Non-mydriatic ultrawide-field retinal imaging

Abstract

Disclosed are non-mydriatic UWF retinal imaging laser scanners capable of comprehensive imaging the entire retina with lightweight, ergonomic, and cost-effective formfactor. The scanners include an ultrawide field of view lens systems (eyepiece and optical relay), interchangeable rigid contact lens, and all-fiber polarization rejection design. Also disclosed is an augmented reality spatial display.

Description

NON-MYDRIATIC ULTRAWIDE-FIELD RETINAL IMAGINGACKNOWLEDGEMENT OF GOVERNMENT SUPPORT

[0001] This invention was made with government support under R01 HD 107494 awarded by the National Institutes of Health. The government has certain rights in the invention.RELATED APPLICATION

[0002] This application claims priority benefit of U.S. Provisional Patent Application No. 63 / 625,953 filed January 27, 2024, which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0003] This disclosure relates generally to optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) and, more particularly, to ultrawide field (UWF) SLOs.BACKGROUND INFORMATION

[0004] Ophthalmology has witnessed tremendous strides in technology, particularly in the field of retinal imaging. The scanning laser ophthalmoscope (SLO), developed in the early 1980s by Webb, Hughes, and Pomerantzeff, represents a significant milestone in this journey [1], The SLO is a diagnostic instrument that offers high-resolution, non-invasive, and in vivo imaging of the retina. This makes it a valuable tool for ophthalmologists in the diagnosis and management of various eye conditions. The SLO scans the retina sequentially instead of the simultaneous flood illumination found in traditional retina cameras. The SLO operates by employing a narrow beam of laser light that scans across the retina in a raster pattern, producing a series of point illuminations. The reflected light from each point is detected and processed to generate a two-dimensional image of the retina.

[0005] The main advantage of the SLO over traditional fundus photography lies in its ability to reject out of focus scattered light with a confocal gating [2], This leads to higher resolution images that are less impacted by cataracts and other media opacities, providing more precise and detailed information about the retina. SLO has wide-ranging applications in ophthalmology, from diagnosing conditions such as age-related macular degeneration, diabetic retinopathy, and glaucoma, to monitoring disease progression and response to treatment [3],

[0006] As SLO technology matured, efforts have been made to expand the field of view (FOV) of these devices, leading to the development of wide field and ultrawide field (UWF) SLO. Traditional SLOs offer a FOV of around 30-40 degrees. In contrast, wide field SLOs provide a FOV of around 90-100 degrees, and UWF-SLOs, such as those developed by Optos pic, deliver a field of view of up to 200 degrees (measured from the center of the eye globe), or approximately 82% of the retina, in a single image [4], The ability to capture such a broad field in a single scan reduces the need for image stitching, thus offering time efficiency in clinical and research settings. Studies comparing UWF-SLO and traditional fundus imaging have demonstrated superior peripheral retinal visualization with UWF-SLO, which is beneficial for the diagnosis and management of peripheral retinal pathologies such as retinal tears, retinal detachment, and peripheral retinal degeneration [5], Furthermore, UWF imaging has demonstrated advantages in managing patients with diabetic retinopathy by revealing more extensive disease than conventional imaging [6], Additionally, some of the more recent research has centered on the combination of UWF imaging with angiography, called UWF angiography. This technology has enabled the visualization of peripheral retinal vascular changes not previously seen with older imaging techniques. This advancement has potential implications for improved diagnosis and management of various vascular retinal diseases [7], Despite the apparent advantages of UWF-SLO, some challenges persist. Image quality in the periphery may be compromised due to the inherently curved shape of the retina and the oblique incidence of the scanning laser beams [5],

[0007] Retinal imaging in pediatric patients, particularly infants, and neonates, presents unique challenges due to patient cooperation and anatomical factors. One such example is imaging in Retinopathy of Prematurity (ROP), the most common cause of visual impairment in children worldwide. ROP is a vasoproliferative disorder affecting premature infants, characterized by abnormal vascular growth in the peripheral retina. Timely diagnosis and treatment are essential in preventing adverse outcomes such as retinal detachment and blindness. Traditionally, the gold standard for ROP screening and monitoring has been binocular indirect ophthalmoscopy (BIO). However, it requires pupil dilation and scleral depression, which can be uncomfortable for the patient and technically challenging for the examiner. Moreover, it lacks the ability to capture permanent, shareable, and comparable images of the retinal findings. The introduction of wide-field digital imaging (WFDI) systems like the RetCam has revolutionized ROP screening. It allows for the capture of wide-field images of the neonatal retina, which can be reviewed and compared over time or shared for telemedicine purposes. However, scaling this technology globally remains challenging, given the high cost of cameras. Furthermore, both the ophthalmoscopic examand widefield retina cameras, which utilize stimulating white light and necessitate pupil dilation, can cause stress to the infant, and often yield poor interobserver agreement due to a limited field of view (FOV) and / or low image contrast [8],

