Chromatic Pupillometry

Photoreceptor Assessment
via Pupil Dynamics

Chromatic pupillometry uses spectrally controlled light stimuli to assess the functional integrity of rods, cones, and ipRGCs through the monitoring of the pupil response.
Objective, non-invasive, no dilation required.

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420-630 nm

6 Monochromatic LEDs
420 · 450 · 470 · 520 · 590 · 630 nm

50 Hz

Bilateral pupil imaging frame rate, measuring both eyes simultaneously

35°

Maximal stimulated area in the retina during assessment

940 nm

Automatic pupil detection under near-infrared (NIR) illumination

The figures above are characteristics of retinaWISE

Overview

What is Chromatic Pupillometry?

Chromatic pupillometry has emerged as a powerful non-invasive method for evaluating retinal and neuroretinal function. It uses spectrally controlled light stimuli to selectively activate different photoreceptors and intrinsically photosensitive retinal ganglion cells (ipRGCs), while monitoring the pupil response.^1,2 The pupillary light reflex comprises two overlapping components: 1) a fast, transient constriction driven by the rods and cones and 2) a sustained component mediated by the inner-retinal melanopsin-containing ipRGCs, known as the Post-Illumination Pupil Response (PIPR).^2,3

Unlike structural imaging modalities such as OCT or fundus photography, chromatic pupillometry assesses function rather than anatomy and may reveal photoreceptor dysfunction before structural changes become apparent.¹ However, interpretation is inherently complex due to overlapping spectral sensitivities among photoreceptor classes. To address this, chromatic pupillometry increasingly employs silent substitution.^4,5 This approach leverages the principle of univariance by using pairs of spectrally distinct but perceptually matched stimuli (metamers) to selectively modulate a target photoreceptor class while maintaining constant excitation of others. As a result, changes in pupil response can be attributed to specific photoreceptor pathways.^1,2

By applying contrast definitions such as Michelson contrast, silent substitution enables precise control of photoreceptor-specific contrast while minimising activation of non-target photoreceptors.⁶ This selective stimulation enhances chromatic pupillometry's ability to probe the functional integrity of individual retinal pathways.

Technique typeFunctional assessment: photoreceptor-specific, objective, quantitative

MethodControlled light stimuli to activate photoreceptors and ipRGCs, while monitoring pupil's response

What is measuredBaseline diameter, latency and amplitude of constriction, constriction and redilation velocity, post-illumination pupil response (PIPR)

Patient requirementsNo dilation, no subjective response, no contact with the eye

Key advantageResearch suggests functional decline may be measurable before structural changes appear on OCT or fundus imaging

Current LimitationsConcurrent activation of different photoreceptors with monochromatic light complicates the assessment of specific pathways

Technical Foundations of Chromatic Pupillometry

From Light Stimulus to Clinical Insight

Chromatic pupillometry combines controlled light stimulation and fast pupillary-response tracking to perform
reliable assessments of photoreceptor functions, based on key requirements for accurate and reproducible measurements.

Spectrally Controlled Stimulation

Selective photoreceptor stimulation requires fine spectral control across the visible spectrum. A chromatic pupillometer incorporates a calibrated light source with sufficient primaries to independently target each photoreceptor class.^1,2 A possible wavelength selection tuned to the characteristics of the receptors includes: multiple short-wavelength (420-470 nm) to optimise S-cone versus ipRGC discrimination, mid-spectrum wavelengths (520-590 nm) to isolate M-cones and L-cones, and long-wavelength (630 nm) for L-cone selective stimulation. Targeting of a single-type photoreceptor class must be performed independently and in parallel on both eyes.²

retinaWISE: 6 LEDs · 420-630 nm

Dichoptic Maxwellian Arrangement

Having bilateral independent stimulation channels is fundamental in a chromatic pupillometer. It allows simultaneous assessment of the consensual pupillary reflex and comparison of monocular versus binocular responses.¹¹
To ensure consistent retinal illuminance independent of pupillary size, a Maxwellian optical arrangement is used.^1,2 Light in a Maxwellian arrangement is delivered through a fixed exit pupil smaller than the minimum physiological pupil, providing standardised conditions essential for reproducible quantitative measurements across testing sessions and clinical sites.²

retinaWISE: Maxwellian & Dichoptic

Retinal Imaging System

Measurements performed with a chromatic pupillometer typically include estimates of the constriction velocity, the maximum constriction amplitude, and the post-illumination pupil response (PIPR).^1,2 Fundamental to this is the use of high-speed imaging systems to capture pupillary dynamics at high frame rates (50 Hz), enabling precise measurement of response kinetics.²
A Scheimpflug optical arrangement for the cameras ensures optimal depth of field for accurate pupil edge detection across varying pupil sizes and positions.^2,11

retinaWISE: 50 Hz bilateral imaging

Assessed Photoreceptor Classes

Three Photoreceptor Families,
Contributing to Retinal Function

Chromatic pupillometry delivers comprehensive retinal insights
by isolating the distinct responses of the three photoreceptor families.

Cone Photoreceptors

Photopic function · colour & central vision · peak sensitivity ~ 430 nm (S), ~ 535 nm (M), and ~ 560 nm (L)

The three classes of cones mediate photopic vision, colour discrimination, and high-acuity central retinal function. Cone-weighted pupillary responses are preferentially triggered under light-adapted conditions with a bright, long-wavelength (red) stimulus together with a short-wavelength (dim-cyan) adapting background to suppress rod contribution. This configuration drives the fast, transient component of the pupillary light reflex, while minimising contributions from rods and melanopsin. ^1,2

When cone function is selectively compromised, the red-light pupillary response is markedly reduced, while rod- and melanopsin-weighted responses remain intact. This photoreceptor-specific dissociation makes chromatic pupillometry a valuable tool for distinguishing outer retinal dysfunction from inner retinal or optic nerve pathology, providing functional information that structural imaging alone cannot offer ¹

Photopic function · macular diseases · colour pathway assessment

ipRGCs

Non-image-forming photoreception · sustained PLR & circadian entrainment · peak sensitivity ~480 nm

Melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) are inner retinal neurons that respond to light. They drive the sustained component of the pupillary light reflex and contribute to circadian light entrainment.
Under high-irradiance blue-light stimulation or by using silent substitution, ipRGCs can dominate the pupillary response. This allows chromatic pupillometry to selectively isolate inner retinal function.^1,2

A key metric is the post-illumination pupil response (PIPR). PIPR is a sustained pupillary constriction that persists after light offset and is selectively driven by blue-light stimulation. ³ A reduced or absent PIPR indicates compromised inner retinal function, even when the initial pupillary constriction appears normal. The PIPR has been shown to detect ipRGC dysfunction in glaucoma ⁷before visual field loss is measurable, in early AMD, ⁸and across a range of neuro-retinal conditions.^9,10

PIPR · glaucoma · AMD · neuro-ophthalmology · circadian pathway

Rod Photoreceptors

Scotopic function · low-light vision · peak sensitivity ~498 nm

Rods are the dominant photoreceptor class in the peripheral retina and mediate vision under scotopic conditions. They represent the most sensitive photoreceptor type within the pupillary reflex pathway.¹

In chromatic pupillometry, rod-weighted responses are probed under dark-adapted conditions using short-wavelength stimuli in the scotopic irradiance range. In patients with outer retinal disease, rod-mediated pupillary responses to cyan light can be absent or severely reduced, while the melanopsin-driven post-illumination pupil response (PIPR) may remain intact, reflecting preserved inner retinal function despite degeneration of the outer retina. ¹

Scotopic dysfunction · outer retinal degeneration · dark adaptation

Oculox solution

Bilateral Chromatic Pupillometer with Maxwellian Optical Arrangement

Oculox has developed retinaWISE, a CE Class I bilateral pupillometer combining a Maxwellian optical design with advanced light stimulation.

retinaWISE

Bilateral chromatic pupillometer · Maxwellian Optical Configuration · Retinal Functional Assessment

420

450

470

520

590

630

Six monochromatic LEDs · nominal peak wavelengths (nm)

retinaWISE is a dichoptic pupillometer with a Maxwellian optical arrangement for the stimulation of both eyes, independently. Its exit pupil is smaller than the minimum human pupil, which ensures that retinal illuminance remains constant and independent of natural pupil constriction, a critical requirement for reproducible quantitative measurements. Six high-brightness LEDs spanning 420-630 nm are used to stimulate the different photoreceptor classes.¹¹

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Clinical Research Applications

A Multi-Domain Research Technology

Published research has explored photoreceptor-specific pupillary assessment as a functional tool across a broad range of conditions,
from retinal disease and neuro-ophthalmology to sleep medicine and psychiatry.

The application examples below reflect published research findings and do not constitute approved diagnostic indications for retinaWISE.

Glaucoma

Glaucoma causes progressive retinal ganglion cell loss that can precede detectable visual field deficits. Because ipRGCs are a subclass of retinal ganglion cells, a reduced PIPR reflects inner retinal dysfunction at a stage when standard perimetry still appears normal.⁷ The PIPR amplitude also correlates with retinal nerve fibre layer thickness on OCT, providing a functional complement to structural imaging.⁷

Age-Related Macular Degeneration

In early stages of age-related macular degeneration (AMD), the melanopsin-driven PIPR has been found to be altered while the retina can still appear largely normal on imaging. This makes photoreceptor-specific pupil testing of interest as a functional measure, capturing change that structural imaging alone may miss at an early stage.⁸

Diabetic Retinopathy

Retinal dysfunction with diabetes can begin before any lesion is visible on fundus examination. Changes in the melanopsin-driven PIPR have been observed in patients with diabetes in the absence of clinical retinopathy,⁹ while cone-weighted responses become progressively attenuated as retinopathy advances. This pattern suggests that chromatic pupillometry captures both inner and outer retinal involvement across the disease spectrum.¹

Parkinson's Disease

Parkinson's disease is associated with retinal dopamine depletion that affects both outer retinal function and melanopsin/ipRGC response. In early-stage patients whose retinal structure appears normal on OCT, chromatic pupillometry detects significant dysfunction across both cone/rod-mediated and melanopsin-driven responses.¹⁰

Alzheimer's Disease

Loss of melanopsin-expressing retinal ganglion cells is observed as early degeneration in patients with Alzheimer's disease. In patients with mild-to-moderate Alzheimer's, chromatic pupillometry reveals abnormal photoreceptor-specific responses while retinal structure on OCT remains normal.¹²

Traumatic Brain Injury

Mild traumatic brain injury disrupts the pupillary light reflex across multiple dynamic parameters, including constriction latency, constriction velocity, and redilation speed.¹³ Chromatic stimulation reveals these abnormalities consistently across both short- and long-wavelength conditions, supporting the use of quantitative pupillometry as an objective, bedside-compatible tool for assessment and follow-up.¹³

Circadian Rhythm & Sleep

Light entrains the circadian clock primarily through melanopsin-expressing retinal ganglion cells. Individual differences in ipRGC-driven pupil responses have been shown to correlate with sleep timing and the disruption caused by misalignment between biological and social schedules in healthy individuals, suggesting that chromatic pupillometry can quantify differences in circadian light sensitivity.¹⁴

Depression & Mood Disorders

In non-seasonal major depressive disorder, patients show significantly reduced daily light exposure compared to healthy controls, a pattern that directly limits melanopsin-driven phototransduction across the day.¹⁵ Chromatic pupillometry can objectively quantify this deficit in melanopsin activation, offering a measurable correlate of the disrupted light-mood relationship that is otherwise difficult to capture in clinical practice.¹⁵

Seasonal Affective Disorder

Seasonal affective disorder (SAD) has been linked to reduced light exposure, but the mechanism underlying this has been difficult to measure. Chromatic pupillometry addresses this: in patients with SAD, the melanopsin-driven pupil response is significantly lower than in healthy controls and decreases further from summer to winter, a variation that is not observed in controls.¹⁶ This measurable retinal signature may help identify patients who could benefit from light therapy.¹⁶

Diagnostic & Assessment Medical Devices

How Chromatic Pupillometry
Compares with Other Tools

Retinal assessment relies on two main approaches: structural imaging and functional testing.
Structural imaging shows anatomical change, while functional tests measure photoreceptor and neural activity. Structural and functional changes do not always move together, so either approach alone can miss important aspects of retinal health.
Chromatic pupillometry is a functional method that provides class-specific information on rods, cones, and melanopsin-containing ipRGCs that is not available from the other tests.

Modality	Type	Key Advantage	Limitation	Best Use
Colour Fundus Photography	Structural	Provides a widefield retinal image that documents the presence and distribution of drusen, retinal haemorrhages, exudates, and neovascularisation. Universally available	Does not provide information on photoreceptor functions. Subtle early changes, such as small drusen or early RPE alterations, can be missed without the resolution of OCT	Screening across a range of retinal and optic-nerve disorders, including AMD, diabetic retinopathy, retinal vascular disease, and glaucoma
OCT	Structural	Most informative structural tool available in routine clinical practice. Provides cross-sectional imaging of all retinal layers, enabling measurement of layer thickness, detection of subretinal fluid, and assessment of structural integrity¹⁷	It cannot assess photoreceptors' functionality. Functional decline often precedes detectable structural loss: layer thickness may appear normal even if a significant functional impairment is already present.	Structural diagnosis and treatment monitoring across a wide range of retinal conditions
Dark Adaptation	Functional	It measures how quickly rods recover their sensitivity after exposure to bright light, therefore, providing, before standard imaging, a warning of rod dysfunction at a stage when intervention may still prevent irreversible losses¹⁸	The test takes 20-40 minutes and requires patients to remain cooperative throughout. This can limit its use in elderly or cognitively impaired individuals. Results are influenced by the amount of light the patient was exposed to before the test. The measurement does not pinpoint which retinal layer is affected	Detects rod dysfunction before structural changes become apparent. Assessment of rod-mediated (scotopic) function, including early and intermediate AMD and retinitis pigmentosa
Microperimetry	Functional	Maps retinal sensitivity point-by-point using simultaneous fundus imaging and eye-tracking. This enables direct correlation between functional loss and structural changes on imaging. It can detect sensitivity loss in AMD even when visual acuity remains normal¹⁹	Results depend on patient cooperation throughout the long test, which can affect reliability. The technique lacks age-corrected statistical reference analyses that standard visual field testing provides, making it harder to distinguish clinically meaningful change from normal variation	Suited to patients with preserved visual acuity but suspected localised vision loss
Electroretinography (ERG)	Functional	Measures the electrical response of the entire retina to light, allowing rod and cone function to be assessed separately and objectively. This provides a direct, quantifiable readout of photoreceptor activity that does not depend on the patient's subjective responses²⁰	Requires pupil dilation, electrodes, and precise dark or light adaptation periods of up to 20 minutes before testing. Results also vary with electrode type, recording conditions, and patient cooperation	Objective assessment of generalised rod and cone function. It helps localise photoreceptor dysfunction when structural imaging is inconclusive
Chromatic Pupillometry	Functional	Independently isolates rod, cone, and melanopsin-ipRGC pathway responses. Bilateral stimulus and measurement. Does not require pupil dilation. It can detect functional decline in each photoreceptor class separately, at a stage when structural imaging may still appear normal ^1,2,11	Separating the contribution of individual photoreceptor classes is technically demanding. Results are influenced by baseline pupil size, the patient's level of alertness, and the retina's adaptation state before testing. Disease-specific assessment protocols are under development	Patients in whom functional decline is suspected across one or more photoreceptor classes, such as in patients with suspected AMD, retinitis pigmentosa, or glaucoma. Research in neuro-ophthalmology, Psychiatry, and Sleep Science

Frequently asked

Questions About Chromatic Pupillometry

What is Chromatic Pupillometry?

Chromatic pupillometry is a non-invasive technique that measures the pupil's response to spectrally controlled light stimuli to independently assess the functional integrity of rods, cones, and melanopsin-containing retinal ganglion cells (ipRGCs). It can be used to generate objective, quantitative biomarkers of retinal and neuroretinal function without any subjective patient input.

How is it different from conventional handheld pupillometry?

Conventional handheld pupillometers are designed for rapid assessment of the pupillary light reflex but have several limitations for evaluating retinal function. They typically use a single white LED stimulus, preventing selective assessment of different photoreceptor classes. Their stimulus parameters, including wavelength, intensity, and duration, are often fixed or have a limited range, and recording times are generally too short to capture slow responses such as the post-illumination pupil response (PIPR). In addition, most devices perform only monocular stimulation and recording, limiting the assessment of direct and consensual responses and inter-eye differences.
Chromatic pupillometry overcomes these limitations by using precisely controlled coloured light stimuli to selectively activate rods, cones, and melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). It also allows flexible stimulus protocols, longer recordings, and simultaneous bilateral pupil measurements, enabling a more comprehensive assessment of retinal function.

What is the PIPR and why does it matter?

The pupil constricts when light enters the eye and dilates when the light goes off. A small population of cells in the inner retina, however, contain a light-sensitive pigment called melanopsin that reacts more slowly than rods and cones. Even after the light is switched off, these melanopsin-containing cells, called intrinsically photosensitive retinal ganglion cells (ipRGCs), keep sending a signal that holds the pupil constricted for several seconds. This prolonged constriction after light offset is the Post-Illumination Pupil Response (PIPR). Although the PIPR is primarily driven by melanopsin-mediated activity in ipRGCs, it is not exclusively controlled by these cells. Rods and cones also contribute to the PIPR, particularly during its early phase, through their synaptic input to ipRGCs.
Clinically, PIPR matters because it reflects directly how well these inner retinal cells are functioning. A reduced or absent PIPR indicates that they are damaged or not working normally. Loss of PIPR has been reported in glaucoma, Parkinson's disease, Alzheimer's disease, diabetes, and conditions affecting sleep and circadian rhythm. Because it depends on the response of a specific cell type, the PIPR cannot be measured with conventional pupillometry. A chromatic pupillometer capable of selectively stimulating photoreceptors is required.

What is a Maxwellian optical arrangement and why does it matter?

In a standard "free viewing" configuration, also called Newtonian optical arrangement, the amount of light reaching the retina changes as the pupil constricts or dilates. This creates a fundamental problem for precise and quantitative measurements. A Maxwellian optical arrangement solves this by focusing the light beam to a point smaller than the smallest possible pupil opening. Whether the pupil is open or constricted, the retinal illumination remains constant throughout the test. This matters because chromatic pupillometry relies on delivering precisely controlled, repeatable light stimuli to each eye. Without a Maxwellian arrangement, changes in pupil size during the test would distort the stimulus and make results unreliable, particularly for comparing measurements across visits or between patients. It is what makes the technique quantitative rather than merely qualitative.

Why does retinaWISE use six monochromatic LEDs?

Each photoreceptor class in the eye has a different sensitivity to wavelengths of light. However, there is some overlap between the classes, particularly between S-cones and the inner retinal cells that express melanopsin, both of which respond strongly to blue light. To test each cell type independently, chromatic pupillometry uses a technique called silent substitution: pairs of light stimuli that appear identical to most photoreceptors but differ specifically for the targeted cell type. The quality of this separation depends directly on how many monochromatic light sources are available. With only four, the contrast achievable for certain photoreceptor types, particularly melanopsin, is too low to yield reliable, clinically meaningful results. retinaWISE uses six LEDs at 420, 450, 470, 520, 590 and 630 nm. This six-primary configuration enables a substantially higher stimulation contrast than four-primary devices. The three short-wavelength LEDs work together to sharpen the separation between S-cones and ipRGCs.

Explore Chromatic Pupillometry with retinaWISE

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References

Scientific References

References include foundational papers on photoreceptor biology, and representative peer-reviewed clinical studies supporting the diagnostic techniques and applications described.
Application findings do not constitute approved diagnostic indications

1. Rukmini AV, Milea D, Gooley JJ. Chromatic pupillometry methods for assessing photoreceptor health in retinal and optic nerve diseases. Front Neurol. 2019;10:76. doi:10.3389/fneur.2019.00076

2. Kelbsch C, Strasser T, Chen Y, et al. Standards in pupillography. Front Neurol. 2019;10:129. doi:10.3389/fneur.2019.00129

3. Adhikari P, Zele AJ, Feigl B. The post-illumination pupil response (PIPR). Invest Ophthalmol Vis Sci. 2015;56(6):3838-3849. doi:10.1167/iovs.14-16233

4. Spitschan M, Woelders T. The method of silent substitution for examining melanopsin contributions to pupil control. Front Neurol. 2018;9:941. doi:10.3389/fneur.2018.00941

5. Zele AJ, Feigl B, Adhikari P, Maynard ML, Cao D. Melanopsin photoreception contributes to human visual detection, temporal and colour processing. Sci Rep. 2018;8:3842. doi:10.1038/s41598-018-22197-w

6. Evéquoz G, Truffer F, Geiser M. Maximum possible contrast level for silent substitution: a theoretical model applied to melanopsin stimulation. J Opt Soc Am A. 2021;38(9):1312-1319. doi:10.1364/JOSAA.420373

7. Adhikari P, Zele AJ, Thomas R, Feigl B. Quadrant field pupillometry detects melanopsin dysfunction in glaucoma suspects and early glaucoma. Sci Rep. 2016;6:33373. doi:10.1038/srep33373

