Pupil assessment in optic nerve disorders

Basics, benefits, and pitfalls of pupillometers assessing visual function

Numerous commercially and non-commercially available pupillometers are nowadays able to assess various biological functions in humans, by evaluating pupils' dynamics in response to specific stimuli. However, the use of pupillometers for ophthalmic afferent evaluations (i.e., photoreceptoral responses) in real-world settings is relatively limited. Recent scientific and technological advances, coupled with artificial intelligence methods have improved the performance of such devices to objectively detect, quantify, and classify functional disturbances of the retina and the optic nerve. This review aims to summarize the scientific principles, indications, outcomes, and current limitations of pupillometry used for evaluation of afferent pathways in ophthalmic clinical settings.

Method to Quickly Map Multifocal Pupillary Response Fields (mPRF) Using Frequency Tagging

We present a method for mapping multifocal Pupillary Response Fields in a short amount of time using a visual stimulus covering 40° of the visual angle divided into nine contiguous sectors simultaneously modulated in luminance at specific, incommensurate, temporal frequencies. We test this multifocal Pupillary Frequency Tagging (mPFT) approach with young healthy participants (N = 36) and show that the spectral power of the sustained pupillary response elicited by 45 s of fixation of this multipartite stimulus reflects the relative contribution of each sector/frequency to the overall pupillary response. We further analyze the phase lag for each temporal frequency as well as several global features related to pupil state. Test/retest performed on a subset of participants indicates good repeatability. We also investigate the existence of structural (RNFL)/functional (mPFT) relationships. We then summarize the results of clinical studies conducted with mPFT on patients with neuropathies and retinopathies and show that the features derived from pupillary signal analyses, the distribution of spectral power in particular, are homologous to disease characteristics and allow for sorting patients from healthy participants with excellent sensitivity and specificity. This method thus appears as a convenient, objective, and fast tool for assessing the integrity of retino-pupillary circuits as well as idiosyncrasies and permits to objectively assess and follow-up retinopathies or neuropathies in a short amount of time.

Light Color and the Commercial Broiler: Effect on Ocular Health and Visual Acuity

Light is a critical management factor for broiler production, and the wavelength spectrum, one of its components, can affect bird physiology, behavior and production. Among all the senses, sight is important to birds, and their visual system possess several adaptations that allow them to perceive light differently from humans. Therefore, it is critical to consider whether the exposure to monochromatic light colors influences broiler visual ability, which could affect behavioral expression. The present study examined the effects of various light colors on the visual systems of broiler chickens. Ross 708 males were raised from 0 to 35 days under three wavelength programs [blue (dominant wavelengths near 455 nm), green (dominant wavelengths near 510 nm) or white]. Broilers were given a complete ophthalmic examination, including chromatic pupillary light reflex testing, rebound tonometry, anterior segment biomicroscopy and indirect ophthalmoscopy (n = 36, day 21). To assess ocular anatomy, broilers were euthanized, eyes were weighed, and dimensions were taken (n = 108, day 16 and day 24). An autorefractor was used to assess the refractive index and the corneal curvature (n = 18, day 26). To evaluate spatial vision, broilers underwent a grating acuity test at one of three distances–50, 75, or 100 cm (n = 24, day 29). Data were analyzed as a one-way ANOVA using the MIXED procedure or Proc Par1way for non-normally distributed data. Significant differences were observed for refractive index and spatial vision. Birds raised under blue light were slightly more hyperopic, or far-sighted, than birds raised under white light (P = 0.01). As for spatial vision, birds raised under blue light took less time to approach the stimulus at distances of 50 cm (P = 0.03) and 75 cm (P = 0.0006) and had a higher success rate (choosing the right feeder, P = 0.03) at 100 cm than birds raised under white light. Improvements in spatial vision for birds exposed to blue light can partially explain the behavioral differences resulting from rearing broilers under different wavelengths.

