What Is a Fundus Camera? A Complete Guide to How It Works, Its Types, Modes and Applications
- Vadzo Imaging
- 3 days ago
- 17 min read
Updated: 2 days ago
If you have ever wondered what a fundus camera is and why it sits at the center of modern eye care, you are in the right place. A fundus camera is a specialized optical instrument designed to photograph the interior surface of the eye, the retina, optic disc, macula, and posterior pole. These detailed retinal fundus imaging systems have become indispensable in diagnosing and monitoring conditions like diabetic retinopathy and glaucoma.
Eye diseases are among the leading causes of preventable blindness worldwide. The ability to capture clear, repeatable images of the back of the eye allows ophthalmologists to track disease progression over time and make treatment decisions with far greater confidence than traditional examination methods allow. That is exactly what a fundus camera delivers.
The global fundus cameras market is growing fast. A recent industry report projects the market will reach USD 535 million by 2030, growing at a CAGR of 6.2% from 2023 onward. This momentum is driven by rising rates of diabetes, an aging global population, and rapid advances in imaging sensor technology.
In this blog, we break down what fundus imaging is, how fundus cameras work, the different types available, the imaging modes they support, and the clinical and research applications they serve. We also share camera modules from Vadzo Imaging that are well-suited for OEM fundus camera development.
What Is a Fundus Camera?
Picture the back of your eye as a living map. The retina covers it like wallpaper, is light-sensitive, richly vascular, and connected to the brain through the optic nerve. Damage to any part of that map, whether from diabetes, elevated pressure, or aging, shows measurable structural changes long before a patient notices anything is wrong. A fundus camera is the instrument clinicians use to photograph the fundus repeatedly and reliably over time.
At its core, a fundus camera is an ophthalmic device built around one unusual constraint: both the light going in and the image coming back have to travel through the same tiny opening, the pupil. The optical engineering that solves that problem is what separates a fundus camera from every other imaging system in a clinical setting.
When people ask what a fundus image is, the short answer is: a photograph of the retinal surface taken from inside the eye. You see the optic disc, the pale circle where the nerve exits, surrounded by branching blood vessels, with the darker macula sitting off to one side. The background color shifts from orange-red in healthy tissue to pale, hemorrhagic, or drusen-spotted in disease. Depending on the imaging mode, that same field can be rendered in natural color, near-infrared, or lit up with fluorescent dye to trace blood flow in real time.
Think of a fundus camera as a specialized macro-photography system engineered to work inside the constraints of the human eye. Light must enter through the pupil, illuminate the retina without causing glare, and the reflected light must then exit through the same pupil and be captured cleanly on a sensor. Getting all of that right in a compact clinical device is a meaningful engineering achievement.
How Fundus Camera Work?
The physics here are worth understanding, because they explain why fundus cameras look and behave the way they do. The challenge is not illuminating the retina. That is straightforward enough. The challenge is doing it through a pupil that is typically 4–6mm wide, without the light bouncing back off the cornea and lens and washing out the retinal image you are trying to capture.
The Annular Illumination Solution
Most fundus cameras solve this with an annular (ring-shaped) illumination design. Light from the source is a xenon flash, an LED array, or, in SLO systems, a scanning laser that is shaped into a ring that enters through the outer edge of the pupil. The imaging path uses the central pupil area. Because the two paths are spatially separated, the corneal reflex that would otherwise obscure the image never reaches the sensor. A semi-transparent mirror or beam splitter handles the separation cleanly.
Step-by-Step: Light Path Through the Eye
The illumination source fires a controlled burst of light through condenser optics and a beam-splitter, shaped into an annular ring aimed at the outer pupil margin.
That ring of light passes through the cornea, travels through the aqueous humor, crystalline lens, and vitreous humor before landing on the retinal surface.
The retina scatters and reflects the light out through the center of the pupil on the path that the imaging optics are watching.
Depending on the imaging mode, the returning light passes through color, red-free, or barrier filters before hitting the sensor.
A high-resolution CCD or CMOS sensor converts the optical signal into a digital image, one that can be stored, compared against prior visits, or fed into an AI grading system.
