More plants validated for treating glaucoma, cataracts, conjunctivitis

Ahead of the World Sight Day (WSD), today, October 8, 2020, scientists have validated more plants for the treatment of ocular (connected with the eye or vision) diseases such as glaucoma, conjunctivitis, cataract, ocular allergies, ocular inflammation among others.

WSD focuses global attention on blindness and vision impairment. The theme for this year is “Hope In Sight”.

According to the World Health Organisation (WHO), one billion people around the world have a preventable vision impairment or one that has yet to be addressed. Reduced or absent eyesight can have major and long-lasting effects on all aspects of life, including daily personal activities, interacting with the community, school and work opportunities, and the ability to access public services.

Reduced eyesight can be caused by several factors, including diseases like diabetes and trachoma, trauma to the eyes, or conditions such as refractive error, cataracts, age-related macular degeneration, or glaucoma.

The majority of people with vision impairment are over the age of 50 years; however, vision loss can affect people of all ages.

But researchers have made progress in using natural products to prevent the development of eye diseases and blindness. They have developed eye drops that could be used to reverse glaucoma and cataracts.

Previous studies had validated extracts of bitter kola (Garcinia kola), garden egg (Solanum melongena), pepper fruit (Dennettia tripetala), and vitamin C to provide the elusive natural cure for eye diseases especially cataracts and glaucoma.

In fact, a Professor of Ophthalmology at Lagos University Teaching Hospital (LUTH) and now Chairman, Lagos State Traditional Medicine Board (LSTMB), Adebukunola O. Adefule-Ositelu, told The Guardian that her team had patented eye drops made with bitter kola for preventing blindness in patients with glaucoma.

The ophthalmologist said: “I got the mixture from one of my patients who I promised we will work on it. I can tell you authoritatively now that we have done extensive research on this extract as an eye drop and we are successfully using it in our clinic in successfully treating patients with glaucoma.”

But a recent study published in International Journal of Medicine Research and titled “Medicinal plants with anti-ocular activities” reviewed some of the medicinal plants which proved to be beneficial in the treatment of different ocular disease such as Cassia fistula (golden shower, Indian laburnum), Capsicum frutescens (long cayenne pepper), Capparis zeylanica (Ceylon Caper), Catharanthus roseus (bright eyes, periwinkle), Camellia sinensis (tea plant), Caesalpinia volkensii, Buddleja officinalis (sagewood), Cheilanthes glauca, Centella asiatica (Indian pennywort or Asiatic pennywort), Curcuma longa (turmeric), Emblica officinalis (Phyllanthus embilica or emblic), Erythrina indica (tiger’s claw or Indian coral tree), Eucalyptus deglupta (Mindanao gum or rainbow eucalyptus), Eugenia borinquensis, Eugenia jambolana (black plum), Ginkgo biloba, Lantana camara (big sage), Mangifera indica (mango tree), Ocimum sanctum (scent leaf), Plantago ovate (blond plantain), Tagetes erecta (African marigold), Tamarindus indica (tamarind), Terminalia arjuna (arjuna or arjun tree), Tinospora cordifolia (heart-leaved moonseed), Tribulus terrestris (devil’s-weed), Withania Somnifera (Indian ginseng), Zingiber officinalis (ginger).

The Indian researchers from the Shree Dev Bhoomi Institute of Education, Science, and Technology, Poundha, Dehradun, Uttarakhand, India, concluded: “ Herbal medicine is the most ancient form of health care known to man. Herbal medicine has such an extraordinary influence that numerous alternative medicine therapies treat their patients with herbal remedies, including naturopathy, orthomolecular medicine, and Ayurveda. Approximately 25 percent of all prescription drugs are derived from trees, shrubs, or herbs. Herbal medicines are popular due to their efficiency, low toxicity, and absence of side effects.”

A very recent study published in Avicenna Journal of Phytomedicine showed ginger extract can improve the levels of some trace elements and total homocysteine and prevent oxidative damage induced by ethanol in the rat eye.

The researchers concluded that ginger extract has protective effects against toxicity induced by ethanol in the eye of the male rat.

Another study published in the Journal of Natural Remedies concluded: “Ginger lowers Intra Ocular Pressure (IOP) in rabbits so can be used in humans in the management of glaucoma. Based on the results obtained we suggest that after the complete phytochemical analysis and the individual pharmacological evaluation of phytoconstituents, ginger may be useful in improving the glaucoma condition.”