[0008] References:1. Webb, R. H., Hughes, G. W., & Pomerantzeff, O. (1980). Flying spot TV ophthalmoscope. Applied Optics, 19(17), 2991-97.2. Drexler, W., & Fujimoto, J. G. (2008). State-of-the-art retinal optical coherence tomography. Progress in Retinal and Eye Research, 27(1), 45-88.3. Keane, P. A., & Sadda, S. R. (2014). Imaging the retina. In Ryan's Retina (6th ed., pp. 61-100). Elsevier.4. Witmer, M. T., & Patel, S. N. (2013). Wide-field imaging of the retina. Survey of Ophthalmology, 58(2), 143-54.5. Tan, C. S., Chew, M. C., Van Hemert, J., & et al. (2013). Measuring the precise area of peripheral retinal non-perfusion using ultra-widefield imaging and its correlation with the ischaemic index. British Journal of Ophthalmology, 97(8), 1010-14.6. Silva, P. S., Cavallerano, J. D., Tolls, D., & et al. (2013). Potential efficiency benefits of nonmydriatic ultrawide field retinal imaging in an ocular telehealth diabetic retinopathy program. Diabetes Care, 36(7), 1918-20.7. Hirano, T., lesato, Y., Toriyama, Y., & Murata, T. (2016). Ultra-wide-field indocyanine green angiography for evaluation and treatment of retinal vasculitis. Journal of Ophthalmology, 2016, 5802104.8. Wu, W. C., Shih, C. P., Lien, R., & et al. (2020). Assessment of clinical risk factors for proliferative retinopathy in retinopathy of prematurity using wide-angle imaging system. Eye, 34(11), 2015-21.BRIEF SUMMARY OF THE DISCLOSURE

[0009] The UWF-SLO system’s broad imaging capabilities offer superior peripheral retinal visualization, crucial for diagnosing and managing peripheral retinal pathologies, including diabetic retinopathy. Its application extends to pediatric care, particularly for conditions like Retinopathy of Prematurity (ROP). Traditional methods such as binocular indirectophthalmoscopy (BIO) have faced limitations, paving the way for wide-field digital imaging (WFDI) systems like RetCam, which revolutionized ROP screening. However, challenges such as cost and infant discomfort hinder the widespread adoption of WFDI.

[0010] Advancements in SLO technology, including handheld and UWF versions, present promising solutions. UWF-SLOs, with their high resolution, can provide detailed visualization of peripheral vascular changes in the retina, essential for ROP evaluation, potentially reducing examination times and stress for patients and clinicians. This innovation could improve care for various blinding pediatric retinal diseases, such as retinoblastoma, retinal vascular disorders, and inherited retinal dystrophies.

[0011] Disclosed is an ergonomic, cost-effective, non-mydriatic UWF-SLO, capable of comprehensive retinal imaging. This system integrates an ultra-wide field of view lens system, interchangeable rigid contact lenses, an all-fiber polarization rejection design, and an augmented reality spatial display, addressing aberrations, distortions, and back reflections. Such a system may significantly advance care for pediatric retinal disorders.

[0012] The all-fiber polarization rejection reduces lens back reflections in the scanning laser ophthalmoscope, optimizing the system’s size and weight for handheld operation. The novel lens design, including an ultra-compact telecentric relay lens and an ultra-wide field eyepiece, facilitates a comprehensive retinal screening and accommodates small pupil sizes.

[0013] The disclosed scanning laser imaging technology allows a wider field of view and better imaging contrast than traditional fundus cameras. Near-infrared imaging is used instead of bright white light, reducing stress on infants during exams.

