Ultrahigh speed OCT angiography in age-related macular degeneration using swept source optical coherence tomography

Abstract

 

Purpose

 

To investigate the use of ultrahigh speed swept source optical coherence tomography (SSOCT) angiography for characterizing microvascular changes in patients with age-related macular degeneration (AMD).

 

Methods

 

A 1050nm wavelength, 400 kHz A-scan rate SSOCT system was used to perform volumetric optical coherence tomography angiography (OCTA) of the retinal and choriocapillaris vasculature in normal volunteers and AMD patients. The normal group consisted of 63 eyes (32 subjects; 40.7 ± 14.1 years; 13 males; 19 females). The AMD group included 17 eyes with wet AMD (15 patients; 79.7 ± 8.3 years; 6 males; 9 females), 35 eyes with dry AMD without geographic atrophy (GA) (26 patients; 77.5 ± 9.0 years; 11 males; 15 females) and 12 eyes with dry AMD with GA (7 subjects; 75.9 ± 6.1 years; 6 males; 1 female). A technique called variable interscan time analysis was developed to differentiate flow impairment from atrophy; the technique works by varying the effective interscan time between repeated B-scans.

 

Results

 

Choroidal neovascularization (CNV) was visualized in 16 of the 19 eyes with wet AMD. In these 16 eyes the CNV was found above regions of choriocapillaris atrophy. In 14 of these eyes the CNV was surrounded by choriocapillaris alteration. Eyes with dry AMD without GA showed varying severities of choriocapillaris alterations, some of which were associated with drusen and/ or retinal pigment epithelium/ photoreceptor alteration. In all 12 eyes with GA, OCTA showed choriocapillaris atrophy within the GA region. In 10 of these eyes OCTA showed choriocapillaris flow impairment beyond the GA margin.

 

Conclusions

 

OCTA appears to be a promising modality for non-invasive imaging of retinal and choriocapillaris vasculature in eyes with AMD.  

 

CNV located adjacent to GA in a 75 year old AMD patient. (A) En face OCT projection. (B) OCTA of choriocapillaris. (C) En face OCTA projection. (D) Fundus autofluorescence. (E) OCT and (F) OCTA B-scans through the dashed line in (A). Scale bars: 1mm.

 

 

75 year old GA patient. (A) Fundus autofluorescence. (B) En face OCT projection. (C) OCTA of retinal microvasculature. (D) OCTA of choriocapillaris. (E) OCTA of choriocapillaris as in (D) but generated using variable interscan time analysis. (F-I) Magnified views. OCT intensity (top) and OCTA (bottom) B-scans through dashed lines in (D) are shown in (J-L). Scale bars: 1mm.