Pharmacological reprogramming of zebrafish lateral line supporting cells to a migratory progenitor state.

In the zebrafish lateral line, non-sensory supporting cells readily re-enter the cell cycle to generate new hair cells and supporting cells during homeostatic maintenance and following damage to hair cells. This contrasts with supporting cells from mammalian vestibular and auditory sensory epithelia which rarely re-enter the cell cycle, and hence loss of hair cells results in permanent sensory deficit. Lateral line supporting cells are derived from multipotent progenitor cells that migrate down the trunk midline as a primordium and are deposited to differentiate into a neuromast. We have found that we can revert zebrafish support cells back to a migratory progenitor state by pharmacologically altering the signaling environment to mimic that of the migratory primordium, with active Wnt signaling and repressed FGF signaling. The reverted supporting cells migrate anteriorly and posteriorly along the horizontal myoseptum and will re-epithelialize to form an increased number of neuromasts along the midline when the pharmacological agents are removed. These data demonstrate that supporting cells can be readily reprogrammed to a migratory multipotent progenitor state that can form new sensory neuromasts, which has important implications for our understanding of how the lateral line system matures and expands in fish and also suggest avenues for returning mammalian supporting cells back to a proliferative state.

Local impedance-guided radiofrequency ablation with standard and high power: Results of a preclinical investigation.

BACKGROUND: Local impedance (LI) drop measured with microfidelity electrodes embedded in the tip of an ablation catheter accurately reflects tissue heating during radiofrequency (RF) ablation. Previous studies found 15-30 Ω LI drops created successful lesions, while more than 40 Ω drops were associated with steam pops. The objective of this study was to evaluate the safety and efficacy of LI-guided ablation using standard (30 W) and high-power (50 W) in a preclinical model. METHODS: RF lesions were created in explanted swine hearts (n = 6) to assess the feasibility of LI-guided ablation by targeting 10, 20, or 30 Ω (n = 20/group) drops. Subsequently, LI-guided ablation was evaluated in a chronic animal model (n = 8 Canines, 25-29 kg, 30/50 W). During the index procedure point-by-point intercaval line ablation and left inferior pulmonary vein (PV) isolation were performed. RF duration was at the operators' discretion but discontinued early if a 15-30 Ω drop was achieved. Operators attempted to avoid LI drops of more than 40 Ω. At 1-month, durable conduction block was evaluated with electroanatomic mapping followed by necropsy and histopathology. RESULTS: In explanted tissue, terminating ablation at 10, 20, or 30 Ω LI drops created statistically larger lesions (p < .05; 1.8 [1.6-2.4] mm, 3.3 [3.0-3.7] mm; 4.9 [4.3-5.5] mm). LI-guided high-power ablation in vivo significantly reduced RF duration per application compared to standard-power (p < .05; intercaval: 8.9 ± 5.2 vs. 18.1 ± 11.0 s, PV: 9.6 ± 5.4 vs. 23.2 ± 10.3 s). LI drops of 15-40 Ω were more readily achievable for high-power (90.1%, 318/353) than standard-power (71.7%, 243/339). All intercaval lines and PV isolations were durable (16/16) at 1-month. Necropsy revealed no major collateral injury to the pericardium, phrenic nerve, esophagus, or lungs. There was no pericardial effusion, stroke, tamponade, or PV stenosis. Vagal nerve injury was found in two 30 W animals after using 19.7 ± 13.9 and 19.5 ± 11.8 s RF applications. CONCLUSION: LI-guided ablation was found to be safe and efficacious in a chronic animal model. High-power ablation more readily achieved more than 15 Ω drops, reduced RF duration compared with standard-power, and had no major RF collateral injury.

High-risk catheter ablation of refractory atrial fibrillation using Impella CP in a patient with cardiogenic shock.

