Eye refractive power measurement apparatus
An eye refractive power measurement apparatus includes a measurement optical system, a calculator and an output unit. The measurement optical system projects measurement light onto a fundus of an examinee's eye, extracts the measurement light reflected on the fundus as ring-shaped light, and causes an imaging device to capture a ring-shaped image. The calculator measures eye refractive power of the examinee's eye, based on the ring-shaped image captured by the imaging device, specifies a position of the ring-shaped image to calculate a measured line of the image, performs approximate processing on the measured line to calculate an approximate curve, and calculates a displacement between the measured line and the approximate curve in a meridian direction for each divided region. The output unit outputs a measurement result of the eye refractive power and a calculation result of the displacement in each divided region.
1. An eye refractive power measurement apparatus comprising:
a measurement optical system configured to project measurement light onto a fundus of an examinee's eye, to extract the measurement light reflected on the fundus as ring-shaped light, and to cause an imaging device to capture a ring-shaped image;
a calculator configured to measure eye refractive power of the examinee's eye, based on the ring-shaped image captured by the imaging device, by
specifying a position of the ring-shaped image to calculate a measured line of the image,
performing approximate processing on the measured line to calculate an approximate curve, and
calculating a displacement between the measured line and the approximate curve in a meridian direction for each divided region of the ring-shaped image; and
an output unit configured to output a measurement result of the eye refractive power and a calculation result of the displacement in each divided region.
2. The eye refractive power measurement apparatus according to claim 1 , wherein
the output unit is configured to classify the calculation result of the displacement in each divided region by a level, and to output a classification result as a degree of reliability in each divided region.
3. The eye refractive power measurement apparatus according to claim 1 , wherein
the output unit is configured to output a measurement image based on the ring-shaped image, and to make the calculation result of the displacement in each divided region correspond to each divided region in the measurement image.
4. The eye refractive power measurement apparatus according to claim 1 , wherein
the calculator is configured to virtually change a relative position of (i) the measured line or the divided approximate curve and (ii) an overall approximate curve, obtained by performing approximate processing on the entire ring-shaped image, in the meridian direction for each divided region,
the calculator is configured to obtain a state where (i) the measured line or the divided approximate curve and (ii) the overall approximate curve come into contact with or cross each other, and
the calculator is configured to calculate a displacement between (i) the measured line or the divided approximate curve and (ii) the overall approximate curve in the meridian direction for each divided region in that state.
5. The eye refractive power measurement apparatus according to claim 1 , wherein
the calculator is further configured to calculate a displacement between a center of an ellipse obtained by performing elliptic approximate processing on the entire ring-shaped image, and a center of an ellipse obtained by the divided approximate curve.
6. An error detection apparatus for extracting, as a ring image, reflected light from an examinee's eye and detecting an error region on the examinee's eye, based on the ring image,
the error detection apparatus comprising:
a calculator configured to
acquire a measured line corresponding to an edge of the ring image,
divide the measured line into predetermined divided regions,
perform approximate processing on the measured line to calculate an approximate curve,
calculate a displacement between the measured line and the approximate curve for each divided region of the ring image, and
detect an error state in each divided region, based on the displacement.
7. An error detection method for extracting, as a ring image, reflected light from an examinee's eye and detecting an error region on the examinee's eye, based on the ring image,
the error detection method comprising the steps of:
acquiring a measured line corresponding to an edge of the ring image;
dividing the measured line into predetermined divided regions;
performing approximate processing on the measured line to calculate an approximate curve;
calculating a displacement between the measured line and the approximate curve for each divided region of the ring image; and
detecting an error state in each divided region, based on the displacement.
8. The eye refractive power measurement apparatus according to claim 1 , wherein the calculator is configured to angularly divide the ring-shaped image, with respect to a circumferential direction of the ring-shaped image, into the divided regions.
9. The eye refractive power measurement apparatus according to claim 8 , wherein the divided regions extend over equal angle ranges with respect to a center of the ring-shaped image.
10. The error detection apparatus according to claim 6 , wherein the calculator is configured to angularly divide the measured line, with respect to a circumferential direction of the ring image, into the divided regions.
11. The error detection apparatus according to claim 10 , wherein the divided regions extend over equal angle ranges with respect to a center of the ring image.
12. The error detection method according to claim 7 , wherein said dividing comprises angularly dividing the measured line, with respect to a circumferential direction of the ring image, into the divided regions.
13. The error detection method according to claim 12 , wherein the divided regions extend over equal angle ranges with respect to a center of the ring image.