Why are nitrates contraindicated in closed-angle glaucoma?
Why are nitrates contraindicated in closed-angle glaucoma?
Nitrates/nitrites (applies to nitroglycerin) glaucoma Some medical references state that organic nitrates and nitrites may increase intraocular pressure and should be used with caution in patients with glaucoma.
How does nitric oxide lower IOP?
Nitric oxide donors have been shown to mediate IOP-lowering effects in both preclinical models and clinical studies, primarily through cell volume and contractility changes in the conventional outflow tissues.
Why is epinephrine contraindicated in closed-angle glaucoma?
These agents stimulate both alpha-1 and alpha-2 adrenergic receptors, thus topical administration can induce transient mydriasis, either with or without the use of concomitant miotic agents. In patients with narrow angles, any degree of pupillary dilation can provoke an acute attack of angle-closure glaucoma.
Does nitroglycerin increase intraocular pressure?
Nathanson and colleagues have demonstrated that topical nitroglycerin can lower IOP in glaucoma patients, probably because of the ability of nitroglycerin and related compounds to activate guanylate cyclase and thereby modulate IOP 11, 12.
Why are nitrates contraindicated in right ventricular infarction?
Nitroglycerin is also contraindicated in the setting of an inferior MI with right ventricular involvement because, in this specific situation, the heart is dependent on preload.
How do nitrates work?
How does it work? Nitrates are vasodilators, which means they help widen (dilate) your blood vessels, making it easier for blood to flow through and let more oxygen-rich blood reach your heart. Better blood flow means your heart doesn’t have to work as hard.
Does nitric oxide affect glaucoma?
As a nitric oxide-donating prostaglandin F2-alpha receptor agonist, it has proven to effectively, and with good tolerability, reduce IOP in glaucoma and ocular hypertensive patients.
When is nitrous oxide contraindicated?
Thus nitrous oxide is contraindicated in pneumothorax, small bowel obstruction, middle ear surgery, and retinal surgeries involving the creation of an intraocular gas bubble. In laparoscopic cases, nitrous oxide can accumulate in the pneumoperitoneum, and some avoid its use in these cases.
How does epinephrine decrease IOP?
Epinephrine is reported to reduce intraocular pressure by decreasing aqueous formation and increasing outflow facility.
What medications should be avoided with glaucoma?
Medications to Avoid with Glaucoma
- Allergy/Cold Remedies: Diphenhydramine, Ephedrine.
- Anxiety: Vistaril (hydroxyzine)
- Asthma/COPD: Atrovent (ipratroprium bromide), Spiriva (tiotropium bromide)
- Depression: Prozac (fluoxetine), Paxil (paroxetine), Elavil (amitryptiline), Tofranil (imipramine)
What is closed angle glaucoma?
Angle-closure glaucoma, also called closed-angle glaucoma, occurs when the iris bulges forward to narrow or block the drainage angle formed by the cornea and iris. As a result, fluid can’t circulate through the eye and pressure increases.
What is the mechanism of action of nitroglycerin?
Mechanism of Action: Nitroglycerin forms free radical nitric oxide (NO) which activates guanylate cyclase, resulting in an increase of guanosine 3’5′ monophosphate (cyclic GMP) in smooth muscle and other tissues.
What are the 5 contraindications of nitroglycerin?
Contraindications of nitroglycerin
- Have a known sensitivity to nitrate medications.
- Have taken erectile dysfunction medications within the past 24 hours, such as Viagra, Cialis, Levitra, Stendra, Staxyn, sildenafil, avanafil, tadalafil or vardenafil.
- Are hypotensive (typically <90 SBP or <65 MAP)
How does nitroglycerin work as a vasodilator?
Nitroglycerin is denitrated by mALDH in smooth muscle and other cells. This results in the release of nitrite ion, which is then converted to nitric oxide. Nitric oxide that is released stimulates guanylyl cyclase in smooth muscle, producing an increase in cGMP which causes vasodilation.
Can nitric oxide affect eyes?
Both underproduction and overproduction of nitric oxide (NO) could lead to various eye diseases. It is known that endothelial NO synthase (eNOS) and neuronal NOS (nNOS) are activated in normal tissues to produce NO for physiological functions.
What are the contraindications for nitrous oxide?
Is nitrous oxide contraindicated in glaucoma?
Abstract. Nitrous oxide is absolutely contraindicated after vitreoretinal surgery that uses intraocular gas, as the mixture of gas and nitrous oxide can cause catastrophic vision loss. Professional awareness and communication are vital to prevent this iatrogenic complication.
What is the mechanism of action of nitrous oxide?
The mechanism of action of nitrous oxide is trifold and includes analgesia, anxiolysis, and anesthesia. Its analgesic mechanism of action is described as opioid in nature and may involve a number of spinal neuromodulators.
Why epinephrine used in open angle glaucoma?
Because epinephrine is devoid of accommodative and miotic effects, is administered twice a day, and is accompanied by relatively minor complications, it can be used as the initial therapy for primary open angle glaucoma, as an additive to current therapy, and as part of maximal medical therapy for glaucoma.
How do beta blockers reduce intraocular pressure?
Topical beta-blockers reduce the intraocular pressure (IOP) by blockade of sympathetic nerve endings in the ciliary epithelium causing a fall in aqueous humour production.
What are the angle closure mechanisms of glaucoma?
[Angle closure mechanisms of glaucoma] Glaucoma caused by primary closure of the iridocorneal angle accounts for half of the glaucoma cases in the world, 9 out of 10 in patients of Sino-Mongolian origin. The most frequent mechanism involved is anterior chamber angle blockage, but glaucoma can also be the result of a plateau iris structur …
How does botulinum toxin cause angle closure glaucoma?
Botulinum toxin is thought to induce acute angle closure glaucoma due to its anticholinergic effect on the sympathetic ganglia, preganglionic and postganglionic nerve terminals of the parasympathetic nervous system. This subsequently results in inhibition of the pupillary sphincter that causes pupil dilatation and pupillary block.
Do alpha-adrenergic agonists precipitate acute angle closure glaucoma?
Alpha-adrenergic agonists can precipitate acute angle closure glaucoma by pupillary block due to pupil dilatation in individuals with innately narrow iridocorneal angles.
What drugs can cause acute angle closure glaucoma?
Sulfa-based agents such as topiramate, acetazolamide and hydrochlorothiazide are among the few drugs that can induce “non-pupillary block” acute angle closure glaucoma.