[0014] Interchangeable contact lenses, tailored to patient eye parameters, support non- mydriatic imaging and help prevent disease transmission. Non-mydriatic imaging eliminates the need for pharmacologic dilation, avoiding systemic complications associated with cycloplegic medications, and reducing time and costs in patient care.

[0015] Augmented reality displays enhance ergonomic handling and provide superior retinal visualization, improving the functionality of the handheld imaging system.

[0016] Further details and benefits of this technology will be outlined in the detailed description that accompanies the drawings.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0017] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

[0018] FIG. l is a block diagram of a conventional SLO system.

[0019] FIG. 2 is a block diagram of an all-fiber retinal imaging laser scanner including a selectable optical fiber imaging system and a handheld optical system.

[0020] FIG. 3 is an exploded view of the handheld optical system shown in FIG. 2.

[0021] FIG. 4 is a pictorial view of UWF OCT / OCT angiography (OCTA) ROP bedside screening in a NICU, showing a doctor holding the handheld optical system of FIG. 2 (also shown enlarged) and wearing an augmented reality spatial display.

[0022] FIG. 5 is a cross sectional view of an eyeball wearing an interchangeable gas- permeable contact lens and showing a pivot point for a scanning beam.

[0023] FIG. 6 is an optical design with ray tracing for the handheld optical system shown in FIG. 2 in accordance with one embodiment.

[0024] FIG. 7 is a scanning beam footprint diagram for the optical design of FIG. 6.

[0025] FIG. 8 are a set of pointing spread function plots for the optical design of FIG. 6.

[0026] FIG. 9 is a block diagram of a telecentric relay optical design for the optical design of FIG. 6.

[0027] FIG. 10 is a table showing lens prescriptions for the telecentric relay optical design of FIG. 9.

[0028] FIG. 11 is a block diagram of an eyepiece optical design for the optical design ofFIG. 6.

[0029] FIG. 12 is a table showing lens prescriptions for the eyepiece optical design of FIG.11.

[0030] FIG. 13 is an optical design with ray tracing for the handheld optical system shown in FIG. 2 in accordance with another embodiment.

[0031] FIG. 14 is a scanning beam footprint diagram for the optical design of FIG. 13.

[0032] FIG. 15 are a set of pointing spread function plots for the optical design of FIG. 13.DETAILED DESCRIPTION OF EMBODIMENTS

[0033] FIG. 1 illustrates a conventional design for a SLO imaging system 100 configured to produce an image of a retina 102 of an eyeball 104. In SLO imaging system 100, a significant source of image artifacts is back reflections from optical elements 106, such as lenses. These back reflections degrade the quality of the image, obscure critical diagnostic information, and complicate the interpretation of details in the images.

[0034] To prevent or reduce these back reflections, several techniques are employed. These include anti-reflective coatings (not shown), a confocal pinhole 108, and a bulk free- space optic polarizing beam splitter (PBS) 110 that assists in the rejection and differentiation of depolarized backscattered light 112 from polarized reflected light 114.

[0035] Confocal pinhole 108 is positioned at the confocal plane of SLO imaging system 100, which permits only in-focus backscattered light 112 from retina 102 to reach a detector 116, while blocking out-of-focus light, which includes most back reflections.

[0036] A near-infrared (NIR) laser source 118, equipped with a free-space linear polarizer 120, generates polarized light 122. Linear polarizer 120 acts as an optical filter, allowing passage of light 122 with a specific polarization and blocks others. PBS 110, incorporated into an optical path 124 of SLO imaging system 100, serves to segregate reflected light 114 based on its polarization state. Reflected light 114 that retains its initial polarization is transmitted, while backscattered light 112, which is depolarized or possesses a different polarization state, is reflected by PBS 110 toward detector 116. Consequently, PBS 110 separates backscattered light 112, effectively mitigating back reflections at detector 116. Precise alignment of PBS 110 is achieved using a kinematic mount (not shown), allowing for meticulous positional and angular adjustments. Likewise, linear polarizer 120 is typically mounted on a precision rotation mount to facilitate careful orientation adjustments, ensuring its axis aligns accurately with that of PBS 110 for optimal separation of polarized reflected light 114 and minimization of back reflections.

