Ophthalmic Method and Apparatus for Noninvasive Diagnosis and Quantitative Assessment of Cataract Development

Abstract

An optoelectronic apparatus and method is provided. The application of which provides a quantitative index of cataract opacity in the human eye to help the clinical practitioner screen patients for referral for cataract lens replacement surgery. The invention includes at least one adjustable intensity optical reference light source selected from the group consisting of a green light source and a red-light source. The invention also includes at least one fixed intensity cataract absorption light source, selected from the group consisting of a blue light source, an indigo light source, and a violet light source.

Claims

1. An ophthalmic apparatus for noninvasive diagnosis and quantitative assessment of cataract development, the apparatus comprising: at least one optical reference light source, wherein the at least one optical reference light source comprises an adjustable intensity light source, and wherein the at least one optical reference light source is selected from the group consisting of a green light source and a red-light source; and at least one optical test light source, wherein the at least one optical test light source comprises a predetermined intensity light source, and wherein the at least one test light source is selected from the group consisting of a blue light source, an indigo light source, and a violet light source.

2. The apparatus as in claim 1 further comprising at least one linear neutral density filter for attenuating the at least one optical reference light source.

3. The apparatus as in claim 1 further comprising at least one rotary polarization filter for attenuating the at least one reference light source.

4. The apparatus as in claim 1 further comprises: wherein the adjustable intensity light source comprises a first laser light source; and wherein the predetermined light source comprises a second laser light source.

5. The apparatus as in claim 1 further comprises: wherein the adjustable intensity light source comprises a first LED light source; and wherein the predetermined light source comprises a second LED source.

6. The apparatus as in claim 1 further comprises an index of opacity calculator and display.

7. A method for noninvasive diagnosis and quantitative assessment of cataract development, the method comprising: providing a cataract testing device; calibrating the cataract testing device, wherein calibrating the cataract testing device comprises: providing a cataract absorption light (CAL) source at a first preset intensity (CALI); providing a reference light (RL) source at a second preset intensity RLI greater than the first preset intensity; observing RLI and CALI simultaneously via a cataract free lens; and decreasing RLI in predetermined calibration steps (CS) to substantially equal CALI.

8. The method as in claim 7 wherein the CAL source is selected from the group consisting of a blue light source, an indigo light source, and a violet light source.

9. The method as in claim 7 wherein the RL source is selected from the group consisting of a green light source, and a red-light source.

10. The method as in claim 7 wherein decreasing RLI in predetermined calibration steps further comprises decreasing RLI with at least one shift in position of at least one first linear neutral density filter.

11. The method as in claim 7 wherein decreasing RLI in predetermined calibration steps further comprises decreasing RLI with at least one shift in position of at least one rotary polarization filter.

12. The method as in claim 7 further comprising: providing the reference light (RL) at the second preset intensity RLI greater than the first preset intensity; observing RLI and CALI simultaneously via a cataract lens; decreasing RLI in predetermined absorption steps (AS) to substantially equal CALI; and calculating a cataract index of opacity O=ASCS.

13. The method as in claim 12 further comprising observing the CAL within random colored dots.

14. The method as in claim 13 further comprising saving the index of opacity 0 in a medical health record.

15. A method for noninvasive diagnosis and quantitative assessment of cataract development, the method comprising: providing a cataract testing device; calibrating the cataract testing device, wherein calibrating the cataract testing device comprises: providing a cataract absorption light (CAL) source at a first preset intensity (CALI), wherein the CAL source is selected from the group consisting of a blue light source, an indigo light source, and a violet light source; providing a reference light (RL) source at a second preset intensity RLI greater than the first preset intensity, wherein the RL source is selected from the group consisting of a green light source, and a red-light source; observing RLI and CALI simultaneously via a cataract free lens; and decreasing RLI in predetermined calibration steps (CS) to substantially equal CALI, wherein decreasing RLI in predetermined calibration steps further comprises decreasing RLI with a least one filter selected from the group consisting of a linear neutral density filter and a rotary polarization filter.