BACKGROUND: Impella CP support during Posterior Vein Isolation/Posterior Wall Isolation (PVI/PWI) in the setting of persistent cardiogenic shock from refractory atrial fibrillation with rapid ventricular response (AF/RVR), has not been reported in the literature to the best of our knowledge. CASE: A 61-year-old male truck driver was admitted with acute HFrEF with AF/RVR 130 - 150. His EF was 20% with global hypokinesis. He was diuresed and cardioverted to sinus rhythm and had QTc of 532. He reverted to AF/RVR in less than 24 hours, requiring amiodarone drip. Shortly, amiodarone was discontinued because of intense anorexia, nausea, and vomiting. Class III and Class 1c agents were contraindicated due to prolonged QTc and cardiomyopathy. He developed cardiogenic shock, worsening cardiorenal syndrome, and shock liver requiring continuous renal replacement therapy (CRRT). Inotropes and vasopressors were contraindicated. AVN ablation was refused because he wanted to return to truck driving. EF dropped to 10%, and moderate RV dysfunction ensued. Right heart catheterization showed PASP 53, PADP 38, and PCWP 37 with RAP 28mmHg. Coronary angiogram was normal. An Impella device was inserted, and support was set to P6 with 3.4 L/min cardiac output. PVI with cryoablation, PWI, and anterior mitral isthmus ablation was successful. The adequacy of isolation was verified by demonstrating a complete exit block 30 mins after ablation. Normal sinus rhythm was restored after cardioversion. Echo 48 hours later revealed improvement in EF from 10% to 40% in sinus rhythm. Impella and CRRT were weaned. He was discharged on GDMT. CONCLUSION: There are no recommendations regarding PVI for AF/RVR on mechanical circulatory support (MCS). MCS assisted PVI/PWI may be the only resort to restore hemodynamic stability in cases where a pacemaker is not desirable. PVI/PWI is a lengthy procedure; the use of the Impella support for PVI/PWI in cardiogenic shock allows adequate time for exit block testing and PWI. The operator can do thorough mapping and ablation, knowing that the patient is receiving adjustable support based on hemodynamic demands. We had a good outcome; nevertheless, the potential pitfalls are unknown.

Stratifying risk of recurrence of atrial fibrillation following balloon cryoablation using the CAAP-AF risk scoring system.

OBJECTIVE: To determine if the CAAP-AF tool could be applied to a cohort of patients in the United States undergoing cryoablation or AF utilizing second-generation cryoballoons. BACKGROUND: Atrial fibrillation (AF) is a major source of morbidity and expense, with over 33 million individuals affected worldwide and over 450 000 hospitalizations annually in the United States. Catheter ablation for AF is a class I indication for patients with symptomatic AF. The ability to predict postablation recurrence would have an enormous impact on both patient outcomes and cost to the health care system. METHODS: Our study was an observational, single-center retrospective study to evaluate the utility of the CAAP-AF risk scoring system in predicting recurrence of AF following second-generation balloon cryoablation for AF. RESULTS: There were a total of 235 patients. From the initial cohort, 30.2% (71) had a recurrence of AF within 1 year of the cryoablation procedure. There was a statistically significant increase in mean age, left atrial diameter, left atrial volume index, CHADS2 , CHADS2 -VASc, and number of antiarrhythmics failed in the group that had recurrence of AF. There was also a statistically significant increase in the CAAP-AF score in patients who had recurrence of AF. CONCLUSIONS: The CAAP-AF score predicted the freedom from AF 1 year following cryoablation for AF. The CAAP-AF score can aid in selecting patients most likely to benefit from cryoablation, which includes patients with a low CAAP-AF score, as they are most likely to remain AF free at 1 year.

Sulf1 modulates BMP signaling and is required for somite morphogenesis and development of the horizontal myoseptum.

Heparan sulfate proteoglycans (HSPGs) are glycosylated extracellular or membrane-associated proteins. Their unbranched heparan sulfate (HS) disaccharide chains interact with many growth factors and receptors, modifying their activity or diffusion. The pattern of HS sulfation can be altered by the enzymes Sulf1 and Sulf2, secreted extracellular 6-O endosulfatases, which remove specific sulfate groups from HS. Modification by Sulf enzymes changes the binding affinity of HS for protein such as ligands and receptors, affecting growth factor gradients and activities. The precise expression of these sulfatases are thought to be necessary for normal development. We have examined the role of the sulf1 gene in trunk development of zebrafish embryos. sulf1 is expressed in the developing trunk musculature and as well as in midline structures such as the notochord, floorplate and hypochord. Knockdown of sulf1 with antisense morpholinos results in poor differentiation of the somitic trunk muscle, loss of the horizontal myoseptum, lack of pigmentation along the mediolateral stripe, and improper migration of the lateral line primordium. sulf1 knockdown results in a decrease in the number of Pax7-expressing dermomyotome cells, particularly along the midline where the horizontal myoseptum develops. It also leads to decreased sdf1/cxcl12 expression along the mediolateral trunk musculature. Both the Pax7 and cxcl12 expression can be restored by inhibition pharmacological inhibition of BMP signaling, which also restores formation of the myoseptum, fast muscle development, and pigmentation patterning. Lateral line migration and neuromast deposition depend on sdf1/cxcl12 and FGF signaling respectively, both of which are disrupted in sulf1 morphants. Pharmacological activation of FGF signaling can rescue the spacing of neuromast deposition in these fish. Together this data indicate that sulf1 plays a crucial role in modulating both BMP and FGF signaling along the developing myoseptum to coordinate the morphogenesis of trunk musculature, associated pigment cells, and lateral line neuromasts.