[0037] In some designs, a quarter-wave plate (QWP) 126 is situated between eyeball 104 and an adjacent lens L2. QWP 126 rotates the polarization axis by 45 degrees each time light traverses it, causing most of the scattered light from retina 102 to rotate by 90 degrees after passing through the QWP 126 twice, aligning its polarization along the slow axis. This configuration enhances the detection of light reflected from retina 102 but also significantly augments the undesirable back reflections from the cornea.

[0038] While the aforementioned techniques effectively reduce back reflections, their efficacy depends on the precise alignment and calibration of the optical components. Such alignment is vulnerable to being compromised by movement and vibration, especially in portable devices. Moreover, the integration of polarization optical components 120 and 110, confocal pinhole 108, and additional supporting optics contributes to an increase in the size and weight of the SLO imaging system 100, which is not conducive to portability.

[0039] Achieving a wide field of view retinal imaging entails the design of optics that effectively address aberrations and distortions while maintaining image quality across theentire field. The disclosed designs of practical handheld imaging systems also attempt to minimize the size and weight of these wide-field optics. Furthermore, providing uniform illumination across the entire retina without excessive light exposure is a significant challenge faced by conventional retina cameras.

[0040] Accordingly, FIG. 2 depicts a retinal imaging laser scanner 200 with features designed for balancing the aforementioned weight, size, and optical performance criteria. Retinal imaging laser scanner 200 also includes a selectable optical fiber imaging system 202 for a handheld optical system 204, while facilitating non-mydriatic and ultrawide field retinal imaging on an eyeball 206 of a non-sedated infant. Two example options for selectable optical fiber imaging system 202 that are shown in FIG. 2 include an OCT system 208 and SLO system 210, either of which may be optically coupled (using an FC / APC connector, for example) to a collimator 212 of handheld optical system 204. An example of collimator 212 is an RC02APC-P01 Protected Silver Reflective Collimator, 450 nm - 20 pm, RFL = 7 mm, FC / APC, available from Thorlabs, Inc.

[0041] SLO system 210 features an NIR single-mode fiber-coupled laser source 214 that emits a low-power laser beam (780 nm). The design aims to obviate the need for pharmacological dilation during imaging due to the laser beam’s small size on the pupil (<1.5mm). The beam is directed to an in-line fiber polarizer 216. This polarizer 216 ensures the passage of linearly polarized light, predominantly along the fast axis, while attenuating light polarized orthogonally from an unpolarized or randomly polarized light source. In-line fiber polarizer 216 thus polarizes light along one axis, which is then channeled through optical fiber 218 to a fiber polarization combiner / splitter (FPCS) 220. An example of FPCS 220 is a PFC780A Fused Fiber Polarization Combiner / Splitter, 780 ± 15 nm, FC / APC, available from Thorlabs, Inc. Another example available from Thorlabs, Inc. is a Fiber- Based Polarization Beam Combiner / Splitter, 3 PM Ports, having an in-line micro prism PBC980PM-FC.

[0042] FPCS 220 has three ports: two legs of polarization-maintaining (PM) fiber on one side of a calcite prism and a PM fiber 222 on the other side. One of the PM ports is aligned with the output polarization axis of in-line fiber polarizer 216 resulting in linearly polarized light 224 directed into handheld optical system 204 via PM fiber 222, collimator 212, and an electronically focus tunable lens 226 (see, e.g., EL-3-10 lens available from Optotune). The other PM port is coupled to optical fiber 228 for directing light to a SLO image detector 230 (detector 230 receives light, so FPCS 220 essentially functions as a splitter in this case). Return light 232, reflected from lens surfaces and maintaining its polarization along the fast axis, is redirected back to NIR single-mode fiber-coupled laser source 214 via optical fiber218 by FPCS 220. Depolarized backscattered light from the retinal pigment epithelium is split at FPCS 220, with the slow axis polarization directed to SLO image detector 230 via optical fiber 228. The single-mode and polarization-maintaining nature of FPCS 220 functions akin to a confocal pinhole, enhancing image sharpness and differentiation of retinal layers. This all-fiber approach for ophthalmic imaging circumvents the need for alignment mechanisms associated with free-space optics, facilitating the handheld system’s compactness.

