Patient co-design of digital health storytelling tools for multimorbidity: A phenomenological study.

BACKGROUND: Interest in both narrative medicine and electronic health records has increased over the past 30 years. However, electronic health records are mainly written by and for clinicians, and the patient narrative and voice are not incorporated. Recent studies within the United Kingdom have indicated that there is a need to incorporate patient stories into health records, to improve quality and continuity of care. This is particularly important when treating people with multiple long-term health conditions (multimorbidity), whose health stories can be particularly complex. OBJECTIVE: To understand the goals and requirements of people with multimorbidity for digital health storytelling tools. METHODS: The methodology uses narrative within a phenomenological approach to inform a process of co-design. RESULTS: The findings indicate that people living with multimorbidity would use health storytelling tools to understand and reflect on their journeys, convey their experiences to others and advocate for themselves against scepticism. CONCLUSION: Outputs from the project give insight into the lived experience of multimorbidity, as well as understanding the goals of people living with multimorbidity for using health storytelling tools as part of treatment and self-management. Future research could explore other areas such as collaborative health storytelling or the technical implementation of tools. PATIENT OR PUBLIC CONTRIBUTION: Five adults with multiple long-term conditions participated in the project, and research was carried out in three stages. First, semistructured interviews were used to understand each participant's health story. Second, each participant worked with the researcher to co-design a visual representation of their story. Finally, digital prototypes based on their health story were reviewed with each of the participants.

User Requirements for Comanaged Digital Health and Care: Review.

BACKGROUND: The sustainability of health and social care has led to an imperative to shift the balance of care to communities and support person-centered, integrated, preventive, comanaged, and sustainable care. The digital tool set can support this shift; however, it must extend beyond a clinical focus to include broader personal, social, and environmental needs, experiences, and outcomes. The existing digital health and care design and user requirements literature focuses mainly on specific digital products or design methods. There is little whole-system or whole-of-life consideration, which is crucial to enacting more significant transformations that span different groups and domains. OBJECTIVE: This study aimed to present a set of recurring user requirements and themes for comanaged digital health and care services derived from the body of co-design projects within a digital health and care program. This study aimed to enable people and organizations looking to reorient their approach to health and care research and delivery from a system-led and condition-specific approach to a more person-centric, whole-of-life model. METHODS: Participatory design formed the core methodological approach in underlying the design research, from which user requirements were derived. The process of surfacing requirements involved a selection framework for the identification of eligible projects and a structured review process to consolidate user requirements. RESULTS: This paper presents a set of 14 common user requirements that resulted from a review of co-design projects. The findings demonstrate overlapping and reinforcing sets of needs from citizens and care professionals related to how data are comanaged to improve care and outcomes. This paper discusses the alignment, contrasts, and gaps with broader, comparable literature. It highlights consensus around requirements for personal health storytelling, sharing data on care experiences and how this can support personalized guidance, visualize trends to support decision-making, and generally improve dialog between a citizen and care professionals. These findings identify gaps around how groups and networks of people engage, posing difficult questions for people designing support services as some of the user requirements are not easily met by organizations operating in silos. CONCLUSIONS: This study proposes future recommendations for citizens as active, informed, and consenting partners using new forms of privacy-preserving digital infrastructure that puts the citizen in firm control. It is also recommended that these findings be used by people developing new digital services to ensure that they can start with knowledge of the broader user requirement context. This should inform domain-specific research and development questions and processes. Further work is needed to extend these common requirements to more explicitly consider the trust framework required when citizens comanage their data and care across a broad range of formal and informal actors. Consideration of how authority, delegation, and trust function between members of the public will be critical.

Transforming Capillary Alginate Gel (Capgel) into New 3D-Printing Biomaterial Inks.