How lesions at different locations along the visual pathway influence pupillary reactions to chromatic stimuli

PURPOSE

To examine systematically how prechiasmal, chiasmal, and postchiasmal lesions along the visual pathway affect the respective pupillary responses to specific local monochromatic stimuli.

METHODS

Chromatic pupil campimetry (CPC) was performed in three patient groups (10 subjects with status after anterior ischemic optic neuropathy, 6 with chiasmal lesions, and 12 with optic tract or occipital lobe lesions (tumor, ischemia)) using red, low-intensity red, and blue local stimuli within the central 30° visual field. Affected areas - as determined by visual field defects revealed using conventional static perimetry - were compared with non-affected areas. Outcome parameters were the relative maximal constriction amplitude (relMCA) and the latency to constriction onset of the pupillary responses.

RESULTS

A statistically significant relMCA reduction was observed in the affected areas of postchiasmal lesions with red (p = 0.004) and low-intensity red stimulation (p = 0.001). RelMCA reduction in the affected areas seemed more pronounced for low-intensity red stimulation (46.5% mean reduction compared to non-affected areas; 36% for red stimulation), however statistically not significant. In prechiasmal lesions, a statistically significant latency prolongation could be demonstrated in the affected areas with low-intensity red stimulation (p = 0.015).

CONCLUSION

Our results indicate that the choice of stimulus characteristics is relevant in detecting defects in the pupillary pathway of impairment along the visual pathway, favoring red stimuli of low intensity over blue stimuli. Such knowledge opens the door for further fundamental research in pupillary pathways and is important for future clinical application of pupillography in neuro-ophthalmologic patients.

A haploscope based binocular pupillometer system to quantify the dynamics of direct and consensual Pupillary Light Reflex

This study described the development of a haploscope-based pupillometer for the parametrization of the Pupillary Light Reflex (PLR), and its feasibility in a set of 30 healthy subjects (light or dark-colored irides) and five patients diagnosed with Relative Afferent Pupillary Defect (RAPD). Our supplementary aim focused on evaluating the influence of iris colour on the PLR to decide whether a difference in PLR parameters should be anticipated when this system is used across ethnicities. All the participants underwent a customized pupillometry protocol and the generated pupil traces, captured by an eye tracker, were analyzed using exponential fits to derive PLR parameters. A Pupil Response Symmetry (PRS) coefficient was calculated to predict the presence of RAPD. The mean (SD) Initial PD during dilation (3.2 (0.5) mm) and the minimum PD during constriction (2.9 (0.4) mm) in the light iris group had a statistically significant (p < 0.001) higher magnitude compared to the dark iris group. The normal limits of the PRS coefficient ranged from - 0.20 to + 1.07 and all RAPD patients were outside the calculated normal limits. This proposed system, analysis strategies, and the tested metrics showed good short-term repeatability and the potential in detecting pupil abnormalities in neuro-ophthalmic diseases.

Evidence That Pupil Size and Reactivity Are Determined More by Your Parents Than by Your Environment

Purpose: A classic twin study to evaluate the relative contributions of genetic and environmental factors to resting pupil size and reactivity. Methods: Pupillometry was performed on 326 female twins (mean age 64 years) from the TwinsUK Adult Twin Registry, assessing resting pupil diameter in darkness and increasing levels of ambient light, alongside dynamic pupillary characteristics. Maximum-likelihood structural equation models estimated the proportion of trait variance attributable to genetic factors. Results: Mean (SD) pupil diameter in darkness was 5.29 mm (0.81), decreasing to 3.24 mm (0.57) in bright light. Pupil light reaction (PLR) had a mean (SD) amplitude of 1.38 mm (0.27) and latency of 250.34 milliseconds (28.58). Pupil size and PLR were not associated with iris colour, intraocular pressure or refractive error, but were associated with age (diameter β = -0.02, p = 0.016, constriction amplitude β = -0.01, p < 0.001, velocity β = 0.03, p < 0.001, and latency β = 0.98, p < 0.001). In darkness the resting pupil size showed a MZ intraclass correlation coefficient of 0.85, almost double that of DZ (0.44), suggesting strong additive genetic effects, with the most parsimonious model estimating a heritability of 86% [95% confidence interval (CI) 79-90%] with 14% (95% CI 10-21%) explained by unique environmental factors. PLR amplitude, latency and constriction velocity had estimated heritabilities of 69% (95% CI 54-79%), 40% (95% CI 21-56%), and 64% (95% CI 48-75%), respectively. Conclusion: Genetic effects are key determinants of resting pupil size and reactivity. Future studies to identify these genetic factors could improve our understanding of variation in pupil size and pupillary reactions in health and disease.