Getting consistent, high-quality images across different patients' different pupil sizes, different degrees of media opacity, and different refractive errors is where modern fundus camera engineering earns its complexity. Multi-element optical designs, precision anti-reflection coatings, and real-time autofocus preview all contribute to making the clinical capture process fast enough to be practical and reliable enough to be diagnostic.
The sensor at the heart of the system is where hardware suppliers like Vadzo Imaging make a direct contribution to OEM device performance. Resolution, low-light sensitivity, NIR response, and dynamic range all feed directly into what the finished fundus camera can actually see.
Types of Fundus Camera
Fundus cameras are not a single product category; they are a family of instruments with meaningfully different optical approaches, clinical profiles, and patient requirements. Picking the right type is less about feature lists and more about understanding the clinical context each was designed for.
Camera Type | Pupil Dilation | Field of View | Best Used For |
Mydriatic | Yes (required) | 50°–60° | Detailed retinal diagnosis |
Non-Mydriatic | No | 30°–50° | Mass screening, routine exams |
Stereoscopic | Optional | 30°–50° (3D) | Retinal edema, depth assessment |
SLO | No (2mm pupil) | 30°–60° | High-contrast, real-time imaging |
Ultra-Widefield | No | Up to 200° | Peripheral retinal conditions |
1. Mydriatic Fundus Camera
Mydriatic cameras are the traditional benchmark of retinal photography. Before imaging, the patient receives pharmacological drops, typically tropicamide, to dilate the pupil to 5mm or wider. That wider opening gives the camera more working room: brighter illumination, better optical access, and a field of view that typically runs from 50° to 60°.
The images you get from a well-set-up mydriatic system are hard to beat for sheer diagnostic detail, fine vessel caliber, subtle disc changes, and early drusen. The cost is patient time and discomfort: dilation takes the better part of half an hour, and the light sensitivity that follows can last several hours. In specialist ophthalmology clinics where comprehensive retinal assessment is the goal, that trade-off is accepted without much debate.
2. Non-Mydriatic Fundus Camera
Non-mydriatic camera skips the dilation step. They use infrared pre-illumination in the 700–900nm range to align and focus in near-dark conditions, the pupil does not constrict to infrared, then fire a brief white-light flash for the actual exposure. The field of view is typically 30°–50°, slightly narrower than a dilated mydriatic system, but usually sufficient for the conditions being screened for.
For diabetes screening programs run through GP surgeries, community pharmacies, or mobile units, non-mydriatic cameras are the only workable option. They cut total appointment time dramatically, removed the need for specialist nursing to administer drops, and allowed patients to drive home immediately afterward.
3. Stereoscopic Fundus Cameras
Standard fundus photography produces a 2D image of what is fundamentally a 3D structure. Stereoscopic cameras address this by capturing two images from slightly offset angles either simultaneously through a beam-splitting system or sequentially by shifting the camera position and combining them into a stereo pair that gives depth information.
That depth reading is particularly valuable for two clinical problems: grading optic disc cupping in glaucoma (where the 3D relationship between cup and disc margin matters), and assessing retinal elevation, such as macular edema or epiretinal membranes, where the height of the lesion is as diagnostically important as its surface appearance.
4. Scanning Laser Ophthalmoscope (SLO)
SLO takes a fundamentally different approach to illumination. Rather than a flash, it uses a low-power laser, often multiple wavelengths simultaneously, to scan the retina point by point. The detector picks up the reflected signal as the beam moves, building the image line by line.
The confocal design that results from this scanning approach delivers noticeably better contrast and a deeper depth of field than conventional flash systems. Crucially, it works through pupils as small as 2mm, which matters for patients whose pupils dilate poorly. In teleophthalmology program and research environments where you are imaging patients in non-clinical settings without access to dilation drops, SLO systems give you a reliable image quality floor that flash-based non-mydriatic cameras sometimes struggle to match.
5. Ultra-Widefield Fundus Cameras
Conventional fundus cameras show you the central 45°–50° of the retina, the region around the macula, and the optic disc. Ultra-widefield systems expand that to 100°–200° in a single frame, pulling in the peripheral retina that standard cameras simply cannot reach.