16. The method as in claim 15 further comprising providing the reference light (RL) at the second preset intensity RLI greater than the first preset intensity; observing RLI and CALI simultaneously via a cataract lens; decreasing RLI in predetermined absorption steps (AS) to substantially equal CALI; calculating a cataract index of opacity O=ASCS; and saving the cataract index of opacity 0 in a medical health record

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0027] FIG. 1 is a flow chart for one method of detecting cataracts in accordance with the invention described herein;

[0028] FIG. 2 is an illustration of a system for employing the method shown in FIG. 1;

[0029] FIG. 2A is an illustration of an alternate system for attenuating light in the system shown in FIG. 2;

[0030] FIG. 3 is an illustration of an alternate system for employing the method shown in FIG. 1;

[0031] FIG. 3A is an illustration of a system for generating a reference light and a cataract absorption light (CAL) in the system shown in FIG. 3; and

[0032] FIG. 4 is a system flow chart for one method of detecting cataracts and color blindness in a mobile device in accordance with the invention shown in FIG. 1.

DETAILED DESCRIPTION

[0033] The following brief definition of terms shall apply throughout the application:

[0034] The term comprising means including but not limited to, and should be interpreted in the manner it is typically used in the patent context;

[0035] The phrases in one embodiment, according to one embodiment, and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present invention, and may be included in more than one embodiment of the present invention (importantly, such phrases do not necessarily refer to the same embodiment);

[0036] If the specification describes something as exemplary or an example, it should be understood that refers to a non-exclusive example; and

[0037] If the specification states a component or feature may, can, could, should, preferably, possibly, typically, optionally, for example, or might (or other such language) be included or have a characteristic, that particular component or feature is not required to be included or to have the characteristic.

[0038] Referring to FIG. 1 there is shown a flow chart of one method 10 for implementing features of the present invention. Steps 11-18 calibrate the invention to minimize differences in the perceived intensity of green light (490-570 nm) or red light (620 nm-780 nm) compared with the cataract absorption light intensity (CALI) that may be apparent with a cataract free lens. It will be understood that the CAL may be any suitable light, such as, for example, a blue light (i.e., 440 nm-490 nm, or a violet light (i.e., 400 nm-420 nm), or an indigo light (i.e., 420 nm-440 nm). The perceived differences or variances may be due to different factors such as differences in intrinsic light intensity related to power output variances, power degradation, or differences in transmissibility (T) of light through a clear lens.

[0039] Still referring to FIG. 1, A green light (GL) source is set to its maximum intensity 12. It will be understood that a red light (RL) source may be used in place of GL. A cataract free subject eye compares 13 the GL intensity (GLI) against the intensity of the CAL. If the GLI is not greater 15 than the CALI, and the GLI has been set to maximum 12, then the CALI is decreased 14 until the GLI is greater than CALI 15. It will be understood that throughout the patient test, the CALI is held as the reference light and not adjusted further.

[0040] Step 13A and step 16 compares the GLI to the CALI. If the intensities are approximately equal then the patent test 19 is started. If the intensities are not approximately equal the GLI is decreased by one step. The resulting fractional change in transmittance of GLI is measured relative to its initial setting; that is, the extent to which the intensity of the green light is reduced in order to match the perceived intensity of the blue light. The OD or T of the corresponding filter(s) steps establishes the standard (null point) against which further changes in perceived intensity of the blue light is measured.

[0041] Still referring to FIG. 1, it will be understood that decreasing GLI by one step 17 may be decreasing GLI by any suitable measure. (See, for example, FIG. 2, where the light intensities may be reduced by using a linear graduated neutral density filter 22.) The transmittance range of the filter is, approximately, 100% at one end of the filter, i.e., step 0, to 0% transmittance at the other end of the filter, step x. The transmittance graduation steps of the filter from step 0 to step x may be any suitable number of graduating transmittance steps. For example, the filter graduation steps may be 21 steps (from step 0 to step 20), where each step corresponds to a 5% of transmittance blocking such that step 0 corresponds to 100% transmittance (no blocking), step 10 corresponds to 50% transmittance blocking, and step 20 corresponds to 0% transmittance (light is fully blocked). It will also be understood that light intensity may be reduced by with rotating filters (see. FIG. 2A), or electronic control (see FIG. 3).