Significant correlations between photopic negative response, afferent pupillary defect, and mean defects of visual fields in asymmetric optic nerve disorders

PURPOSE

The photopic negative response (PhNR) is a negative wave following the b-wave of the photopic electroretinogram (ERG). The PhNR originates from the retinal ganglion cells (RGCs), and it can be used to assess the function of RGCs noninvasively and objectively. The purpose of this study was to determine whether the relative amplitudes (affected/normal eye) of the PhNR are significantly correlated with the degree of the relative afferent pupillary defect (RAPD) in eyes with unilateral or asymmetrical damage of the optic nerve.

METHODS

The PhNRs of the full-field photopic ERGs were measured. In addition, videopupillography and automated perimetry were performed on 27 cases with asymmetrical optic nerve disorders including glaucoma. The differences of these assessments were expressed by the relative amplitudes of the PhNRs of the two eyes, the neutral density (ND) filter required to equate the amplitudes of the pupillary light reflexes between the two eyes, and differences of the mean defects (ΔMDs) of the sensitivities of the Humphrey visual fields. The correlations between these values were determined by linear regression analyses.

RESULTS

The relative PhNR amplitudes were significantly and negatively correlated with the ΔMDs (R² = 0.58, P = 0.0001). In addition, the relative PhNR amplitudes were moderately but significantly and positively correlated with the RAPDs (R² = 0.36, P = 0.002).

CONCLUSION

The relative amplitudes of the PhNR of the affected eyes to the contralateral eyes indicate an asymmetric alteration of the RGCs, and they can be used to monitor the physiology of the RGCs objectively.

Chromatic Pupillometry Methods for Assessing Photoreceptor Health in Retinal and Optic Nerve Diseases

The pupillary light reflex is mediated by melanopsin-containing intrinsically-photosensitive retinal ganglion cells (ipRGCs), which also receive input from rods and cones. Melanopsin-dependent pupillary light responses are short-wavelength sensitive, have a higher threshold of activation, and are much slower to activate and de-activate compared with rod/cone-mediated responses. Given that rod/cone photoreceptors and melanopsin differ in their response properties, light stimuli can be designed to stimulate preferentially each of the different photoreceptor types, providing a read-out of their function. This has given rise to chromatic pupillometry methods that aim to assess the health of outer retinal photoreceptors and ipRGCs by measuring pupillary responses to blue or red light stimuli. Here, we review different types of chromatic pupillometry protocols that have been tested in patients with retinal or optic nerve disease, including approaches that use short-duration light exposures or continuous exposure to light. Across different protocols, patients with outer retinal disease (e.g., retinitis pigmentosa or Leber congenital amaurosis) show reduced or absent pupillary responses to dim blue-light stimuli used to assess rod function, and reduced responses to moderately-bright red-light stimuli used to assess cone function. By comparison, patients with optic nerve disease (e.g., glaucoma or ischemic optic neuropathy, but not mitochondrial disease) show impaired pupillary responses during continuous exposure to bright blue-light stimuli, and a reduced post-illumination pupillary response after light offset, used to assess melanopsin function. These proof-of-concept studies demonstrate that chromatic pupillometry methods can be used to assess damage to rod/cone photoreceptors and ipRGCs. In future studies, it will be important to determine whether chromatic pupillometry methods can be used for screening and early detection of retinal and optic nerve diseases. Such methods may also prove useful for objectively evaluating the degree of recovery to ipRGC function in blind patients who undergo gene therapy or other treatments to restore vision.

