Q: deafness etc. in Indian Medical literature?

[Birgit Kellner]

I am currently looking for sources on deafness, blindness and
corresponding deficiencies of the senses in ancient Indian medical
literature. I have browsed through the Carakasam.hitaa and checked some
secondary literature - as far as it is available to me -, but could not
find any specific mention. My curiosity applies particularly to the
following three points: 

(1) How can the complete absence of a certain sense-faculty's function
be diagnosed?

(2) What are the causes that are recognized as inevitably leading to a
loss of a sense-faculty?

(3) Is there a distinction between a natural inability to use a certain
sense and one that is brought about by accidents or other extraneous
causes? And if so, how does that reflect in the diagnosis?

Along the same lines, I would like to know what kinds of sensory defects
Indian medical literature recognizes, and, in particular, to what extent
and in which way their causes are investigated. Philosophical literature
deals with perceptual errors a lot, and with the question whether and
how such errors could or should be attributed to defects in the actual
sense-faculty/sense-organ, but I have so far not come across any
secondary literature where such discussions are linked to a medical
analysis. 

Any references will be greatly appreciated, 

-- 
Birgit Kellner
Department of Indian Philosophy
Hiroshima University