OCT-based whole eye biometry system
1
OCT-based whole eye biometry system M. Mujat 1 , A. Patel, G. Maguluri 1 , N. Iftimia 1 , Akula, James D. 2 ; Fulton, Anne B. 2 , R. D. Ferguson 1 1 Biomedical Optical Technologies Group, Physical Sciences Inc, Andover, MA, United States. 2 Ophthalmology, Boston Children's Hospital, Boston, MA, United States. Our preliminary corneal/scleral, lenticular and retinal imaging demonstrations (performed at safe light levels for retinal imaging under NEIRB human subjects protocols) have shown coordinated optical delays and focal conjugate zoom control produce high quality SDOCT images ranging throughout the whole eye. Simultaneous measurement of anterior and posterior ocular anatomic structures and surfaces, and their precise spatial relationship to each other over wide angles, is feasible with a two-channel, dual-conjugate non-contact optical ocular biometry system in the optically accessible regions of the eye. The precise measurement of ocular anatomy and pathology, from cornea, sclera and crystalline lens in the anterior segment to retina spanning the large posterior part of the globe, are fundamental in diagnosis and management of many eye conditions and diseases. A very broad range of specialized techniques and instruments enable measurement of ocular surfaces, layers, curvatures, shapes and positions, eye length, accommodation, etc. However at present, there is no accurate whole eye optical biometry alternative to a piecemeal approach. No single instrument is available on the market to rapidly and simultaneously capture 3D ocular surface shapes with micron-scale resolution and their precise spatial relationships to each other in the optically accessible regions of the eye. The purpose of this research program is to demonstrate a new dual-conjugate, dual-band approach to whole eye optical biometry. The flexibility and utility of such a system for wide-field measurements and diagnostics far exceeding axial lengths and thicknesses, and IOL power calculations is anticipated to make it commercially viable in many research and clinical applications. The optical head (Fig. 3) contains all the imaging optics, the OCT components including the light source, circulator, coupler, polarization controllers, and delay line, the imaging path for the pupil camera including the pupil camera. Purpose An Optical Coherence Tomography (OCT) – based whole eye biometry (WEB) system has been developed for rapid measurement of the shape of the eye with micron scale resolution. Radial scanning geometry has been chosen for the OCT imager, in which a pair of elliptical mirrors is used to relay the pivot point from the scanners into the center of the eye, such that the laser beam is always near- normal to several eye surfaces as the beam scans. Methods Conclusions Support: NIH grant R44EY025895. Commercial Relationships: M. Mujat, Physical Sciences Inc (E); A. Patel, None; G. Maguluri, Physical Sciences Inc (E); N. Iftimia, Physical Sciences Inc (E), Akula, James D., None; Fulton, Anne B., None; R. D. Ferguson, Physical Sciences Inc (E) . Acknowledgements New design concept Figure 3: Complete system including optical head, computer, electronics box. Position adjustments Optical head Foot pedal Electronics This method permits simultaneous imaging of pairs of ocular surfaces with respect to the scan pivot point, by integration of dual-conjugate optics. Coordinated dual-reference arms enable ranging to these two focal surfaces at precisely known locations with respect to the scan pivot, and to each other, on a single SDOCT spectrometer without imposing extreme requirements on the axial imaging range. Direct imaging of the eye through the reflective scan optics allows the system pupil/pivot location to be precisely positioned by the operator, while the eye’s position and orientation are monitored by a camera and controlled by a fixation display. A B C D E Figure 4. A: averaged image of the cornea; B: average image of the iris and top of the lens; C: average image of the retina; D: same optical configuration as C, configured as 3D raster, 50x100 deg (640 A-lines x 90 B-scans), corrected for eye motion and aligned; E: tangential and sagittal sections of the 3D data set. Figure 2. Left; Dual-conjugate (F1: posterior, F2: anterior) input beam shaping approach with coordinated zoom. Right: Zemax optical eye models showing focal planes at fundus and cornea, with pivot at the nodal-point. Results Dual-band Spectrometer Source 2 DCBS R 1,2 =Z 0 R2 R1 Dual-range delay line Dual-focus Beam F1, F2 F1, R1 F2, R2 Scan-pivot WEBS SDOCT IMAGER CONCEPT R 1 , R 2 Dual-conjugate SDOCT Images Camera/ Fixation VBS Scan Head Θ,φ Source 1 2x1 WDM (isolated) R 1,2 = Z 0 90:10 Figure 1. WEB pairwise, dual-surface SDOCT imaging concept. A dual-range delay line with dual-focus input beam shaping allows high speed SDOCT raster scans on two selected ocular surfaces to be completed simultaneously. The OPD between surface 1 and surface 2 on the single B-scan indicated is the separation in the segmented image plus a refractive corrected function of the delays and scan angles f(R1+R2, θ,φ). PSI recently developed a high-speed SDOCT-based scanning/imaging system design for corneal/scleral topography that is currently being adapted for application to the whole eye. The innovation described herein extends this approach, permitting simultaneous imaging of pairs of ocular regions or surfaces with respect to the fixed scan pivot point (system pupil), by a dual-conjugate, dual-band OCT optical design. Selected scans at 850 nm at various depths both 2D averages and 3D retinal views are shown in Fig. 4. The pilot testing images shown demonstrate the range of imaging modalities and accessible conjugates within the eye with the fixed relay optics when the delay range and focal planes are shifted in coordination.
