye OPD or the Neonatal center according to the convenience.=20

=B7 =20 Infants with = normal=20 vascularization of fundus up to the periphery will not be=20 reexamined.

=B7 =20 Infants with = peripheral=20 avascular retina but no clinical ROP will be examined biweekly until = normal=20 vascularization or ROP develops.

=B7 =20 Stage 2 or=20 less: Once every 2 weeks = until there is=20 complete vascularization, then 1 year.

=B7 =20 Stage3: Weekly until threshold stage or develop a = mature=20 vascular pattern in periphery or until = progresses to=20 threshold ROP when they will be treated.

Threshold ROP: Treat within 48 hours and weekly post = treatment to=20 monitor the disease.

Procedure of=20 Examination:

=D8 = Examination area = should be=20 warm & comfortable

=D8 = The anterior = segment will be=20 evaluated by the magnification offered by the + 20 Diopter lens and = illumination=20 of the indirect ophthalmoscope

=D8 = Pupillary=20 dilatation done using 2.5% phenylephrine & 1% tropicamide installed = twice at=20 15 minutes interval.

=D8 = Examination will = be done=20 without anesthesia.

=D8 = Data on babies = Gestational=20 age, Birth Weight, gender, Mode of delivery, significant postnatal = problems=20 like, Need of O₂ inhalation or blood transfusion, septicemia, = Neonatal Jaundice, or apnoetic spell and Anterior Segment findings will = be=20 recorded.

=D8 = Fundus findings = will be=20 noted according to the ICROP³.

Precautions during = Examination:

1. = Check-up heart = rate (as=20 during scleral depression there is chance of = bradycardia)

2. = To allow the baby = to=20 cry.

3. = Stop examination = if=20 bradycardia develops or the baby does not cry. Then to restart the = procedure=20 once the heart rate becomes normal and the baby starts=20 crying

Instruments

1. = Indirect=20 Ophthalmoscope

2. = +20Diopter = lens &nbs= p; = ; =20

3. = Alfonso=20 speculum

4. = Wire Vectis to = depress and=20 stabilize the eye

Except 1 and 2, = other=20 instruments will be sterilized

Management=20 Approach:

=B7 =20 85% of ROP babies = without=20 visual threat.

=B7 =20 Standard Rx can = prevent=20 visual loss in 50% of the remaining babies.

Treatment=20 modalities:

Once the disease = has reached=20 threshold stage, treatment is recommended

Two=20 treatment modalities are available presently for treating threshold=20 ROP.

1)=20 CRYOTHERAPY

2)=20 LASER PHOTOCOAGULATION

In=20 stage IV or stage V of ROP vitreoretinal surgery is=20 necessary.

Conclusion:

The=20 real problem in tackling this condition

is that, till now = there no=20 national structured program for screening ROP babies in our country. = This is due=20 to the lack of awareness and coordination among health professionals.=20

A dedicated teamwork by the=20 ophthalmologists, Pediatricians, and Obstetricians can help our future=20 generation from this devastating vision threatening disease.

Bibliography:

=20

1. = Gopal L, Sharma T, = Ramachandran S, Shanmugasundaram R, Asha V.Retinopathy of prematurity: a = study.=20 Indian J Ophthalmol 1995; 43:59-61

2. = Charan R, Dogra = MR, Gupta A,=20 Narang A. The incidence of retinopathy of prematurity in a neonatal care = unit.=20 Indian J Ophthalmol 1995; 43:123-26

3. = Committee for = Classification=20 of Retinopathy of Prematurity. An International Classification of = Retinopathy of=20 Prematurity. Arch Ophthalmol 1984; = 102:1130-34.

4. = Terry TL. Extreme=20 Prematurity and fibroblastic overgrowth of persistent vascular sheath = behind=20 each crystalline lens: I preliminary report. Am J Ophthalmol=20 25:203-204,1942

5. = Kinsey VE, Arnold = HJ, Kalina=20 RE etal. PaO₂ levels and retrolental fibroplasias: a report = of the=20 cooperative study. Pediatrics 1977; 60:655-668

6. = Campbell = K:Intensive oxygen=20 therapy as a possible cause of retrolental fibroplasias: a clinical = approach.=20 Med J Aust 2:48, 1951

7. = Palmer EA, Flynn = JT,=20 HardyRJ, et al. Incidence and early course of retinopathy of = Prematurity.=20 Ophthalmology 98: 1628-1640, 1991

8. = Darlow BA. = Incidence of=20 retinopathy of Prematurity in NewZealand. Arch Dis in Childhood.=20 63:1083-1086,1988

Screening=20 Proforma

Sl: &nbs= p; = ; = &= nbsp; &n= bsp;=20 MRD:

1. Date of = birth &nbs= p; = ; = =20 2. Gestational Age

3. Age at first=20 presentation &nbs= p; = ; =20 4. Sex: Male/Female

5. Birth = weight: &nbs= p; = ; =20 6. Antenatal Problem:

=20

7. Mode of = delivery:=20 NORMAL/LSCS/FORCEPS

8 =20 Any complication = during=20 delivery:

9. = Significant post = natal=20 problems;

a) Apnoetic=20 spell

b) =20 Septicemia

c) Need for blood=20 transfusion

d) =20 Requirement of = oxygen=20 inhalation

e) = Neonatal=20 jaundice

Ocular=20 examinations

OD &nbs= p; = ; = &= nbsp; =20 OS

Anterior=20 segment

Corneal=20 opacity

Non- dilating=20 pupil

Iris=20 abnormality

Others

Fundus

&nbs= p; =20 OD &nbs= p; = ; = &= nbsp; &n= bsp; =20 OS

Diagnosis: = (According to=20 classification):

Treatment:

Follow=20 up:

Comment: