Retinopathy of prematurity

Associated with blindness and other visual disabilities in preterm infants.

It is a disorder of the developing retinal blood vessels in preterm infants.

A neovascular retinal disorder that causes vision impairment by macular dragging and retinal detachment.

Fewer than 10% of infants who undergo retinopathy of prematurity screening examinations require treatment.

Occurs in settings of high-quality care and affects primarily extremely preterm infants.

The leading cause of childhood blindness in the US and other highly industrialized nations.

Incidence of premature birth is increasing throughout the world, and retinopathy of prematurity is increasing as a result.

This process becoming the leading cause of childhood blindness worldwide.

Incidence inceased with exposure to unrestricted oxygen therapy in preterm infants.

There are five stages of ROP indicating disease severity from stage one to stage five.

Most cases of ROP are mild and regress spontaneously, and rarely warrant treatment.

Guidelines for retinopathy of prematurity detection are for infants with a birth weight of less than 1501 g or a gestational age of 30 weeks or younger, with the addition of infants with birth weights up to 2000 g if a poor neonatal indicates an examination is needed.

A variety of factors induce a first phase of reduced retinal vessel growth and microvascular degeneration, followed by a second phase of pathologic neovascularization, which may lead to retinal detachment.

Low birth weight and prematurity or strongly associated with increased risk.

The improved use of supplemental oxygen has reduced the most severe stages of ROP among preterm infants, but the survival of smaller and less mature infants in high-income countries and the introduction of neonatal intensive care in low and middle income countries has led to a second and third wave of ROP.

Early Treatment for Retinopathy of Prematurity study found 68% of premature infants born in the US developed this disorder and they weighed less than 1251 g.

Among infants with the disease, 37% develop severe disease.

Retinopathy of prematurity is reported in 32% very low birthweight infants and in those with serious ROP (stages 3 to 5) as many as 6% of very low birthweight infants.

Occurs primarily in in since of low birth weight 1250 g or less, with the mean weight of 700 g (Gilbert C.).

The incidence of blindness due to this process is about one case in 820 infants (Lad EM et al).

In developing countries childhood blindness manifests in larger premature infants.

Worldwide prevalence of blindness due to ROP is 50,000.

Pathophysiology involves phase 1 with delayed physiologic retinal vascular development, and phase 2 involves vasoproliferation.

In the retinopathy of prematurity first a delay in physiologic retinal vascular development , with subsequent vasoproliferation.

Retinal vascularization of the internal surface of the retina begins at 16 weeks gestation at the optic nerve and processes anteriorly to reach the edge of the temporal retina at 40 weeks: Zone I refers to a circle whose radius extends from the optic disk and is twice the distance between the center of the disk in the center of the macula, Zone II encircles zone one and extends from Zone 1 to the nasal extent of the retina.

Vasculogenesis of the eye is ongoing until 22 weeks of gestation and thereafter vascularization progresses by angiogenesis and vascular endothelial growth factor.

ROP is classified on the location, the severity, and vascular characteristics in the posterior pole

The practice of restricting the fraction of inspired oxygen to 0.5 or less results in an excess of 16 deaths per case of blindness prevented (Bolton DP).

Data suggest levels of oxygen saturation previously felt to be at the upper end of the normal range may increase the risk of retinopathy compared with levels at the lower range of normal (Tin W, Chow,LC Anderson CG).

When treatment is needed, timely action is required to prevent retinal detachment and consequent vision impairment and loss.

Improved by laser and cryotherapy.

Laser photocoagulation of the avascular retina retina has been standard treatment with the aim of removing the source of excessive angiogenic stimulus originating from the avascular peripheral retina.

Laser photocoagulation is associated with irreversible visual field loss and a high level of myopia.

The upregulation of vascular endothelial growth factor (VEGF) promotes abnormal vascular proliferation during the vasoproliferative phase of ROP.

Among infants with ROP, intravitreal aflibercept compared with photocoagulation did not meet criteria for non-inferiority with respect to achieving treatment success at 24 weeks.

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