[0042] Still referring to FIG. 1, once the GLI has been calibrated the patient test starts 19. The GL is reset to its maximum 110 and the cataract subject eye compares 111 the GL and CAL intensities. If the GLI is approximately equal to the CALI 112, then the cataract index of opacity O is calculated 115 as the Absorption Step Counter (ASC)the Calibration Step Counter (CSC).

[0043] Still referring to FIG. 1, if the GLI is not substantially equal to CALI then the GLI is decreased 113, as described earlier in the calibration steps. The ASC is incremented by one and the patient again compares 111 the GLI and CALI until the GLI is substantially equal 112. When the GLI substantially equals the CALI the cataract index of opacity (O) is calculated 115.

[0044] For example, using a blue CAL for one test subject, two steps (0 to 2) of the GLI filter was required to reduce the GLI to match CALI subject's healthy eye. Seven steps (0 to 7) were required to reduce the GLI to match the CALI in the cataract eye. Similarly, four steps (0 to 4) of the GLI filter were required to reduce the GLI to match a violet CALI in the subject's healthy eye, and 10 steps (0 to 10) in the cataract eye, i.e., consistent with the wave-length dependent transmissibility of light through a cataract lens.

[0045] The difference in graduated steps is denoted as an index of opacity, O, where Oblue is determined by ASC-CSC 115 using blue light CAL or Oviolet using violet light CAL. In the example, the index of opacity is Oblue is 5 (=72) and Oviolet is 6 (=104), indicating an advanced cataract. Gradations in opacity index may be any suitable gradation, limited by the gradation and range of the neutral density filter and ability of the subject to perceive light intensity differences.

[0046] In many cases the patient does not have a (control) healthy eye which serves as a within-patient standard by which the opacity of a cataract, Oblue and Oviolet, can be calculated as shown in FIG. 1. Thus, in many patients, the steps required to reduce the GLI to match the CALI as in a healthy eye, is determined by using the average values from many system measurements conducted by subjects without cataracts.

[0047] For example, using the prototype system shown in FIG. 2A, a subject with cataracts required 5 steps (0 to 5) of the GLI filter (v.2, FIG. 2A) to reduce the GLI to match that of the blue CALI in one eye, and 5 steps (0 to 5) to match the blue CALI in the other eye. Using a violet CAL, six steps (0 to 6) were required to reduce the GLI to match that of the violet CALI light in both the first and second eye, consistent with the wave-length dependent transmissibility of light through a cataract lens. In this example, the reference GLI standard for the system used to calculate 0 was the average number of steps required to reduce the GLI to match that of the blue CALI (2 steps) or violet CALI (3 steps) by three cataract free subjects. Thus, Oblue is 3 (=52) and Oviolet were 3 (=63), indicating cataracts, but, not as pronounced as in the first example.

[0048] Referring also to FIG. 2 there is shown one system for employing the method shown in FIG. 1. Light sources 23-26 may be any suitable combination of reference light sources, e.g., a red or green light source, and any suitable combination of CAL. For example, in one application (i), a green (or red) laser is aligned alongside a blue laser. In a more complex application (ii), a green (or red) laser is aligned alongside both a blue and a violet laser. In the most complex application iii), all four lasers are aligned side-by-side. Light 23A, 24A, 25A, and 26A emitted by light sources 23-26 is intensity attenuated 23B, 24B, 25B, 26B by linear graduated neutral density filters 22, discussed above.

[0049] The intensity of the light sources 23-26 is attenuated by a graduated neutral density filter 22, allowing optical density (OD) or transmittance (T) to be altered. In one embodiment, the filters 22 may be constructed of plastic (as in a plastic film strip) or glass (as in a rotating glass filtersee FIG. 2A). In another embodiment, the filters may be constructed of liquid crystals, where light is altered electronically. Using this system, for example, the index of opacity is Oblue is 5 (=72) and Oviolet is 6 (=104), indicating an advanced cataract.

[0050] Referring also to FIG. 2A there is shown an alternate system for employing the method shown in FIG. 1. Light source 27 emits CAL. Reference light source 28 emits light 28A which is intensity attenuated by rotary filter 222 to transmit attenuated intensity light 28B.

