Claims:We claim:
1. A fundus imaging apparatus (100), said apparatus (100) comprising an optical unit (106) comprising plurality of lenses, a display unit (102), said optical unit (106) is driven by an actuator (108), characterized in that:
a controller (104) adapted to:
? receive input of refractive power of an eye (110) of a subject,
? determine a diopter correction value based on said refractive power, and
? send a drive signal to said actuator (108) for adjusting said optical unit (106) based on said diopter correction value to focus said fundus.
2. The apparatus (100) as claimed in claim 1, wherein said controller (104) receives said refractive power of the eye (110) from at least one means selected from a group comprising a manual input, an input from a storage member (112), and an input from a refractive power measuring device.
3. The apparatus (100) as claimed in claim 1, wherein said diopter correction value is indicated as a suggestion to an operator on said display unit (102), and said optical unit (106) is adjusted corresponding to said computed diopter correction value only upon a confirmation from said operator to said suggestion.
4. The apparatus (100) as claimed in claim 1, allows manual adjustment of said optical unit (106) after said optical unit (106) has already adjusted corresponding to said diopter correction value.
5. The apparatus (100) as claimed in claim 1, wherein in addition to said refractive power of the eye (110), at least one additional parameter in relation with said diopter correction value is selected from a group comprising a duration of a disease affecting the eye (110), a demography of said subject, a clinical history of said subject, a size of the pupil, a visual field, a visual acuity, a subject’s spectacle power and the like.
6. The apparatus (100) as claimed in claim 1, wherein said controller (104) is further adapted to learn from at least one determined diopter correction value to improve determination of a new diopter correction value.
7. A method of operating a fundus imaging apparatus (100) said method comprises the steps of:
? receiving refractive power of the eye (110) of a subject;
? determining a diopter correction value based on said refractive power, and
? driving an actuator (108) for adjusting an optical unit (106) based on said diopter correction value to focus said fundus.

8. The method as claimed in claim 7, wherein said refractive power of the eye (110) is received from at least one means selected from a group comprising a manual input, an input from a storage member (112), and an input from a refractive error measuring device.
9. The method as claimed in claim 7, wherein said diopter correction value is indicated as a suggestion to an operator on said display unit (102), and said optical unit (106) is adjusted corresponding to said computed diopter correction value only upon confirmation from said operator to said suggestion.
10. The method as claimed in claim 7, wherein a manual adjustment of said optical unit (106) is allowed after said optical unit (106) has already adjusted corresponding to said diopter correction value.
, Description:Field of the invention:
[0001] The present disclosure relates to a fundus imaging apparatus, and specifically relates to an improved method for operating the fundus imaging apparatus.
Background of the invention:
[0002] According to a patent literature US7377642, a fundus camera which includes an illumination optical system for projecting an illumination light to a fundus of a subject's eye: a photographing device for photographing the fundus; and light-receiving optical systems, which include a focus lens disposed in a light-receiving optical path for focusing the photographing devices with respect to the fundus and diopter compensation lenses disposed for being inserted into or withdrawn from the light-receiving optical path for guiding reflected light from the fundus to the photographing devices; a controlling device for determining whether a feasible focusing range of the focus lens is surpassed; and driving devices for inserting the diopter compensation lenses into or withdrawing them from the light-receiving optical path. The controlling device controls the driving devices in a defined manner.
Brief description of the accompanying drawings:
[0003] An embodiment of the invention is described with reference to the following accompanying drawings,
[0004] Fig.1 illustrates a fundus imaging apparatus, according to an embodiment of the present disclosure, and
[0005] Fig. 2 illustrates a method of operating the fundus imaging apparatus, according to an embodiment of the present disclosure.
Detailed description of the embodiments:
[0006] Fig.1 illustrates a fundus imaging apparatus, according to an embodiment of the present disclosure. The fundus imaging apparatus 100 (also referred to as a fundus camera) comprises an optical unit 106 comprising plurality of lenses, and a display unit 102. The optical unit 106 is driven by an actuator 108 wherein a controller 104 is adapted to receive input of refractive power of an eye 110 of a subject, compute a diopter correction value based on the refractive power, and send a drive signal to the actuator 108 for adjusting the optical unit 106 based on the diopter correction value to focus the fundus of the eye 110. The subject refers to a patient whose eyes need to be diagnosed/ tested.