Also, curcumin, a polyphenol extracted from turmeric (Curcuma longa), could be used in eye drops to treat the early stages of glaucoma and other eye diseases with neuronal pathology, according to a new study published in the journal Scientific Reports.

Another study published in Central-European Journal of Immunology and titled “Therapeutic potential of curcumin in eye diseases”, concluded: “Curcumin, a natural polyphenol agent isolated from Curcuma longa exhibits a wide range of pharmacological properties including antioxidant, anti-inflammatory, antimutagenic, antimicrobial and anticancer activity. The influence of curcumin on oxidative stress, angiogenesis, and inflammatory processes indicates that it may inhibit these pathological conditions and restore homeostasis. The analysis of a number of clinical and preclinical investigations shows that curcumin may be used as a therapeutic agent in the treatment of various eye diseases such as glaucoma, cataract, age-related macular degeneration, diabetic retinopathy, corneal neovascularisation, corneal wound healing, dry eye disease, conjunctivitis, pterygium, and anterior uveitis.”

Another study published in Polim Med showed tamarind seed could be used in the development of an ocular delivery system for glaucoma therapy using natural hydrogel as a film-forming agent and release modifier.

The researchers concluded: “It can be concluded that the hydrogel from tamarind seeds can be used as a film-forming and release-controlling agent for the development of an ocular drug delivery system for the effective therapy of glaucoma.”

Researchers have also demonstrated that scent leaf (Ocimum sanctum) could be used to treat eye diseases.

The study published in the Journal of Phytopharmacology concluded: “The leaf juice of Ocimum sanctum along with triphala is used in ayurvedic eye drop preparations recommended for glaucoma, chronic conjunctivitis and another painful eye disease. In daily routine, one may use about three drops of tulsi oil along with honey and it is supposed to improve eyesight.

Another study by researchers from Modupe Eye Centre, Ogbomoso, Oyo State; Department of Optometry, University of Benin, Benin City, Edo State; and Department of Optometry and Vision Science, University Of Ilorin, Kwara State, examined the effect of combined intake of Garcinia kola (bitter kola) and ascorbic acid (vitamin C) on intraocular pressure of normotensive (having or denoting a normal blood pressure) Nigerians.

The study was carried out to determine the effect of combined intake of Garcinia kola and ascorbic acid on Intraocular pressure (IOP) of normotensive Nigerians.

IOP is the fluid pressure inside the eye. Tonometry is the method eye care professionals use to determine this. IOP is an important aspect in the evaluation of patients at risk of glaucoma.

The researchers concluded: “It was concluded from this study that combined intake of Garcinia kola and Ascorbic acid had a greater effect on IOP than Garcinia kola or Ascorbic acid alone. However, this effect was transient, since the reduction was not sustained after 60 minutes of ingestion. This may form the basis for the development of affordable medicine for lowering IOP.”

A study by Adefule-Ositelu and her team published in the Middle East African Journal of Ophthalmology concluded: “Topical Garcinia kola 0.5 per cent aqueous eye drops are as effective as timolol maleate 0.5 per cent eye drops in lowering IOP in newly diagnosed glaucoma and ocular hypertensive patients. The mean IOP reducing efficacy after six months of use was similar in both groups. Garcinia kola extract may represent an alternate topical medication for a patient with open-angle glaucoma and ocular hypertensives in a resource-limited population.”

The study is titled “Efficacy of Garcinia kola 0.5 per cent aqueous eye drops in patients with primary open-angle glaucoma or ocular hypertension.”

The other members of the research team include: Adebayo K Adefule from the Department of Ophthalmology, LUTH, Idi-Araba, Bernice O. Adegbehingbe, Olayinka O. Adegbehingbe, and Elsie Samaila from Departments of Surgery, (Ophthalmology Unit) and Orthopaedic Surgery and Traumatology, Obafemi Awolowo University, Ile-Ife, and Kehinde Oladigbolu of the Department of Surgery, National Eye Centre, Kaduna.

Also, Nigeria researchers have shown that eating pepper fruits could decrease the risk of blindness caused by glaucoma.

The researchers at the Department of Optometry Abia State University, Uturu, Abia State, have demonstrated how a meal rich in pepper fruit reduces the risk of glaucoma by stabilising the IOP of the eye.

The study is titled “Effect of Dennettia tripetela Seed Intake on the Intra Ocular Pressure (IOP) of normotensive Emmetropic Nigerian Igbos.”

