How is choroidal neovascularization (CNV) staged following photodynamic therapy (PDT)?

Updated: Jul 27, 2020
  • Author: Lihteh Wu, MD; Chief Editor: Andrew A Dahl, MD, FACS  more...
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A proposed classification scheme of CNV following photodynamic therapy (PDT) is as follows [1] :

  • Stage I – Occurs shortly after PDT and lasts for about a week; characterized by an inflammatory reaction that causes an increase in intraretinal fluid in a circular fashion that corresponds with the treatment spot
  • Stage II – Restoration of a near-normal foveal contour with diminished subretinal fluid; occurs 1-4 weeks after treatment
  • Stage III – Represents reperfusion and involution of CNV; typically occurs 4-12 weeks following treatment and is subdivided into 2 categories based on the ratio of subretinal fibrosis to fluid present; stage IIIa is characterized by a higher subretinal fluid to fibrosis ratio, indicating active CNV; while lesions in Stage IIIb have more prominent fibrosis with minimal intraretinal fluid, indicating inactive CNV
  • Stage IV – Further involution of CNV leading to cystoid macular edema
  • Stage V – CNV and the subretinal fluid resolve, leading to fibrosis and retinal thinning

See Workup for more detail.

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