Prevalence and significance of acquired immunodeficiency syndrome-related retinal microvasculopathy

CD8+ T lymphocytes and cytomegalovirus retinitis in patients with the acquired immunodeficiency syndrome

PURPOSE

We compared the levels of CD8+ and CD4+ cells in human immunodeficiency virus (HIV)-seropositive patients who had normal eye examinations, microvasculopathy, or ocular infections other than cytomegalovirus retinitis to those of patients with cytomegalovirus retinitis, to determine whether lymphocyte counts other than CD4+ are predictive of cytomegalovirus retinitis.

METHODS

The records of HIV-positive patients who had a lymphocyte subset analysis within three months of a complete eye examination were reviewed for age, gender, mode of HIV transmission, stage of disease, ocular findings, and absolute lymphocyte counts. Data for patients without cytomegalovirus retinitis were compared with those for patients with cytomegalovirus retinitis.

RESULTS

Ninety-three HIV-positive patients had a lymphocyte subset analysis within three months of a complete eye examination; 76 patients had no cytomegalovirus retinitis and 17 had cytomegalovirus retinitis. Patients without cytomegalovirus retinitis and those with cytomegalovirus retinitis had the following median cell counts: CD4+, 76.0 and 15.0 cells/microliters; CD8+, 634.5 and 280.0 cells/microliters, respectively. Patients with cytomegalovirus retinitis had significantly lower CD4+ and CD8+ cell counts than those without cytomegalovirus retinitis (P < .001). CD4+ and CD8+ cells are significantly correlated with each other, and the correlation is much higher in patients with cytomegalovirus retinitis (r = .80, P < .001) than in patients without cytomegalovirus retinitis (r = .57, P < .001). Stepwise logistic regression analysis showed that CD8+ cell counts were also predictive of cytomegalovirus retinitis.

CONCLUSION

Patients with low CD4+ cell counts are known to be at high risk for cytomegalovirus retinitis. We showed that patients with low CD8+ cell counts are also at high risk for cytomegalovirus retinitis.

AIDS-related optic neuropathy: a histological, virological and ultrastructural study

BACKGROUND

Clinical and histopathological evidence of optic nerve axonal loss has been reported in AIDS patients without retinitis. The study was carried out to investigate the possible involvement of HIV-infected cells in the development of optic nerve degeneration.

METHODS

Optic nerves were obtained from eight AIDS patients and four normal controls. These nerves were morphologically and immunohistochemically analyzed. Additionally, using PCR amplification techniques, the retina and optic nerve samples obtained from three HIV-seropositive patients and one control were examined for the presence of HIV and cytomegalovirus antigens.

RESULTS

We noted various stages of axonal degeneration in the optic nerves obtained from AIDS patients in whom there was an absence of retinal findings. Characteristic glial changes involving hypertrophic astrocytes, vacuolated oligodendrocytes, and mononuclear phagocyte series cells were also seen in the AIDS optic nerves. HIV DNA was present in at least four of five optic nerves but in only one of five retinas. Control specimens were each negative for all cytomegalovirus and HIV antigens.

CONCLUSIONS

Degeneration in the optic nerve may be mediated by HIV-infected macrophages rather than by direct viral infection of neurons. Axonal degeneration due to AIDS at the level of the optic nerve can occur independently of retinal infection.

Noncytomegalovirus-related chorio-retinal manifestations of the acquired immunodeficiency syndrome

The diagnosis of the ocular manifestations of AIDS is based initially on the clinical appearance of the lesions. However, retinal and choroidal lesions in AIDS patients are frequently the manifestation of disseminated disease. In one autopsy series, 15 of 18 patients with infectious choroiditis died of systemic infection by the same organism causing the choroiditis. Despite the fact that more than 90% of posterior segment infections in AIDS patients are caused by CMV, careful examination with appropriate consideration of differential diagnosis is necessary in all cases in which a classic pattern of CMV retinitis is not seen. Extensive history taking, discussion with the primary care physician, and the appropriate systemic work-up can greatly facilitate the diagnosis of the most likely cause of the apparent opportunistic infection. It is important to remember that noninfectious causes of HIV-related retinal disease can have a similar clinical pattern as infectious causes. In particular, physicians must be careful not to confuse early CMV retinitis with HIV-related noninfectious retinal vasculopathy, the most common retinal finding in patients with HIV disease. In a patient with multifocal superficial lesions in the posterior pole, particularly if the CD4+ count is more than 100 cells/microL, reevaluation rather than immediately initiating therapy may prevent the inadvertent commitment to chronic therapy implicit in a diagnosis of CMV retinitis.