[0051] Referring also to FIG. 3 and FIG. 3A there is shown another system 30 embodiment for employing the method shown in FIG. 1. System 30 employs light emitting diodes (LEDs) 37, 38. Light from an LED is nearly monochromatic (narrow bandwidth of light), and is available in red, green, blue, violet, pink, yellow/orange, and white. In alternate embodiments, the transparent glass can be colorized, or pigmented, such that white light from LEDs 37, 38, entering the colorized transparent glass 36 is emitted as blue CAL 34 and GLI 33 (or any suitable colored CAL such as violet or indigo, and any suitable colored reference light such as red light). Light divider 39 separates the LEDs 37, 38. The patient views light from the colored (or white) LEDs 37, 38, transmitted through a transparent glass 36 and adjusts the intensities as described in FIG. 1. System 30 includes an optical index O calculator and display 35.

[0052] The use of LEDs 37, 38 allows for versatile presentation of lights of different wavelengths. For example, LEDs of many colors can be activated and displayed in various combinations of reference light (e.g., GL) and CAL.

[0053] Referring also to FIG. 4 there is shown a flow chart for one method 40 of detecting cataracts and color blindness in a mobile device in accordance with the method shown in FIG. 1. Device 416 may be any suitable device such as a tablet, cell phone, or other mobile device. Step 49 presets test color, e.g., the blue light CAL 41 to a preset intensity. The user selects 45 a test color 41. The test color or CAL is displayed as a number or letter 41 within random colored dots 41A. If the patient cannot see the number or letter 41 the patient may be color blind to that color and selects another test color.

[0054] The patient or user selects 46 a reference color 42, e.g., a green light GL. The patient blocks the eye not being tested 47 and adjusts 48 intensity 42A until the intensity of the reference color 42 substantially matches 410 the intensity of the test color 41. If the reference color intensity is maximum 411 and the patient or user has not perceived the intensities of the reference color and test color as substantially equal then the patient may be tested 413 for color blindness of the reference color and selects another reference color 412.

[0055] Still referring to FIG. 4, once the patient perceives equal intensities of the reference color 42 and the test color 41 the test data is captured 414 and the optical index O is calculated as described earlier. The test data may be stored for later retrieval and analysis in a local medical record 415 or in a network or cloud storage 44.

[0056] It will be appreciated that an important feature of the invention discussed herein is the means (whether mechanically or electronically) to modulate the intensity of light from each light source. As discussed above, cataracts absorb blue (and to an even greater extent) violet light more than a cataract-replacement lens or a cataract-free lens, and the method relies on the subject to adjust the intensity of light from the green or red-light source to match that of the blue or violet light source. The difference in intensity (in OD units or other graduated scales) is the measure, or index, of relative opacity of the cataract compared with a clear lens.

[0057] In one test using the prototype system shown in FIGS. 3 and 3A, (using green and blue LEDs), 10 subjects (ages 23-82), where the intensity of the green LED used as the reference light was sequentially altered before each cataract test in which the intensity of the blue test LED was varied. The data was acquired sequentially from lowest to highest intensity with the same relative green intensities for each subject. At the lowest value of the green reference LED, Oblue averaged 1.40 for subjects >50 years and 0.04 for subjects <50 years, given a mean reference standard value obtained from two subjects with artificial lens. At the highest value of the green reference LED, Oblue averaged 1.8 for subjects >50 years and 0.02 for subjects <50 years, given the same mean reference standard value (two subjects with artificial lens). The differences appear to be most significant at the brighter readings,

[0058] It will be appreciated that criteria derived from the invention discussed herein may be used for establishing a referral for CLRS. For example, in the system shown in FIG. 2 any eye with an Oblue above 3.0 and an Oviolet above 4.0 may be classified as indicating CLRS and require referral to a specialist. Values below these thresholds but above 2.0 may require retesting every year to track the cataract development, given the patient's baseline results. Similarly, the cataract measuring systems shown in FIG. 3 and FIG. 4 may be used to develop cataract baselines unique to the measuring system.

[0059] It should be understood that the foregoing description is only illustrative of the invention. Thus, various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims.