Blinking and Looking: An Eye-Tracking Approach to Studying Cognitive Processing Differences in Individuals with Speech, Language, and Communication Disorders
Stavros Hatzopoulos, Andrea Ciorba, Mark Krumm in Advances in Audiology and Hearing Science, 2020
Pupillometry is fully non-volitional and involves measurement of pupil diameter (see Fig. 4.3 for an example). Similar to endogenous blinking behavior, increased pupil dilation allows the eyes to receive more visual input. However, pupil dilation, and this measure, are thought to reflect processing load relative to decision making. Pupil dilation is not always attached to visual stimulus processing; there have been results linking pupil dilation to auditory processing load. For instance, Engelhardt et al. (2009) found that when listeners heard prosodic variation (e.g., tone of voice) that conflicted with the sentence semantics, pupil diameter increased. Zekveldet al. (2011) also found larger pupil diameters in aging individuals with hearing loss when they processed speech in noise, indicating an increase in perceptual demands required for perceptual speech processing. Pupil dilation is a highly sensitive measure and requires careful consideration and planning for valid measurement. Pupil dilation is very sensitive to illumination of visual stimuli, general lighting features of the environment (luminescence), as well as carry-over effects from previously shown/seen visual stimuli; it is very important for researchers to control the visual environment when collecting pupillometry data. Stable fixations (>300 ms) on a researcher-defined AOI are also required to achieve accurate measurements of pupil dilation.
Trauma principles
Alexander Trevatt, Richard Boulton, Daren Francis, Nishanthan Mahesan in Take Charge! General Surgery and Urology, 2020
Rapid neurological assessment should be performed to assess: Consciousness level: Using GCS All patients with a significant reduction in GCS (<13) as a result of head injury should undergo a CT head to look for evidence of contusion and exclude haemorrhage.Document the GCS breakdown (eyes, voice and motor response) to aid early identification of deterioration. See Chapter 22 on how to calculate the GCS.Pupils: Size, symmetry and reaction Pupil dilation or asymmetry, with impaired or absent light reflexes may indicate an expanding intracranial bleed. An urgent CT head is necessary and prompt referral to neurosurgeons if the diagnosis is confirmed as they may require emergency surgery to reduce the pressure effect. Document clearly any discussions with the neurosurgeons and advice given.
Toxins in Neuro-Ophthalmology
Vivek Lal in A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Clinical features of methanol intoxication include nausea, vomiting and abdominal pain. The CNS effects of methanol result from accumulation of formic acid within the optic nerve and leads to flashes of light. It progresses further to scotomas and scintillations. Vision loss is probably caused by interruption of mitochondrial function in the optic nerve which results in hyperemia, edema and optic nerve atrophy. Pupillary response to light is compromised and subsequently lost. Confirmation of diagnosis is by serum methanol level with gas chromatography (>20 mg/dL). Serum levels peak after 60–90 min of ingestion, but these do not correlate with the level of toxicity. Accumulation of formate leads to decrease in pH (<7.2 is a severe intoxication). Imaging findings may be suggestive with bilateral enhancing optic nerves and putaminal necrosis.
Systematic review of light exposure impact on human circadian rhythm
Published in Chronobiology International, 2019
Leena Tähkämö, Timo Partonen, Anu-Katriina Pesonen
Given the scope of collected data from the 128 studies in the literature review, several limitations can be identified among the studies. First, the sample size was small in many studies: 39 studies out of 128 used sample size of 10 or less subjects. Second, the pupil size was controlled or measured only in very few studies. Pupil dilation is a way to control the pupil size. When the interest is in the impacts of light exposure in typical living environments, the pupil should not be dilated, as it is likely to exaggerate the results. Third, many studies did not indicate where the light level was measured. The light level should be measured at the eye level, that is cornea, when eyes are open. Fourth, part of the studies did not clearly state the status of the eyes during the exposure. The eyelid acts as a red-pass filter (Zeitzer et al. 2014) and transmits only approximately 3%–14% of light (Robinson et al. 1991) in a wavelength-dependent manner. Thus, the retinal exposure of light depends on the status of the eyes (open, closed). Fifth, many studies failed to indicate the spectral characteristics of the exposure in an accurate manner. This would require a presentation of SPD, the wavelength, or the peak wavelength with bandwidth. Overall, it is necessary that the intensity, spectral and temporal characteristics of the exposure are accurately and clearly expressed together with the qualities of the subjects, including age, status of eyes, pupil size, length and pattern of baseline period prior to exposure, and sleep pattern (sleep deprivation or habitual sleeping rhythm).
Sex Differences in Sexual Arousal and Finger Length Ratio
Published in The Journal of Sex Research, 2022
Luke Holmes, Tuesday M. Watts-Overall, Erlend Slettevold, Dragos C. Gruia, Gerulf Rieger
Additionally, we note that the sexual response patterns found in pupil dilation did not fully reflect those found in genital arousal, and that for one variable (pupil dilation to the less-arousing sex), the sex difference was in the opposite direction to that predicted (Figure 2b). While genital arousal is a well-evidenced measure of sexual arousal (Janssen, 2002; Suschinsky et al., 2009), pupil dilation is comparatively newer and has a smaller body of associated evidence. In some studies it has produced results which match with those found through genital arousal (Rieger et al., 2015), but in others it has produced results which are not fully identical to genital arousal patterns (Watts et al., 2018). Because pupil dilation indicates not only sexual arousal, but also emotion, cognition, or non-sexual interest in stimuli (Bradley et al., 2008; Goldinger & Papesh, 2012), it is likely that for some participants, pupillary responses were driven by factors other than sexual interest. Despite this limitation, the present unexpected finding that men showed greater pupil dilation to their more-arousing sex than women is still in line with the general observation that men, unlike women, respond more strongly to one sex than the other.
Corectopia grading: A novel classification system
Published in Seminars in Ophthalmology, 2022
Natalia Anisimova, Lisa Arbisser, Argyrios Tzamalis, Beáta Éva Petrovski, Natalya Shilova, Goran Petrovski, Sergey Anisimov, Boris Malyugin
The pupil is a critical element of the eye’s optical system. Its exact size and location are important in forming the visual axis. The threshold of visually significant optical aberrations increases with pupil dilation.13 Normally, the pupil is located about 0.5 mm inferonasal from the center of the iris and is characterized by an average pupil non-circularity of 0.016614. The tendency for mirror symmetry of the pupil shape and location is present between left and right eyes in healthy individuals during both constriction and dilation in response to lighting variation.14 Pupil constriction is associated with an average movement of approximately 0.2 mm nasally and superiorly with respect to the limbus center.14,15 However, larger shifts in pupil decentration up to 0.6 mm have been shown in normal individuals when the reference point was set at the initial position of the pupil center.16 Age-related changes of the iris include the phenomenon of senile miosis over a wide range of ocular illuminance levels,17 and non-circularity is known to increase with age (0.0015/decade) (ref. 14).
Related Knowledge Centers
- Iris Sphincter Muscle
- Miosis
- Mydriasis
- Oculomotor Nerve
- Optic Nerve
- Physiology
- Parasympathetic Nervous System
- Opiate
- Opioid
- Iris Dilator Muscle