[0007] The fundus imaging apparatus 100 also comprises other parts conventionally required in a fundus camera which are not mentioned in this disclosure such as illumination unit, image capturing unit, alignment unit and the like as these are known and obvious for a person skilled in the art. The actuator 108 is controlled or driven by the controller 104 to adjust the focus of the fundus before capturing the image. The actuator 108 adjusts/ moves the plurality of lenses to obtain a desired focus of the fundus. The controller 104 functions as a focus adjusting unit or a separate focus adjusting unit is provided to control the optical unit 106.

[0008] The controller 104 receives the refractive power of the eye 110 from at least one means selected from a group comprising a manual input, an input from a storage member 112, and an input from a refractive power measuring device. The manual input corresponds to determining the refractive power of the subject’s eye 110 by an operator, a user, a physician, an ophthalmologist, or an examiner. The operator uses a digital or a non-digital optometer, a phoropter, a refractometer or other refractive power measuring device/instrument to determine the refractive power of the eye 110. Alternatively, the subject provides the refractive error based on an earlier examination result. There exist still another alternative wherein, if the subject is wearing spectacles due to vision correction, the spectacles of the subject is analyzed by the operator to obtain the refractive power of the eye 110.

[0009] The input from a storage member 112 corresponds to retrieving the refractive power of the subject’s eye 110 from a memory element, a database, or cloud storage, a network and the like. The storage member 112 is connectable with the controller 104 through wireless or wired means as known in the art. The input from the storage member 112 is used only if the refractive power of the eye 110 for the subject has already been measured and saved earlier.

[00010] In accordance to an embodiment of the present disclosure, a refractive power measuring device is coupled with the apparatus 100 in communication with the controller 104. The refractive power measuring device automatically determines the refractive power of the subject’s eye 110 when placed in alignment with the eye 110. The refractive power measuring device comprises but not limited to an automated optometer, phoropter, refractometer which determines the refractive error of the subject’s eye 110 in real time. The measured refractive power is then stored in a storage member 112 and used for examination either instantly or later.

[00011] Before driving the actuator 108, the diopter correction value is indicated as a suggestion to an operator on the display unit 102. After receiving the refractive power/ error of the subject’s eye 110, the controller 104 determines/ estimates a diopter correction value. Alternatively, the controller 104 determines the diopter correction value from a look-up table stored in the memory element. The memory element is either same or different than the storage member 112.

[00012] The controller 104 then displays a computed diopter correction value through the display unit 102. Alternatively, the controller 104 indicates the operator through at least one means comprising audio, visual, light pattern, vibration and the like. The diopter correction value is provided as a suggestion to the operator. If the operator accepts/ confirms the suggestion, the controller 104 sends the drive signal to adjust the optical unit 106 as per the diopter correction value. The optical unit 106 is automatically adjusted corresponding to the computed diopter correction value based on an input from the operator. Otherwise, the operator manually adjusts the optical unit 106 to focus the fundus.

[00013] According to an embodiment of the present disclosure, the apparatus 100 comprises three modes of operation which are a manual mode, a semi-automatic mode, and an automatic mode. The apparatus 100 is configurable to operate as any one mode by default. The present disclosure describes the semi-automatic mode. In the semi-automatic mode, the apparatus 100 allows focusing the fundus based on the suggestion as discussed above. If the operator is not satisfied with the focus achieved by selecting the suggested diopter correction, the apparatus 100 allows further fine tuning of the focus (fundus diopter correction) manually. The manual mode and the automatic mode are operated as known in the art. Also, the operator is allowed to switch between three modes at any point of time. Example: the apparatus 100 allows to be switched to manual mode while in middle of automatic mode. Further, the controller 104 allows manual adjustment of the optical unit 106 even after the optical unit 106 has already adjusted corresponding to the suggested diopter correction value.

[00014] According to an embodiment of the present disclosure, in addition to the refractive power of the eye 110, at least one additional parameter in relation with the diopter correction value is selected from a group comprising a duration of a disease affecting the eye 110, a demography of said subject, a clinical history of said subject, a size of the pupil, a visual field, a visual acuity, a subject’s spectacle power, and the like. The refractive power comprises a spherical refractive errors and cylindrical refractive errors. The at least one parameter improves the determination/ estimation/ prediction of the diopter correction value to focus the fundus in order to capture clear fundus image.