Quantitative analysis of pupillometry in isolated third nerve palsy

OBJECTIVES

To objectively assess pupillary involvement according to various etiologies of acquired isolated third nerve palsy using automated pupillometry, and evaluate the efficacy of digital pupillometry in discriminating compressive lesions from microvascular ischemic third nerve palsy.

DESIGN

Retrospective, observational case series.

METHODS

A total of 171 subjects were included in this study, consisting of 60 subjects with presumed microvascular ischemic third nerve palsy, 51 with non-ischemic third nerve palsy, and 60 controls whose pupillary light responses were measured using a dynamic automated pupillometer. Subjects with non-ischemic third nerve palsy were divided into subgroups according to their etiology; inflammatory and compressive groups including tumor and aneurysm. Pupillometry parameters including minimum and maximum pupil diameters, constriction latency and ratio, maximum and average constriction velocities and dilation velocity were noted. The diagnostic ability of pupillometry parameters for discriminating compressive vs microvascular ischemic third nerve palsy was evaluated. The inter-eye difference of the involved eye and the uninvolved fellow eye was calculated to adjust for individual variability.

RESULTS

Among all parameters, reduced pupillary constriction ratio was the most specific parameter for detecting non-ischemic third nerve palsy, as a large inter-eye difference beyond the normative range of controls was found in 0% of ischemic, 20% of inflammatory and 60% of compressive third nerve palsy. With the diagnostic criteria using inter-eye differences of 1) minimum pupil diameter > 0.45 mm, or 2) pupillary constriction ratio < -7.5% compared to the fellow eye, the sensitivity and specificity for diagnosing compressive third nerve palsy were 95% and 88%, respectively. In the compressive group, positive correlations were found between the degree of external ophthalmoplegia and constriction ratio (r = 0.615, p<0.001), average constriction velocity (r = 0.591, p = 0.001) and maximum constriction velocity (r = 0.582, p = 0.001).

CONCLUSIONS

Abnormal pupillary constriction ratio was highly specific for detecting compressive third nerve palsy, although the sensitivity was not high. Digital pupillometry demonstrated relatively good performance for discriminating compressive lesions from microvascular ischemic third nerve palsy.

Objective assessment of a relative afferent pupillary defect by B-mode ultrasound

PURPOSE

To evaluate B-mode ultrasound as a novel method for objective and quantitative assessment of a relative afferent pupillary defect (RAPD) in a prospective case-control study.

METHODS

Seventeen patients with unilateral optic neuropathy and a clinically detectable RAPD and 17 age and sex matched healthy controls were examined with B-mode ultrasound using an Esaote-Mylab25 system according to current guidelines for orbital insonation. The swinging flashlight test was performed during ultrasound assessment with a standardized light stimulus using a penlight.

RESULTS

B-mode ultrasound RAPD examination was doable in approximately 5 minutes only and was well tolerated by all participants. Compared to the unaffected contralateral eyes, eyes with RAPD showed lower absolute constriction amplitude of the pupillary diameter (mean [SD] 0.8 [0.4] vs. 2.1 [0.4] mm; p = 0.009) and a longer pupillary constriction time after ipsilateral light stimulus (mean [SD] 1240 [180] vs. 710 [200] ms; p = 0.008). In eyes affected by RAPD, visual acuity correlated with the absolute constriction amplitude (r = 0.75, p = 0.001).

CONCLUSIONS

B-mode ultrasound enables fast, easy and objective quantification of a RAPD and can thus be applied in clinical practice to document a RAPD.

A novel method of inducing endogenous pupil oscillations to detect patients with unilateral optic neuritis

Purpose

To use and test a new method of inducing endogenously generated pupillary oscillations (POs) in patients with unilateral optic neuritis (ON), to describe a signal analysis approach quantifying pupil activity and to evaluate the extent to which POs permit to discriminate patients from control participants.

