Ocular tuberculosis meets rather frequently among nonlung forms of the disease. Primary and secondary ocular tuberculosis are differed.
The term «primary ocular tuberculosis» has been used when the tuberculosis lesions are confined to the eyes and no systemic lesions are clinically evident. The term has also been used to describe the cases where the eye has been the initial portal of entry. MBT can enter in the eye, under the eyelids by dust or by the coughing from an infected person.
«Secondary ocular tuberculosis» has been defined as ocular infection resulting from contiguous spread from adjacent structures or haematogenous spread from the lungs.
Primary infection of the conjunctiva. If tubercle bacilli lodge under the upper or lower eyelid of a child who has not so far had a primary infection in the lung or abdomen they can multiply and form a tuberculous lesion. This is the same as a primary infection anywhere else. Multiplication is followed by caseation. It is possible to find small yellow areas if to evert the eyelid.
The eye may water and be rather irritable; the lid may become rather swollen. But as the process in the eye develops the lymph drainage from the area passes to the small lymph node just in front of the ear. This becomes involved in the tuberculous process, enlarges and may soften. It may be the swelling or softening, or even the rupture of the nodal abscess. It is a good example of the fact that the first infection with tuberculosis always has both a place of entry of the bacilli and enlargement of the nearest lymph node. From this type of infection bacilli can also escape into the bloodstream and be carried to other tissues such as bones just as they can from a primary infection in the lung.
Phlyctenular conjunctivitis begins with pain, irritation, lachrymation (tears) and photophobia (unwillingness to face light) in one or both eyes. One or more small grey or yellow spots are found round the limbus where the cornea meets the white of the eye. A number of small blood vessels run up from the edge of the conjunctival sac to meet the spots. Each spot lasts about a week and then slowly disappears. But others may replace it. If secondary infection should follow, there may be a purulent discharge and the cornea may be permanently scarred with white spots where the ulcers had formed. This painful and sometimes repeated condition is most likely to occur between the ages of 5 and 15 years and is common in Africa, India and South-East Asia. It is usually due to tuberculosis, but can occur with infection by hemolytic streptococci.
Choroidal (retinal) tubercles.
Search of the retina with an ophthalmoscope after the pupil has been dilated with 0.25 per cent atropine ointment may sometimes establish the diagnosis of tuberculosis. The examination is particularly worth doing when rapid diagnosis is required in cases of miliary spread or tuberculous meningitis. At the retina examination it is very important to pay attention to the optic disc and the central artery of the retina, which spreads out from its center. If tubercles are present and recent they appear as 1-3 mm yellowish, rounded, slightly raised spots. The edges fade into the general pinkness of the retina. They are most likely to be found within two disc-diameters of the center of the optic disc. As the tubercle gets older the edge becomes more definite and the center white. Depending on what structure of the oculus mainly defeated by tuberculosis differ: panophthalmitis; uveitis; choroiditis; tuberculosis of lacrimal system and etc. Acute tuberculous panophthalmitis is a highly destructive abscess of the whole eye. The patient loses vision progressively. Removal of the eye may be necessary eventually.
Tuberculosis of the uveal tract.
Lesions may occur on the back of the cornea and iris. Keratitis, conjuctivitis, keratoconjuctivitis could be met among tubercular-allergic eye diseases.
Treatment of ocular tuberculosis.
The treatment should be conducted under supervision of ophthalmologist.