gets blurred vision and mydriasis. Dry mouth is not uncommon, so ocular sicca may be aggravated or occur. In long-term therapy, however, cases of corneal or lens deposits or lens pigmentation have been reported. Retinal pigmentary changes are exceedingly rare, and only occur with long-term therapy. These are strong photosensitizing agents.

References and Further Reading

Drug Evaluations, 6th edn, American Medical Association, Chicago, pp 126–127, 1986.

Drugs for psychiatric disorders. Med Lett Drugs Ther 25: 45, 1983. Drugs that cause photosensitivity. Med Lett Drugs Ther 28: 51, 1986. Eberlein-Konig B, Bindl A, Przybilla B. Phototoxic properties of neuroleptic

drugs. Dermatology 194: 131–135, 1997.

McNevin S, MacKay M. Chlorprothixene-induced systemic lupus erythematosus. J Clin Psychopharmacol 2: 411, 1982.

Physician’s Desk Reference, 60th edn, Thomson PDR, Montvale NJ, pp 2124–2125, 2006.

Class: Psychedelic Agents

Generic names: 1. Dronabinol (tetrahydrocannabinol, THC); 2. hashish; 3. marihuana (marijuana).

Proprietary name: 1. Marinol (Canad.).

Street names: 1. The one; 2. bhang, charas, gram, hash, keif, black Russian; 3. ace, Acapulco gold, baby, Belyando sprue, boo, brown weed, bush, cannabis, charas, dank, dope, gage, ganja, grass, green, gungeon, hay, hemp, herb, home grown, jay, joint, kick sticks, kryptonite, lid, locoweed, Mary Jane, Mexican green, MJ, muggles, OJ (opium joint), Panama red, pot, rainy-day woman, reefer, roach, rope, sinsemilla, stick, tea, twist, weed, wheat.

Primary use

These psychedelic agents are occasionally used as cerebral sedatives and are narcotics commonly available on the illicit drug market. Dronabinol is also medically indicated for the treatment of the nausea and vomiting associated with chemotherapy.

Ocular side effects

Systemic administration

Certain

1.Visual hallucinations

2.Problems with color vision

a.Color vision defect

b.Objects have yellow or violet tinge

c.Colored flashing lights

d.Heightened color perception

3.Nystagmus

4.Non-specific ocular irritation

a.Hyperemia

b.Conjunctivitis

c.Photophobia (variable)

d.Burning sensation

5.Decreased accommodation

6.Decreased dark adaptation

7.Decreased vision

8.Blepharospasm

9. Decreased intraocular pressure

10. Decreased lacrimation

11. Pupils

a.Miosis

b.Anisocoria

12. Extraocular muscles

a.Increased phorias

b.Intermittent tropia

c.Diplopia

13. Binocular depth inversion – reduced

Clinical significance

Marihuana is the most widely used illicit drug in the USA and one of the oldest recorded medicines in the world. It is almost always smoked. The oral form, dronabinol, is largely unappealing to the addict and therefore has a very low abuse potential. Levi and Miller (1990) as well as Laffi and Safran (1993) found vision disturbances lasting 24 hours after marihuana use. Each report involved only a few patients but included alterations of depth perception, sensorial disconnection when talking with people, intermittent light phenomena, strobe-like effects, bright spots flickering randomly in high frequency and alteration of the sensory perception of one’s external environment. Ocular side effects due to these agents are transient and seldom of clinical importance.

Semple et al (2003), using binocular depth inversion testing, discovered persistent sensory visual abnormalities in chronic marihuana users. There is some evidence that marijuana ­decreases basal lacrimal secretion, decreases photosensitivity, increases dark adaptation, increases color-match limits and increases Snellen visual acuity. Possibly within the first 5–15 minutes some people will get some pupillary constriction; however, most do not and, to date, there is no long-term pupillary effect noted. Conjunctival hyperemia is not uncommon and is more pronounced at 15 minutes after exposure.

The cannabinols found in marihuana can lower intraocular pressure by an average of 25%, but the effect only lasts 3–4 hours. There is significant variation in the individual response to these agents, as well as diminished response with time. Most patients on this agent for glaucoma control cannot use it for prolonged periods­ due to lack of glaucoma control. Isolated cannabinols, which lower intraocular pressure, have the complicating factor that one cannot separate the central nervous system high from its ocular pressure lowering effect, so their value clinically is quite limited. Few patients are able to use marihuana for long-term control of their glaucoma and remain functional in the workplace.

These drugs are occasionally used medically, but have no long-term value in clinical ophthalmology.

References and Further Reading

Flach AJ. Delta-9-tetrahydrocannabinol (THC) in the treatment of end-stage open-angle glaucoma. Trans Am Ophthalmol Soc 100: 215–222, 2002.

Fried PA. Marihuana use by pregnant women and effects on offspring: an update. Neurobehav Toxicol Teratol 4: 451, 1982.

Gaillard MC, Borruat FX. Persisting visual hallucinations and illusions in previously drug-addicted patients. Klin Monatsbl Augenheilkd 220: 176–178, 2003.

Green K. Marijuana and the eye – a review. J Toxicol Cut Ocular Toxicol 1: 3, 1982.

Green K, Roth M. Ocular effects of topical administration of .9-tetrahydro- cannabinol in man. Arch Ophthalmol 100: 265, 1982.

Jay WM, Green K. Multiple-drop study of topically applied 1% .9-tetrahydro- cannabinol in human eyes. Arch Ophthalmol 101: 591, 1983.

Laffi GL, Safran AB. Persistent visual changes following hashish consumption. Br J Ophthalmol 77: 601–602, 1993.

Levi L, Miller NR. Visual illusions associated with previous drug abuse. F Clin Neuro-ophthalmol 10: 103–110, 1990.

CNS the affecting Agents • 2 Section