Emmetropia describes the state of vision where an object at infinity is in sharp focus with the eye lens in a neutral or relaxed state. This condition of the normal eye is achieved when the refractive power of the cornea and the axial length of the eye balance out, which focuses rays exactly on the retina, resulting in perfect vision. An eye in a state of emmetropia requires no correction.

According to the Abia State University study, results obtained showed that consumption of 0.75g of seed gradually reduced the mean IOP from 15.6mmHg to 11.20mmHg, (25.64 per cent reduction) after 60 minutes; and gradually reversed towards baseline value at 120mins-post ingestion. The mean induced change in IOP at 60 minutes was 4.00mmHg. The effect was found to be statistically significant.

The researchers wrote: “…There was a statistically significant reduction of IOP after 30 minutes and 60 minutes. This reduction in IOP recorded was probably due to the ascorbic acid, magnesium, flavonoid, melatonin, thiamin, vitamin B, the lipoid acid content of Ascorbic acid had been established to support the osmotic influx of water following osmolarity elevation of blood artificially leading to the fall in IOP.

“The effect of flavonoid in IOP reduction is thought to be as a result of the reduction in excessive permeability of blood-aqueous membrane within the eye. The presence of lipoic acid (fatty acid) probably helped in the reduction of IOP by increasing glutathione in red blood cells and lacrimal fluid of glaucomatous patients thereby reducing the IOP.

“Finally, the presence of melatonin, thiamine (vitamin B), and vitamin B perhaps also contributed to the reduction in IOP. This is due to the fact that melatonin levels have been found to decrease in glaucomatous patient and normal diurnal rhythms of IOP fluctuation reflect melatonin rhythms.”

Also, Nigerian researchers led by the former Director-General of NAFDAC and professor of pharmacology at University of Nigeria (UNN), Prof. Dora Nkem Akunyili, had demonstrated how a meal of garden egg would be of benefit to patients suffering from raised intraocular pressure (glaucoma) and convergence insufficiency, as well as in diseases associated with hyperlipidemia (high lipids/fats) such as ischaemic heart diseases and arteriosclerosis (stiffening of the arteries).

The study on garden egg and glaucoma is titled “Effects of Solanum melongena (garden egg) on some visual functions of visually active Igbos of Nigeria.”

The study was published in the Journal of Ethnopharmacology.

The effects of bolus consumption of 10 grammes of Solanum melongena were undertaken on visually active male volunteers so as to determine its ocular complications. Results of the study showed that the pupil size was reduced (23 per cent), Near Point of Convergence (NPC) was decreased (nine per cent) and the Anecortave Acetate (AA) was increased (22 per cent) and the intraocular pressure dropped by 25 per cent while there was no effect on Visual Acuity (VA), and the habitual phoria. Anecortave (rINN) is a novel angiogenesis inhibitor used in the treatment of the exudative (wet) form of age-related macular degeneration (blindness).

The miotic effect lowered the intraocular pressure appreciably and the reduced NPC, which was still within normal range, did not produce any vision discomfort. The increased AA and convergence excess positively correlated provide an efficient visual mechanism.

The researchers concluded: “It is suggested that S. melongena would be of benefit to patients suffering from raised intraocular pressure (glaucoma) and convergence insufficiency.”

Also, two earlier studies published in Archives of Ophthalmology offer hope of reducing the risk of blindness due to Age-related Macular Degeneration (AMD) and cataract.

Three leading causes of blindness are age-related macular degeneration, diabetic retinopathy, and retinopathy related to premature birth. All three conditions involve retinopathy, which is the abnormal development of blood vessels in the eye.

Researchers have found that regular consumption of fish; nuts, olive oil, and other foods containing omega-three fatty acids and avoiding trans-fats may significantly lower the risk for AMD.

Food sources of omega-3s include leafy green vegetables, walnuts, flaxseeds, and fatty fish such as salmon, herring, and sardines. Omega-6s are found in meat and vegetable oils such as safflower oil, sunflower oil, corn oil, and soy oils.

Previous studies have shown that extracts of carrots, garlic, pumpkin (Ugu in Igbo), amaranth (commonly called green vegetable) aniseed, almonds contain antioxidants that may decrease the development or progression of cataract.

Several research studies show that the antioxidant properties of vitamins C and E contained in these plants may protect against the development and progression of cataracts.

Early evidence also suggested that the carotenoids lutein and zeaxanthin, which are also antioxidants, might also be protective against cataracts. Some recent studies compared to diet and supplement intake of the antioxidant vitamins C and E with the development of cataracts. However, naturopaths recommend eating plenty of fruits and vegetables.