Immune predispositions for cytomegalovirus retinitis in AIDS. The HNRC Group

CMV retinitis develops in approximately 28-35% of all AIDS patients at later stages of disease, often leading to blindness. To determine whether the subset of AIDS patients who developed CMV retinitis (CMV-R) were immunologically predisposed, T cell proliferation responses to CMV were examined prospectively in an HIV infected, HLA typed, longitudinal study population. Individuals who developed CMV-R had significantly lower T cell proliferation responses to CMV, both early and late in disease, compared to CD4 matched controls who have not developed CMV-R. Since HLA proteins influence T-cell recognition, phenotypes of 21 CMV-R patients were examined to determine whether certain HLA alleles were associated with low immune response and predisposed AIDS patients to CMV-R. HLA DR7 and B44 were at increased (nearly twice the expected) frequency in those with CMV-R. The combined association of either B44, 51 or DR7 with CMV-R was highly significant (P = .008, relative risk of CMV-R = 15) with correction for multiple comparisons. Low immune responses were twice as frequent in those with (61%) compared to those without (30%) predisposing alleles. Thus, AIDS patients with immunogenetically related hyporesponsiveness to CMV antigens may be at increased risk of retinitis.

Retinal findings in Malawian patients with AIDS

The purpose of this study was to determine the prevalence of retinal disease in a group of patients with AIDS in Malawi. Indirect ophthalmoscopy was performed on 99 patients with AIDS who were admitted consecutively to a medical ward at a central hospital. Necrotising retinitis was present in one eye of one patient examined. Non-infectious retinopathy was present in 13%. Retinitis is less common in AIDS patients from Africa compared with those from developed countries; it is believed that most patients die before acquiring it. Non-infectious retinopathy may also be less common.

Optic nerve morphometry following axonal degeneration from SAIDS in rhesus monkeys

In order to further study AIDS (acquired immunodeficiency syndrome) related neuropathologic findings, specifically progressive diffuse leuko-encephalopathy (PDL) and optic neuropathy, ten macaque monkeys (Macaca mulatta) were infected with simian immunodeficiency virus (SIV), observed for varying periods, and then sacrificed and tissue prepared for analysis. A marked difference from human AIDS pathology was found: in all monkeys, there was significant peripheral axonal dropout, as opposed to relatively little dropout in the central areas of the nerves (t stat. = -5.9, p < .001). In those monkeys infected with SIV for over one year, the axonal loss in the periphery was also greater than in the central optic nerve (t stat. = -5.03, p < .001); monkeys infected with SIV for less than one year had slightly less peripheral than central loss (t stat. = -4.5, p = .001). When compared with humans, however, it was found that the overall loss of axons was less (15% in monkeys vs. up to 45% in humans). There was also a lack of discernible retinal pathology, such as cotton wool spots, in the monkey tissue.

Ophthalmic manifestations of infections with Cryptococcus neoformans in patients with the acquired immunodeficiency syndrome

The present study was undertaken to determine the nature and the prevalence of ophthalmic manifestations of infections with Cryptococcus neoformans in human immunodeficiency virus seropositive patients and to analyze whether the presence or absence of ocular signs is associated with improved survival. Eighty human immunodeficiency virus seropositive patients with cryptococcal infection were enrolled. We observed papilledema in 26 of the 80 patients (32.5%). Visual loss and abducens nerve palsy occurred in seven patients (9%). Only two patients (2.5%) had optic atrophy. Visual loss caused by optic nerve involvement was less frequent among the 62 patients treated with oral conazoles exclusively than among the 18 patients who had received amphotericin B or a combination of amphotericin B and conazoles. Actual invasion of the intraocular structures with Cryptococcus neoformans was an uncommon complication in our series. In addition to the ocular manifestations attributable to cryptococcal disease, human immunodeficiency virus-related retinopathy was present in nearly half of the patients. Cytomegalovirus retinitis was diagnosed in four patients (5%). The 26 patients (32.5%) with papilledema had a median survival of 182 days vs 160 days for the patients without papilledema. The median survival for 18 patients (22.5%) with cotton-wool spots was 102 days vs 186 days for those without cotton-wool spots. The differences between these subgroups were not statistically significant.