Three-dimensional (3D) printing has great potential for creating tissues and organs to meet shortfalls in transplant supply, and biomaterial inks are key components of many such approaches. There is a need for biomaterial inks that facilitate integration, infiltration, and vascularization of targeted 3D-printed structures. This study is therefore focused on creating new biomaterial inks from self-assembled capillary alginate gel (Capgel), which possesses a unique microstructure of uniform tubular channels with tunable diameters and densities. First, extrusions of Capgel through needles (0.1-0.8 mm inner diameter) were investigated. It was found that Capgel ink extrudes as slurries of fractured and entangled particles, each retaining capillary microstructures, and that extruded line widths W and particle sizes A were both functions of needle inner diameter D, specifically power-law relationships of W~D0.42 and A~D1.52, respectively. Next, various structures were successfully 3D-printed with Capgel ink, thus demonstrating that this biomaterial ink is stackable and self-supporting. To increase ink self-adherence, Capgel was coated with poly-L-lysine (PLL) to create a cationic "skin" prior to extrusion. It was hypothesized that, during extrusion of Capgel-PLL, the sheared particles fracture and thereby expose cryptic sites of negatively-charged biomaterial capable of forming new polyelectrolyte bonds with areas of the positively-charged PLL skin on neighboring entangled particles. This novel approach resulted in continuous, self-adherent extrusions that remained intact in solution. Human lung fibroblasts (HLFs) were then cultured on this ink to investigate biocompatibility. HLFs readily colonized Capgel-PLL ink and were strongly oriented by the capillary microstructures. This is the first description of successful 3D-printing with Capgel biomaterial ink as well as the first demonstration of the concept and formulation of a self-adherent Capgel-PLL biomaterial ink.

High-sensitivity detection of optogenetically-induced neural activity with functional ultrasound imaging.

Whole-brain imaging approaches and optogenetic manipulations are powerful tools to map brain-wide neural circuits in vivo. To date, functional magnetic resonance imaging (fMRI) provides the most comprehensive evaluation of such large-scale circuitry. However, functional ultrasound imaging (fUSI) has recently emerged as a complementary imaging modality that can extend such measurements towards the context of diverse behavioral states and tasks. Nevertheless, in order to properly interpret the fUSI signal during these complicated scenarios, it must first be carefully validated against well-established technologies, such as fMRI, in highly controlled experimental settings. Here, to address this need, we compared subsequent fMRI and fUSI recordings in response to direct neuronal activation via optogenetics in the same animals under an identical anesthetic protocol. Specifically, we applied various intensities of light stimulation to the primary motor cortex (M1) of mice and compared the spatiotemporal dynamics of the elicited fMRI and fUSI signals. Overall, our general linear model analysis (t-scores) and time series analysis (z-scores) revealed that fUSI was more sensitive than fMRI for detecting optogenetically-induced neuronal activation. Local field potential recordings in the bilateral M1 and striatum also better co-localized with fUSI activation patterns than those of fMRI. Finally, the fUSI response contained distinct arterial and venous components that provide vascular readouts of neuronal activity with vessel-type specificity.

Patient Size-Dependent Dosimetry Methodology Applied to 18F-FDG Using New ICRP Mesh Phantoms.

Despite the known influence of anatomic variability on internal dosimetry, dosimetry for 18F-FDG and other diagnostic radiopharmaceuticals is routinely derived using reference phantoms, which embody population-averaged morphometry for a given age and sex. Moreover, phantom format affects dosimetry estimates to varying extent. Here, we applied newly developed mesh format reference phantoms and a patient-dependent phantom library to assess the impact of height, weight, and body contour variation on dosimetry of 18F-FDG. We compared the mesh reference phantom dosimetry estimates with corresponding estimates from common software to identify differences related to phantom format or software implementation. Our study serves as an example of how more precise patient size-dependent dosimetry methodology could be performed. Methods: Absorbed dose coefficients were computed for the adult mesh reference phantoms and derivative patient-dependent phantom series by Monte Carlo simulation using the PHITS radiation transport code within PARaDIM software. The dose coefficients were compared with reference absorbed dose coefficients obtained from ICRP Publication 128, or generated using software including OLINDA 2.1, OLINDA 1.1, and IDAC-dose 2.1. Results: Differences in dosimetry arising from anatomical variations were shown to be significant, with detriment-weighted dose coefficients for the percentile-specific phantoms varying by up to ±40% relative to the corresponding reference phantom effective dose coefficients, irrespective of phantom format. Similar variations were seen in the individual organ absorbed dose coefficients for the percentile-specific phantoms relative to the reference phantoms. The effective dose coefficient for the mesh reference adult was 0.017 mSv/MBq, which was 5% higher than estimated by a corresponding voxel phantom, and 10% lower than estimated by the stylized phantom format. Conclusion: We observed notable variability in 18F-FDG dosimetry across morphometrically different patients, supporting the use of patient-dependent phantoms for more accurate dosimetric estimations relative to standard reference dosimetry. These data may help in optimizing imaging protocols and research studies, in particular when longer-lived isotopes are employed.