That peripheral access changes what is clinically visible. Retinal tears and the early signs of detachment often originate at the far periphery. Peripheral ischaemia in diabetic patients may predict disease progression more accurately than central lesion burden. Sickle cell retinopathy, lattice degeneration, and some forms of uveitis all show their most characteristic signs away from the central field. Ultra-widefield systems use specialized ellipsoidal mirrors and aspheric lens designs to achieve this coverage. They are larger and more expensive, but for a vitreoretinal specialist, the peripheral visibility they provide is genuinely irreplaceable.
Modes of Fundus Photography
The camera type determines how light gets to the retina. The imaging mode determines which wavelengths and contrast agents are used to interrogate it. Choosing the right mode is choosing which clinical question you are actually asking.
Color Fundus Photography
White light through color filters produces a natural-color image of the retinal surface, the starting point for most examinations and the mode most clinicians mean when they say, 'fundus photo'. Blood vessel caliber, disc pallor, hemorrhages, exudates, drusen, and pigment changes all show up in color photography without any dye or special preparation.
Red-Free Fundus Photography
A green filter in the 540–570nm range blocks red wavelengths and lifts contrast for the superficial retinal structures in the nerve fiber layer, blood vessels, and fine hemorrhages. The background becomes lighter, making the dark vascular details stand out more sharply. Red-free imaging is commonly used to identify subtle nerve fiber defects in early glaucoma and as a preparatory step before angiography.
Fluorescein Angiography (FA)
Sodium fluorescein is injected intravenously. Blue excitation light (~490nm) causes the dye to fluoresce as it moves through the retinal vasculature, and a barrier filter on the camera captures only the fluorescent emission. A time series of frames over the following minutes shows the dye front entering the arteries, filling the capillary bed, and draining through the veins.
What that sequence reveals is the functional state of the retinal circulation, not just what the vessels look like, but how they are behaving. Areas of leakage show up as spreading fluorescence beyond vessel walls. Blocked capillary beds appear as dark, non-perfused zones. New vessels from diabetic or other ischaemic disease leak intensely and uncontrollably. For conditions like diabetic macular edema, branch retinal vein occlusion, and wet AMD, FA remains the definitive functional imaging tool.
Indocyanine Green Angiography (ICGA)
ICGA goes a layer deeper, literally. Indocyanine green dye binds to plasma proteins and fluoresces in the near-infrared, roughly 800nm. At that wavelength, light penetrates the retinal pigment epithelium far more effectively than visible wavelengths do, which means you can see the choroidal circulation that sits beneath it.
That matters clinically because several important conditions originate in the choroid rather than the retinal vasculature. Polypoidal choroidal vasculopathy, central serous chorioretinopathy, and some forms of choroidal neovascularization are essentially invisible on standard fluorescein angiography but show up clearly on ICGA. For a retinal specialist trying to differentiate subtypes of AMD before deciding on treatment, ICGA is often the investigation that settles the question.
Near-Infrared Reflectance Imaging
Near-infrared reflectance imaging uses wavelengths of 800nm or longer without any dye. Different retinal and sub-retinal structures reflect near-infrared light differently, which makes this mode useful for examining outer retinal health photoreceptors, RPE, and the interface between them in ways that visible-light photography struggles to achieve.
It is also a practical workaround when dye injection is contraindicated. Patients with poor venous access, prior fluorescein reactions, or conditions where dye pharmacokinetics are unpredictable can still have their outer retinal structure assessed. NIR is routinely acquired alongside OCT scans for structural correlation, giving the clinician a surface map that contextualises the depth cross-sections OCT provides.
Key Applications of Fundus Camera Solutions
The clinical and research utility of retinal cameras spans a wide range of conditions and settings.
Diabetic Retinopathy Detection and Monitoring
Diabetes quietly damages the small blood vessels of the retina microaneurysms to form, capillaries to leak, and eventually new fragile vessels to grow in places they should not be. None of this causes symptoms in the early stages, which is precisely why structured screening matters. Regular fundus photography gives clinicians a dated, documented record of the retinal vasculature so they can spot the first signs of damage and intervene before vision is threatened.
Glaucoma Management
Glaucoma damage shows up in the optic disc before it shows up in a visual field test. The optic cup gradually enlarges relative to the disc, nerve fiber bundles thin and drop out, and small disc hemorrhages appear as the nerve tissue is progressively lost. Serial fundus photographs document these structural changes over time, allowing clinicians to identify progression even when it is subtle, and to act before the patient notices any change in their vision.