[0043] OCT system 208 comprises an NIR laser source 234 and an OCT image detector 236, both fiber-coupled to an interferometer 238, which in turn is connected to a reference arm 240 and collimator 212 (using the FC / APC, mentioned above). For OCT system 208, a 2x2 fiber coupler is used, such as the 1064 nm, Single Mode Fused Fiber Optic Couplers / Taps available from Thorlabs, Inc., or TW1064R5A2A 2x2 Wideband Fiber Optic Coupler, 1064 ± 100 nm, 0.14 NA, 50:50 Split, FC / APC connectors. Depending on the system design, sometimes three sets of these couplers are coupled together, to achieve certain splitting ratios.

[0044] Processing and control circuitry 242 is depicted as communicatively coupled to SLO system 210 and can similarly interface with OCT system 208 when it is deployed. This circuitry 242 includes a data acquisition (DAQ) system controller 244, shown interfacing with SLO image detector 230 and dispatching scanning control commands to a galvanometer driver 246. This driver 246 controls an x-galvanometer scanner 248 and a y- galvanometer scanner 250, examples of which are the SATURN-1 GALVO available from ScannerMAX.

[0045] A personal computer 252 processes the imaging data. In some configurations, personal computer 252 supports a display 254 for the user, potentially via an on-probe display (FIG. 3) or an augmented reality (AR) headset (see e.g., FIG. 4). An example of display 254 is a 5.5inch Capacitive Touch AMOLED Display, 1080x 1920, HDMI, Toughened Glass Cover available from Waveshare.

[0046] Handheld optical system 204 is further detailed as comprising three subsystems. Firstly, an interchangeable set of gas-permeable contact lenses 256 is provided. Each member of the set sized for infants’ eyes at various developmental ages. Additional details are described with reference to FIG. 5.

[0047] Secondly, an ultrawide eyepiece lens system 258 is situated between y- galvanometer scanner 250 and interchangeable set of gas-permeable contact lenses 256. Ultrawide eyepiece lens system 258 has a compact, lightweight design with a short workingdistance that works together with gas-permeable contact lens. Additional details are described with reference to FIG. 6 and FIG. 11-FIG. 13.

[0048] Lastly, a telecentric optical relay lens system 260 optically conjugate x- galvanometer scanner 248 with y-galvanometer scanner 250. Typically, the two orthogonal scanners are placed 5-10 mm to each other. Because of this separation distance, the imaging beam position on the pupil (iris plane) when scanned at different angles does not overlap (i.e., is not suitable for non-mydriatic imaging), thus requires a larger pupil diameter than the imaging beam itself. But separating the two scanners with a telecentric optical relay lens system 260 allows the two scanners to be optically conjugated. In other words, it is as if both x-galvanometer scanner 248 and y-galvanometer scanner 250 are positioned on top of each other, or perfectly overlapped. Hence, the minimum pupil size is no smaller than the imaging beam size, which is about a millimeter. And in normal day light conditions, the pupil of an infant is actually much larger than the imaging beam size, which allows non- mydriatic imaging, i.e., without pupil dilation. Additional details are described with reference to FIG. 9 and FIG. 10.

[0049] In some embodiments, a QWP (not shown) can be placed between interchangeable set of gas-permeable contact lenses 256 and ultrawide eyepiece lens system 258 for use with SLO system 210. The QWP would return more light from the retina and without the QWP more light is returned from sclera and deeper in eyeball 206. The tradeoff with the QWP is it increase in corneal back reflection and retinal light at the same time.

[0050] FIG. 3 shows components of handheld optical system 204, according to one embodiment. Specifically, FIG. 3 depicts collimator 212, electronically focus tunable lens 226, x-galvanometer scanner 248, y-galvanometer scanner 250, display 254 (on-probe), interchangeable set of gas-permeable contact lenses 256, ultrawide eyepiece lens system 258, and telecentric optical relay lens system 260. One of interchangeable set of gas- permeable contact lenses 256 fit within a retaining cup 316 so that they can be pressed onto an eye.

[0051] FIG. 3 also shows a housing 302 with top enclosure 304 and a base enclosure 306 to enclose and mount the optics. Inside housing 302 is a threaded cage 308 (to attach eyepiece 258), a hypothetical beam shape 310, a ring mount 312 (for collimator 212), and another mount 314 (for electronically focus tunable lens 226).

