Naphazoline is a direct acting sympathomimetic adrenergic alpha-agonist used to induce systemic vasoconstriction, thereby decreasing nasal congestion and inducing constriction around the conjunctiva. The sympathomimetic action of Naphazoline constricts the smaller arterioles of the nasal passages, producing a decongesting effect. Naphazoline ophthalmic causes constriction of blood vessels in the eyes. It also decreases itching and irritation of the eyes. aphazoline constricts the vascular system of the conjunctiva. It is presumed that this effect is due to direct stimulation action of the drug upon the alpha adrenergic receptors in the arterioles of the conjunctiva resulting in decreased conjunctival congestion. Naphazoline belongs to the imidazoline class of sympathomimetics. Naphazoline is a direct acting sympathomimetic drug, which acts on alpha-adrenergic receptors in the arterioles of the nasal mucosa. This activates the adrenal system to yield systemic vasoconstrction. In producing vasoconstriction, the result is a decrease in blood flow in the nasal passages and consequently decreased nasal congestion. The vasoconstriction means that there is less pressure in the capillaries and less water can filter out, thus less discharge is made. Naphazoline is primarily indicated in conditions like Corneal vascularity, Hyperaemia, Itching, Nasal congestion, and can also be given in adjunctive therapy as an alternative drug of choice in Sinusitis.

Emedastine is an antihistaminic agent, which was approved by FDA for the treatment of allergic conjunctivitis (Emadine brand name). The drug acts selectively on H1 receptors with lower affinity to H2 and H3 subtypes. Emedastine has a relatively unfavorable CNS effect profile. A small percentage of patients reported somnolence as an adverse effect after administration.

Levocabastine (trade name Livo) is a selective second-generation H1-receptor antagonist used for allergic conjunctivitis. Levocabastine binds the G protein-coupled neurotensin receptor 2 (NTR2), but not NTR1, where it behaves as a weak partial inverse agonist. In an environmental study, LIVOSTIN 0.05% (levocabastine hydrochloride ophthalmic suspension) instilled four times daily was shown to be significantly more effective than its vehicle in reducing ocular itching associated with seasonal allergic conjunctivitis. After instillation in the eye, levocabastine is systemically absorbed. However, the amount of systemically absorbed levocabastine after therapeutic ocular doses is low (mean plasma concentrations in the range of 1-2 ng/mL). Brand name Livostin is no longer available in the U.S., but generic versions may still be available. Common side effects include burning, stinging, itching, or watering of the eyes, eye irritation or discomfort, blurred vision, dry or puffy eyes, headache, nosebleed, nausea, or fatigue.

Nedocromil is a medication considered as mast cell stabilizer used to treat itching associated with allergic conjunctivitis. Nedocromil has been shown to inhibit the in vitro activation of, and mediator release from, a variety of inflammatory cell types associated with asthma, including eosinophils, neutrophils, macrophages, mast cells, monocytes, and platelets. Nedocromil inhibits activation and release of inflammatory mediators such as histamine, prostaglandin D2 and leukotrienes c4 from different types of cells in the lumen and mucosa of the bronchial tree. These mediators are derived from arachidonic acid metabolism through the lipoxygenase and cyclo-oxygenase pathways. The mechanism of action of nedocromil may be due partly to inhibition of axon reflexes and release of sensory neuropeptides, such as substance P, neurokinin A, and calcitonin-geneñrelated peptides. The result is inhibition of bradykinin-induced bronchoconstriction. Nedocromil does not possess any bronchodilator, antihistamine, or corticosteroid activity. Nedocromil is indicated for the treatment of itching associated with allergic conjunctivitis.

Oxedrine (Sympatol, p-synephrine) is a naturally occurring alkaloid molecule first appeared in Europe towards the end of the 1920s being sold as a drug under the brand name Sympatol. Oxedrine was then being prescribed as a remedy for a number of respiratory conditions, which include asthma, whooping cough, colds, and hay fever. More recently, synephrine gained popularity as a weight loss aid and it has become a favored component in the more popular brands of weight loss supplement stacks. This popularity can be attributed in part to the ban imposed on ephedra, to which it shares similar mechanisms of action. Most, if not all of the synephrine being sold as a dietary supplement is extracted and synthesized from the Citrus aurantium plant, more commonly known as bitter orange. Just like ephedrine, synephrine has vasoconstrictive abilities, although at a lesser potency compared to ephedrine. There is no mention of synephrine in editions of Drill's Pharmacology in Medicine later than the 3rd, nor is there any reference to synephrine in the 2012 Physicians' Desk Reference, nor in the current FDA "Orange Book". One current reference source describes synephrine as a vasoconstrictor that has been given to hypotensive patients, orally or by injection, in doses of 20–100 mg.

Spaglumic acid (NAAG) is the β-aspartyl isoform of N-Acetyl-l-aspartylglutamate (isospaglumic Acid is N-(N-Acetyl-l-α-aspartyl)-l-glutamic acid). In eye drops, spaglumic acid is either a magnesium or sodium salt of N-Acetyl-l-aspartylglutamate. Spaglumic acid is a mast cell stabilizer. Thus it is used in allergic conditions such as allergic conjunctivitis. Specifically spaglumic acid is approved in Portugal under the brand name Naabak and in Greece under the brand name Naaxia for use in patients with allergic conjunctivitis. Spaglumic Acid is a peptide neurotransmitter and the third-most-prevalent neurotransmitter in the mammalian nervous system. It is a weak activator of NMDA receptors and a highly selective agonist for mGlu3 receptors. Spaglumic Acid is neuroprotective under non-hydrolysing conditions in vivo.

Berefrine (also known as phenylephrine oxazolidine), a prodrug of phenylephrine, is a mydriatic agent. Berefrine was developed for improving ocular absorption and reducing systemic side effects.