Age-Related Macular Degeneration (AMD)
In dry AMD, the retinal pigment epithelium breaks down, and drusen deposits of cellular waste accumulate beneath the macula. In wet AMD, abnormal blood vessels grow from the choroid, leaking fluid and blood that rapidly destroy central vision if untreated. Fundus photography tracks both processes: documenting drusen burden in dry AMD and detecting the sudden changes in retinal architecture that signal conversion to wet disease. For patients receiving anti-VEGF injections for wet AMD, fundus images alongside OCT are how the treating clinician judges whether treatment is working.
Retinal Detachment and Tears
Ultra-widefield retinal cameras make peripheral retinal breaks and detachments far easier to identify and document compared to conventional imaging. Conditions that might be missed entirely with standard field-of-view cameras become clearly visible when the full peripheral retina is captured in a single frame.
Hypertensive Retinopathy
Vascular changes caused by chronically elevated blood pressure, such as arteriovenous nicking, flame-shaped hemorrhages, and cotton wool spots, are clearly visible on color fundus photographs and give clinicians a window into the systemic vascular status of the patient.
Pre- and Post-Operative Assessment
Surgeons use fundus imaging to document retinal status before and after vitreoretinal procedures, establishing a baseline before surgery and tracking recovery and any complications afterward.
Research and Clinical Trials
Standardised fundus photography is a core outcome measure in studies evaluating new treatments for retinal disease. The ability to compare images collected at different sites, at different time points, against a documented baseline is what makes fundus photography a rigorous research tool.
Telemedicine and Remote Screening
Non-mydriatic and SLO-based retinal cameras enable remote image acquisition, which can be graded asynchronously by specialists anywhere in the world. Compact USB camera modules with high NIR sensitivity, like those in Vadzo's medical imaging portfolio, are enabling this model in settings that previously had no access to ophthalmic services.
Emerging Innovations in Fundus Imaging Technology
Artificial Intelligence and Machine Learning
The most consequential shift in fundus imaging over the last decade has not been in the cameras themselves; it has been in what happens to the images once they are captured. Deep learning models trained on hundreds of thousands of labelled fundus photographs can now detect diabetic retinopathy, flag glaucoma suspects, and identify AMD features with sensitivity and specificity that hold up well against experienced human graders in controlled studies.
The practical effect is that screening programs no longer need a specialist at every reading station. Automated grading handles the routine cases, and clinicians review only the images flagged as abnormal or borderline. In settings where ophthalmology expertise is scarce in much of sub-Saharan Africa, rural South Asia, and parts of Latin America, this changes what is achievable at a population level.
One constraint worth keeping in mind: AI grading performance drops significantly on poor-quality images. An out-of-focus, underexposed, or artefact-heavy fundus photograph will generate lower-confidence output or an outright ungradable result. The sensor hardware and optical design of the camera are not separate from the AI system; they are the foundation it runs on.
Integration with Optical Coherence Tomography
Combining fundus photography with OCT gives clinicians complementary views of the retina. While a fundus camera captures the surface and face view, OCT provides a cross-sectional depth view of the retinal layers. Together, these modalities provide a complete structural picture that can be delivered alone.
Augmented and Virtual Reality in Retinal Surgery
AR-assisted retinal surgery is a genuinely emerging field.
The idea is that fundus photographs and live imaging data can be overlaid directly onto the surgeon's field of view through an AR headset or microscope-integrated display, ay so the surgeon is not switching attention between the imaging system and the operative field. In macular surgery, where the target structures are measured in microns and the margin for error is correspondingly small, that kind of spatial overlay could meaningfully reduce operative risk. The technology is still largely in research and early clinical stages, but the foundational work is moving quickly.
Multispectral and Hyperspectral Imaging
Imaging the retina across multiple discrete wavelength bands beyond the visible spectrum reveals tissue characteristics invisible to standard color photography. Multispectral fundus imaging is being explored for detecting early metabolic changes associated with Alzheimer's disease as well as for mapping retinal oxygenation in vascular disease.
Smartphone-Based and Portable Fundus Imaging
Compact clip-on adapters and purpose-designed handheld devices are extending retinal imaging into settings that never had it. While they do not match table-top systems for image quality or field of view, the access they provide is a meaningful step forward. Vadzo's compact low-light USB camera modules are designed for exactly these space-constrained, power-sensitive embedded imaging environments.