Impairment of colour contrast sensitivity and neuroretinal dysfunction in patients with symptomatic HIV infection or AIDS

Ophthalmic and neurological complications are frequent findings in patients with AIDS. Little is known about neuroretinal dysfunction in patients with HIV infection. The purpose of this study was to measure and evaluate colour vision in patients with HIV infection or AIDS. Colour contrast sensitivity tests were performed on 75 patients (150 eyes) in different stages of HIV infection. A highly sensitive computer graphics system was used to measure tritan, deutan, and protan colour contrast thresholds. Patients were classified into three clinical groups: (a) asymptomatic HIV infection, (b) lymphadenopathy syndrome or AIDS-related complex, and (c) AIDS. Overall, tritan (p < 0.0001), deutan (p = 0.003), and protan (p = 0.009) colour contrast sensitivities were significantly impaired in patients with HIV infection compared with normal controls. Colour thresholds in patients with asymptomatic HIV infection (mean tritan threshold: 4.33; deutan: 4.41; protan: 3.97) were not impaired compared with normal controls. Colour vision was slightly impaired in patients with lymphadenopathy syndrome or AIDS-related complex (tritan: 6.25 (p < 0.0001); deutan: 4.99 (p = 0.02); protan: 4.45 (p = 0.05)). In patients with AIDS the impairment was even more marked (tritan: 7.66 (p < 0.0001); deutan: 5.15 (p < 0.0009); protan: 4.63 (p = 0.004)). Analysis of covariance controlling for age demonstrated a close association between impairment of tritan colour contrast sensitivity and progression of HIV disease (p < 0.0001). Following Köllner's rule, our study suggests that neuroretinal dysfunction occurs in patients with symptomatic HIV infection or AIDS. This is emphasised by the finding that the relative impairment in tritan vision compared with deutan/protan vision might reflect the difference in the number of cones or receptive fields. Measurement of tritan colour contrast sensitivity appears to be an appropriate and easily applicable method to detect early neuroretinal dysfunction in patients with HIV disease.

Correlation between CD4+ counts and prevalence of cytomegalovirus retinitis and human immunodeficiency virus-related noninfectious retinal vasculopathy in patients with acquired immunodeficiency syndrome

We prospectively studied 132 patients with acquired immunodeficiency syndrome (AIDS) to determine the cross-sectional prevalence of cytomegalovirus retinitis. All patients had serum CD4+ lymphocyte counts to determine the degree of immune dysfunction. Correlations between CD4+ counts, the presence of cytomegalovirus retinitis or human immunodeficiency virus (HIV)-related noninfectious retinal vasculopathy, and ocular symptoms were made. The study disclosed that 26 of 132 patients with AIDS (20%) had cytomegalovirus retinitis. However, subset analysis according to CD4+ count disclosed that in patients with CD4+ counts of 50 cells/mm3 or less, 26 of 87 (30%) had cytomegalovirus retinitis, whereas in patients with CD4+ counts of 50 cells/mm3 or more, none of 45 was noted to have cytomegalovirus retinitis. Similarly, 46 of 132 patients (35%) were noted to have HIV-related noninfectious retinal vasculopathy, with a trend toward increasing prevalence associated with declining CD4+ count. In patients with CD4+ counts of 50 cells/mm3 or less, 39 of 87 (45%) had HIV-related noninfectious retinal vasculopathy, whereas seven of 45 patients (16%) with CD4+ counts of 50 cells/mm3 or more were noted to have these changes. We confirmed the clinical impression that cytomegalovirus retinitis and HIV-related noninfectious retinal vasculopathy are late manifestations of AIDS, demonstrated an increased risk for patients with low CD4+ counts, and suggested a basis for coherent chemoprophylaxis and screening strategies for cytomegalovirus retinitis.

Retinal disease associated with AIDS

In recent years an enormous amount of new information in the area of retinitis and retinal disease in immunosuppressed patients has been acquired. There have been exciting new developments in our understanding of the pathogenesis of retinal disease in AIDS patients as well as important advances in the diagnosis and therapy of infectious retinitis. This article will summarise the recent advances in this area and outline the direction of future research as it applies to the clinical management of patients with retinal manifestations of AIDS. Diagnostic and therapeutic difficulties will be addressed including the appropriate selection of antiviral drugs and other therapeutic modalities in patients with sight-threatening retinitis.

