Research Applications for Striatech Products

Sodium Iodate Retinal Toxicity Model: RPE Loss, Visual Function Decline, and Use as a Preclinical Platform

A selective RPE toxin producing reproducible, dose-dependent outer retinal degeneration — the benchmark chemical model for AMD-like geographic atrophy. Bridges retinal degeneration research with toxicology methodology.

Introduction

Animal Models

Research Questions

Measurement Modalities

Publications

Journal Clubs

Introduction

What Is the Sodium Iodate Retinal Toxicity Model?

Sodium iodate (NaIO₃) is the most widely used chemical model of selective retinal pigment epithelium (RPE) toxicity in rodent vision research. A single systemic dose produces an oxidative insult that selectively destroys RPE cells. The loss of RPE in turn drives secondary photoreceptor degeneration, geographic-atrophy-like outer retinal disorganisation, and progressive visual function decline (Carido et al., 2014, IOVS). The phenotype mimics the central RPE pathology of dry, late-stage age-related macular degeneration (AMD) closely enough that the NaIO₃ model has become the standard preclinical platform for RPE replacement and neuroprotection therapies.

This page focuses specifically on the use of NaIO₃ as a controlled, reproducible RPE-toxicity model in mouse and on the visual-function readouts that resolve its progression.

Also see: Retinal Degeneration and Inherited Retinal Disease and Ocular and CNS Toxicity Models.

Vision: A Window into the brain

Why Vision Matters in Sodium Iodate Model Research

For researchers using NaIO₃ primarily as a structural RPE-injury model, optomotor-reflex visual function provides three concrete advantages over structure-only readouts. First, the functional consequence of RPE loss is the clinically meaningful endpoint: vision, not RPE pixel count, is what AMD therapies must ultimately rescue, so a behavioural functional readout aligns the preclinical study design with the translational objective. Second, optomotor visual function is non-invasive and repeatable, so the same animal can be tested before injection, at the acute RPE-loss phase, and across the secondary photoreceptor degeneration and (where applicable) post-transplantation rescue phases -- a within-animal trajectory that terminal histology and ERG-under-anaesthesia cannot match (Carido et al., 2014, IOVS). Third, contrast sensitivity and acuity capture different aspects of the retinal-circuit consequences of RPE loss and can be combined to characterise the functional phenotype with greater resolution than acuity alone.

The implication is methodological: an OptoDrum station already in a vision-research lab is a high-throughput, non-invasive functional sensor that complements OCT and ERG in NaIO₃ studies and is particularly well-suited to longitudinal designs evaluating RPE-replacement, neuroprotection, or anti-oxidant interventions.

Animal Models

Animal Models with Documented Retinal Phenotypes Relevant to Sodium Iodate Toxicity

C57BL/6 mouse with single systemic NaIO₃ dose (50 mg/kg, intravenous): This dose produces complete, reproducible RPE loss within days, followed by secondary photoreceptor degeneration over weeks, and is the model of choice when the experimental aim is a clean RPE-ablation substrate (for example, before RPE transplantation). OptoDrum was used for longitudinal photopic visual acuity assessment alongside OCT and ERG, establishing the functional decline trajectory that follows the structural RPE loss. (Carido et al., 2014, IOVS)
Lower-dose and partial-RPE-loss NaIO₃ protocols (10-30 mg/kg): Lower NaIO₃ doses produce patchy RPE damage and slower, milder photoreceptor degeneration, more closely resembling early AMD. These dose variants extend the temporal window for testing neuroprotective interventions and fall squarely within the OptoDrum capability (acuity, contrast sensitivity).
Rat NaIO₃ models: Rat NaIO₃ protocols predate the mouse model and produce comparable RPE-and-secondary-photoreceptor pathology.

Research Questions

How Can Striatech Tools support Your Study?

Select a question that matches your research objective to see which instruments are relevant, what challenge they address, and what the published evidence shows.

How Does NaIO3-Induced RPE Loss Translate Into Measurable Visual Function Decline, and What Are the Kinetics in Mouse?