Method

Pupil size was recorded with an eye-tracker and converted in real time to modulate the luminance of a stimulus (a 20° disk) presented in front of participants. With this biofeedback setting, an increasing pupil size transforms into a high luminance, entraining a pupil constriction that in turn decreases the stimulus luminance, and so on, resulting in endogenously generated POs. POs were recorded for 30 seconds in the affected eye, in the fellow eye and in binocular conditions with 22 patients having a history of unilateral ON within a period of 5 years, and with 22 control participants. Different signal analysis methods were used to quantify the power and frequency of POs.

Results

On average, pupil size oscillated at around 1 Hz. The amplitude of POs appears not to be a reliable marker of ON. In contrast, the frequency of POs was significantly lower, and was more variable over time, in the patients’ affected eye, as compared to their fellow eye and to the binocular condition. No such differences were found in control participants. Receiver operating characteristic analyses based on the frequency and the variability of POs to classify patients and control participants gave an area under the curve of 0.82, a sensitivity of 82% (95%CI: 60%-95%) and a specificity of 77% (95%CI: 55%-92%).

Conclusions

The new method used to induce POs allowed characterizing the visual afferent pathway defect in ON patients with encouraging accuracy. The method was fast, easy to use, only requiring that participants look ahead, and allows testing many stimulus parameters (e.g. color, stimulus location, size, etc).

Blindness in echolocating bats

Vision in echolocating bats works complementary to their echolocation signals and is especially important in long-range orientation. Contrary to previous predictions, we report here the first case of blindness and ocular anomalies in healthy adult echolocating bats. Two anomalous individuals of Carollia perspicillata, two Artibeus planirostris and one Artibeus lituratus were captured in highly human-modified areas (urban and agricultural). One C. perspicillata was totally blind exhibiting completely closed eyelids and the others presented strong corneal opacity in their right eye. Our finding brings new insights about the habitat perception in mammals and suggests an unreported ecological compensation of the sensory system in bats.

Gaze-Contingent Flicker Pupil Perimetry Detects Scotomas in Patients With Cerebral Visual Impairments or Glaucoma

Background: The pupillary light reflex is weaker for stimuli presented inside as compared to outside absolute scotomas. Pupillograph perimetry could thus be an objective measure of impaired visual processing. However, the diagnostic accuracy in detecting scotomas has remained unclear. We quantitatively investigated the accuracy of a novel form of pupil perimetry.

Methods: The new perimetry method, termed gaze-contingent flicker pupil perimetry, consists of the repetitive on, and off flickering of a bright disk (2 hz; 320 cd/m²; 4° diameter) on a gray background (160 cd/m²) for 4 seconds per stimulus location. The disk evokes continuous pupil oscillations at the same rate as its flicker frequency, and the oscillatory power of the pupil reflects visual sensitivity. We monocularly presented the disk at a total of 80 locations in the central visual field (max. 15°). The location of the flickering disk moved along with gaze to reduce confounds of eye movements (gaze-contingent paradigm). The test lasted ~5 min per eye and was performed on 7 patients with cerebral visual impairment (CVI), 8 patients with primary open angle glaucoma (age >45), and 14 healthy, age/gender-matched controls.

Results: For all patients, pupil oscillation power (FFT based response amplitude to flicker) was significantly weaker when the flickering disk was presented in the impaired as compared to the intact visual field (CVI: 12%, AUC = 0.73; glaucoma: 9%, AUC = 0.63). Differences in power values between impaired and intact visual fields of patients were larger than differences in power values at corresponding locations in the visual fields of the healthy control group (CVI: AUC = 0.95; glaucoma: AUC = 0.87). Pupil sensitivity maps highlighted large field scotomas and indicated the type of visual field defect (VFD) as initially diagnosed with standard automated perimetry (SAP) fairly accurately in CVI patients but less accurately in glaucoma patients.

