Dr. N. Srikanth
Shalakya Tantra is one of the 8 branches of Ayurveda. It deals with the diseases of eyes, ear, nose and throat and organs situated above the level of the clavicle and their management. When we refer our classics for therapeutic measures adopted for the treatment of eye diseases, many of the topical treatments along with systemic ones are observable. The reason might be non-crossing of the blood-aqueous, blood vitreous and blood-retinal barriers of the drugs administered systemically. The topical measures are called as “Kriya Kalpas”.
The term Kriya Kalpa is composed of 2 words Kriya and Kalpa. Kriya means the therapeutic procedures which cures the disease without causing any adverse effects. Kalpa indicates the specific formulation adapted for the therapeutic procedures. These are specifically designed according to the stage and severity of the disease. Sushruta the father of Indian Ophthalmology mentioned 5 Kriyakalpas, Tarpana, Putapaka, Seka, Aschotana and Anjana in the 18th chapter of Uttara Sthana. Pindi and Bidalaka are the 2 inclusions made by Sharangadhara and Vagbhata. The mechanism of action of these ancient ocular therapies could be well understood with the following basic principles of ocular pharmacology.
BASIC PRINCIPLES OF OCULAR PHARMACOLOGY
Routes of administration of drugs.
Compliance (Giving detail explanation to patients regarding drugs/therapy)
Disposal (Time and path of excretion of the drug)
Absorption (Time and rate of absorption)
Drug Vehicles and Bioavailability (Aqueous or lipid media)
Duration and quantum of bioavailability of the drug.
Routes of Administration of drugs
Instillation into the conjunctival sac
Sub Conjunctival injections.
Systemic administration.
Instillation into the conjunctival sac
Drugs are applied to the conjunctival sac as drops, ointments which are thin discs of gelatin which can be placed in the conjunctival sac (aschotana and anjana). Only substances which are soluble both in water and fat penetrate through the Cornea. The main site of resistances is the epithelium for once the epithelium is destroyed the passage is simple, as stroma is permeable to all water-soluble substances. The passage of the drug through the epithelium is determined by the factors controlling the penetration of the drug into other cells. Two of the most important such factors are Fat and Solubility, Degree of dissociation of electrolytes.
Sub conjunctival injections
They can be employed to introduce a wide range of substances for the sclera allows free and indiscriminate passage of molecules of big size. Perhaps ointments and ocular inserts (anjana/applications of collyrium) act in the same way.
Systemic administration
The systemic route has limitation because of the blood-aqueous barrier. Large-sized molecules, arsenic, antimony compounds which are commonly used in different collyria cannot cross this barrier and do not enter the eye. When the molecular size of the substance is at the borderline, penetration depends on lipid solubility. Many of collyria preparations prescribed contain arsenic and antimony compounds which are administered topically. This reveals the awareness of ancients regarding the blood-aqueous barrier.
A drug cannot act on the intact eye unless it reaches its receptors in the adequate concentration. The bioavailability of drugs used in the eye depends on many factors.
Compliance
Adequate and repeated explanation to the patient as well as practical advice about dose, time tables help to reduce non-compliance. To avoid this, Ayurvedic scholars prescribed particular dosage to each Kriyakalpa.
Disposal
About 80% of each drop drain immediately through the nasolacrimal canal. Normal tear volume is restored 2-3 minutes after installation (aschotana). Small drops of high concentration present more drug to the cornea than large drops of low concentration. In addition, dilution of the drop by tear occurs rapidly particularly as the basal tear turnover rate of 60% per minute can be trebled by increased lacrimation by instilling an eye drop. Drops larger than 50 m/units cannot be accommodated by the conjunctival sac. For this reason, there should be an interval of 5-10 minutes in between applying drops, if more than one type is being used.
Absorption
The main barrier to drug absorption through the cornea is the epithelium which is lipophilic. After entering the stroma which is hydrophilic, the passage of the drug through the endothelium is rapid. A drug, therefore, best absorbed if it is lipid and water-soluble. Agents which reduce surface tension increase the corneal wetting and therefore present more drugs for absorption.
