External environmental acquaintance with the living body is executed by five sense organs namely netra (eye), karna (ear), nasa (nose), jivha (taste buds), and twak (skin)- S.Sh.1-15.

All dnyanendriyas i.e. sense organs are panchbhautic in composition. In spite of this fact, every indriya or sense organ perceives object/tanmatra of that mahabhuta from which it is originated or one which is predominant. For example, the eye is originated from teja mahabhuta and hence perceives the object of teja mahabhuta only i.e. it is capable of performing ‘rupagrahana’, i.e. visual perception only. An eye is not capable of perceiving senses like audio, tactile etc. Virtual dnyanendriyas or sense organs or centers of perception are minute and are located in brain and organs perceiving them like the eye, ear etc. are the instrumental sense organs or ‘adhishthana’ (Charaka Sh.1-138).

Charaka in Sutrasthana Ch. 8 has explained the functioning of Dnyanendriya. He has laid down panch-panchaka concept for this. It includes pancha dnyanendriya, predominant mahabhoota originating them, adhishthana, artha i.e. sense objects and buddhi i.e. interpreting brain center of that sense organ. It is as follows in case of Netra.

 

Sense organ Chakshurindriya
Mahabhuta Teja mahabhuta
Dnyanendriya adhishthana Netra (Eye)
Artha/ sense object Roopa tanmatra/sight i.e. perception of size, shape, colour etc. of an object.
Indriya buddhi / Visual centres. It is created by togetherness of Chakshurindriya buddhi i.e. visual centres in occipital cortex, mann (mind) and atma (soul)

 

Perception of an image is the function of drushti which is the location of Alochaka pitta. This sensation is conveyed through dhamanis to mann and atma through pranavayu and the sequence is responsible for the perception of an object. In this way the external object is perceived when atma unites/linked with mann; Mann unites with indriyabuddhi; Indriyabuddhi unites with tanmatra; Tanmatra unites with adhishthana; Adhishthana unites with mahabhuta; and Mahabhuta unites with minute virtual dnyanendriya located in the brain. In this process of perception of an object by eye, pranavayu and kapha located in shira play an important role. Healthy status of all sense organs depends upon homeostatic i.e. physiological conditions especially of pranavayu and tarpaka kapha. Once the above sequence is completed, then the image of a particular object is interpreted and perceived.

Role of Dosha-Dhatu-Mala

The living body is sustained by 3 dosha, 7 dhatu, and 3 mala. All body functions are controlled by dnyanendriya, karmendriya, mann, and atma (S.Su 15-3). Dosha-dhatu-mala has to stay in equilibrium, their deviation either from physiology or towards pathology; triggers genesis of diseases. Following passages will explain how homeostatic conditions of dosha-dhatu-mala become responsible for normal functioning of dnyanendriya like Netra.

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Before considering the Samprapti of Netraroga, I would like to highlight the following important points.

Importance of equilibrium of Dosha-
The homeostatic condition of Dosha, Dhatu, and Mala is essential for maintaining the normal functioning of various Dnyanendriya, Karmendriya, Mann (mind) and Atma (soul). Their deviation either from physiology or towards pathology triggers genesis of disease (A.H.Su.1-20).

Six stages of Samprapti / Pathogenesis-
According to Sushruta( S. Su. 21-36), 6 stages are necessary for generating disease of a particular structure. They are Chaya (accumulation), Prakopa (excitation), Prasara (spread), Sthanasanshraya (localization), Vyakta and Bheda (complete manifestation of disease).

Importance of Srotovaigunya i.e. Abnormality-
The spreading vitiated Dosha get localized / settled / lodged wherever Kavaigunya / Srotovaigunya i.e. abnormality is present (S. Su. 24-10).

General Samprapti of Netraroga-
Dosha vitiated by various etiological factors; especially the ones specifically acting on eyes (caused by unwholesome diet and injudicious activities); when passes upwards through sira; occupy different structures like Vartma, Sandhi, Shukla, Krushna, Drushti and Sarva / all parts of eye; and then precipitate diseases of that particular structure only if Srotovaigunya is present there (S.U. 1-20, 21 and A.H.U. 8-1, 2; A.H.Ni.1-12).

In very few diseases Sushruta described some specific Samprapti e.g. Srava, Savrana Shukra, Ajakajata, Timira, etc. Timira, Kacha, and Linganasha are 3 main diseases of Drushtigata Roga causing partial or total blindness if not treated properly and promptly. Hence their specific Samprapti is described here.
Specific Samprapti / Pathogenesis of Timira / Kacha / Linganasha
Dosha, vitiated by various etiological factors / specifically some Timira generating dosha (Dalhana), when enters the Eye through sira and get lodged in the First Patala i.e. Tejojalashrita (due to pre-existing Srotovaigunya); generate pathology there i.e. Timira. If neglected / untreated, these Dosha become more and more intensified / aggravated and invade 2nd, 3rd, and 4th Patala and precipitate Kacha and Linganasha. The mild blurring of vision in the affliction of 1st Patala gradually increases leading to the visual loss in the 4th Patala.

Thus derangement of the environment in the vicinity of Tejojala i.e. aqueous humor is responsible for the development of Timira / Kacha / Linganasha. If the environment remains within the physiological limits, vitiated dosha shall not be able to get settled in the 1st Patala.

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