Epistaxis in a patient on antiplatelet therapy: not always benign.

Epistaxis in patients on antiplatelet and anticoagulant therapy is common and typically benign. We present a case of a rare nasal septal malignancy in a patient on antiplatelet therapy and discuss worrisome symptoms and signs which should prompt early referral to a specialist.

Activation of canonical Wnt/ß-catenin signaling stimulates proliferation in neuromasts in the zebrafish posterior lateral line.

BACKGROUND: The posterior lateral line in zebrafish develops from a migrating primordium that deposits clusters of cells that differentiate into neuromasts at regular intervals along the trunk. The deposition of these neuromasts is known to be coordinated by Wnt and FGF signals that control the proliferation, migration, and organization of the primordium. However, little is known about the control of proliferation in the neuromasts following their deposition. RESULTS: We show that pharmacological activation of the Wnt/ß-catenin signaling pathway with 1-azakenpaullone upregulates proliferation in neuromasts post-deposition. This results in increased size of the neuromasts and overproduction of sensory hair cells. We also show that activation of Wnt signaling returns already quiescent supporting cells to a proliferative state in mature neuromasts. Additionally, activation of Wnt signaling increases the number of supporting cells that return to the cell cycle in response to hair cell damage and the number of regenerated hair cells. Finally, we show that inhibition of Wnt signaling by overexpression of dkk1b suppresses proliferation during both differentiation and regeneration. CONCLUSIONS: These data suggest that Wnt/ß-catenin signaling is both necessary and sufficient for the control of proliferation of lateral line progenitors during development, ongoing growth of the neuromasts, and hair cell regeneration.

Complication from hearing aid mold material: a case report and review of legal matters.

Ear mold impression middle ear foreign bodies are a rare complication of hearing aid fitting. Only a small number of cases have been reported; however, the actual incidence is unknown and likely much higher than expected. We present the case of a 77-year-old man with a history of preexisting tympanic membrane perforations who presented with an ear mold impression middle ear foreign body that required surgical removal. We explore the state and federal laws that guide the interaction between patients, hearing aid sellers and otolaryngologists. We highlight steps that can be taken to reduce the incidence of this complication.

White epaxial muscle aerobic and anaerobic potential and muscle fiber structure in surface and cave morphotypes of the Mexican cavefish (Astyanax mexicanus).

Proper muscle function and muscle fiber structures that match the environmental demands of organisms are imperative to their success in any ecosystem. The Mexican cavefish, Astyanax mexicanus, has two morphotypes: an obligate cave-dwelling form that lives in thermally insulated caves and an O2 poor environment, and a surface form that lives in a more thermally variable, but O2 rich river environment. As environment can determine physiological adaptations, it is of interest to compare the aerobic and anaerobic metabolic profiles of white muscle metabolism in both morphotypes of this species, as well as their muscle structures. Here, we used white muscle of both morphotypes of the Mexican cavefish to determine citrate synthase (CS) activity as a measure of aerobic potential, and lactate concentration as a measure of anaerobic potential at three different chronic acclimation temperatures (14°C, 25°C, and 31°C). By examining aerobic and anaerobic potential in both morphs, we sought to link environmental thermal flexibility to muscle metabolism. We found that the surface morphotype had higher CS activity and lower lactate concentration, suggesting an overall more efficient usage of aerobic metabolism; whereas the cave morphotype showed lower CS activity and higher lactate concentration, suggesting a stronger reliance on anaerobic pathways. We also measured white muscle histological variables that have been previously linked to whole-animal metabolism: fiber diameter, number of nuclei per mm of fiber and myonuclear domain (MND) of both morphotypes at 25°C to examine cell-level differences in muscle morphology. However, we found no differences in fiber diameter, number of nuclei per mm of fiber or MND between the two morphotypes. Thus, although the cellular morphology is similar in these species, the environmental differences in the evolution of the two morphs has led to differences in their metabolic profiles.