Spatial-temporal aspects of continuous EEG-based neurorobotic control.

Objective.The goal of this work is to identify the spatio-temporal facets of state-of-the-art electroencephalography (EEG)-based continuous neurorobotics that need to be addressed, prior to deployment in practical applications at home and in the clinic.Approach.Nine healthy human subjects participated in five sessions of one-dimensional (1D) horizontal (LR), 1D vertical (UD) and two-dimensional (2D) neural tracking from EEG. Users controlled a robotic arm and virtual cursor to continuously track a Gaussian random motion target using EEG sensorimotor rhythm modulation via motor imagery (MI) commands. Continuous control quality was analyzed in the temporal and spatial domains separately.Main results.Axis-specific errors during 2D tasks were significantly larger than during 1D counterparts. Fatigue rates were larger for control tasks with higher cognitive demand (LR, left- and right-hand MI) compared to those with lower cognitive demand (UD, both hands MI and rest). Additionally robotic arm and virtual cursor control exhibited equal tracking error during all tasks. However, further spatial error analysis of 2D control revealed a significant reduction in tracking quality that was dependent on the visual interference of the physical device. In fact, robotic arm performance was significantly greater than that of virtual cursor control when the users' sightlines were not obstructed.Significance.This work emphasizes the need for practical interfaces to be designed around real-world tasks of increased complexity. Here, the dependence of control quality on cognitive task demand emphasizes the need for decoders that facilitate the translation of 1D task mastery to 2D control. When device footprint was accounted for, the introduction of a physical robotic arm improved control quality, likely due to increased user engagement. In general, this work demonstrates the need to consider both the physical footprint of devices, the complexity of training tasks, and the synergy of control strategies during the development of neurorobotic control.

A Low-Cost, Passive Release Device for the Surveillance and Control of Mosquitoes.

Mosquitoes continue to be a major threat to global health, and the ability to reliably monitor, catch, and kill mosquitoes via passive traps is of great importance. Global, low-cost, and easy-to-use outdoor devices are needed to augment existing efforts in mosquito control that combat the spread of disease, such as Zika. Thus, we have developed a modular, portable, non-powered (passive), self-contained, and field-deployable device suitable for releasing volatiles with a wide range of applications such as attracting, repelling, and killing mosquitoes. This unique device relies on a novel nested wick and two-reservoir design that achieves a constant release of volatiles over several hundred hours. Devices loaded with one of either two compounds, geraniol or 1-methylpiperazine (MP), were tested in a controlled environment (32 °C and 70% relative humidity), and both compounds achieved a constant release from our devices at a rate of 2.4 mg/h and 47 mg/h, respectively. The liquid payload can be volatile attractants or repellants as well as mosquitocide-containing feeding solutions for capture and surveillance. This low-cost device can be utilized for both civilian and military mosquito control purposes, but it will be particularly important for protecting those in economically repressed environments, such as sub-Saharan Africa and Central and South America.

Multiplex Viral Detection Platform Based on a Aptamers-Integrated Microfluidic Channel.

A polydimethylsiloxane-based microfluidic device has been developed for the multiplex detection of viral envelope proteins such as Zika and chikungunya on a single platform using aptamer-analyte interactions. The channel is integrated with microsized pillars that increase the surface area allowing more aptamers to attach to the incoming envelope protein molecules, thus increasing the overall sensitivity of the system. The working of the device depends on the formation of protein-mediated sandwich morphology that is obtained using an aptamer and aptamer-functionalized gold nanoparticle (AuNP) pair. The colorimetric signal is obtained upon introduction of silver reagents into the channel, which are selectively deposited on the AuNP surface, providing a gray contrast in the testing zone. The microfluidic channel approach successfully detected clinically relevant concentrations of Zika and chikungunya envelope proteins in phosphine-buffered saline (1 pM) and calf blood (100 pM) with high specificity using gold-decorated aptamers integrated in a microfluidic channel.

Aptamer-gold nanoparticle conjugates for the colorimetric detection of arboviruses and vector mosquito species.

