Fundus imaging apparatus, method of controlling fundus imaging apparatus, and storage medium

Abstract

A fundus imaging apparatus comprising: position detection means for detecting a position of a pupil of an eye to be examined; wavefront detection means for detecting a wavefront of return light from the eye irradiated with light through an illumination optical system; correction means for correcting an aberration based on the detected wavefront; and determination means for determining a correction effective region of the correction means based on the detected position.

Description

TECHNICAL FIELD[0001]The present invention relates to a fundus imaging apparatus, a method of controlling the fundus imaging apparatus, and a storage medium and, more particularly, to a fundus imaging apparatus having an adaptive optics function, a method of controlling the fundus imaging apparatus, and a storage medium.BACKGROUND ART[0002]As fundus imaging apparatuses designed to observe and capture two-dimensional front images and tomographic images of the retina of the eye to be examined, fundus camera, scanning laser ophthalmoscope (SLO), optical coherence tomography (OCT), and the like are well known and have long been in practical use.[0003]These apparatuses are designed to obtain a retinal image by irradiating the retina as an imaging target with illumination light and forming return light from the retina into an image on a light-receiving element or to obtain a tomographic image by interference with reference light. Light having a near-infrared wavelength is often used as th...

AI Technical Summary

Benefits of technology

The present invention provides a technique of performing aberration correction in fundus imaging based on the positional shift of the eye being examined. This includes position detection of the pupil, wavefront detection of the return light from the eye, and correction of aberration using a determined correction effective region based on the detected position. This technique helps to improve the image quality of fundus imaging by reducing the effect of aberration and positional shift.

Problems solved by technology

This causes high-order aberrations on the wavefront of light transmitted through these organs.

For this reason, even if illumination light having a large light beam diameter is made to strike the retina, it is not possible to focus a spot on the retina at a desired diameter.

One major factor that makes it difficult to obtain stable images in a fundus imaging apparatus using adaptive optics is that the position of the pupil (iris) of the eye to be examined varies.

This is caused because the head of an object to be examined moves back and forth and left and right, and the eyeball inevitably rotates in various ways in spite of the attempt to fix the line of sight by making the object observe a fixation lamp.

Using a bite bar can suppress variations in the position of the head, but will impose a burden on the object.

The first problem is that when the position of the head, that is, the position of the pupil of the eye to be examined, varies in a direction perpendicular to the optical axis of an eyepiece optical system, return light (reflected / backscattered light) from the retina also shifts on an aberration correction device placed at a position optically conjugate with the pupil.

At this time, when wavefront feedback correction is performed in an open loop manner, since return light strikes the aberration correction device while shifting relative to the aberration correction value formed on the aberration correction device, the aberration correction residue increases, resulting in a deterioration in image quality, for example, a decrease in brightness or resolution.

In a closed-loop real-time aberration correction system as well, expressing this shift component will lead to a deterioration in the reproducibility of a curved surface unless using functions up to high-order functions.

Limiting the number of orders for a reduction in calculation time makes it impossible to perform ideal aberration correction.

This becomes a cause of the above deterioration in image quality.

Second, image obtaining illumination light is vignetted (limited).

In addition, the amount of illumination light reaching the retina is lost by 10% to 20% due to vignetting.

Third, although the pupil of the eye to be examined, an aberration correction device, and a wavefront detector are arranged at optically conjugate positions with an afocal optical system, if return light falls outside the effective diameter of the optical system, even partly, the consistency of the wavefront at each position deteriorates.

As a consequence, the feedback accuracy of aberration correction deteriorates.

This leads to an increase in time for convergence or to divergence instead of convergence.

However, this arrangement can solve the first problem but cannot solve the second problem.

In addition, since the aberration correction device generally has a volume of several cm3 to 10 cm3, the mechanical stage to be used inevitably has a large size, resulting in increases in the size and cost of the system.

Furthermore, the vibrations of the stage may affect image quality.

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