[0052] FIG. 4 shows a doctor using handheld optical system 204 and viewing resulting images 402 of a retina of an infant 404. In this example, doctor 406 is wearing an AR headset 408 (such as Air AR glasses available from XREAL, Inc. of Santa Monica,California), which presents images 402. Images 402 are showing OCT data, in this example, since handheld optical system 204 is coupled to OCT system 208 (FIG. 2). With AR headset 408, an on-probe display is optional, which further reduces size and weight of handheld optical system 204. Handheld optical system 204 is expected to weigh 450 grams, which is over 50% lighter than previous attempts, thereby considerably improving its portability and ease of use.

[0053] In addition to the improved ergonomics, see-through augmented reality goggles provide a large spatial display and superior visualization of the OCT / OCTA images compared to a 5-inch on-probe screen, without obstructing the direct view of the patient. This facilitates obtaining quality images without extending or rescheduling imaging sessions — actions that would increase the physiological stress for patients and waste resources.

[0054] FIG. 5 shows how a lens member 502 of interchangeable set of gas-permeable contact lenses 256 (FIG. 2) fits on an anterior corneal radius (ACR) 504 coated with a gel 506. In this example, lens member 502 has a lens diameter 508 of about 80% of corneal diameter (CD) 510. The posterior surface of lens member 502 matches the corneal surface curvature, and the anterior GP lens surface power matches the overall axial eye length (AEL) 512 and eye lens power. Anterior chamber depth (ACD) 514, together with AEL 512, ACR 504, and CD 510 are specified so that a scanning beam pivot point 516 is at or near pupillary / iris plane P2 518 (optimal for both non-mydriatic and ultrawide field of view imaging), instead of at a corneal plane Pl 520 or a lens plane P3 522. The distance between the GP lens and the preceding aspherical lens is controlled to ensure that scanning beam pivot point 516 stays close to pupillary / iris plane P2 518 for non-mydriatic imaging. A significant deviation from the desired parameters, however, displaces the scanning beam pivot from pupillary / iris plane P2 518 (toward corneal plane Pl 520 and lens plane P3 522), limiting the FOV due to the constriction of the non-dilated pupil, which is about 1 mm.

[0055] Employing a contact-based approach allows maximal eye position control, reduces patient alignment time, minimizes optical aberrations and corneal reflection artifacts, and enhances image quality. Moreover, the contact-based lens design is an enabler of an FOV encompassing an entire 165° visual angle, as measured from pupillary / iris plane P2 518. This is sufficient to resolve all major blood vessels and neovascularization over the entire 165° pivot angle, as measured from pupillary / iris plane P2 518 (note that FIG. 5 is a simplified schematic, so angles are representative and not exactly 165°). This angle roughly translates to >220° if measured from a center 524 of eyeball 206. Ignoring effects of refraction within the eye, these angles roughly correspond to visual angles.

[0056] Interchangeable set of gas-permeable contact lenses 256 also addresses deficiencies in a fixed lens system. First, a fixed contact surface cannot be readily deep cleaned, which raises concerns about communicable disease transmission. This issue has increasingly been a focus of the NICU and infectious disease community, is on the radar screen of the FDA, and is handled differently by different hospital systems, some requiring deep cleansing between uses, which adds time and expense to ROP screening and can damage optical systems that are not designed for such procedures. Second, the working distance of the imaging probe cannot be adjusted to accommodate AEL 512 differences with a single, fixed contact lens, precluding non-mydriatic imaging.

[0057] Because the eyes of premature infants at birth are significantly smaller than the adult eyes and undergo rapid growth from birth until a few months of age, the following table shows how members of interchangeable set of gas-permeable contact lenses 256 are designed to match the eye parameters of infants at different gestational ages (GA), e.g., 30, 35, 40, and 50 weeks. Four rows in the table correspond to a different set of corneal rigid gas permeable lenses. Using sets of different GP lenses that match with the rapidly growing eyes of infants, controlling the lens curvature, size and the distance between the GP lens and the eyepiece group, ensures that the beam scanning pivot point is placed on pupillary / iris plane P2 518.GA AEL ACD ACR CD30 14.18 1.79 5.73 7.8135 15.82 2.12 6.49 8.7040 17.05 2.38 6.93 9.3750 18.68 2.73 7.34 10.29

[0058] FIG. 6 shows an optical design 600 for telecentric optical relay lens system 260 and ultrawide eyepiece lens system 258, according to one embodiment. Optical design 600 includes a telecentric relay optical design 900 and an eyepiece optical design 1100 which are described in further detail in connection with, respectively, FIG. 9-FIG. 10 and FIG. 11-FIG. 12.

