Optical Frequency Domain Imaging of Type I Choroidal Neovascular Membranes in Age Related Macular Degeneration Patients Treated With Ranibizumab

Abstract

 

Purpose:

 

Optical frequency domain imaging (OFDI) is a novel optical coherence tomography modality that utilizes a center wavelength of 1050 nm for improved image penetration into the choroid. This study applies OFDI to assess type I (sub-RPE) choroidal neovascularization (CNV) and its associated exudative changes in patients with age related macular degeneration (AMD) undergoing treatment with ranibizumab.

 

Methods:

 

A prototype high-speed OFDI system was used to evaluate three eyes of three patients with neovascular AMD before and after 4-8 treatments with intravitreal ranibizumab. Three-dimensional data sets encompassing a 9 by 8 by 2.5 mm (x, y, z) scanning area of the macula were acquired in 2-4 seconds, and en-face images were compiled from cross-sectional OFDI data and co-registered with color fundus photography and fluorescein angiograms (FA). The correlated cross-sectional images were analyzed and intraretinal edema, subretinal fluid, and CNV volumes were quantified during post-image processing.

 

Results:

 

OFDI revealed a band of reduced reflectivity between the RPE and Bruchs membrane in all eyes that corresponded to areas of confirmed and suspected occult CNV on FA. Following treatment, the volume of this band was reduced in all patients (mean 0.309 mm³ pre-treat, 0.165 mm³ post-treat; 46.6% reduction). Subretinal fluid (mean 0.515 mm³ pre-treat, 0.002 mm³ post-treat; 99.6% reduction) and intraretinal edema (mean 0.98 mm³ pre-treat, 0.0 mm³ post-treat) were each present in 2 eyes and essentially resolved following treatment.

 

Conclusions:

 

High speed OFDI revealed subretinal fluid, intraretinal edema, and a hyporeflective sub-RPE band presumed to be type I CNV and/or sub-RPE fluid that decreased substantially following treatment with ranibizumab. The developed OFDI system is a promising technology for imaging the retina and choroid in neovascular AMD and may be a valuable tool for assessing response to therapy.  

 

Keywords: imaging/image analysis: clinical • choroid: neovascularization • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)