The real-time, colorimetric detection of analytes via aptamer-gold nanoparticle technology has proven to be an important, emerging technique within the medical field. Of global health importance, the ability to detect vector mosquito species, such as the Aedes (Ae.) aegypti mosquito, and transmitted arboviruses, such as Zika virus, is paramount to mosquito control and surveillance efforts. Herein, we describe the detection of Ae. aegypti salivary protein for vector identification and the detection of Zika virus to assess mosquito infection status by aptamer-gold nanoparticle conjugates. Key to optimization of these diagnostics were gold nanoparticle capping agents and aptamer degree of labelling (i.e., the amount of aptamers per gold nanoparticle). In the present study, detection was achieved for as little as 10 ng Ae. aegypti salivary protein and 1.0 × 105 PFU live Zika virus. These aptamer-gold nanoparticle conjugate diagnostics could one day prove to be useful as deployable nano-based biosensors that provide easy-to-read optical read outs through a straightforward red-to-blue colour change either within a diagnostic solution or atop a card/membrane-based biosensor.

Manual no-fold push-in DSAEK graft insertion technique.

PURPOSE: To describe the manual no-fold push-in technique for Descemet stripping automated endothelial keratoplasty (DSAEK) graft insertion and analyze postoperative endothelial cell loss. METHODS: Twenty consecutive patients underwent DSAEK surgery using the manual no-fold push-in technique. This insertion technique uses a 6-mm limbal wound, a Sheets glide, and a Sinskey hook without the need for an inserter or additional instrumentation. RESULTS: Three patients developed graft dislocation, requiring re-bubbling. No primary graft failures were encountered. With an average postoperative follow-up of 13.22 months (SD, 7.94; range, 2.23-26.87), average automated endothelial cell count was 2329.62 cells per mm (SD, 312.78; range, 1657-2928) and the average cell loss was 23.31% (SD, 11.33; range, 5.56-42.76). CONCLUSIONS: This technique uses standard instrumentation and is simple to perform. This series demonstrates that manual graft insertion techniques can be effectively used in DSAEK surgery and provide patients with excellent postoperative results.

Comparison of a monocular pupillometer and the pupillometry function of a binocular free-viewing autorefractor.

PURPOSE: To compare a binocular free-viewing autorefractor pupillometer (WAM 5500 Binocular Accommodation Instrument) and a monocular occlusion pupillometer (Neuroptics pupillometer). SETTING: Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas, USA. DESIGN: Evaluation of diagnostic test or technology. METHODS: Normal subjects were tested under 1 lux and 7 lux ambient illumination with controlled distance fixation. The monocular occlusion pupillometer and free-viewing autorefractor pupillometer test order and eye test order were randomized. Devices were compared using Bland-Altman plots. Effects of eye test order and device test order were analyzed. The number of outliers (ie, difference ≥ 0.5 mm between devices) was tabulated. RESULTS: The mean device difference (monocular pupillometer minus binocular pupillometer) was +0.51 mm ± 0.36 (SD) (range -0.20 to +1.50 mm) in right eyes and +0.27 ± 0.31 mm (SD) (range -0.30 to +1.00 mm) in left eyes at 1 lux and +0.26 ± 0.28 mm (range -0.30 to +0.90 mm) and +0.21 ± 0.24 mm (range -0.80 to +0.40 mm), respectively, at 7 lux. The outlier frequency (N = 49) at 1 lux was 23 (47%) in right eyes and 7 (14%) in left eyes and at 7 lux, 11 (22%) and 10 (20%), respectively. At all age decades, the free-viewing autorefractor underestimated dark-adapted pupil diameter. Eye test order and device order did not cause unidirectional bias. CONCLUSIONS: The free-viewing pupillometer frequently disagreed with the monocular occlusion pupillometer by more than 0.5 mm. Testing the first eye with the monocular pupillometer did not induce sustained pupillary constriction that might bias results in the second eye.

Comparison of 2 monocular pupillometers and an autorefractor for measurement of the dark-adapted pupil diameter.