[00015] According to an embodiment of the present disclosure, the controller 104 is further adapted to learn from at least one determined diopter correction values to improve determination of new diopter correction value. The controller 104 comprises a learning module (not shown in the Fig. 1). The learning module determines a co-relation of diopter correction value with a refractive power of the eye 110 and/or with at least one parameter. As the number of past observations, results and the like increases, the learning module keeps on updating the co-relation. The learning module assists the controller 104 in estimating a very accurate diopter correction value to focus the fundus. The controller 104 comprises the learning module, or a separate learning module unit is provided as an attachment to the apparatus 100.

[00016] The apparatus 100 comprises an interface through which the operator provides input to the controller 104. An output is also obtained either through the interface or a separate output unit is attached to provide the output. The interface is at least one selected from a group comprising a touch screen based display unit 102, a keypad, a slider based control and a wheel based control. The keypad is an alphanumeric, numeric, alphabetic or dedicated buttons to operate the apparatus 100. The slider based or wheel based control buttons may be used for focus adjustment.

[00017] Fig. 2 illustrates a method of operating the fundus imaging apparatus, according to an embodiment of the present disclosure. The method comprises the step 202 receiving refractive power of the eye 110 of a subject. The refractive power of the subject’s eye 110 is received from at least one means selected from a group comprising a manual input, an input from a storage member 112, and an input from refractive error measuring device. The step 204 comprises determining a diopter correction value based on the refractive power of the eye 110. A controller 104 of the fundus imaging apparatus 100 determines the approximate/ optimal diopter correction value based on the received refractive power of the subject’s eye 110. Optionally, in addition to the refractive power of the eye 110, at least one additional parameter in relation with the diopter correction value is allowed to be selected from a group comprising a duration of a disease affecting the eye 110, a demography of said subject, a clinical history of said subject, a size of the pupil, a subject’s spectacle power, and the like. The additional parameter assists the operator in achieving a very accurate focus of the fundus. The step 206 comprises driving an actuator 108 of the apparatus 100 for adjusting an optical unit 106 based on the determined diopter correction value to focus the fundus. Before driving the actuator 108, the controller 104 indicates the operator an availability of fundus diopter correction value. After receiving the confirmation from the operator, the optical unit 106 is adjusted automatically corresponding to the computed diopter correction value. The operator manually provides an input to the controller 104 through the interface to automatically focus as per the suggestion.
[00018] Once the controller 104 has adjusted the optical unit 106, the operator is still allowed to fine tune or adjust the focus (diopter correction) of the optical unit 106 to obtain a clear image. After a desired focus is achieved/ set, the fundus image is captured/ acquired.

[00019] According to an embodiment of the present disclosure, the apparatus 100 provides utilities for examining patients with refractive error (ametropia). A dioptre correction range but not limited to from -20 di. to +20 di is provided. The range of refractive power and the corresponding diopter power correction is calibrated and maintained in a lookup table. Alternatively, the diopter power correction is computed in real time. An automatic diopter correction setting based on the patient’s refractive power/ error is performed. The present disclosure provides automatic sensing of the refractive power of the eye 110 in the manual mode in an eye care fundus camera (mydriatic or non-mydriatic). The apparatus 100 acquires/ captures the image of eye 110 after optimal fundus diopter correction for getting a good quality image. The present disclosure is applicable to handheld, tabletop or other types of fundus imaging apparatuses 100. The present disclosure avoids/eliminates or improves the cumbersome or erroneous manual mode diopter correction before acquiring the fundus image. The diopter correction is adjusted to the approximate correct level based on the refractive power inputs leading to good quality images. The apparatus 100 helps non-specialists and general physicians and also paramedical workers using it in camps. The apparatus 100 provides manual intervention or override to an automatic mode.

[00020] Further, the learning module assists the apparatus 100 in performing smart diagnosis. The learning module is an adaptive unit with intelligence which improves over time. The apparatus 100 not only considers refractive power of the eye 110, but also considers other at least one attribute of the eye which influences fundus diopter correction. A robust estimation is provided by the apparatus 100.

[00021] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.