Conclusions: We provide the first quantitative and objective evidence of flicker pupil perimetry's potential in detecting CVI-and glaucoma-induced VFDs. Gaze-contingent flicker pupil perimetry is a useful form of objective perimetry and results suggest it can be used to assess large VFDs with young CVI patients whom are unable to perform SAP.

Detection of asymmetric glaucomatous damage using automated pupillography, the swinging flashlight method and the magnified-assisted swinging flashlight method

PURPOSE

To determine the sensitivity and specificity of various methods of detecting a relative afferent pupillary defect (RAPD) in patients with glaucoma-related diagnoses.

PATIENTS AND METHODS

Patients underwent RAPD evaluation using the swinging flashlight method (SFM), the magnifier-assisted SFM, and pupillography using the Konan RAPDx. Main outcome measures were sensitivity and specificity of three methods of RAPD evaluation in detecting visual field mean deviation (MD), cup to disc ratio (CDR), disc damage likelihood scale (DDLS), and retinal nerve fiber layer (RNFL) asymmetry.

RESULTS

Eighty-one consecutive patients from the Wills Eye Hospital glaucoma service were enrolled, 60 with glaucoma and 21 with ocular hypertension or glaucoma suspect. Thirty-one percent of subjects had MD asymmetry>5 dB, 19.7% had CDR asymmetry≥0.20, 26.7% had DDLS asymmetry≥2, and 38.2% had RNFL asymmetry>10 microns. Sensitivity values for pupillography were 93.3% (95% CI, 68.1-99.8) for detecting MD asymmetry, 80.0% (95% CI, 51.9-95.7) for CDR asymmetry, 100.0% (95% CI, 73.5-100.0) for DDLS asymmetry, and 69.2% (95% CI, 38.6-90.9) for RNFL asymmetry. Specificity values were 41.2% (95% CI, 24.7-59.3) for detecting MD asymmetry, 32.8% (95% CI, 21.3-46.0) for CDR asymmetry, 33.3% (95% CI, 18.0-51.8) for DDLS asymmetry, and 42.9% (95% CI, 21.8-66.0) for RNFL asymmetry. Pupillography amplitude score was correlated with MD asymmetry (r2=0.41, P<0.001) and area under the curve was 0.84.

CONCLUSION

Automated pupillography had higher sensitivity and lower specificity in detecting MD, CDR, DDLS, and RNFL asymmetry. Within the bounds of the cohort tested, this method had limited case-finding ability.

System and measurement method for binocular pupillometry to study pupil size variability

BACKGROUND

An objective and noninvasive examination of pupil size variability can be used to assess the activity of the autonomous nervous system. We designed a system that enables binocular, fast, and accurate recordings of different types of pupil variabilities, which are synchronous with other biosignals. This type of measurement system is needed to extend the scope of pupillometry applications.

METHODS

In the proposed system, the left and right eyes are independently and interchangeably illuminated to generate alternating images, which are successively acquired by a single camera. The system is composed of four functional modules: the image acquisition module, the image processing unit, the light stimulator, and the controller. The proposed image processing algorithm approximates the shape of the pupil using the best-fit ellipse. The user control panel (controller) precisely sets the stimuli parameters and controls the entire measurement procedure.

RESULTS

The computer-based binocular system records the pupil size during the pupil light reflexes (direct and indirect) and spontaneous pupil size fluctuations, at a sampling rate up to 75 Hz, with a resolution better than 0.02 mm. Our initial laboratory tests confirmed that the new system is fast and precise (system accuracy better than 0.5% and repeatability better than 4%).

CONCLUSIONS

The proposed system's unique geometry and construction, and the method it uses to detect images from each eye, allows us to monitor the right and left eyes using a single camera with no overlap between the images. The system does not require a very experienced operator, because it is relatively simple and easy to use. Importantly, it is comfortable for the subjects. Additionally, the presented system can operate with other bio-measurement systems using a synchronous signal. These system capabilities can expand the scope of pupillometry research applications.

