Retinopathy of prematurity (ROP) is a leading cause of childhood blindness. Vascular endothelium growth factor (VEGF) is an important component of this disease. The goal of treatment is to reduce the production of VEGF in the immature retina and to eliminate the abnormal growth of new vessels. Currently, laser photocoagulation of the peripheral avascular retina is the treatment standard. Intravitreal injection of anti-VEGF antibody Bevacizumab (IVB) has been used clinically off-label as an alternative therapy. However, VEGF is important for the development of neurons and vessels in the systemic organs in premature infants. Pharmaceutical study showed that IVB was absorbed into the bloodstream. It is unclear if the systemic absorption of Bevacizumab is dose related, and the short and longterm effects on ocular and systemic systems, especially neurological development. In this study, our goals are to establish the pharmacokinetics of Bevacizumab in the premature infant and to compare the short and long-term vision and neurodevelopmental outcomes of infants treated with IVB compared to laser ROP.

This study will enroll preterm infants who were scheduled to receive treatment for ROP by laser or Bevacizumab. We will observe the patients in the hospital for the cure of ROP until 54 weeks' postmenstrual age. We will check the changes of chemicals in the blood and observe short-term and long-term effects on visual system, brain and other body organs. Descriptive statistics from a two sample t-test or Fisher's exact test will be used to compare the short and long-term vision and neurological development outcomes. We predefined a statistical significance level p=0.05.

Inclusion Criteria:

Premature infants who were scheduled to receive laser or BEvacizumab treatment for type I ROP .

Exclusion Criteria:

1. Have unilateral or Bilateral ROP Stage 4 or 5 ROP;
2. Lack of signed consent by the parent or legal guardian.

Premature infants