[0059] Optical design 600 also shows ray traces 602 for beam positions under different angular scanning positions of x-galvanometer scanner 248 and y-galvanometer scanner 250.The angular scanning positions include 0° 604, X: -70° 606, X: +70° 608, Y: -70° 610, Y: +70° 612, X: -140° 614, X: +140° 616, Y: -140° 618, and Y: +140° 620.

[0060] FIG. 7 shows a scanning beam footprint diagram 700 on pupillary / iris plane P2 518. The scanning beam pivots 516 at pupillary / iris plane P2 518, well within a minimum pupillary size 702 of approximately 1 mm diameter 704.

[0061] FIG. 8 is a set of pointing spread function plots 800 corresponding to ray traces 602 of FIG. 6. These are point spread function plots at the image plane (i.e., on the retina). They are intended to be as small as possible, but their sizes are ultimately limited by diffraction (indicated by the black circle). The units in FIG. 7 are 100 pm. In this example, pointing spread function plots 800 show diffraction-limited performance of 20 pm transverse resolution with 17 mm axial eye length AEL 512. This is sufficient to resolve all major blood vessels and neovascularization over the entire 165° visual angle, discussed previously.

[0062] FIG. 9 shows an arrangement of lenses for telecentric relay optical design 900. Telecentric relay optical design 900 comprises a first doublet lens 902, and a second doublet lens 904, and a central lens group 906. First doublet lens 902 includes a biconvex lens 908 and a negative meniscus lens 910. Second doublet lens 904 includes a negative meniscus lens 912 and a biconvex lens 914. Central lens group 906 includes a positive meniscus lens 916, a biconcave lens 918, a biconcave lens 920, and a positive meniscus lens 922.

[0063] The following lens surfaces are also identified in FIG. 9: SI 924, S2 926, S3 928, S4 930, S5 932, S6 934, S7 936, S8 938, S10 940, Si l 942, S12 944, S13 946, S14 948, S15 950, S16 952, and S17 954. Table 1000 in FIG. 10 specifies example lens prescriptions for these surfaces.

[0064] FIG. 11 shows an arrangement of lenses for eyepiece optical design 1100. Eyepiece optical design 1100 comprises a biconvex lens 1102, a first doublet lens 1104 including a negative meniscus lens 1106 and a positive meniscus lens 1108, a second doublet lens 1110 including a negative meniscus lens 1112 and a negative meniscus lens 1114, a positive meniscus lens 1116, a biconvex lens 1118, a third doublet lens 1120 including a positive meniscus lens 1122 and a positive meniscus lens 1124, and a positive meniscus lens 1126.

[0065] The following lens surfaces are also identified in FIG. 11 : SI 1128, S2 1130, S3 1132, S4 1134, S5 1136, S6 1138, S7 1140, S8 1142, S9 1144, S10 1146, Si l 1148, S12 1150, S13 1152, S14 1154, S15 1156, S16 1158, S17 1160, and S18 1162. Table 1200 in FIG. 12 specifies example lens prescriptions for these surfaces.

[0066] FIG. 13 shows first example of an optical design 1300 for handheld optical system 204 (FIG. 2), according to another embodiment. Optical design 1300 includes telecentricrelay optical design 900 and an eyepiece optical design 1302 available from Volk Optical Inc. of Mentor, Ohio.

[0067] Unlike eyepiece optical design 1100, eyepiece optical design 1302 includes aspheric lenses, but also has fewer total lenses. Specifically, optical design 1300 includes a first aspheric lens 1304, a plano-concave lens 1306, a double-convex lens 1308, and two aspheric lenses 1310. The reduction in the number of lenses helps reduce weight, but has worse optical performance.

[0068] For instance, optical design 1300 also shows ray traces 1312 for beam positions under different angular scanning positions of x-galvanometer scanner 248 and y- galvanometer scanner 250. The angular scanning positions include 0° 1314, X: -70° 1316, X: +70° 1318, Y: -70° 1320, Y: +70° 1322, X: -140° 1324, X: +140° 1326, Y: -140° 1328, and Y: +140° 1330.

