HIV VISION LOSS

In the early days of HIV-AIDS, opportunistic ocular infections were common in severely immune-compromised patients. Cytomegalovirus (CMV) retinitis was the most prevalent, affecting 15 to 40 per cent of patients with advanced HIV disease, with toxoplasmosis also a frequent problem. The advent of effective anti-retroviral therapy, which allows patients’ natural immune systems to recover, reduced CMV retinitis rates about 75 per cent, William R Freeman MD, director of the Jacobs Retina Center at the University of California – San Diego, La Jolla, US, told the American Academy of Ophthalmology annual meeting.

“Our residents and medical students see these things and have no idea what they are because they have no experience with them.” Nonetheless, infectious retinitis and choroiditis remain among several ways HIV disease threatens sight and ophthalmologists must be on guard, Dr Freeman said. They can occur alone or in combination, and may result in acute retinal necrosis, which can spread quickly in both eyes. “It really requires clinical acumen to diagnose quickly and choose the right treatment.”

Atypical presentation

Infectious retinitis often presents differently in immune-suppressed patients, which can make diagnosis and monitoring progression challenging, Dr Freeman said. In HIV patients with old toxoplasmosis scars, toxo retinitis often becomes confluent and may not look like toxoplasmosis. CMV retinitis may present with a classic tomato ketchup and cheese appearance, or it may be much subtler, resembling cotton wool spots, and may recur after it appears cured as a slow advance of lesion borders, Dr Freeman said.

CMV progresses slowly, so he recommends waiting a week if it’s not clear. Overall, clinical guidelines allow about 95 per cent of cases to be diagnosed by ophthalmoscope and fundus photographs, but sometimes a transvitreal retinal biopsy is needed.

The patient’s CD4 count can help with differential diagnosis – CMV retinitis occurs almost exclusively in patients with less than 40 cells per ml, Dr Freeman noted. “As ophthalmologists, we have to be cognizant of the patient’s medical condition. We are all physicians and we have to know how to order the tests and interpret them.” Systemic ganciclovir typically halts initial CMV progression, but the virus becomes resistant, and progression can resume. “We have to realise that if a patient is already on treatment and CD4 is low, we are going to have to supplement with intravitreal ganciclovir implants or other therapies,” Dr Freeman said.

Other infectious agents include syphilis and herpes zoster or simplex, which can rapidly propel progressive outer retinal necrosis. These also must be identified and treated early, Dr Freeman said. Aggressive management of retinal detachment is also indicated, with vitrectomy and permanent silicone oil tamponade as first line treatment to prevent recurrent detachments due to expanding lesions, Dr Freeman added. Even without retinitis, HIV patients still lose vision, Dr Freeman said. “Cotton-wool spots add up in time. We see a degeneration of axon profiles at autopsy in patients without retinitis but with a history of cotton-wool spots.”