RETINOPATHY OF NEWBORN A) What is retinopathy of newborn ? Retinopathy of newborn is a disorder of the blood vessels of the retina. ROP is most common in premature babies. The blood vessels of the retina proliferate and scar when exposed to certain postulated incriminating factors. This disorder has in the past been called retrolental fibroplasias. B) What causes retinopathy of prematurity? The exact mechanism of ROP is not fully understood. The retina is the thin layer of light-sensitive nerve fibers and cells that covers the inside and back of the eye. The blood vessels of the retina are not completely developed until the baby reaches full term. When a baby is born prematurely, the blood vessels may not have fully developed. The vessels proliferate and scar when exposed to high and prolonged levels of oxygen , blood transfusion, sepsis other factors. The scarring and bleeding can lead to retinal scarring or detachment from the back of the eye, resulting in vision loss. C) Why is retinopathy of prematurity a concern? ROP occurs in 16 percent of all premature births. Each year in the US, over 2,100 children experience the complications of ROP. There are five stages of ROP, from a mild Stage 1 to severe Stage 5 when the retina detaches in the eye. Babies with Stage 1 and 2 ROP are called prethreshold, and those with Stages 3 through 5 are called threshold. About 90 percent of babies with Stage 1 and 2 ROP show improvement without treatment. However, about half of babies with Stage 3 and most of those with Stage 4 may develop serious eye damage. Each year, approximately 400 to 600 children are blinded by ROP. D) Screening newborns for ROP Which Babies are Screened? 1. All babies who are: 1. <1250g birth weight, or 2. <30 weeks gestation, or 3. Selected infants ≥1250g and ≥30 weeks with an unstable clinical course (on ventilators, requiring high FIO2, ) who are believed to be at high risk by their attending neonatologist. D) Consistently reported risk factors for the development of ROP include: 1.Prematurity 2. Intrauterine growth restriction 3. Male gender 4.Hyperoxia. Note that although the initial epidemic of ROP in the mid 20th century was due to excessive oxygen administration, this is not proven to be the only causative agent. 5. Erythropoietin (in high cumulative doses), sepsis, blood transfusions, postnatal dexamethasone use and GM-IVH have been implicated as associations, but may reflect extreme prematurity and severity of illness rather than causation. E) Classification of ROP Demarcation line -a flat, thin, whiteish, Stage 1 clear-cut demaraction between vascularised and avascular retina (normal retina has a tenuous, non- linear, feathery border) Elevated ridge - demarcation line now Stage 2 has "3" dimensions Neovascularisation - extra-retinal, Stage 3 fibrovascular proliferative tissue Retinal detachment - may be exudative Stage 4 and/or tractional, and may be partial or total 4A – macular not involved 4B – macular detached Total retinal detachment Stage 5 Presence of dilatation and tortuosity of Plus Disease the posterior pole blood vessel involving at least two quadrants of the retina. This is associated with severe disease and worse outcomes. It is more likely to occur with higher stages and lower zones Pre-Plus Disease: more arterial tortuosity and venous dilatation than normal but not severe enough to be classified as "Plus disease". "Rush" Disease (Aggressive Posterior ROP, AP-ROP): A rare and severe form of ROP with increased tortuosity and dilatation of vessels present in all 4 quadrants of zone 1 and sometimes zone 2. May not sequentially advance through Stage 1 to 3 but often rapidly advances to stage 4 or 5. F) Treatment of ROP 1. Laser photocoagulation- this procedure produces scars which then seal the borders of the retina preventing retinal detachment. 2. Cryopexy- this method uses freezing to stop the process of vascular proliferation 3. Angiogenesis and the study of how the retinal vessels proliferate is an exciting potential option for the treatment of this disease. G) Prevention of ROP. Preventing premature births is the key to preventing ROP. Research is ongoing to find ways to treat this and other problems of premature babies. During anesthetic care, most textbooks recommend keeping the FIO2 as low as possible (at least <60%) while tolerating a SPO2 as low as 88%. Newborns are considered to be at risk for ROP from hyperoxia up until 45 weeks gestation age.