![]() ![]() Currently, pupillometers are either commercially available and accessible pupillometers or laboratory-based prototypes. The technological advancements have led to multiple attempts to improve the objectivity of pupil response analysis by introducing pupillometer systems that aid in quantifying not just pupil diameters but also additional parameters that can be documented and monitored over time 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21. ![]() Thus, well-controlled systems are required to precisely quantify the parameters of both pupils 6, 7, 8. Moreover, this method does not provide information regarding the delay, the speed, the extent, and the sustainability of pupil response. However, it is prone to substantial inconsistency and inter-examiner variability due to its dependence on the examiner’s judgment and clinical expertise. This deceptively simple approach is crucial and beneficial in routine clinical practice for defect detection and monitoring. are also found to have an effect 5.Ĭonventionally, the PLR is evaluated using a Swinging Flashlight Test (SFT), which is a qualitative assessment of the direct and consensual pupillary reflexes 1, 2, 3. Even though the key determinant of PLR is the level of retinal illuminance, additional factors such as age, gender, iris color, clarity of optical media of eye, the integrity of optic nerve, etc. ![]() Hence, the analysis of PLR provides essential information regarding the integrity of these neural pathways 1, 2, 3, 4. This reflexive process is directed by the antagonistic action of sphincter and dilator pupillae muscles subserved by the parasympathetic and sympathetic nerves, respectively. The PLR pathway is controlled by the integration of signals from the photoreceptors as well as the intrinsically photosensitive Retinal Ganglion Cells (ipRGCs), a subpopulation of Melanopsin containing RGCs that are sensitive to blue light. In such instances, PLR results in a rapid change in PD, thereby optimising the influx of light that strikes the retina 1, 2. In addition, PLR also acts as a protective mechanism to safeguard the retinal cells from phototoxic damage caused by any exposure to intense visible light. When transitioning from various light intensity levels, Pupil Diameter (PD) undergo dynamic alterations elicited by Pupillary Light Reflex (PLR), thereby assisting in the process of visual adaptation. ![]() The photosensitive cells in the human retina are uniformly adapted to function over a wide range of ambient light conditions. 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. The normal limits of the PRS coefficient ranged from − 0.20 to + 1.07 and all RAPD patients were outside the calculated normal limits. 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. A Pupil Response Symmetry (PRS) coefficient was calculated to predict the presence of RAPD. 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. 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. 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). ![]()
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