PURPOSE: To compare the performance of the Marco Nidek ARK-530A autorefractor pupillometer function and the Keeler PupilScan II pupillometer (study pupillometer) against the clinical standard NeurOptics PLR-200 pupillometer (standard pupillometer) for measurement of the dark-adapted pupil diameter. SETTING: Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas, USA. DESIGN: Evaluation of diagnostic test or technology. METHODS: Subjects aged 20 to 60 years were dark-adapted for 2 minutes at 1 lux ambient illumination. Accommodation was controlled through distance fixation. The dark-adapted pupil diameter was measured with the standard pupillometer, then the study pupillometer, then the autorefractor. Results were compared using Bland-Altman graphs. RESULTS: The autorefractor underestimated the dark-adapted pupil diameter by a mean of 1.03 mm (range 0.0 to 2.3 mm). Thirty-four (85%) measurements were at least 0.5 mm smaller than the corresponding standard pupillometer values, and 16 (40%) were more than 1.0 mm smaller. Observer experience did not improve accuracy. The study pupillometer underestimated the dark-adapted pupil diameter by a mean of 0.31 mm (range 0.0 to 0.9 mm). Ten (25%) measurements were at least 0.5 mm smaller than the standard pupillometer values. Accuracy improved in the final 10 subjects (study pupillometer smaller; mean difference 0.16 mm; range 0.0 to 0.4 mm). CONCLUSIONS: The autorefractor pupillometry function had an unpredictable negative bias (variable underestimation of dark-adapted pupil diameter). The study pupillometer had a slight negative bias but required significant examiner skill and knowledge of normal pupil movement to obtain a valid result. Neither device was sufficiently accurate for confident surgical planning or clinical diagnosis. FINANCIAL DISCLOSURE: Neither author has a financial or proprietary interest in any material or method mentioned.

Gelatinized copper-capillary alginate gel functions as an injectable tissue scaffolding system for stem cell transplants.

In severe hypoxic-ischemic brain injury, cellular components such as neurons and astrocytes are injured or destroyed along with the supporting extracellular matrix. This presents a challenge to the field of regenerative medicine since the lack of extracellular matrix and supporting structures makes the transplant milieu inhospitable to the transplanted cells. A potential solution to this problem is the use of a biomaterial to provide the extracellular components needed to keep cells localized in cystic brain regions, allowing the cells to form connections and repair lost brain tissue. Ideally, this biomaterial would be combined with stem cells, which have been proven to have therapeutic potentials, and could be delivered via an injection. To study this approach, we derived a hydrogel biomaterial tissue scaffold from oligomeric gelatin and copper-capillary alginate gel (GCCAG). We then demonstrated that our multipotent astrocytic stem cells (MASCs) could be maintained in GCCAG scaffolds for up to 2 weeks in vitro and that the cells retained their multipotency. We next performed a pilot transplant study in which GCCAG was mixed with MASCs and injected into the brain of a neonatal rat pup. After a week in vivo, our results showed that: the GCCAG biomaterial did not cause a significant reactive gliosis; viable cells were retained within the injected scaffolds; and some delivered cells migrated into the surrounding brain tissue. Therefore, GCCAG tissue scaffolds are a promising, novel injectable system for transplantation of stem cells to the brain.

Cautery fixation for amniotic membrane transplant in pterygium surgery.

PURPOSE: To report a technique using cautery fixation of the amniotic membrane transplant in pterygium excision. METHODS: The amniotic membrane transplant is oversized 3-4 mm in both dimensions (1.5-2 mm on each side). The transplant is placed in position, and the excess is tucked subconjunctivally 270 degrees. Limbal fixation sutures using 9-0 Vicryl in a buried fashion are placed, and then, amniotic membrane transplant (AMT) overlying the cornea is excised. Cautery fixation of the AMT in a grid pattern using the eraser tip is performed. The cautery power is started low and titrated up until the appropriate reaction of the graft is noted upon application. Forceps are used for countertraction to prevent the eraser tip from lifting the AMT graft after fixating it to the underlying episclera. RESULTS: This technique was used on 17 consecutive patients with pterygia (12 primary and 5 recurrent). Average surgical time was 22.65 ± 2.57 minutes. No AMT malposition, dislocation, or loss and no granuloma formation were experienced. Although follow-up up to this point is short (average: 7.12 months, range: 2-18 months), no recurrences have occurred. CONCLUSIONS: This technique provides a quick, inexpensive, and effective method of AMT fixation for use in pterygium surgery.

Dark-adapted pupil diameter as a function of age measured with the NeurOptics pupillometer.