Chronic Thermal Acclimation Effects on Critical Thermal Maxima (CTmax) and Oxidative Stress Differences in White Epaxial Muscle between Surface and Cave Morphotypes of the Mexican Cavefish (Astyanax mexicanus).

AbstractIn the face of increasing environmental temperatures, operative differences between mitochondrial function and whole-animal phenotypic response to the environment are underrepresented in research, especially in subtemperate ectothermic vertebrates. A novel approach to exploring this connection is to examine model species that are genetically similar but that have different whole-animal phenotypes, each of which inhabits different environments. The blind Mexican cavefish (Astyanax mexicanus) has the following two morphotypes: a surface form found in aboveground rivers and an obligate cave-dwelling form. Each morphotype inhabits vastly different thermal and oxygen environments. Whole-animal and mitochondrial responses to thermal acclimation and oxidative stress, with respect to increasing temperatures, have not been previously determined in either morphotype of this species. Here, we chronically acclimated both morphotypes to three temperatures (14°C, 25°C, and 31°C) to establish potential for acclimation and critical thermal maxima (CTmax) for each morphotype of this species. After measuring CTmax in six cohorts, we additionally measured enzymatic antioxidant capacity (catalase, superoxide dismutase, and glutathione peroxidase activities), peroxyl scavenging capacity, and lipid peroxidation damage in white epaxial muscle for each individual. We found a significant effect of acclimation temperature on CTmax (F=29.57, P<0.001) but no effect of morphotype on CTmax (F=2.092, P=0.162). Additionally, we found that morphotype had a significant effect on glutathione peroxidase activity, with the surface morphotype having increased glutathione peroxidase activity compared with the cave morphotype (F=6.270, P=0.020). No other oxidative stress variable demonstrated significant differences. Increases in CTmax with chronic thermal acclimation to higher temperatures suggests that there is some degree of phenotypic plasticity in this species that nominally occupies thermally stable environments. The decreased glutathione peroxidase activity in the cave morphotype may be related to decreased environmental oxygen concentration and decreased metabolic rate in this environmentally constrained morphotype compared to in its surface-living counterparts.

Catheter ablation of atrial fibrillation in hypertrophic cardiomyopathy: A proportional meta-analysis and systematic review of single-arm studies.

Background: Atrial fibrillation (AF) is the most common arrhythmia in patients with hypertrophic cardiomyopathy (HCM). Limited data exists about the efficacy and clinical outcomes of AF ablation in HCM. Objective: The purpose of this meta-analysis was to evaluate the role of catheter-based ablation for treatment of AF in patients with HCM. Methods: PubMed, SCOPUS, Web of Science, Embase, Cochrane library, and ClinicalTrials.gov were searched for studies discussing outcomes of catheter-based ablation for AF in patients with HCM. Two reviewers independently screened studies and extracted relevant data. Incidence rate estimates from individual studies underwent logit transformation to calculate the weighted summary proportion under the random effect model. Results: A total of 19 reports met the inclusion criteria (1183 patients). The single ablation procedure was successful in 39% patients. Up to 34% patients underwent a repeat ablation. About 41% patients in normal sinus rhythm after successful AF ablation received postprocedure antiarrhythmic drug (AAD) therapy. Patients undergoing successful AF ablation experienced a significant improvement in the New York Heart Association functional class (standardized mean difference -1.03; 95% confidence interval -1.23 to -0.83; P < .00001). Conclusion: AF ablation appears to be safe and feasible in patients with HCM. Freedom from AF after undergoing successful ablation is associated with significant improvement in heart failure symptoms.

Improved Ablation Efficiency in PVI Guided by Contact Force and Local Impedance: Chronic Canine Model.

