“first generation” “second “third generation”...
TRANSCRIPT
Table e-1. Comparison of Optical Coherence Tomography Systems.
“First Generation”
Time-Domain OCT
“Second
Generation”
Spectral Domain
OCT
“Third Generation”
Swept-Source
OCT
Signal-to-Noise +++ ++ +
Speed of image
acquisition 1X 50X 100X
A-scans/sec 400 16K-55K 100K-400K
Motion Artifacts +++ + -
Volumetric scans No Yes Yes
Axial Resolution
(microns) 7-10 3.26 - 7 5-8
Lateral Resolution
(microns)
20-30 6.5-10 10-12
Comments - Needs pupillary
dilation.
- Only one
commercially
available unit
available. Not
currently
marketed.
- No pupillary
dilation needed.
- Multiple
commercial
systems available
on the market.
- No pupillary
dilation needed
- Deeper
penetration, good
for choroid and
optic nerve lamina
cribosa
FIGURE LEGENDS (SUPPLEMENTAL FIGURES)
Figure e-1
Figure e-1. Three OCT modalities currently commercially available. From left to
right: In Time-Domain OCT, the low coherence light is divided by the splitter in to two phase-
matched arms one to the eye and the other to the reference arm. The backscattered light from
both paths interfere constructively and this signal is measured by the detector utilizing the
principle of interferometry. In Spectral-Domain OCT, the backscattered light is combined by a
spectrometer using a Fourier-Domain algorithm. In swept-source OCT, the backscattered laser
light merges and is read at a photodiode detector. In all three modalities, the data from the
detector is inputted into a computer with software that converts the A-scans into readable
images.
Figure e-2
Figure e-2. Optic nerve head drusen. A. Fundoscopic image obtained with scanning laser
ophthalmoscope showing optic nerve head elevation suspicious for papilledema. B. OCT color
thickness maps shows in white color the area of optic nerve elevation. C. Cross sectional image
of the optic nerve shows the optic nerve head drusen as a hyperreflective structure underneath
the elevated tissue (arrow), suggesting pseudopapilledema.
Figure e-3
Figure e-3. Neuroretinitis observed by OCT. A. Color fundus photograph demonstrating optic
nerve edema with a normal macular appearance. B. OCT circular scan showing retinal nerve
fiber layer thickening (with a green color thickness showing values above the normal limit). C.
OCT scan through the macula demonstrates hyperreflective spots (green line) and subretinal
fluid (white line) consistent with an exudative process. These macular OCT findings preceded
the classic appearance of a macular star.
Figure e-4
Figure e-4. Recovery of visual field following resection of pituitary adenoma. A 44 year-old
man presented with complaints of blurred vision in both eyes. Visual acuity was 20/20 in each
eye. Visual field testing demonstrated a bitemporal heminaopsia. Pre-operatively, the optic
nerves appeared normal and the measurements of the RNFL were within normal limits. Post-
operatively, visual fields showed marked improvement, despite the RNFL measurements
demonstrating global thinning.
Figure e-5
Figure e-5. Fingolimod associated macular edema. Severe macular edema of the left eye in a
patient being treated with fingolimod. Macular edema developed 2.5 months into therapy. White
arrow indicates area or intraretinal cystoid spaces characteristic of macular edema.