Audience A - Vision-focused

Audience B - CNS/Systemic

Quick Answer

A single systemic NaIO₃ dose in mouse causes complete RPE loss within days. OptoDrum captures the resulting decline in photopic visual acuity over the subsequent weeks as secondary photoreceptor degeneration progresses, providing a longitudinal functional readout that pairs naturally with OCT and ERG structural endpoints.

The challenge

NaIO₃ produces a temporally compound phenotype: an acute, near-immediate selective RPE injury followed by a slower, secondary photoreceptor degeneration. Resolving the functional consequence of this two-phase pathology in a single cohort is not straightforward with structure-only or terminal-only endpoints. ERG under anaesthesia gives a snapshot of retinal-circuit response, but in the awake animal the integrated, perceptually-relevant readout that translational AMD work most needs is a functional acuity or contrast-sensitivity measure. Histology and OCT capture the RPE-and-photoreceptor structural cascade but only at fixed time points, and -- in the case of histology -- only terminally.

A non-invasive, repeated-measures functional readout that follows the same animal across the acute RPE-loss phase, the secondary degeneration phase, and (where applicable) any post-treatment recovery phase is the methodological link between NaIO₃-induced structural pathology and the translationally relevant functional outcome. Such a readout also supports tighter cohort designs, since each animal acts as its own baseline.

How Striatech products help

OptoDrum

Measures photopic spatial visual acuity (cycles per degree) and contrast sensitivity via the subcortical optomotor reflex in awake, freely moving mice. Provides a non-invasive, repeatable functional readout that follows NaIO₃-induced visual decline across the acute RPE-loss phase and the slower secondary photoreceptor degeneration phase, complementing OCT and ERG.

AcuiSee

Measures visual acuity via operant visual-reward paradigm requiring cortical visual processing. Applicable where researchers want to confirm that NaIO₃-driven retinal pathology propagates to suprathreshold cortical visual perception.

Non-aversive Animal Platform

Reduces handling stress in NaIO₃-treated animals during the acute systemic-toxicity phase, where conventional restraint can compound systemic stress and confound functional outcomes.

UV ERG Booster

For the cone side of ERG monitoring, the UV ERG Booster adds a UV S-cone response after sodium iodate injury.

Evidence from the Literature

Remlinger et al (2023) Neurol. Neuroimmunol. Neuroinflamm.
Feature →
Carido et al (2014) IOVS
Single-dose systemic NaIO₃ in C57BL/6 mouse produced complete RPE loss within days followed by progressive photoreceptor degeneration. OptoDrum-measured photopic visual acuity declined in parallel with the structural pathology over the post-injection weeks.

Is the NaIO3 Mouse Model Suitable as a Preclinical Platform for RPE Cell Transplantation, and How Should Visual Function Be Used as a Rescue Endpoint?

Audience A - Vision-focused

Audience B - CNS/Systemic

Quick Answer

The complete RPE ablation produced by systemic NaIO₃ creates a clean recipient substrate for RPE cell transplantation, and OptoDrum-measured visual function provides the longitudinal functional rescue endpoint required to evaluate whether transplanted RPE protects the underlying photoreceptors and preserves vision.

The challenge

RPE cell-replacement therapy is one of the most clinically advanced retinal regenerative approaches, but preclinical evaluation requires a model in which native RPE is reliably ablated -- so that transplant survival and function can be assessed without confounding from residual host RPE -- and in which the functional consequence of any rescue can be quantified longitudinally. Most genetic RPE-degeneration models produce slow, partial RPE loss with significant background variability. NaIO₃ ablation is faster, more uniform, and dose-controllable, but its rapid pathology is also unforgiving: any rescue endpoint must be sensitive enough to detect functional preservation against a steeply declining baseline.

Designing a rescue study therefore requires two elements that historically have been in tension: a well-characterised structural ablation timeline (RPE loss, photoreceptor decline) and a non-invasive longitudinal functional readout that resolves graft-mediated preservation against that timeline.

Also see: Maintaining and Restoring Vision.

How Striatech products help

OptoDrum

Provides the longitudinal, non-invasive functional rescue endpoint required to evaluate RPE-transplantation outcomes against the steep NaIO₃ functional decline baseline. Within-animal acuity tracking allows each animal to act as its own pre-injection control, increasing the statistical power of rescue studies with limited graft material.

AcuiSee

Provides cortical-pathway acuity assessment via operant visual discrimination. Applicable where researchers want to test whether RPE-transplant-mediated photoreceptor preservation supports suprathreshold cortical visual perception, complementing the subcortical OptoDrum endpoint. No NaIO₃-specific publications yet; inclusion is based on confirmed product capability.

Non-aversive Animal Platform

Important in transplantation studies where subretinal injection and post-operative management already tax the animal; reducing handling-induced stress improves the reliability of repeated functional measurements.

UV ERG Booster

The UV ERG Booster isolates the UV S-cone ERG, testing whether RPE transplantation restores cone-driven as well as rod-driven responses.

Evidence from the Literature

Remlinger et al (2023) Neurol. Neuroimmunol. Neuroinflamm.
Feature →
Carido et al (2014) IOVS
Demonstrated that NaIO₃-treated mice are a viable recipient substrate for RPE cell transplantation, with OptoDrum visual acuity providing the functional context against which transplant-mediated preservation can be evaluated. Establishes the methodological pattern for combining a clean RPE-ablation baseline with longitudinal functional readouts in regenerative-medicine studies.
Sharma et al (2019) Sci Transl Med.
Demonstrated subretinal transplantation of induced-pluripotent-stem-cell-derived RPE patches in a NaIO₃-injured pig model with structural and functional preservation, illustrating the translational arc that begins with murine NaIO₃ studies.

Product Fit

Summary: Striatech Products supporting your research questions

Research Question	OptoDrum	ScotopicKit	AcuiSee	Photorefractor	Keratometer	DarkAdapt	Non-aversive platform
RPE loss kinetics and secondary photoreceptor function decline	Yes		Yes				Yes
RPE transplantation rescue endpoint	Yes		Yes				Yes

Notes: ScotopicKit and DarkAdapt are not central in NaIO₃ studies in the available preclinical evidence -- the model is dominated by photopic acuity decline tracking the structural RPE-and-photoreceptor cascade, and Carido (2014) used OptoDrum in its photopic configuration. They could be added in study designs that specifically interrogate scotopic / rod-pathway function during partial-loss NaIO₃ protocols. Photorefractor and Keratometer are not applicable in NaIO₃ contexts; they measure refractive state and corneal curvature, neither of which is a primary endpoint in chemically-induced RPE-and-photoreceptor pathology. AcuiSee has no NaIO₃-specific publications yet; inclusion is based on its confirmed capability for cortical visual function assessment.

Measurement Modalities

Measuring Functional Visual Outcomes in Sodium Iodate Retinal Toxicity Model: How Do Available Methods Compare?

Modality	Invasiveness	Repeatability	Training required	Automation	3Rs impact	Scope in NaIO₃ models
OptoDrum (optomotor reflex)	Non-invasive; awake, unrestrained animal	High; same animal pre-injection and across the post-injection weeks	Low; automated threshold tracking	Fully automated threshold determination	Supports Replacement (vs. terminal histology for some questions) and Refinement	Subcortical retina-to-brainstem pathway integrity; integrated functional consequence of RPE-and-photoreceptor loss
AcuiSee (operant visual discrimination)	Non-invasive; reward-based operant task	High after training; repeatable longitudinally	Moderate; days to weeks of animal training	Automated task delivery	Refinement; reward-based, stress-minimised	Cortical visual processing; suprathreshold visual perception consequence of NaIO₃ retinal injury
OCT (optical coherence tomography)	Requires topical anaesthetic / sedation	Moderate	High; equipment and analysis expertise	Semi-automated layer segmentation	Refinement possible; equipment access may limit use	RPE and outer-retinal layer architecture; structural backbone of NaIO₃ phenotyping
ERG (full-field electroretinogram)	Requires anaesthesia and corneal contact	Moderate; anaesthesia confounds repeated testing	High	Semi-automated waveform analysis	Refinement; minimises terminal sacrifice when used longitudinally	Photoreceptor-and-bipolar-cell electrophysiological response; complementary to OptoDrum behavioural function
Fundoscopy and autofluorescence imaging	Requires topical anaesthetic / sedation	High	Moderate	Manual or semi-automated grading	Refinement; non-terminal	Macroscopic RPE-loss territory; useful for confirming dose-induced ablation extent
RPE histology (terminal)	Terminal	None (terminal)	Moderate	Semi-automated quantification	Reduction; terminal sacrifice required	Direct structural confirmation of RPE loss and graft survival

OptoDrum-based functional testing and the structural and electrophysiological endpoints classically used in NaIO₃ research are complementary rather than competing. OptoDrum captures an integrated, non-invasive, retina-driven functional outcome at high temporal resolution across the post-injection course; OCT, ERG, fundoscopy, and terminal histology each contribute different layers of information at lower temporal or terminal resolution. A study design that combines longitudinal OptoDrum testing with OCT-and-fundoscopy structural tracking and terminal histology delivers a multidimensional view of NaIO₃-induced RPE-and-photoreceptor pathology -- and of any therapeutic rescue against it -- not achievable by any single modality alone.

Supported by Striatech Products

Publications on Sodium Iodate Retinal Toxicity Model

Investigative Ophthalmology & Visual Science (Aug 07, 2014) Characterization of a mouse model with complete RPE loss and its use for RPE cell transplantation

Carido M, Zhu Y, Postel K, Benkner B, Cimalla P, Karl MO, Kurth T, Paquet-Durand F, Koch E, Münch TA, Tanaka EM, Ader M

DOI: 10.1167/iovs.14-14325 >>

Featured image for “Characterization of a mouse model with complete RPE loss and its use for RPE cell transplantation”

Carido et al present the sodium iodate mouse model of age-related macular degeneration. Systemic injection of sodium iodate leads to death of retinal pigment epithelium, with subsequent photoreceptor cell death. OptoDrum measurements show that the vision loss can be tracked at the behavioral level.

Purpose: Age-related macular degeneration (AMD) is a major leading cause of visual impairment and blindness with no cure currently established. Cell replacement of RPE is discussed as a potential therapy for AMD. Previous studies were performed in animal models with severe limitations in recapitulating the disease progression. In detail, we describe the effect of systemic injection of sodium iodate in the mouse retina. We further evaluate the useful-ness of this animal model to analyze cell-specific effects following transplantation of human embryonic stem cell (hESC)-derived RPE cells. Methods: Morphologic, functional, and behavioral changes following sodium iodate injection were monitored by histology, gene expression analysis, electroretinography, and optokinetic head tracking. Human embryonic stem cell–derived RPE cells were transplanted 1 week after sodium iodate injection and experimental retinae were ana-lyzed 3 weeks later. Results: Injection of sodium iodate caused complete RPE cell loss, photoreceptor degeneration, and altered gene and protein expression in outer and inner nuclear layers. Retinal function was severely affected by day 3 and abol-ished from day 14. Following transplantation, donor hESC-derived RPE cells formed extensive monolayers that dis-played wild-type RPE cell morphology, organization, and function, including phagocytosis of host photoreceptor outer segments. Conclusions: Systemic injection of sodium iodate has considerable effects on RPE, photoreceptors, and inner nu-clear layer neurons, and provides a model to assay reconstitution and maturation of RPE cell transplants. The avail-ability of an RPE-free Bruch's membrane in this model likely allows the unprecedented formation of extensive polar-ized cell monolayers from donor hESC-derived RPE cell suspensions.