[0069] FIG. 14 shows a scanning beam footprint diagram 1400 on pupillary / iris plane P2 518. In UWF-SLO imaging using ultrawide FOV eyepiece optical design 1302 and telecentric relay optical design 900 — when aligned with the desired parameters for the eyeball distances shown in FIG. 5 (including ACD 514, ACR 504, and CD 510) — the scanning beam pivots 516 at pupillary / iris plane P2 518, necessitating a minimum pupillary size 702 of approximately 2 mm diameter 1402 for most angles in a beam footprint 1404.

[0070] FIG. 15 is a set of pointing spread function plots 1500 corresponding to ray traces 1312 of FIG. 13. Pointing spread function plots 1500 show diffraction-limited performance up to 70-degree scanning angle, and the PSF deteriorates quickly at larger scanning angles.

[0071] In light of this disclosure, skilled persons will appreciate that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. For example, a variant of ultrawide eyepiece lens system 258 with some adjustments to eyepiece optical design 1100 may also be used for adults, e.g., in a desktop version without interchangeable set of gas-permeable contact lenses 256. The scope of the present invention should, therefore, be determined only by claims and equivalents.

Claims

CLAIMSWhat is claimed is:

1. A handheld optical system for a retinal imaging laser scanner that enables ultrawide field retinal imaging of pediatric patients under non-mydriatic conditions, the system comprising: a housing configured to be manually positioned adjacent to an eye of a patient; first and second galvanometer scanners that are orthogonal to each other and located within the housing for scanning an imaging beam across a retina of the eye; an integrated telecentric optical relay lens system located within the housing and between the first and second galvanometer scanners for optically conjugating them; and an ultrawide eyepiece lens system for positioning proximal to the eye and configured to interface with a gas-permeable contact lens that is selectable from a set of interchangeable lenses sized based on gestational ages.

2. The handheld optical system of claim 1, in which the integrated telecentric optical relay lens system is free from aspheric lenses.

3. The handheld optical system of claim 1, in which the ultrawide eyepiece lens system includes aspheric lenses.

4. The handheld optical system of claim 1, in which the ultrawide eyepiece lens system is free from aspheric lenses.

5. The handheld optical system of claim 1, including a collimator and fiber coupler for receiving light from a selectable optical fiber imaging system.

6. The handheld optical system of claim 5, in which the selectable optical fiber imaging system is an OCT system.

7. The handheld optical system of claim 5, in which the selectable optical fiber imaging system is an SLO system.

8. A retinal imaging laser scanner including the handheld optical system of claim 1 and an interchangeable set of gas-permeable contact lenses.

9. The retinal imaging laser scanner of claim 8, further comprising a selectable optical fiber imaging system.

10. The retinal imaging laser scanner of claim 9, in which the selectable optical fiber imaging system includes an OCT system.

11. The retinal imaging laser scanner of claim 9, in which the selectable optical fiber imaging system includes an SLO system.

12. The retinal imaging laser scanner of claim 11, in which the SLO system includes an inline fiber polarizer and a fiber polarization combiner / splitter (FPCS), the FPCS configured to split return polarized light from depolarized backscattered light.

13. The retinal imaging laser scanner of claim 8, further comprising an AR headset display.

14. An ultrawide eyepiece lens system for positioning proximal to the eye that enables ultrawide field retinal imaging of patients under non-mydriatic conditions.

15. The ultrawide eyepiece lens system of claim 14 that is free from aspheric lenses.

16. The ultrawide eyepiece lens system of claim 14 configured to interface with a gas- permeable contact lens that is selectable from a set of interchangeable lenses sized based on gestational ages.

17. A telecentric optical relay lens system located within a retinal imaging housing and configured to be located between first and second galvanometer scanners for optically conjugating them.

18. The telecentric optical relay lens system of claim 17, in which the system comprises a first doublet lens, a second doublet lens, and a central lens group, the central lens group including at least one positive meniscus lens and at least one biconcave lens.

19. The telecentric optical relay lens system of claim 18, in which the first doublet lens includes a first biconvex lens and a first negative meniscus lens, and the second doublet lens includes a second negative meniscus lens and a second biconvex lens.

20. The telecentric optical relay lens system of claim 18, in which the central lens group comprises a positive meniscus lens, two biconcave lenses, and another positive meniscus lens, arranged sequentially.

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