Transcript of OCT-based whole eye biometry system
OCT-based whole eye biometry systemM. Mujat1, A. Patel, G. Maguluri1, N. Iftimia1, Akula, James D.2; Fulton, Anne B.2, R. D. Ferguson1
1Biomedical Optical Technologies Group, Physical Sciences Inc, Andover, MA, United States.2Ophthalmology, Boston Children's Hospital, Boston, MA, United States.
Our preliminary corneal/scleral, lenticular and retinal imaging demonstrations(performed at safe light levels for retinal imaging under NEIRB human subjectsprotocols) have shown coordinated optical delays and focal conjugate zoomcontrol produce high quality SDOCT images ranging throughout the whole eye.Simultaneous measurement of anterior and posterior ocular anatomic structuresand surfaces, and their precise spatial relationship to each other over wide angles,is feasible with a two-channel, dual-conjugate non-contact optical ocular biometrysystem in the optically accessible regions of the eye.
The precise measurement of ocular anatomy and pathology, from cornea, scleraand crystalline lens in the anterior segment to retina spanning the large posteriorpart of the globe, are fundamental in diagnosis and management of many eyeconditions and diseases. A very broad range of specialized techniques andinstruments enable measurement of ocular surfaces, layers, curvatures, shapes andpositions, eye length, accommodation, etc. However at present, there is noaccurate whole eye optical biometry alternative to a piecemeal approach. Nosingle instrument is available on the market to rapidly and simultaneously capture3D ocular surface shapes with micron-scale resolution and their precise spatialrelationships to each other in the optically accessible regions of the eye.
The purpose of this research program is to demonstrate a new dual-conjugate,dual-band approach to whole eye optical biometry. The flexibility and utility ofsuch a system for wide-field measurements and diagnostics far exceeding axiallengths and thicknesses, and IOL power calculations is anticipated to make itcommercially viable in many research and clinical applications.
The optical head (Fig. 3) contains all the imaging optics, the OCT componentsincluding the light source, circulator, coupler, polarization controllers, and delay line,the imaging path for the pupil camera including the pupil camera.
Purpose
An Optical Coherence Tomography (OCT) – based whole eye biometry (WEB)system has been developed for rapid measurement of the shape of the eye withmicron scale resolution. Radial scanning geometry has been chosen for the OCTimager, in which a pair of elliptical mirrors is used to relay the pivot point fromthe scanners into the center of the eye, such that the laser beam is always near-normal to several eye surfaces as the beam scans.
Methods
Conclusions
Support: NIH grant R44EY025895.
Commercial Relationships: M. Mujat, Physical Sciences Inc (E); A. Patel,None; G. Maguluri, Physical Sciences Inc (E); N. Iftimia, Physical Sciences Inc(E), Akula, James D., None; Fulton, Anne B., None; R. D. Ferguson, PhysicalSciences Inc (E).
Acknowledgements
New design concept
Figure 3: Complete system including optical head, computer, electronics box.
Positionadjustments
Optical head
Foot pedal
Electronics
This method permits simultaneous imaging of pairs of ocular surfaces withrespect to the scan pivot point, by integration of dual-conjugate optics.Coordinated dual-reference arms enable ranging to these two focal surfaces atprecisely known locations with respect to the scan pivot, and to each other, on asingle SDOCT spectrometer without imposing extreme requirements on the axialimaging range. Direct imaging of the eye through the reflective scan optics allowsthe system pupil/pivot location to be precisely positioned by the operator, whilethe eye’s position and orientation are monitored by a camera and controlled by afixation display.
A
B
CD
E
Figure 4. A: averaged image of the cornea; B: average image of the iris and top of the lens;C: average image of the retina; D: same optical configuration as C, configured as 3D raster,50x100 deg (640 A-lines x 90 B-scans), corrected for eye motion and aligned; E: tangential
and sagittal sections of the 3D data set.
Figure 2. Left; Dual-conjugate (F1: posterior, F2: anterior) input beam shaping approach withcoordinated zoom. Right: Zemax optical eye models showing focal planes at fundus and cornea,
with pivot at the nodal-point.
Results
Dual-bandSpectrometer
Source 2
DCBS
R1,2 = Z0
R2
R1
Dual-range delay line
Dual-focusBeam F1, F2
F1, R1F2, R2
Scan-pivot
WEBS SDOCT IMAGER CONCEPT
R1, R2
Dual-conjugateSDOCT Images
Camera/Fixation VBS
ScanHead
Θ,φSource 1
2x1 WDM
(isolated)
R1,2 = Z0
90:10
Figure 1. WEB pairwise, dual-surface SDOCT imaging concept. A dual-range delay line withdual-focus input beam shaping allows high speed SDOCT raster scans on two selected ocular
surfaces to be completed simultaneously. The OPD between surface 1 and surface 2 on thesingle B-scan indicated is the separation in the segmented image plus a refractive corrected
function of the delays and scan angles f(R1+R2, θ,φ).
PSI recently developed a high-speed SDOCT-based scanning/imaging system designfor corneal/scleral topography that is currently being adapted for application to thewhole eye. The innovation described herein extends this approach, permittingsimultaneous imaging of pairs of ocular regions or surfaces with respect to the fixedscan pivot point (system pupil), by a dual-conjugate, dual-band OCT optical design.
Selected scans at 850 nm at various depths both 2D averages and 3D retinal views areshown in Fig. 4. The pilot testing images shown demonstrate the range of imagingmodalities and accessible conjugates within the eye with the fixed relay optics whenthe delay range and focal planes are shifted in coordination.
