Final answer:
Blindness in patients with AIDS is often caused by opportunistic infections due to their weakened immune systems. Pneumocystis jirovecii, causing pneumonia, is one such organism that can lead to blindness in these individuals. The destruction of helper T cells by HIV limits the body's ability to fight off these infections.
Step-by-step explanation:
Blindness sometimes occurs as a result of Acquired Immunodeficiency Syndrome (AIDS), which is a disorder characterized by frequent opportunistic infections. These infections often occur in individuals with a compromised immune system, such as those infected with the Human Immunodeficiency Virus (HIV). The blindness associated with AIDS is most often the result of an opportunistic infection by organisms such as Pneumocystis jirovecii, which causes a type of pneumonia, and is among the many opportunistic infections including fungal, bacterial, and viral illnesses that can affect various systems in the body, including the eyes.
Without functional helper T cells, which are destroyed by HIV, the immune system cannot properly combat these infections. Other examples of these infections include esophageal candidiasis (yeast infection) and Kaposi's sarcoma (a type of cancer). These conditions can severely impact the health of an individual with AIDS and can result in serious complications such as blindness if the infections spread to the eyes.