The eye

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Chapter 23 The eye

Diagnosis of functional disorders of the eye (glaucoma, etc.) should always be carried out by a medical practitioner. The usual precautions when using extracts in the eye (e.g. sterility of eye drops, absence of irritation of solutions, etc.) must also be taken. Simple eye lotions containing mildly astringent and soothing plant products are very popular, especially those containing distilled witch hazel and eyebright herb extracts. However, ophthalmology clearly is not an area where phytotherapy is of wider importance.

Inflammation of the eye

Inflammation may be a result of an allergic reaction, infection or irritation due to dust or particles. Simple irritation of the eye can be treated with an eye lotion or drops, usually containing either extract of witch hazel (see Chapter 22), or the herb eyebright.

Eyebright, euphrasia officinalis L. and E. rostkoviana hayne (euphrasiae herba)

Euphrasia spp. (Scrophulariaceae) have a long history of use in eye disorders, as the name would suggest. The herb is found in meadows and grassy places throughout Europe and temperate Asia. The leaves are opposite near the base and alternate above, about 1 cm long, lanceolate, with four or five teeth on each side; the axillary flowers are two-lipped, small and white, often tinged with purple or with a yellow spot.

Constituents

Eyebright contains iridoid glycosides, such as aucubin, geniposide, catalpol, luproside, eurostoside, euphroside, veronicoside, verproside and others; lignans, including coniferyl glucosides and eukovoside; tannins; and polyphenolic acids, including gallic, caffeic and ferulic acids.

Therapeutic uses and available evidence

Extract of Euphrasia is a traditional remedy for disorders of the eye such as conjunctivitis. Practically no clinical studies have been carried out, but single-dose eye drops containing extracts of the herb were evaluated in a clinical prospective cohort trial for conjunctivitis, and efficacy and tolerability were deemed ‘good to very good’ by both patients and physicians (Stoss et al 2000). Overall, the evidence for beneficial effects is very limited.

Distilled witch hazel, aqua hamamelidis

Distilled witch hazel is prepared by macerating the dormant and partially dried twigs of Hamamelis virginiana L.,(Hamamelidaceae). It is often used in eye drops and eye lotions to soothe the eye and clear redness (for further details, see witch hazel, Chapter 22, Skin).

Glaucoma

Glaucoma is always treated under medical supervision. It is associated with increased intraocular pressure and can cause blindness if not treated. Most of the drugs used are synthetic sympathomimetics, such as dipivefrine and brimonidine, β-blockers such as timolol, or prostaglandin analogues, but there is a useful plant-derived miotic (a substance causing constriction of the pupil), the alkaloid, pilocarpine, which is widely used. It reduces intraocular pressure by opening the drainage channels in the trabecular meshwork, which may be affected by a spasm or contraction of the ciliary muscle.

Pilocarpine

Pilocarpine (Fig. 23.1) is an alkaloid obtained from Jaborandi leaf (Pilocarpus microphyllus Stapf. and other species of Pilocarpus, Rutaceae). Pilocarpine is a sympathomimetic agent, causing salivation, tachycardia and other effects if taken systemically. Its main use is in ophthalmic preparations as a miotic, in open-angle glaucoma and to contract the pupil after the use of atropine (BNF). It is a prescription-only medicine in most countries.

Fig. 23.1

Anterior uveitis

Anterior uveitis is an inflammatory disorder of the anterior segment. It is treated (under medical supervision) with atropine or its derivatives, homatropine and tropicamide.

Atropine

Atropine (Fig. 23.2) is a tropane alkaloid extracted from deadly nightshade (Atropa belladonna, Solanaceae). It is occasionally used as eye drops (0.5%) or ointment (1%) to open the iris for examination or surgical procedures, and to treat anterior uveitis (BNF). See Chapters 4 and 6.

Fig. 23.2

Stoss M., Michels C., Peter E., Beutke R., Gorter R.W. Prospective cohort trial of Euphrasia single-dose eye drops in conjunctivitis. J. Altern. Complement. Med.. 2000;6:499.

British National Formulary. Published biannually by the BMJ Group and the Pharmaceutical Press. See also http://bnf.org/bnf/index.htm

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