There are 2 possible ways to get a visa for medical purposes, depending on the country.
Some states have an online visa system that issues electronic medical visas or short-stay visas that cover medical visits, among other things. These digital systems allow travelers to get their medical visas quickly and easily, without having to go anywhere.
In other cases, it is necessary to apply for a medical visa in person at a diplomatic mission (embassy or consulate) belonging to the country in which the treatment will take place.
Whether applying online or at an embassy, travelers will need to complete a medical visa application form.
The exact requirements for a medical visa vary from country to country.

The following documents are usually needed to justify the medical visa:

• Referral letterfrom a doctor/hospital/medical professional stating that the traveler needs treatment in the destination country
• Confirmation of the appointmentfrom a hospital or clinic in the destination country

A number of travel documents are usually required, which may include any or all of the following:

• Valid passport and copy of the information page
• Recent passport-style photo(s)
• Medical insurance
• Flight reservations
• Proof of accommodation
• Proof of sufficient funds to pay for the trip

Generally speaking, you need to prepare the following documents for a tourist visa application: 

• Tourist visa application form. 
• Passport with six- or three-months validity period.
• Passport pictures. 
• Valid travel insurance. 
• Evidence of financial means. 
• Proof of accommodation. 
• Proof of a booked return flight ticket. 
• Proof of paid visa fee. 
• Invitation letter. 
• Civil documents (marriage certificate, birth certificate, etc.) 
• Any other supporting documents.