Putting the Findings in Context
- It is important to note that all of the people in the present study had previously been diagnosed with AIDS -- due to the presence of a life-threatening infection or having a CD4+ count below the 200-cell threshold. It is not clear if the study's findings are sufficiently robust that they are relevant to other people who have had AIDS but are enjoying prolonged survival thanks to ART. Also, another area of uncertainty is whether or not the findings are relevant to the average HIV-positive person taking ART who has never had AIDS.
- More research is necessary to determine the long-term consequences of HIV-NRD.
- The present study was observational in design. This means that its findings are not definitive; in other words, it cannot prove that having HIV-HCV co-infection increases the risk for HIV-NRD. What it does is raise a signal about the presence of HIV-HCV co-infection possibly being a factor for HIV-NRD. Another potential flaw is that the study was not randomized; from the start it was designed to explore trends in visual health. It may therefore have biased its recruitment by inadvertently favouring volunteers with visual problems or who were predisposed to develop such problems.
- HIV-NRD seems unusually common in the present study. Other studies in other parts of the world need to be done to assess the health of the retinas of HIV-positive people. As scientists strive to better understand the potential cause(s) of HIV-NRD, there are at least several additional research issues that need to be explored, including the following:
- Assessments of inflammation -- If inflammation does play a role in gradually degrading the retina, can anti-inflammatory agents counter this?
- The potential role of cardiovascular disease on the retina -- This is important because at least one study has found that the tiny vessels that supply the retina with blood are not always in the best health in some people with AIDS.
- Other health conditions -- Studies in HIV-negative people suggest that in conditions such as type 2 diabetes, kidney injury and higher-than-normal blood pressure are associated with abnormal health of blood vessels in the retina. Therefore, the impact of these other co-morbidities needs to be explored in people with HIV who might also have HIV-NRD.
- The potential impact of other co-infections, such as syphilis, on the retina -- Rates of syphilis are high among some MSM, particularly those who are HIV positive. In part, syphilis can cause injury by triggering the onset of inflammation in affected organs and tissues. There are reports of visual damage caused by syphilis in HIV-positive people. Furthermore, there are reports of the rapid development of neurosyphilis in this population.
- The role of gender in the development of HIV-NRD -- In the present study, it could be that women were more likely to inject street drugs than men and so gender itself may not be a risk factor but merely be a statistical mask for behaviour such as injecting drugs (IDU). Such behaviour could expose people to more germs, including HCV. However, it is also possible that gender could play an important role because generally women are more likely than men to develop certain inflammatory disorders linked to a dysfunctional immune system.
Bear in Mind
The findings from the present study are interesting -- some people who have survived long after a diagnosis of AIDS may be at increased risk for gradually thinning retinas (a condition called HIV-associated neuroretinal disorder). None of these participants have had decreased sharpness of vision so it is not clear if HIV-NRD has very serious consequences.
Researchers are not certain as to the causes of retinal thinning among some HIV-positive people and years of intensive research lies ahead to uncover possible causes. What is certain is that relatively early initiation of ART and high adherence can prevent AIDS-related diseases from ever occurring. Scientists need to assess ART users who have never had AIDS to determine if thinning retinas is also an emerging health issue for them.
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