Vadzo Imaging Camera Modules for Fundus Camera Development
Building a fundus camera requires an image sensor that delivers high resolution, excellent low-light performance, accurate color rendering, and reliable NIR sensitivity depending on the imaging mode. Below are Vadzo Imaging camera modules well-suited for fundus and retinal imaging device development.
1. AR1335 13MP Autofocus Color USB 3.0 Camera
Best For , | Color fundus photography, routine retinal examination, and diabetic retinopathy screening |
Sensor | Onsemi AR1335 |
Resolution | 13 MP (4208 × 3120) | 4K |
Interface | USB 3.0 |
Focus System | Continuous autofocus maintains a consistent focal distance across varying patient working distances. |
Why for Fundus | 13MP resolution resolves fine retinal vessel caliber, early drusen, and subtle disc changes. Autofocus reduces the refocus step between patients in high-throughput screening workflows where technician time per patient directly affects program capacity. |
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2. AR1335 13MP OIS Autofocus Color USB 3.0 Camera
Best For | Handheld fundus camera, portable retinal screeners, community and mobile eye care units |
Sensor | Onsemi AR1335 |
Resolution | 13 MP (4208 × 3120) | 4K |
Interface | USB 3.0 |
Stabilization | OIS (Optical Image Stabilization) + Continuous Autofocus |
Why for Fundus | In a table top instrument, stabilization is marginal. In a handheld or portable fundus camera, the difference is between a diagnostically usable retinal image and one that is motion-blurred and upgradeable. Same 13MP color performance as Module 1, with OIS making it viable outside a fixed clinical setting. |
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3. IMX258 13MP PDAF Color USB 3.0 Camera
Best For | Fluorescein angiography (FA) time-series imaging, rapid multi-frame retinal capture. |
Sensor | Sony IMX258 |
Resolution | 13 MP (4208 × 3120) | 4K |
Interface | USB 3.0 |
Focus System | PDAF (Phase-Detection Autofocus) single-step focus acquisition, no iterative hunting |
Why for Fundus | Fluorescein angiography captures the dye front progressing through the retinal vasculature across 60–90 seconds in sequential frames. Contrast-detect autofocus hunts between frames and introduces inconsistent framing. PDAF acquires focus in a single measurement step, delivering consistent focus lock frame-to-frame. which is essential for a usable FA time-series. |
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4. AR0821 8.3MP HDR Color USB 3.0 Camera
Best For | Fluorescein angiography (high-contrast capture), color fundus photography with a wide luminance range |
Sensor | Onsemi AR0821 |
Resolution | 8.3 MP | 4K |
Interface | USB 3.0 |
Imaging Feature | HDR (High Dynamic Range) simultaneously captures bright and dark regions in a single frame |
Why for Fundus | The retinal field spans a significant luminance range: the optic disc reflects brightly while the peripheral retina is comparatively dark. Standard sensors clip one end or the other. In fluorescein angiography specifically, leakage sites and non-perfused zones must both be visible in the same frame. HDR capture is what makes that possible without manual exposure bracketing. |
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5. AR0521 5.1MP NIR Monochrome USB 3.0 Camera
Best For | Scanning Laser Ophthalmoscope (SLO), Indocyanine Green Angiography (ICGA), NIR reflectance imaging, outer retinal assessment |
Sensor | Onsemi AR0521 |
Resolution | 5.1 MP (2592 × 1944) |
Interface | USB 3.0 |
Sensor Type | Monochrome (no CFA) full NIR photon transmission to photodiodes, high quantum efficiency at 780–900 nm |
Why for Fundus | Color sensors use a Bayer color filter array that blocks 60–70% of incident light, including most NIR photons. Monochrome sensors pass NIR light directly to the photodiodes. At 780–900 nm wavelengths, this delivers the sensitivity that SLO imaging, ICGA dye fluorescence detection, and NIR reflectance modes depend on. This is the correct sensor class for any fundus imaging mode where visible-light photography performs poorly. |
Product Page |
How to Choose: Fundus Camera Module Selection Guide
Use the table below to match your fundus camera imaging mode to the correct Vadzo camera module. Each recommendation is based on the primary sensor characteristic that imaging mode requires.