Background: The purpose of this study was to assess the effect local impedance (LI) has on an ablation workflow when combined with a contact force (CF) ablation catheter. Methods: Left pulmonary vein isolation was performed in an in vivo canine model (N = 8) using a nominal (30 W) or an elevated (50 W) power strategy with a CF catheter. The catheter was enabled to measure LI prior to and during ablation. LI was visible for only one of the vein isolations. Results: Chronic block was achieved in all animals when assessed 30 ± 5 days post-ablation procedure with a median LI drop during RF ranging from 23.0 to 34.0 Ω. In both power cohorts, the median radiofrequency (RF) duration decreased if LI was visible to the operator (30 W only CF: 17.0 s; 30 W CF + LI: 14.0 s, p = 0.009; 50 W only CF: 6.0 s; 50 W CF + LI: 4.0 s, p = 0.019). An inverse relationship between the LI prior to RF delivery and the RF duration required to achieve an effective lesion was observed. There was no correlation between the magnitude of the applied force and the drop in LI, once at least 5 g was achieved. Conclusions: An elevated power strategy with the context of CF and LI led to the most efficient titration of successful RF energy delivery. The combination of feedback allows for customization of the ablation strategy based on local tissue variation rather than a uniform approach that could potentially lead to overtreatment. Higher LI drops were more readily achievable when an elevated power strategy was utilized, especially in conditions where the catheter was coupled against tissue with low resistivity. Clinical study is warranted to determine if there is an additive safety benefit to visualizing the dynamics of the tissue response to RF energy with LI when an elevated power strategy is used.

A compact tunable diode laser absorption spectrometer to monitor CO2 at 2.7 µm wavelength in hypersonic flows.

Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship's Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow.

Combined local impedance and contact force for radiofrequency ablation assessment.

BACKGROUND: The combination of contact force (CF) and local impedance (LI) may improve tissue characterization and lesion prediction during radiofrequency (RF) ablation. OBJECTIVE: The purpose of this study was to evaluate the utility of LI combined with CF in assessing RF ablation efficacy. METHODS: An LI catheter with CF sensing was evaluated in swine (n = 11) and in vitro (n = 14). The relationship between LI and CF in different tissue types was evaluated in vivo. Discrete lesions were created in vitro and in vivo at a range of forces, powers, and durations. Finally, an intercaval line was created in 3 groups at 30 W: 30s, Δ20Ω, and Δ30Ω. In the Δ20Ω and Δ30Ω groups, the user ablated until a 20 or 30 Ω LI drop. In the 30s group, the user was blinded to LI. RESULTS: In vivo, distinction in LI was found between the blood pool and the myocardium (blood pool: 122 ± 7.02 Ω; perpendicular contact: 220 ± 29 Ω; parallel contact: 207 ± 31 Ω). LI drop correlated with lesion depth both in vitro (R = 0.84) and in vivo (R = 0.79), informing sufficient lesion creation (LI drop >20 Ω) and warning of excessive heating (LI drop >65 Ω). When creating an intercaval line, the total RF time was significantly reduced when using LI guidance (6.4 ± 2 minutes in Δ20Ω and 8.1 ± 1 minutes in Δ30Ω) compared with a standard 30-second workflow (18 ± 7 minutes). Acute conduction block was achieved in all Δ30Ω and 30s lines. CONCLUSION: The addition of LI to CF provides feedback on both electrical and mechanical loads. This provides information on tissue type and catheter-tissue coupling; provides feedback on whether volumetric tissue heating is inadequate, sufficient, or excessive; and reduces ablation time.

Potential for control of signaling pathways via cell size and shape.