Systemic antiviral drugs used in ophthalmology

Over the past two decades, the recognition of viral enzymes and proteins that can serve as molecular targets of drugs has revolutionized the treatment of viral infections. Beginning with acyclovir, a number of systemically administered agents which are both relatively safe and effective for the treatment of herpetic infections and human immunodeficiency virus (HIV) infections have become widely available. Because of increased numbers of herpes virus infections, as well as the rising epidemic of HIV infections, the ophthalmologist is, more likely than ever before to be involved in the treatment of severe and frequent ocular infections caused by herpes viruses. In addition, the acute retinal necrosis (ARN) syndrome has been demonstrated to be caused by herpes viruses and a once rare retinal infection caused by cytomegalovirus is common in patients with the acquired immunodeficiency syndrome (AIDS). In this article, four systemic antiviral drugs (Vidarabine, Acyclovir, Ganciclovir, and Foscarnet) that have demonstrated usefulness in the treatment of ophthalmic disease are reviewed in detail with regard to their mechanisms, applications, effectiveness, and side effects.

Ocular tissue involvement in HIV infection: immunological and pathological aspects

The CNS afflictions in AIDS are myriad and suggest a tropism of HIV to neural tissue. Ocular involvement is a frequent manifestation of the HIV infection, resulting in a high incidence of blindness within this patient population. Ocular lesions include cotton wool spots, presumably from HIV-induced microvasculopathy, retinal hemorrhage in cytomegalovirus retinitis and conjunctival Kaposi's sarcoma. These manifestations have been noted in up to 71% of AIDS patients. In fact, ocular disease is often the presenting symptom in an HIV-infected individual. Despite the high incidence of ocular involvement in AIDS patients, the etiology and pathogenesis of these manifestations are not well understood. The immunosuppressive action of HIV is the most likely primary cause for the development of ocular complications in AIDS. Here we review some of the important immunological and pathological features of AIDS affliction in the eye.

Visual dysfunction without retinitis in patients with acquired immunodeficiency syndrome

Patients with human immunodeficiency virus infection may have noninfectious and infectious retinopathies, as well as clinical symptoms consistent with optic nerve dysfunction. Noninfectious acquired immunodeficiency syndrome-related retinopathy is seen in most patients with AIDS. Morphologic studies have shown that the number of retrobulbar optic nerve fibers in patients with AIDS is decreased compared to the number of optic nerve fibers in normal control eyes. To determine whether these patients had a visual dysfunction consistent with damage to the macula and optic nerve, 78 subjects (156 eyes) were studied using color-vision and contrast-sensitivity testing. The Farnsworth-Munsell 100-Hue color-vision test was performed on all subjects and age-corrected color-vision scores for all groups were compared. A significant decrease in color discrimination was found in the patients with AIDS (P less than .001). Contrast-sensitivity testing disclosed a deficit of contrast threshold in patients with AIDS at four of five spatial frequencies and in patients with AIDS-related complex at three of the five spatial frequencies examined. This study demonstrated a functional visual deficit in eyes without retinitis consistent with dysfunction of the macula or optic nerve in patients with AIDS.

Morphometric Comparisons of Optic Nerve Axon Loss in Acquired Immunodeficiency Syndrome

Axonal degeneration and diminution of the axonal population in the optic nerve have been documented in aging and in various neuro-ophthalmic conditions. We applied morphometric techniques to the postmortem examination of optic nerves obtained from patients with acquired immunodeficiency syndrome. Twelve optic nerves (eight from patients with AIDS and four from age-matched control eyes) were stained with paraphenylenediamine and morphometrically analyzed with a computer-assisted image and measurement system. Degeneration was often severe and was scattered throughout all of the AIDS-affected optic nerves. In the AIDS-affected optic nerves, the mean axonal population was markedly lower than the mean obtained from normal optic nerves (880,000 vs 1,507,000). Despite the approximate 40% loss of axons, mean axonal diameters were not markedly different, suggesting that no particular class of axon was especially susceptible to AIDS-associated degeneration. The extent and pattern of axonal loss in optic nerves of patients with AIDS suggest that the changes may not only be secondary to damage at the retina, but may reflect an AIDS-associated primary optic neuropathy.

