Retinopathy of Prematurity (ROP) Sarah Kochis RN CPNP Perkins School for the Blind

What is ROP?? ROP is a term used to describe all phases of retinal changes observed in premature infants.

History of ROP ROP was first described in 1942 and was responsible an epidemic of blindness in the 1940s and 1950s 2 studies in the 1950s showed the link between high concentrations of oxygen and the development of ROP. This led to restrictions in the use of oxygen and a decrease in the incidence of ROP. However, there was a corresponding increase in the number of cases of cerebral palsy and lung disease.

History of ROP (cont) Advances in technology in the 1960s and 1970s allowed for more precise measurements of blood oxygen levels. There was an increase in survival of low birth weight infants BUT a resurgence in the numbers of infants with ROP In 1981 the US estimates placed 600 infants a year at risk for developing blindness related to ROP In 1991 a multicenter trial studied 4099 infants <1251gm and reported an overall incidence of ROP at 65.8%. The incidence of ROP infants <1000 gm was 81.6% Currently a fetus at 25 weeks gestation with a weight <700 gm has a survival rate of 50%. These infants are most susceptible to ROP. Premature infants <1000gm are 3x more likely to develop ROP as compared with neonates with birth weights between 1001-1500 gm. 500 infants per year are blinded by ROP in the US The greatest risk factor for development of ROP is prematurity and it associated low birth weight. Other risk factors included sepsis, hypoxia, acidosis and intraventricular hemorrhage

Pathophysiology ROP is characterized by severe vascular constriction in the immature vascular retina which leads to hypoxia. This stimulates a proliferation of retinal capillaries in these hypoxic areas where the veins become numerous and dilate. The numerous dilated capillaries extend toward the lens of the eye causing the aqueous and vitreous humor to become turbid. The retina becomes edematous and hemorrhages separate the retina from its attachment. Scarring occurs from the retina to the lens destroying the architecture of the eye. The combination of these two processes causes irreversible blindness.

Normal Eye Anatomy

Zones of the Retina The retina is divided into 3 zones with the optic nerve at the center. The retinal vasculature grows from the disc toward the ora serrata. Zone III is the area the last area to be vascularized and it is the area most frequently involved in ROP In evaluating for ROP the location is noted by the zone that it is in and related to the face of a clock.

Anatomy of a Full-Term Eye Note that the retina is fully vascularized

Anatomy of Premature Eye Note the developed (vascularized) retina in Orange and the underdeveloped (unvascularized) retina in the white

Stages of ROP-Stage I The first stage of ROP is when the blood vessels stop growing and form a line that separates normal from premature retina. 

Stages of ROP-Stage 2 In the second stage, the line of separation takes on substance as an elevated ridge of tissue. 

Stages of ROP-Stage 3 As the ROP advances fragile new abnormal blood vessels grow toward the center of the eye (Stage 3). At this point, the eye is still capable of repairing itself

Stages of ROP-Stage 3 with “plus disease” As Stage 3 advances the normal vessels dilate, indicating that the ROP may not go away on its own.  This is known as "plus disease." If enough retina has Stage 3 and so-called "plus disease," then treatment is indicated. 

Stages of ROP-Stage 4 In some cases, the ROP continues to progress and the retina detaches.  A partial detachment is Stage 4A. If the center of vision is involved, it is 4B.

Stages of ROP-Stage 5 Left untreated, the retina can become totally detached, Stage 5. These eyes have very poor visual outcomes

Screening Guidelines for ROP Screening is the MOST EFFECTIVE TOOL IN PREVENTION OF ROP Infants recommended for screening Less than or equal to 28 weeks gestational age Birth weight less than or equal to 1500 gm Infants over 1500 gm with an unstable clinical course believed to be at high risk by the attending pediatrician or neonatologist Timeline for screening 4-6 weeks chronological age or 31-33 weeks postconceptional age

Screening Guidelines for ROP Follow-up examinations are determined by the initial findings If the retinal vasculature is immature and in Zone II but no disease is noted then exams should be performed every 2-4 weeks until there is complete vascularization of zone III Infants with ROP in Zone I should be seen at least every week until involution of ROP occurs and normal vascularization of Zone II occurs Infants with immature vessels in Zone I (without ROP) should be seen every 1-2 weeks until normal vascularization is noted in Zone III Follow-up exams should be performed until complete vascularization is noted or 2 successive exams show ROP Stage 2 in Zone III.

Treatment of ROP Treatment is indicated in the presence of “Threshold Disease”: Threshold disease is defined as disease that has a 50% likelihood of progressing to retinal detachment. Threshold disease is considered to be present when Stage 3 ROP is present in either zone I or zone II, with at least 5 continuous or 8 total clock hours of disease, and the presence of plus disease. Progression to stage 4 (partial retinal detachment), or to stage 5 (total retinal detachment), will result in substantial or total loss of vision for the infant. If “Threshold Disease” is noted the infant should undergo ablative therapy within 72 hours or less following diagnosis.

Treatment of ROP-Peripheral Retinal Ablation (Laser Therapy) A Laser is directed at the avascularized retina to ablate these areas. May be performed in the NICU. Conscious sedation is used (fentanyl citrate) Both eyes may be treated in one session Takes 20 min to treat one eye

Retinal Detachment Retinal detachments are often “tractional” and occur due to circumferential traction (imagine a tightening purse string) Management remains controversial Although reattachment may be achieved visual acuity is usually quite low Possible treatments include Scleral buckling: Scleral buckling is a surgical procedure in which a piece of silicone plastic or sponge is sewn onto the sclera at the site of a retinal tear to push the sclera toward the retinal tear. The buckle holds the retina against the sclera until scarring seals the tear. Success rate 54-75% (40% for Stage 5) Open and closed vitrectomy Most useful for Stage 5 Tiny incisions are made in the sclera (the white part of the eye).  Using a microscope to look inside the eye and microsurgical instruments, the surgeon removes the vitreous and repairs the retina through the tiny incisions.

Late Complications of ROP Myopia (nearsightedness) Retinal pigmentation Dragging of the Retina Retinal Folds Retinal Holes Retinal Detachment-may occur in the mid-teen years Secondary Angle Closure Glaucoma Loss of vision for obscure reasons Development of cataracts in adulthood