May 2005
Volume 46, Issue 13
ARVO Annual Meeting Abstract  |   May 2005
New Conception of Retinopathy of Prematurity (ROP): Zone 1 versus Zone 2 ROP
Author Affiliations & Notes
  • J. Flynn
    Ophthalmology, Harkness Eye Institute, Columbia University, NY
  • T. Chan–Ling
    Department of Anatomy, University of Sydney, Sydney, Australia
  • Footnotes
    Commercial Relationships  J. Flynn, None; T. Chan–Ling, None.
  • Footnotes
    Support  Community Foundation,TX,NHMRC 153789,FINANCIAL MKT FDN FOR CHILDREN
Investigative Ophthalmology & Visual Science May 2005, Vol.46, 4110. doi:
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      J. Flynn, T. Chan–Ling; New Conception of Retinopathy of Prematurity (ROP): Zone 1 versus Zone 2 ROP . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4110.

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      © ARVO (1962-2015); The Authors (2016-present)

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Results of current therapy of Zone 1 compared to Zone2 ROP are disappointing (Table 1).





Studies of formation of human retinal vasculature haveshown the process involves 2 steps, vasculogenesis & angiogenesis. Vasculogenesis forms forms the primordial vessels of superficialplexus in posterior retina centered on the optic disc. Migrationof large numbers of ADPase+ / Nissel stained vascular precursercells(VPCs) from the optic disc are apparent before 12 weeksgestation(WG). Vasculogenesis is complete by 21WG and appearsindependent of metabolic demand and hypoxia –induced VEGFexpression. Angiogenesis, forms vessels via budding from existingvessels and is responsible for formation of remaining of remainingvessels , including vessel formation in peripheral retina andformation of deep plexus and radial peripapillary capillaries. Angiogenesis is mediated by hypoxia induced VEGF. Typicalexamples, digital images of Zone 1 &2 ROP, will be contrasted.


Digital images correlated with the 2 distinct processesof retinal vascularizationin Zone 1&2 provide a rationalbasis for the discrepency in the clinical outcome of therapy.What emerges is a picture of bi–phasic ROP: VasculogenicROP, indepedent of metabolic demand, poorly responsive to ablativetherapy, and Angiogenic ROP responsive to therapywhich reducesmetabolic demand . Clinical differences are summarized (Table2).



ROP affects retinal vessel formation at differentstages (weeks GA) of development. This determines ROP location,severity, prognosis . We believe ROP should be re–classifiedon the basis of its ontogeny.


Keywords: retinopathy of prematurity • retinal neovascularization • pathology: experimental 

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