Transient pupillary light reflex in relation to fundus autofluorescence and dark-adapted perimetry in typical retinitis pigmentosa

PURPOSE

To determine whether the pupillary light reflex (PLR) can serve as an indicator of photoreceptor function in patients with advanced typical retinitis pigmentosa (RP).

METHODS

Dark-adapted transient PLRs elicited by blue or white light over a luminance range of 4 log units were recorded from 27 eyes of 19 patients with advanced RP. Retinas were characterized according to fundus autofluorescence (AF) and dark-adapted perimetry. We qualitatively analyzed whether PLR thresholds were correlated with AF patterns or scotopic sensitivity. Quantitative analysis included correlations between relative pupillary constrictions (RPCs) elicited by blue light (≤-1 log cd/m(2)) and the area of abnormal ring or central AF, and between RPCs elicited by white light and perimetric mean sensitivity.

RESULTS

The PLRs of all patients showed varying degrees of threshold elevation and relative afferent pupil defects. We classified three types of abnormal fundus AF: abnormal ring AF, abnormal central AF, and fragmentary AF. PLR thresholds were largely consistent with the patterns of AF and scotopic sensitivity. Rod-mediated RPCs were not correlated with the area of the abnormal ring AF (p > 0.05), but were correlated with the area of abnormal central AF (p < 0.05). RPCs elicited with a white stimulus (-0.3 or 0.7 log cd/m(2)) were significantly correlated with the mean sensitivity of the dark-adapted perimetry.

CONCLUSIONS

PLR testing is a powerful technique for assessing photoreceptor dysfunction. The high correlation with AF and dark-adapted perimetry suggests that the key to quantifying photoreceptor function using the transient PLR is to optimize the luminance of the stimulus.

Approach to optic neuropathies: clinical update

Visual loss is a common symptom brought to the attention of the practicing neurologist. In this circumstance, the proper identification of an optic neuropathy is critical. Recognition of key clinical clues will permit the clinician to construct a likely differential diagnosis and pursue appropriate testing. This review first addresses the elements of the history and examination which are most useful in evaluating a patient with visual loss, and then briefly discusses the main entities responsible for causing unilateral and bilateral optic neuropathies.

Traumatic bitemporal hemianopia

A 45-year-old male pedestrian was struck by a motor vehicle moving at high speed. Upon initial assessment, the patient scored a 3T on the Glasgow Coma Scale. The patient suffered multiple facial and sinus fractures, a right orbital wall fracture, and a depressed open frontal skull fracture with visible brain parenchyma. Due to the nature of the brain injury, the patient was taken to the operating room emergently for a right frontal craniectomy. The patient required prolonged hospitalization followed by transfer to a rehabilitation facility. Six weeks after the accident, the patient underwent an extensive neuro-ophthalmologic evaluation. At that time, visual acuity was 20/200 in both eyes. On visual field testing, a bitemporal hemianopia was noted. Ophthalmoscopic examination revealed bilateral temporal disc pallor, right greater than left. Neuroimaging demonstrated damage to the optic chiasm. Although rare, head trauma may cause a bitemporal hemianopia secondary to optic chiasmal injury.

Measurement of pupil reactivity using fast pupillometry

Analysis of human eye pupil reactivity is a very valuable diagnostic method used mainly for evaluation of the condition of the autonomic nervous system and the visual system. The paper presents an experimental pupillometer built in the Institute of Physics of the Wroclaw University of Technology. The apparatus makes it possible to record and analyze pupillary light reflex and spontaneous changes in the pupil diameter during a session in the dark. The detector system used in the pupillometer allows us to record the pupil diameter at a rate of 90 Hz with a linear accuracy of 0.008 mm. In this paper, the proposed detection method, the principle of operation and calibration of the apparatus and the possibilities of the measurement system are presented.