Retinopathy of prematurity (ROP) is a retinal disorder of low birth weight premature infants. It can be mild with no visual defects, or it may become aggressive with new vessel formation (neovascularisation) and progress to retinal detachment and blindness.1 The stimulus for the abnormal growth of blood vessels comes from the peripheral immature retina. Early detection and effective management of this condition can prevent blindness.
2. Classification of ROP
ROP is categorised based on the severity of the disease into stages (0-5), location of the disease into 3 zones (1-3), extent of the disease based on clock hours (1-12) and the presence of plus disease.1 (Refer Appendix 2 for detailed classification of ROP).
3. Risk factors
3.1 Birth weight and gestational age
Infants with very low birth weight are at significantly higher risk of developing severe ROP that requires treatment. Similarly, the severity of ROP is inversely proportional to gestational age. Present evidence shows that low birth weight and gestational age are the most predictive risk factors for the development of ROP 2-3 level 1; 4- 14 level 8; 15 level 9; 16 level 6.
3.2 Oxygen Use
Oxygen therapy has been previously implicated in the aetiology of ROP 17 level 8; 18 level 6. The use of supplemental oxygen neither caused progression of pre-threshold ROP nor significantly reduced the number of infants requiring peripheral ablative therapy19 level 4. Recent evidence suggests that repeated hypoxic and hyperoxic episodes may be an important factor in the pathogenesis of ROP 20 level 5. Strict management of oxygen delivery without fluctuations and monitoring may be associated with decreased occurrence of ROP 20 level 5. Although the exact relationship between oxygen therapy and ROP is currently not well established, oxygen therapy seemed to play an important role in the pathogenesis of ROP.