Imaging Mode | Recommended Module | Sensor | Resolution | Key Feature | Why This Module |
Color Fundus Photography | Onsemi AR1335 | 13MP | 4K | Autofocus | High resolution + accurate color + continuous AF for clinical workflow speed | |
Portable / Handheld Fundus | Onsemi AR1335 | 13MP | 4K | OIS + AF | OIS eliminates motion blur from hand movement essential for usable handheld retinal images | |
Fluorescein Angiography (FA) Time-Series | Sony IMX258 | 13MP | 4K | PDAF | Single-step focus lock per frame is critical for consistent FA time-series sequencing. | |
FA High Contrast / Leakage Sites | Onsemi AR0821 | 8.3MP | 4K | HDR | Simultaneous capture of bright leakage and dark non-perfused zones in the same frame | |
SLO (Scanning Laser Ophthalmoscope) | Onsemi AR0521 | 5.1MP | NIR Mono | No color filter, full NIR sensitivity at 780–900 nm for laser-illuminated imaging | |
ICGA (Indocyanine Green Angiography) | Onsemi AR0521 | 5.1MP | NIR Mono | ICG dye fluoresces at 800 nm, a monochrome sensor captures the signal, and color sensors miss | |
NIR Reflectance Imaging | Onsemi AR0521 | 5.1MP | NIR Mono | High quantum efficiency in NIR for outer retinal and RPE structure assessment without dye |
Frequently Asked Questions(FAQs)
Which Vadzo camera module is best for color fundus photography?
The AR1335 13MP Autofocus Color USB 3.0 Camera is the primary choice for color fundus photography. It's 13 MP resolution captures fine retinal detail, and the autofocus system maintains consistent focal distance across patients without manual adjustment.
Which Vadzo module should I use for a handheld fundus camera?
The AR1335 13MP OIS Autofocus Color USB 3.0 Camera is designed for portable and handheld fundus camera applications. The optical image stabilisation (OIS) system compensates for hand movement and platform vibration that would otherwise produce motion blur in the retinal image.
What is the best Vadzo sensor for fluorescein angiography?
Two modules are relevant depending on the primary requirement. The IMX258 13MP PDAF is suited to time-series angiography workflows where fast, consistent focus lock between sequential frames is the priority. The AR0821 8.3MP HDR is better suited when the primary requirement is resolving both bright and dark regions in the same frame a direct advantage in capturing leakage sites alongside non-perfused zones.
Which Vadzo module is correct for SLO and near-infrared fundus imaging?
The AR0521 5.1MP NIR Monochrome USB 3.0 Camera. Monochrome sensors without a colour filter array pass near-infrared photons directly to the photodiodes, delivering high sensitivity at 780–900 nm. This makes them the appropriate sensor class for scanning laser ophthalmoscope systems, indocyanine green angiography (ICGA), and near-infrared reflectance imaging modes where standard colour sensors perform poorly.
Do Vadzo camera modules support USB 3.0?
Yes. All five camera modules listed here use USB 3.0 as the primary interface, which provides sufficient bandwidth for 4K resolution video and image transfer without compression. This simplifies integration into OEM fundus camera hardware running on standard embedded computing platforms.
Future of Fundus Imaging
Fundus cameras have been photographing the back of the eye for the better part of a century. What has changed is the breadth of settings they operate in, the sophistication of the modes they support, and the scale at which their images are now being processed and acted on. Screening programs that would have required specialist ophthalmologists are running in community pharmacies. AI systems are grading images faster than any human grader could. Multispectral modes are starting to detect retinal changes that precede any structural damage visible to the naked eye.
For device developers and OEM engineers building the next generation of fundus and retinal imaging systems, the camera sensor is not a commodity component; it is the starting point for everything the system can achieve. Resolution, dynamic range, NIR sensitivity, and readout speed all translate directly into clinical performance. Getting that foundation right is the most important hardware decision in the design process.
Vadzo Imaging supplies OEM-ready CMOS camera modules specifically suited to the demands of medical imaging environments, from 2MP to 20MP, with autofocus, OIS, HDR, and NIR capabilities across USB, MIPI, and GigE interfaces. Browse the full portfolio at vadzoimaging.com or reach out to the engineering team to discuss the right configuration for your ophthalmic device project.
