DO PLATELETS HAVE A ROLE IN THE PATHOGENESIS OF AGGRESSIVE POSTERIOR RETINOPATHY OF PREMATURITY? ANAND VINEKAR, MD, FRCS,* KAUSHIK HEGDE, MD,* CLARE GILBERT, MD,† SHERINE BRAGANZA, MD,* MARALUSIDDAPPA PRADEEP, MD,‡ ROHIT SHETTY, MD, FRCS,* K. BHUJANG SHETTY, MD* Purpose: The purpose of this study was to report the possible role of thrombocytopenia in the pathogenesis of aggressive posterior retinopathy of prematurity (APROP). Methods: The index case described in this study showed spontaneous resolution of APROP with plus disease within 3 days of correcting thrombocytopenia and did not require laser treatment. The retrospective cohort of nine consecutive Asian Indian infants with APROP with similar stage and plus disease as the index case was studied. The mean platelet count of these infants before laser treatment was compared with 21 age- and birth weight-matched control subjects. Correlation of platelet count with APROP is discussed. Results: The mean birth weight of the 10 cases with APROP was 1,030 g (178 g), and the mean period of gestation was 29.4 weeks (2.0 weeks). The mean platelet count of the cases was 82,870/mm 3 (58,702/mm 3 ) and that of the control subjects was 178,285  57,051/mm 3 (P = 0.0002). Five of the 10 cases (50%) and 1 of the 21 control subjects (4.8%) had a platelet count of 100,000/mm 3 (P = 0.007). In all, 19.4% of infants had culture-proven sepsis. There was no correlation between sepsis and thrombocytopenia in our cohort (P = 0.567). Conclusion: The role of low platelets in the etiopathogenesis of APROP has not been previously elucidated. Our study shows that a platelet count of 100,000 was associated with severe disease. Recently, platelets have been reported to play a key role in angiogenic regulatory protein delivery. It is possible that premature infants who develop retinopathy of prematurity in the setting of low platelet counts may lack the function of either delivering the optimal level or incompletely scavenging the excess of vascular endothelial growth factor A present in APROP. The spontaneous resolution of disease in our index case with platelet correction alone needs additional studies to correlate the timing and magnitude of correction that may play a role. RETINA 30:S20 –S23, 2010 T he full understanding of the mechanisms and causative risk factors involved in the etiopatho- genesis of retinopathy of prematurity (ROP) is still not complete. 1 Exploration of hematologic factors as in- dependent risk factors for ROP has been largely lim- ited to anemia and blood transfusion with conflicting results. 2 The role of platelets or its deficiency in ROP has not been studied. Recently, platelets have been identified as having scavenging functions of key angiogenic regulatory proteins (both pro- and antiangiogenic). 3 The abnormal vasculogenesis and/or angiogenesis that underlies the pathoanatomy of severe ROP 4 lends itself to biologic plausibility of correlating the role of platelets in this disease. Aggressive posterior ROP From the *Department of Pediatric Retina, Narayana Nethralaya Postgraduate Institute of Ophthalmology, Bangalore, India; the †Lon- don School of Hygiene and Tropical Medicine, London, UK; and the ‡Department of Neonatology, MS Ramaiah Medical College and Hospital, Bangalore, India. The authors have no financial or competing interests to declare. Reprint requests: Anand Vinekar, MD, FRCS, Department of Pediatric Retina, Narayana Nethralaya Postgraduate Institute of Ophthalmology, 121/C Chord Road, 1st Block, Rajajinagar, Ban- galore 560010, India; e-mail: anandvinekar@yahoo.com S20