8. Maynard ML, Zele AJ, Feigl B. Melanopsin-mediated post-illumination pupil response in early age-related macular degeneration. Invest Ophthalmol Vis Sci. 2015;56(11):6906-6913. doi:10.1167/iovs.15-17357

9. Feigl B, Zele AJ, Fader SM, et al. The post-illumination pupil response of melanopsin-expressing intrinsically photosensitive retinal ganglion cells in diabetes. Acta Ophthalmol. 2012;90(3):e230-e234. doi:10.1111/j.1755-3768.2011.02226.x

10. Joyce DS, Feigl B, Kerr G, Roeder L, Zele AJ. Melanopsin-mediated pupil function is impaired in Parkinson's disease. Sci Rep. 2018;8:7796. doi:10.1038/s41598-018-26078-0

11. Gibertoni G, Hromov A, Piffaretti F, Geiser MH. Development of an innovative pupillometer able to selectively stimulate the eye's fundus photoreceptor cells. Diagnostics (Basel). 2024;14(17):1940. doi:10.3390/diagnostics14171940

12. Romagnoli M, Stanzani Maserati M, De Matteis M, et al. Chromatic pupillometry findings in Alzheimer's disease. Front Neurosci. 2020;14:780. doi:10.3389/fnins.2020.00780

13. Truong JQ, Ciuffreda KJ. Comparison of pupillary dynamics to light in the mild traumatic brain injury (mTBI) and normal populations. Brain Inj. 2016;30(11):1378-1389. PMID:27541745

14. van der Meijden WP, Van Someren JL, te Lindert BHW, et al. Individual differences in sleep timing relate to melanopsin-based phototransduction in healthy adolescents and young adults. Sleep. 2016;39(6):1305-1310. doi:10.5665/sleep.5858

15. Feigl B, Ojha G, Hides L, Zele AJ. Melanopsin-driven pupil response and light exposure in non-seasonal major depressive disorder. Front Neurol. 2018;9:764. doi:10.3389/fneur.2018.00764

16. Roecklein K, Wong P, Ernecoff N, et al. The post illumination pupil response is reduced in seasonal affective disorder. Psychiatry Res. 2013;210(1):150-158. doi:10.1016/j.psychres.2013.05.023

17. Staurenghi G, Sadda SR, Chakravarthy U, Spaide RF; International Nomenclature for Optical Coherence Tomography (IN•OCT) Panel. Proposed lexicon for anatomic landmarks in normal posterior segment spectral-domain optical coherence tomography: the IN•OCT consensus. Ophthalmology. 2014;121(8):1572-1578. PMID:24755005

18. Owsley C, McGwin G Jr, Clark ME, et al. Delayed rod-mediated dark adaptation is a functional biomarker for incident early age-related macular degeneration. Ophthalmology. 2016;123(2):344-351. PMID:26522707

19. Cassels NK, Wild JM, Margrain TH, Chong V, Acton JH. The use of microperimetry in assessing visual function in age-related macular degeneration. Surv Ophthalmol. 2018;63(1):40-55. doi:10.1016/j.survophthal.2017.05.007

20. McCulloch DL, Marmor MF, Brigell MG, Hamilton R, Holder GE, Tzekov R, Bach M. ISCEV Standard for full-field clinical electroretinography (2015 update). Doc Ophthalmol. 2015;130(1):1-12. doi:10.1007/s10633-014-9473-7

What is Chromatic Pupillometry?

From Light Stimulus to Clinical Insight

Spectrally Controlled Stimulation

Dichoptic Maxwellian Arrangement

Retinal Imaging System

Three Photoreceptor Families,Contributing to Retinal Function

Cone Photoreceptors

ipRGCs

Rod Photoreceptors

Bilateral Chromatic Pupillometer with Maxwellian Optical Arrangement

A Multi-Domain Research Technology

Glaucoma

Age-Related Macular Degeneration

Diabetic Retinopathy

Parkinson's Disease

Alzheimer's Disease

Traumatic Brain Injury

Circadian Rhythm & Sleep

Depression & Mood Disorders

Seasonal Affective Disorder

How Chromatic PupillometryCompares with Other Tools

Questions About Chromatic Pupillometry

Explore Chromatic Pupillometry with retinaWISE

Scientific References

Three Photoreceptor Families,
Contributing to Retinal Function

How Chromatic Pupillometry
Compares with Other Tools