Method for finding the lateral position of the fovea in an SDOCT image volume
Embodiments of the present invention provide methods for finding the lateral position of the fovea in an OCT image volume. In one instance, a cost function is developed whose minimum is located at or near the foveal center. This cost function includes one or more measures of retinal layer thickness and/or measures of distance from blood vessels or a priori locations.
1. An apparatus for generating 3D image information from within the eye of a patient and for identifying the location of the fovea from within the image information, said apparatus comprising:
an optical coherence tomography (OCT) system, said system including a light source, a beam splitter for dividing the light along a sample arm and a reference arm, said sample arm further including a scanner for scanning the beam transversely over the eye, said OCT device including a detector for receiving light returned from both the sample and the reference arms and generating signals corresponding to three dimensional image information based on a reflection distribution as a function of depth arising from reflecting features in the eye; and
a processor for segmenting the image information and assigning a single representative intensity value for each transverse location across the segmented region wherein the representative intensity value corresponds to an integrated intensity as a function of depth across the segmented region and determining the location of the fovea based on the transverse location having a minimum representative intensity value.
2. An apparatus are recited in claim 1 further including a display for displaying the image information and the determined foveal location.
3. An apparatus as recited in claim 1 wherein the segmented region corresponds to a region beginning at the inner limiting membrane (ILM) and extending to a predetermined depth below the ILM.
4. An apparatus as recited in claim 1 wherein the processor evaluates a second, different foveal location dependent image quantity that reaches an extremum as the likelihood of that location being at or near the center of the fovea increases and wherein the results of the evaluation of the second different foveal location dependent image quantity are used to improve the determination of the location of the fovea.
5. An apparatus as recited in claim 1 wherein said processor determines the location of the blood vessels in the image information and utilizes the blood vessel location information to improve the determination of the location of the fovea.
6. An apparatus as recited in claim 1 wherein when determining the location of the fovea, the processor further considers the lateral distance from the center of the scanned region in the plane of the scan.
7. An apparatus as recited in claim 1 wherein said processor determines the thickness of the macular layer in the region of the determined foveal location.
8. An apparatus as recited in claim 1 wherein the segmented region corresponds to a region beginning at the inner limiting membrane (ILM) and extending to a depth below the ILM, said depth being determined as a function of the distance from the ILM to the retinal pigment epithelium (RPE).
9. An apparatus for generating 3D image information from within the eye of a patient and for identifying the location of the fovea from within the image information, said apparatus comprising:
an optical coherence tomography (OCT) system, said system including a light source, a beam splitter for dividing the light along a sample arm and a reference arm, said sample arm further including a scanner for scanning the beam transversely over the eye, said OCT device including a detector for receiving light returned from both the sample and the reference arms and generating signals corresponding to three dimensional image information based on a reflection distribution as a function of depth arising from reflecting features in the eye; and
a processor for segmenting the image information to isolate a region wherein the integrated intensity of the image information within the segmented region reaches a minimum as the likelihood of that location being at or near the center of the fovea increases, said integrated intensity being computed as a function of depth, said processor analyzing the integrated intensity image information to determine the location where the intensity has reached a minimum to determine the foveal location.
10. An apparatus are recited in claim 9 further including a display for displaying the image information and the determined foveal location.
11. An apparatus as recited in claim 9 wherein the segmented region corresponds to a region beginning at the inner limiting membrane (ILM) and extending to a predetermined depth below the ILM.
12. An apparatus as recited in claim 9 wherein the segmented region corresponds to a region beginning at the inner limiting membrane (ILM) and extending to a depth below the ILM, said depth being determined as a function of the distance from the ILM to the retinal pigment epithelium (RPE).
13. An apparatus as recited in claim 9 wherein the processor evaluates a second, different foveal location dependent image quantity that reaches an extremum as the likelihood of that location being at or near the center of the fovea increases and wherein the results of the evaluation of the second different foveal location dependent image quantity are used to improve the determination of the location of the fovea.
14. An apparatus as recited in claim 9 wherein said processor determines the location of the blood vessels in the image information and utilizes the blood vessel location information to improve the determination of the location of the fovea.
15. An apparatus as recited in claim 9 wherein when determining the location of the fovea, the processor further considers the lateral distance from the center of the scanned region in the plane of the scan.
16. An apparatus as recited in claim 9 wherein said processor determines the thickness of the macular layer in the region of the determined foveal location.
17. An apparatus for generating 3D image information from within the eye of a patient and for identifying the location of the fovea from within the image information, said apparatus comprising:
an optical coherence tomography (OCT) system, said system including a light source, a beam splitter for dividing the light along a sample arm and a reference arm, said sample arm further including a scanner for scanning the beam transversely over the eye, said OCT device including a detector for receiving light returned from both the sample and the reference arms and generating signals corresponding to three dimensional image information based on a reflection distribution as a function of depth arising from reflecting features in the eye; and
a processor analyzing the image information to determine the location of the fovea within the image, said analyzing step including evaluating a quantity associated with each of at least two different independent indicators of foveal location, said two different indicators being combined and weighted, wherein one of said indicators of foveal location relates to the level of integrated intensity across the image, said integrated intensity being measured as a function of depth.
18. An apparatus as recited in claim 17 wherein the integrated intensity is evaluated in a region the near inner limiting membrane (ILM).
19. An apparatus as recited in claim 17 wherein one of said indicators of foveal location relates to the location of blood vessels in the image information.
20. An apparatus as recited in claim 17 wherein the relative weighting of the indicators is adjusted based on the level of noise associated with the respective measurements.
21. An apparatus are recited in claim 17 further including a display for displaying the image information and the determined foveal location.
22. An apparatus as recited in claim 17 wherein said processor determines the thickness of the macular layer in the region of the determined foveal location.