Drug vehicles And Bio Availability
The forms of drugs instilled into the eye are aqueous solutions (medicated solutions used in aschotana and seka), aqueous suspensions (medicated ghee and oils) ocular inserts and ointments (different Anjana preparations). Each has a different influence on drug bioavailability. In solution, the drug is totally dissolved and therefore totally available. But tissue contact time is short (aschotana and seka). In suspension, the drug is present as small particles kept suspended in an aqueous medium by a dispersing agent. (Medicated ghee and oils), particles do not leave the eye as quickly as solutions which increase the tissue contact time (as in tarpana and putapaka). Ointment increases the bioavailability of the drug by increasing the tissue contact time, and by preventing dilution and drainage of active ingredient (different collyria). Ocular inserts which are placed in upper and lower fornices, allow a drug to be released by a continuous steady rate.
ANALYSIS OF KRIYANKALPAS BASED ON THE BASIC PRINCIPLES OF OCULAR PHARMACOLOGY
ASCHOTANA
Instillation of few drops of medicaments into the conjunctival sac. Vagbhata indicated aschotana as first line of treatment in all ocular inflammatory conditions where Raga (congestion) daha (burning pain) ashru srava (excessive lacrimation) sopha (inflammation) and toda (pricking pain) are present.
Procedure: Instillation of the medicated solution into the conjunctival sac from the height of two angulas when the eye is completely open and the patient is in a supine position.
A drug used: Decoctions prepared out of leaves, bark etc. The decoction should be neither concentrated nor diluted and it should not be too hot or too cold.
Dosage:
Lekhana aschotana- 8 bindus (DROPS)
Snehana aschotana- 10 bindus (DROPS)
Ropana aschotana- 12 bindus (DROPS)
Duration: 3 to 5 days
It is indicated as the first line of treatment in all ocular manifestations in their initial stage. Compliance as physician himself gives the treatment there is no necessity for giving any explanation about the dosage or duration of drug treatment.
Disposal: 80% of each drop instantaneously drains through the nasolacrimal canal.
Absorption: The decoctions are the aqueous extraction of different plant materials containing the active principles in the assimilable form facilitating absorption.
Drug vehicle and Bioavailability: In aschotana, the drug employed is in the form aqueous and the period of tissue contact is very less. Hence the bio availability of the drug is very short.
It is contraindicated in night because pupils being dilated and the angles of the anterior chamber are partially closed, obstruct the drainage of aqueous humor, so that therapeutic concentrations cannot be attained. Even though tissue contact time is very less, the absorption is more. In inflammatory conditions, the corneal permeability is high. Hence, the absorption is maximum.
SEKA
Pouring of thin streams of medicated solution over the closed eye continuously for a stipulated period.
Indications: It is indicated in acute and severe affections of the eye.
Procedure: Pouring of thin streams of medicated solution over the closed eye continuously for a stipulated period from the height of 4 angulas.
Drugs used: Decoction prepared from different parts of the plants.
Duration:
Sneha seka – 600 matra kalas (10 Minutes)
Ropana – 400 kalas (6 Minutes)
Lekhana – 200 matra kalas (4 Minutes)
(Double the time prescribed for puta paka)
Compliance: Same as aschotana
Disposal: Disposal rate is more.
Absorption: Absorption rate is more than aschotana.
Bio Availability and tissue contact period of the drug is more.
In seka, the compliance, duration and absorption is more when compared to aschotana hence, it compensates quick disposal and is indicated in acute and severe eye affections
Prescriptions for Aschotana and seka:
Bacterial and viral inflammatory conditions of the eye
Triphala decoction.
Dadima decoction.
Haridra decoction.
Allergic inflammatory conditions of eye.
Daruharidra decoction
Yasthimadhu decoction
Shireesha decoction.
Painful ophthalmic conditions of the eye
Manjistha decoction
Krishna Jeeraka decoction
Karpura and ksheera (20 ml. of milk and half gm. Karpura)
Note: Method of preparations of ophthalmic decoction.
Take ½ tsp. powder of prescribed drug. Add 50 ml of water. Reduce it to 15 ml and filter it.
ANJANA
(Application of Collyrium): A Topical application of drugs into the eye in the form of smooth paste. Anjana means which spreads or propagates
‘Anakti anena anjanam’. Even though anjanas are meant for eye diseases it has wide applications in systemic diseases too.
