August 2021
Volume 62, Issue 11
Open Access
ARVO Imaging in the Eye Conference Abstract  |   August 2021
Wide field Scleral Topography with Hyper-parallel OCT (HP-OCT™)
Author Affiliations & Notes
  • Trevor Anderson
    Cylite Pty. Ltd., Melbourne, Victoria, Australia
  • Hidemasa Muta
    Cylite Pty. Ltd., Melbourne, Victoria, Australia
  • Grant Frisken
    Cylite Pty. Ltd., Melbourne, Victoria, Australia
  • Steve Frisken
    Cylite Pty. Ltd., Melbourne, Victoria, Australia
  • Footnotes
    Commercial Relationships   Trevor Anderson, Cylite (E), Cylite Pty Ltd (I); Hidemasa Muta, cylite (E); Grant Frisken, cylite (I), cylite (E); Steve Frisken, cylite (I), cylite (E)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science August 2021, Vol.62, 28. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Trevor Anderson, Hidemasa Muta, Grant Frisken, Steve Frisken; Wide field Scleral Topography with Hyper-parallel OCT (HP-OCT™). Invest. Ophthalmol. Vis. Sci. 2021;62(11):28.

      Download citation file:


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

      ×
  • Supplements
Abstract

Purpose : Hyper-parallel optical coherence tomography (HP-OCT) is a high-speed snap-shot spectral domain OCT system robust to patient movement, and particularly well suited for anterior biometry. We demonstrate that HP-OCT can measure cornea and scleral topography over an extended field of view of 20x20 mm and so provides complete OCT topography in a non-invasive approach enabling assessment for scleral lens custom design, fitting and on-going post fit eye health assessment.

Methods : HP-OCT uses a parallel sampling scheme with a grid of 1008 beams that are generated from an 840nm SLED and a 2D micro-lens array of 0.4mm pitch. A grating based spectrometer then disperses all beams on to a 2D CMOS sensor with a frame rate of 300Hz producing a scan speed of 302,400 A-scans per sec. Standard scan pattern options produce refraction corrected true corneal 3D volumes with fields of view of 16.8x 9.6mm and 16.8x14mm captured in 1s and 2s, respectively. Small scan angles compared to point scanning systems minimize distortion and enable accurate stitching. Here we demonstrate that an extended topography coverage of 20x20 mm can be obtained by stitching off-axis volumes.

Results : In Figure 1 we show maximum intensity projection en face images of the 5 volumes to be registered. The fixation offsets of the off-axis volumes are 25 degrees. Rigid body volumetric registration is used to align off-axis volumes with the on-axis volume. The combined volume and sample B-Scans are shown in Figure 2. A comparison of registered anterior surfaces shows that, in common regions of good signal quality, the height difference is less than 5 μm.

Conclusions : The parallel nature of the HP-OCT system enables it to generate true 3D volumes that are free from distortion due to movement and scanning artifacts. This enables accurate scleral measurements over large fields of view to be created from combined off-axis captures. (In future work, we envision a wide field single capture with on-axis fixation and a modified 4s scan pattern and the ability to incorporate OCT Angiography across this same ultra-wide scan.)

This is a 2021 Imaging in the Eye Conference abstract.

 

Figure 1. HP-OCT en face images. The lateral coverage of each volume is 16.8x14 mm. The off-axis fixation is 25 degrees.

Figure 1. HP-OCT en face images. The lateral coverage of each volume is 16.8x14 mm. The off-axis fixation is 25 degrees.

 

Figure 2. (A) shows stitched volume and sample B-scan axes. (B) Lateral extent of the B-scan is 20 mm. (C) Diagonal coverage is 22 mm

Figure 2. (A) shows stitched volume and sample B-scan axes. (B) Lateral extent of the B-scan is 20 mm. (C) Diagonal coverage is 22 mm

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×