Low contrast visual acuity changes in human immuno-deficiency virus (HIV) infection

A pilot study of low contrast visual acuity testing using Regan Charts has been undertaken in 34 patients seropositive for Human Immuno-Deficiency Virus and 20 normal control subjects. Low contrast visual acuities of the HIV (+) patients both with and without HIV retinopathy were found to be significantly lower than the age-matched controls (p < 0.01). This finding is probably attributable to pathology related to HIV in the visual pathways/Central Nervous System. Lowest contrast Chart (Chart C) was found to be a useful diagnostic tool for HIV retinopathy and presumed neuropathy.

Efficacy and tolerance of intravitreal ganciclovir in cytomegalovirus retinitis in acquired immune deficiency syndrome

Forty-four patients with acquired immune deficiency syndrome with cytomegalovirus (CMV) retinitis (64 eyes) intolerant of or refusing systemic antiviral therapy received 710 intravitreal injections of ganciclovir at the dosage of 400 micrograms per injection. The patients were followed for a mean period of 9 weeks. Induction therapy consisted of two injections a week until healing. Maintenance therapy consisted of one injection a week until relapse. All but 1 of 53 induction courses led to cicatrization, after a mean of 6.6 injections. In 54 maintenance courses, the 8-week relapse rate was 53%. During intravitreal therapy, involvement of the fellow eye occurred in 11% of the patients and CMV infection developed in a nonocular site in 16% of the patients. Five retinal detachments and two intravitreal hemorrhages occurred. No endophthalmitis or cataract was noted. Intravitreal ganciclovir appears to be a safe and effective alternative in patients intolerant of intravenous anti-CMV drugs.

Ocular-systemic interrelationships in acquired immunodeficiency syndrome

We analysed the correlation between ophthalmic and systemic findings in 125 subjects with AIDS and 50 subjects with AIDS-related complex (ARC). Positive eye findings were defined as the presence of cotton-wool spots (CWS) or cytomegalovirus (CMV) retinitis. The presence of positive eye findings was significantly more frequent in AIDS than in ARC (P = 0.0001). Both lowest haematocrit and lowest T-helper cell count were significantly lower in AIDS than in ARC, and also lower in subjects with positive eye findings than in those with negative eye findings. No association was found between ocular findings and the following: risk factors for human immunodeficiency virus (HIV) transmission; positive titres for CMV, herpes simplex, Epstein-Barr virus (EBV), and toxoplasmosis; systemic infections; and intake of azidothymidine (AZT). Patients with AIDS and CWS were similar to patients with AIDS and CMV retinitis in viral serology, haematocrit, T-helper count, and survival. Positive eye findings, low haematocrit, and low T-helper count are poor prognostic signs for survival in AIDS.

Hemorheologic abnormalities in patients with human immunodeficiency virus infection and ophthalmic microvasculopathy

The severity of conjunctival microvascular changes and the presence of cotton-wool spots were compared to factors that may affect blood flow (hematocrit level, red cell aggregation, fibrinogen level, plasma viscosity, circulating immune complexes, and quantitative immunoglobulin levels) in 22 human immunodeficiency virus-infected individuals. The severity of conjunctival disease was associated with increased zeta sedimentation ratios (a measure of red cell aggregation) and fibrinogen levels. The presence of cotton-wool spots was also associated with higher fibrinogen levels. Plasma viscosity and quantitative IgG levels were above normal levels in most patients, although a relationship to disease severity was not established. Altered blood flow may contribute to vascular damage and ocular ischemic lesions in patients with human immunodeficiency virus infection.

Cotton-wool spots and AIDS related complex

Twenty-nine patients with the AIDS Related Complex (ARC) were studied retrospectively. Cotton-wool spots (CWSs) were the main ophthalmological finding, present in 9 patients (31%) at this stage of the disease. The CWSs were asymptomatic and were therefore discovered during a routine examination. The proportion of patients with significant weight loss was greater among ARC patients with CWSs than among those with normal fundi. Leukocyte counts were found to be significantly lower (p = 0.03, odds ratio 10.0 [1.24 to 80.4]) among ARC patients with CWSs. Lymphocyte counts and the CD4/CD8 ratio were also found to be diminished in these patients. Among the nine patients with CWSs during ARC, seven developed major opportunistic infections or HIV (Human Immunodeficiency Virus) related neoplasias during the following months (3.8 +/- 3.5 months). These findings are consistent with a poorer prognosis for HIV infected patients who have CWSs.