Indications: Anjana is indicated when clinical features of doshas have become manifested and localized in the eye and acute inflammatory signs such as congestion, redness, epiphora are subsided by the application of seka and aschotana.
Contra-indications: In acute inflammatory conditions.
Procedure: Topical application of the drug in the form of paste into the conjuctival fornices with an applicator (salaka)’.
Drug used: Compound drugs prepared out of metals, minerals and herbs. Generally antimony, lead and tin compounds are frequently prescribed.
Snehana
Drug used: animal fat etc, indicated in timira
Lekhana
Drug used: amla, lavana, katu, kashaya rasa dravyas used in pterygium.
Prasadana used in abhisyanda
Dosage:
Gutikanjana
Lekhana 1 harenu (pea) (Approximately 1 gm.)
Ropana 11/2 harenu (Approximately 11/2 gm.)
Prasadana 2 harenu (Approximately 2 gm.)
Rasakriya
Lekhana 1 harenu (1gm)
Ropana 11/2 harenu (11/2 gm)
Prasadana 2 harenu (2 gm)
Choornanjana
Lekhana 2 applications
Ropana 3 applications
Prasadana 4 applications
It is indicated in advanced stage of all diseases.
Compliance: Dosage and duration are aptly prescribed to avoid non compliance.
Disposal: The disposal rate is minimum and tissue contact time is more, absorption is maximum. It acts as a sub conjuctival injection, perhaps permeability is also possible through the sclera and enters into the systemic circulation and may act on posterior segmental disorders.
Many of the drugs used in Anjanas contain arsenic and antimony compounds. As the molecular size of these compounds is very large, they cannot cross the blood aqueous barrier when they are administered systemically.
Drug vehicle and bio-availability: As it is in the form of ointment applied to the eye, tissue contact time and bio availability is more.
It is indicated in a variety of disorders including systemic manifestations. Tissue contact time, bio-availability and absorptions are maximum. It is contra indicated in inflammatory conditions and corneal ulcers.
TARPANA
Keeping medicated ghee or oil over the eye for a stipulated period.
Drug used: Ghee and oils prepared out of herbal drugs.
Indications: It is indicated in a variety of ocular disorders such as jihyata (squinting) tamyata (symptomatic visual disturbances) rookshata (dryness) adhimantha (glaucoma).
Procedure: Concentric boundary is formed around the orbit and luke warm medicated ghees and oils are filled.
Vata Rogas – 1000 matra kalas = 17 Minutes
Pitta Rogas – 800 matra kalas =14 Minutes
Sandhigata – 300 matra kalas = 4 Minutes
Shukala gata – 500 matra kalas = 7 Minutes
Krishna gata – 700 matra kalas = 12 Minutes
Dristigata – 800 matra kalas = 14 Minutes
Average time prescribed is 20 minutes
Compliance: The dose and duration are fixed for each to avoid non compliance.
Disposal: A drug is retained for a prescribed period.
Absorption: Absorption is more because the drugs used are lipid soluble. Penetration of fat soluble substances is high irrespective of molecular size.
Drug vehicle and bio availability: Ghee preparation used in tarpana in the form of suspension containing different particle of the drug and the particles do not leave the eye as quick as solution. Tissue contact time and bio availability is more, hence therapeutic concentration can be achieved.
Prescriptions:
Patoladi ghritha
Dadimadi ghritha
Mahatriphala ghritha
Triphala ghritha
Gandha taila
Quantity required 25 ml for each eye
PUTAPAKA
Topical application of plant extracts, fats, certain metals and minerals for a stipulated period.
Procedure: Same as tarpana
Drugs used: Plant extracts, metals, minerals and animal extracts.
Indications: Indicated in all conditions where tarpana is advised. When visual activity is impaired by different therapeutic procedures.
Dosage and Duration:
Lekhana Drug used honey, flesh, bhasmas of gold, silver, copper etc.
Duration- 100 matrakalas ½ minutes
Snehana Drugs used Sneha, animal fat etc.
Duration 200 matrakalas as 3 minutes
Prasadana Drug used milk and ghee etc.
Duration 300 matrakalas – 4 minutes
Compliance, disposal and absorption same as in Tarpana, Tissue contact time and bio availability is less than tarpana.
