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An unrousable patient in the recovery room
Published in Tim French, Terry Wardle, The Problem-Based Learning Workbook, 2022
On examination of the patient, she had small equal pupils which had delayed response to light. The possible causes of miosis in this patient are: age, since nearly all elderly patients are miotic. Sluggish pupils may be found if there is coexisting cataract or glaucomaopioid toxicity, which classically causes ‘pinpoint pupils’metabolic comas, which cause the pupils to be normal or mildly contracted. Pupils are never pinpoint, unless there is coexisting opioid toxicity/pontine haemorrhage. However, in this patient, the delayed response to light is a significant indicator that this could be a metabolic coma. The delayed light reflex, or hyporeflexia, is classical of hypothyroidism. This would tie in with the clinical history of weight gain and lethargy. 0ne extreme manifestation of hypothyroidism is myxoedema coma.
Comparative Anatomy and Physiology of the Mammalian Eye
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
When injected intracamerally in the cat, leukotriene C4 (LTC4) and leukotriene D4 (LTD4) cause miosis which is dose dependent.62 This action is not blocked by indomethacin, a specific cyclooxygenase inhibitor, or by atropine, a muscarinic-blocking agent.62 In addition to miosis, decreased ocular blood flow and slightly decreased IOP occurred.62 No effect on the blood-aqueous barrier of the cat was observed, as judged by aqueous protein values.62 Also, LTD4 had no effect on the guinea pig uveal vascular permeability,63 although it did increase the permeability of the conjunctival vasculature.63 In addition to these effects, LTB4 and other lipoxygenase products are important in cell chemotaxis.53,54,64,65
Neuro-ophthalmology
Published in Mostafa Khalil, Omar Kouli, The Duke Elder Exam of Ophthalmology, 2019
Caused by a lesion to the sympathetic pathway. Characterized by: Ptosis: Mild eyelid drooping due to Müller muscle dysfunction.Miosis: Due to dysfunction of the dilator pupillae. The pupil reacts to light and near stimuli.Ipsilateral facial anhidrosis: Not present in third-order neuron lesions.The affected iris in congenital Horner syndrome has a lighter colour.
Accommodative and convergence anomalies in patients with opioid use disorder
Published in Clinical and Experimental Optometry, 2022
Mohaddeseh Ghobadi, Payam Nabovati, Hassan Hashemi, Ali Talaei, Hamid Reza Fathi, Yeganeh Yekta, Hadi Ostadimoghaddam, Abbasali Yekta, Mehdi Khabazkhoob
Some theories can be proposed for this high prevalence of accommodative insufficiency and accommodative infacility in patients with OUD. This finding may be due to changes in the sympathetic or parasympathetic innervation to the ciliary muscle via direct effects of opioids on the CNS. It should be noted that disturbance of balance in sympathetic/parasympathetic innervation to the ciliary muscle has been suggested as one of the possible causes of reduced AA in some studies.20–22 Another possible cause is pupillary miosis, which has been identified as a common complication in OUD patients.23,24 Although miosis occurs due to the effect of opioids on the CNS, the exact mechanism of opioid-related pupillary miosis is still unclear. Theories have been proposed in this regard, including direct stimulation of the Edinger Westphal (EW) nucleus, depression of cortical centres that normally inhibit EW, and stimulation of opioid receptors located on the iris sphincter.11,25 Pupillary miosis increases the depth of focus, which is associated with the need for less accommodative effort. This phenomenon can lead to reduced accommodative amplitude and facility over time. An interesting finding of this study was the significant inverse relationship between accommodative insufficiency and accommodative infacility with the pupil size after controlling for the effect of age, duration of opioid abuse, and refractive error, which is line with this theory.
In Vivo Analysis and Comparison of Anterior Segment Structures of Both Eyes in Unilateral Herpetic Anterior Uveitis
Published in Ocular Immunology and Inflammation, 2021
Muhammet Derda Ozer, Muhammed Batur, Erbil Seven, Serek Tekin, Fatih Kebapci
Pilocarpine hydrochloride drops were administered to both eyes three times in 30 min to decrease iris surface irregularities before image acquisition. Pupillary miosis could not be achieved in the affected eye because of persistent pupillary dilation in some of the participants. Immediately after achieving pharmacological miosis, all patients underwent AS SD-OCT scanning in a dim light room illumination. An angle scan in the automatic real-time mode was selected to achieve enhanced quality imaging. All scans were measured in the high-resolution mode at a resolution of 10.84 µm/pixel on the X-axis and 3.87 µm/pixel on the Z-axis. Figures of the nasal and temporal angles (at the 3 o’clock and 9 o’clock positions) were obtained separately after the adjustment of the fixation to the nasal and temporal areas for analyzing the SCA. Eleven cross-sectional B-scans were obtained for each eye in the scleral enhanced depth imaging mode. If artifacts due to nictitation were noted, the examination was repeated up to three times in each eye. The nasal and temporal limbus images were preferred in this study because of the obstacles to obtain superior and inferior limbal scans.
Fixed-combination topical anti-hypertensive ophthalmic agents
Published in Expert Opinion on Pharmacotherapy, 2020
Lindsay Machen, Reza Razeghinejad, Jonathan S. Myers
Pilocarpine was one of the first medications found to have an impact on IOP [105]. Through its effects on the ciliary body muscle, pilocarpine increases outflow through the trabecular meshwork and reduces IOP. Locally, pilocarpine results in pupillary miosis, stimulation of accommodation, brow ache, and potential ocular surface desiccation and punctal scarring with prolonged use. A theoretical risk of retinal tear and detachment exists due to traction on the ciliary body and peripheral retina; retinal compromise is unlikely in patients without preexisting retinal pathology and rare in general [106]. A dilated and thorough retina exam may be prudent prior to initiation of miosis-inducing medications. Potential systemic side effects include hypersalivation, stomach cramping, and bradycardia in excessive doses. Combination agents containing pilocarpine are less frequently used today; however, they have been demonstrated to have a significant IOP lowering effect.