In addition, AlgiScan™ measures the dynamic pupillary light reflex generated by photo-stimulation. AlgiScan™ is an infrared video pupillometer used to measure the pupil diameter. While patients were sitting on a chair in a room with standard lighting, a silicon positioning eyecup attached to the AlgiScan™ camera was placed over one eye to block out all external light, and an eye-pad was placed on the other eye. The conversion table used was from the New York City Department of Health and Mental Hygiene, The following patients were excluded: (1) patients who had undergone eye surgery that may influence pupillary reflexes, (2) patients on local medication that may influence pupillary reflexes, (3) patients with amyloidosis, multiple sclerosis, Horner’s syndrome, or ongoing migraine attacks, and (4) patients with a brain tumour.ĭynamic pupillometry was performed with a portable, monocular, infrared pupillometer, AlgiScan™ (Idmed, Hôtel Technoptic, 13013 Marseille, France). Patients who had used opioids for a minimum period of 4 weeks and with an opioid dose corresponding to at least an oral morphine equivalent dose of 60 mg per day were included. Written informed consent was obtained from all subjects.Ĭancer patients (in-patients and out-patients) who had been referred to the Pain Section at the Norwegian Radium Hospital were recruited. 420-07197a 1.2007.1165) and Social Science Data Services at Oslo University Hospital (NO. The study was approved by Regional committee for Medical Research Ethics in Eastern Norway (REK No. Furthermore, we wanted to compare dynamic pupillary reactions with doses and blood concentrations of these opioids and their active metabolites. The aims of the study were to monitor the dose and time effects of opioids on pupil size and pupillary reactions in patients using opioids. We also determined pain intensity, sedation score, and other side effects of opioids, and we measured blood concentrations of opioids and their active metabolites. In addition to pupil size measurements under standard room light conditions, the pupillary light reflex was assessed when the pupil was exposed to a standard light stimulus. We wanted to perform a dynamic assessment of the pupillary reflex in patients on high-dose opioids. Clinicians treating cancer patients on high-dose opioids have also noticed that a few patients on high-dose opioids do not always present with small pupil size. However, some claim that tolerance to the miotic effects of opioid agonists exists,. Opioids generally cause pupillary constriction (miosis), which is not affected by opioid tolerance according to the literature, ,, ,, ,. Pupil size and reaction are also influenced by drugs. Pupil size reflects the balance between sympathetic and parasympathetic nervous systems. These findings elucidate previous misconceptions regarding pupillary effects and tolerance to opioids. Dynamic pupillometry can give additional information about the degree of tolerance to opioids. However, tolerance to these changes occurs when medication is not increased over time. Pupillary changes do take place in patients on opioids. We found no statistically significant correlation between total oral morphine equivalents and pupillary reactions or between blood opioid or opioid metabolite concentrations and baseline pupillary changes. When correcting for age, pupil size in the group that had received no increase of opioid dose over the last 14 days was not significantly different from pupil size in the healthy volunteer group ( p = 0.76), while the group that had increased the dose of opioids differed significantly from healthy volunteers ( p = 0.006). Sixty three patients who were on opioids for 2 months (median time) and on an oral morphine equivalent dose of 250 mg (median dose) were investigated. We also performed a clinical examination and measured blood concentrations of opioids and their active metabolites. We performed a dynamic assessment of the pupillary reflex in cancer patients on high-dose opioids and a control group of healthy volunteers using a portable, monocular, infrared pupillometer. As clinicians have observed patients on high-dose opioids who exhibited seemingly normal pupil sizes, we wanted to dynamically assess the pupillary reflex in cancer patients on high-dose opioids.
Pupil size and reaction are influenced by opioids, an effect that is not considered to be affected by opioid tolerance.
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