Mode of action of Topically administered drugs: Drugs used in different therapeutic procedures are absorbed through sandhis sira srotas of eye, nose, mouth etc.
Putapaka swarasa should be made out of the following drugs.
Guduchi patra
Eranda patra
Dadima patra
Nimba patra
Patola patra
Quantity required approximately 25 ml for each eye.
BIDALAKA
Topical application of drugs in the form of paste over eye lids.
Indications: It is indicated in inflammatory conditions with congestion, redness and irritation.
Procedure: Paste made out of different drugs is applied over the eyelid (leaving the eye lashes) and kept for a stipulated period.
Paste is made out of following drugs.
Patola patra
Eranda patra
Sheeghru patra
Nagara, Rasanjana.
PINDI
In Pindi-mild sudation is applied over the eye by lukewarm paste made out of different plant parts.
Mode of action: It is helpful in relieving the inflammatory process, congestion, irritation etc by enhancing Vasodilatation and drainage of toxins from the site.
Drugs used: Sheeghru patra
Eranda patra
Dadima twak,
Nimba twak.
DISCUSSION
Owing to the dilation of the pupils and partial closing of the angles of anterior chamber of the eye, there will be an obstruction in the drainage of aqueous humor, which in turn minimizes the therapeutic concentration of the drug. Hence, any drug advocated topically during night hours is contraindicated. In case of Aschotana, though the tissue contact period of the drug is very short, the drug absorption rate is more. The most probable reason for this may be increased by corneal permeability during inflammatory conditions. Aschotana is advised during inflammatory conditions.
In case of seka, duration of drug administration is more when compared with aschotana, thereby the rate of absorption of the drug and bio-availability of the drug becomes more. So, seka is indicated in acute and severe eye affections.
Most of the anjanas contain arsenic and antimony compounds. The molecular size of these compounds is very large. They cannot cross the blood-aqueous barrier when administrated systematically. But this problem will not arise when applied topically. Having the knowledge of blood aqueous barrier mechanism, our ancients advised to use such vised drugs in the form of anjanas even in many systemic health problems. Here the duration of the therapeutic procedure and tissue contact period will be more. Hence the bio availability of the drug becomes more.
In Tarpana the drugs used in the form of suspensions containing ghee and oils which are lipid soluble. Lipid soluble substance cross corneal epithelium irrespective of their molecular size, hence therapeutic concentrations can be achieved. When visual acuity is found to be impaired, then putapaka is advocated. By pindi and bidalaka therapies, vasodilatation and drainage of toxins from the site of lesion is possible. Hence, to relieve inflammation, congestion, irritation etc. these 2 therapies play a major role.
Note: Duration of time required to pronounce a syllable is called “matra”. For e.g. Ten, six and five minutes respectively is the duration for 600, 400, and 300 matra kalas (approximately).
Conclusion
Our ancient medical scholars were aware of the mechanisms of blood-aqueous barrier as well as ocular pharmacology. For kriya kalpas day time is preferred to obtain highest therapeutic concentration of the drug in the aqueous humor.
Knowing the non crossing of the blood-aqueous barrier by antimony and arsenic compounds orally, they advised to apply topically.
Medicated grithas and oils, the bhasmas of gold, copper, zinc and calcium etc which are absorbable systemically are prescribed for systemic administration to fulfill the essentials of metabolism of eye.
BIBLIOGRAPHY
Chatterjee B.M. (1986) HAND Book of Ophthalmology; CBS Publishers Delhi
Chatterjkee C.C. (1988) Human physiology Medical allied Agency Bombay
Prabha K.V.S. (1990) Shalakya Tantra, A.P. Ayurvedic Literature Improvement Trust, Hyderabad
Sharangadhara (1916)Samhita V.R. Swamy and sons, Madras.
Stephen Miller (1987)Clinical Ophthalmology Varghese company, Bombay
Sushruta (1976) Sushrutha Samhitha Uttara Sthana Chowkhamba Oriental Publishers, Varanasi.
Vagabhata (1979)Astanga Sangraha Telugu Academy, Hyderabad.
DR. N. SRIKANTH is the Deputy Director-General, Central Council for Research in Ayurveda and Siddha, NewDelhi