PURPOSE: To measure the dark-adapted pupil diameter of normal research participants in their second through ninth decades of life using the NeurOptics pupillometer (Neuroptics Inc). METHODS: Individuals aged 18 to 80 years with no history of eye disease or injury, intraocular surgery, or use of systemic antihistamines or opiates were recruited. After 2 minutes of adaptation at 1 lux illumination, the right dark-adapted pupil diameter was measured using the NeurOptics pupillometer, with accommodation controlled by distance fixation. The NeurOptics pupillometer reported a mean dark-adapted pupil diameter and a standard deviation of the mean, which were analyzed as a function of age-decade. RESULTS: Two-hundred sixty-three individuals participated. For participants aged 18 to 19 years (n=6), the mean dark-adapted pupil diameter was 6.85 mm (range: 5.6 to 7.5 mm); 20 to 29 years (n=66), 7.33 mm (range: 5.7 to 8.8 mm); 30 to 39 years (n=50), 6.64 mm (range: 5.3 to 8.7 mm); 40 to 49 years (n=51), 6.15 mm (range: 4.5 to 8.2 mm); 50 to 59 years (n=50), 5.77 mm (range: 4.4 to 7.2 mm); 60 to 69 years (n=30), 5.58 mm (range: 3.5 to 7.5 mm); 70 to 79 years (n=6), 5.17 mm (range: 4.6 to 6.0 mm); and 80 years (n=4), 4.85 mm (range: 4.1 to 5.3 mm). These values were consistent with studies using infrared photography. The standard deviation was >0.1 mm in 10 (3.8%) participants, all of whom were younger than 55 years. CONCLUSIONS: The dark-adapted pupil diameter is an important clinical variable when planning refractive surgery. Surgeons can compare a patient's dark-adapted pupil diameter with the results of this population study to identify outlier measurements, which may be erroneous, and repeat testing prior to surgery.

The effect of gender and iris color on the dark-adapted pupil diameter.

PURPOSE: The aims of this study were to assess the utility of digital color sensing to quantify iris color using digital photographs and to determine whether gender or iris color affects the dark-adapted pupil diameter (DAPD). METHODS: Subjects aged 18-80 years (N = 263) with no eye disease had their right DAPD measured after 2 min of dark adaptation at 1 lux using the NeurOptics pupillometer. A high-resolution digital slit lamp photograph of the iris was taken, and iris color was subjectively classified as blue, blue-green, green-brown, light brown, or dark brown. The digital photographs were objectively measured on-screen with the Minolta TV Color Analyzer II using the Commission Internationale de l'Eclairage system of color description. Regression analyses were performed to identify correlations between subjective iris color, Commission Internationale de l'Eclairage measurements, and DAPD. RESULTS: Gender and iris color had no effect on the DAPD. The Minolta TV Color Analyzer could discriminate all blue eyes (blue and blue-green) from all brown eyes (light and dark) but could not distinguish between shades of blue or shades of brown. Green-brown irises had no unique chromatic properties and could not be distinguished from other colors using our technique of digital color analysis. The Minolta device was simple and efficient to use. CONCLUSIONS: Contrary to long-held beliefs, female patients and blue-eyed patients do not have larger DAPD. Digital color sensing is a useful technique for objectively describing iris color.

Clinical performance of a handheld digital infrared monocular pupillometer for measurement of the dark-adapted pupil diameter.

PURPOSE: To compare the accuracy of a handheld infrared digital pupillometer and digital infrared photography for measurement of the dark-adapted pupil diameter. SETTING: Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas, USA. METHODS: The right horizontal pupil diameter in healthy volunteers was measured using a NeurOptics PLR-200 pupillometer and then videographed using the infrared function of a CyberShot video camera after 2 minutes and 5 minutes dark adaptation at 1 lux ambient illumination. The best still image was extracted from the video file, and the horizontal pupil diameter was determined by comparison against an internal photographic length standard using digital image software. Accommodation and alertness were controlled during testing. RESULTS: The mean horizontal pupil diameter by infrared photography after 2 minutes of dark adaptation by subject age was 7.71 mm for ages 20 to 29 years, 6.80 mm for ages 30 to 39 years, 6.53 mm for ages 40 to 49 years, 5.94 mm for ages 50 to 59 years, and 6.01 mm for ages 60 to 69 years. The mean difference (infrared photography minus pupillometer) was +0.09 mm (range +0.30 to -0.14 mm) at 2 minutes of adaptation and +0.07 mm (range +0.25 to -0.13 mm) at 5 minutes. CONCLUSIONS: The pupillometer accurately measured the horizontal pupil diameter at 1 lux, with no measurement more than 0.3 mm different from infrared photography measurements. The pupillometer had a slight negative bias that is unlikely to introduce an error greater than 0.5 mm in clinical measurements.