A 4 year old African child develops an infection with Chlamydia trachomatis. How does infection with this organism cause blindness?

Chlamydia trachomatis (serotypes A, B, and C) causes a conjunctival and corneal infection that is spread in developing countries by eye-seeking flies. The lesions begin with formation of lymphoid follicles in the conjunctiva. With disease progression, there is tissue necrosis, granulation tissue deposition, and scar formation, leading to lacrimal duct obstruction and distoion of the eyelids. With the loss of an adequate tear system, the cornea becomes vulnerable to dehydration and opacification. Also, the vigorous inflammatory response can directly involve the cornea, with resulting opacity. In developed countries, chlamydial eye infections are often transmitted venereally rather than by flies, and may cause conjunctivitis in the newborn and in sexually active young adults. Ref: Ray C.G., Ryan K.J. (2010). Chapter 39. Chlamydia. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.