BACKGROUND: In order for signals generated at the plasma membrane to reach intracellular targets, activated messengers, such as G proteins and phosphoproteins, must diffuse through the cytoplasm. If the deactivators of these messengers, GTPase activating proteins (GAPs) and phosphatases, respectively, are sufficiently active in the cytoplasm, then the signal could in principle decay before reaching the target and a stable spatial gradient in phosphostate would be generated. Recent experiments document the existence of such gradients in living cells and suggest a role for them in mitotic spindle morphogenesis and cell migration. However, how such systems behave theoretically when embedded in a cell of varying size or shape has not been considered. RESULTS: Here we use a simple mathematical model to explore the theoretical consequences of a plasma membrane bound activator (i.e., guanine nucleotide exchange factor, GEF, or kinase) and a cytoplasmic deactivator (i.e., GAP or phosphatase), and we find that as a model cell grows, the substrate becomes progressively dephosphorylated as a result of decreased proximity to the activator. Conversely, as a cell spreads and flattens, the substrate becomes globally phosphorylated because of increased proximity of the substrate to the activator. Similarly, in the leading edge of polarized cells and in protrusions such as lamellipodia or filopodia, the substrate is highly phosphorylated. As a specific test of the model, we found that the experimentally observed preferential activation of the G protein Cdc42 in the periphery of fibroblasts that was recently reported is consistent with model predictions. CONCLUSIONS: We conclude that cell-signaling pathways can theoretically be turned on and off, both locally and globally, in response to alterations in cell size and shape.

Shape change controls supporting cell proliferation in lesioned mammalian balance epithelium.

Mature mammals are uniquely vulnerable to permanent auditory and vestibular deficits, because the cell proliferation that produces replacement hair cells in other vertebrates is limited in mammals. To investigate the cellular mechanisms responsible for that difference, we created excision lesions in the sensory epithelium of embryonic and 2-week-old mouse utricles. Lesions in embryonic utricles closed in <24 h via localized expansion of supporting cells, which then reentered the cell cycle. Pharmacological treatments combined with time-lapse microscopy demonstrated that the healing depended on Rho-mediated contraction of an actin ring at the leading edge of the lesion. In contrast, lesions in utricles from 2-week-old and older mice remained open even after 48 h. Supporting cells in those utricles remained compact and columnar and had significantly stouter cortical actin belts than those in embryonic sensory epithelia. This suggests that cytoskeletal changes may underlie the age-related loss of proliferation in mammalian ears by limiting the capacity for mature supporting cells to change shape. In mature utricles, exogenous stimulation with lysophosphatidic acid overcame this maturational block and induced closure of lesions, promoting supporting cell expansion and subsequent proliferation. After lysophosphatidic acid treatment, 85% of the mature supporting cells that had spread to a planar area >300 microm2 entered S-phase, whereas only 10% of those cells that had a planar area <100 microm2 entered S-phase. Together, these results indicate that cellular shape change can overcome the normal postnatal cessation of supporting cell proliferation that appears to limit regeneration in mammalian vestibular epithelia.

Late-stage neuronal progenitors in the retina are radial Müller glia that function as retinal stem cells.

Neuronal progenitors in the mammalian brain derive from radial glia or specialized astrocytes. In developing neural retina, radial glia-like Müller cells are generated late in neurogenesis and are not considered to be neuronal progenitors, but they do proliferate after injury and can express neuronal markers, suggesting a latent neurogenic capacity. To examine the neurogenic capacity of retinal glial cells, we used lineage tracing in transgenic zebrafish with a glial-specific promoter (gfap, for glial fibrillary acid protein) driving green fluorescent protein in differentiated Müller glia. We found that all Müller glia in the zebrafish retina express low levels of the multipotent progenitor marker Pax6 (paired box gene 6), and they proliferate at a low frequency in the intact, uninjured retina. Müller glia-derived progenitors express Crx (cone rod homeobox) and are late retinal progenitors that generate the rod photoreceptor lineage in the postembryonic retina. These Müller glia-derived progenitors also remain competent to produce earlier neuronal lineages, in that they respond to loss of cone photoreceptors by specifically regenerating the missing neurons. We conclude that zebrafish Müller glia function as multipotent retinal stem cells that generate retinal neurons by homeostatic and regenerative developmental mechanisms.

Application of video-based technology for the simultaneous measurement of accommodation and vergence.

Accommodation and vergence are two ocular motor systems that interact during binocular vision. Independent measurement of the response dynamics of each system has been achieved by the application of optometers and eye trackers. However, relatively few devices, typically earlier model optometers, allow the simultaneous assessment of accommodation and vergence. In this study we describe the development and application of a custom designed high-speed digital photorefractor that allows for rapid measures of accommodation (up to 75Hz). In addition the photorefractor was also synchronized with a video-based stereo eye tracker to allow a simultaneous measurement of accommodation and vergence. Analysis of accommodation and vergence could then be conducted offline. The new instrumentation is suitable for investigation of young children and could be potentially used for clinical populations.