Morphometric Comparisons of Optic Nerve Axon Loss in Acquired Immunodeficiency Syndrome

Significant loss of retinal nerve fibre layer and contrast sensitivity in people with well controlled HIV disease: implications for aging with HIV

Objective

Antiretroviral therapy has decreased the prevalence of retinal opportunistic infections in people living with HIV (PLWH). However, abnormalities in visual function are evident and may be associated with an early onset of aging in PLWH. In this study, we examined the Retinal Nerve Fibre Layer (RNFL) thickness and visual function in PLWH and HIV non-infected controls in Malaysia.

Design

Cross-sectional study.

Methods

Two hundred and two (202) PLWH without retinal opportunistic infection and 182 age-matched, HIV seronegative individuals were enrolled. PLWH were recruited from the Infectious Disease clinic at the University Malaya Medical Centre. Controls were recruited among the hospital staff and community volunteers. RNFL thickness was measured with spectral domain optical coherence tomography (SDOCT). Visual functions include visual acuity using LogMAR chart and contrast sensitivity using Pelli- Robson Chart.

Results

All PLWH (mean age 46.1 years ± 9.9 years) in the study were on ART and 61.2% had a CD4+ T-cell count more than 500 cell/μl. The mean visual acuity was similar between the two groups (LogMAR 0.05 vs. 0.07, p = 0.115). Contrast sensitivity was lower in PLWH compared to HIV seronegative individuals (1.90 vs 1.93, p = 0.032). RNFL thickness was significantly thinner in the temporal quadrant for PLWH compared to controls (68.89 μm vs 74.08 μm, p = 0.001).

Conclusion

Changes in RNFL thickness and contrast sensitivity were seen in PLWH despite their relatively young age and well controlled HIV disease. The changes reflect structural and functional deficits, and could have long-term implications on their health trajectory.

Morphometric Analysis of Retinal Ganglion Cell Axons in Normal and Glaucomatous Brown Norway Rats Optic Nerves

Purpose

A reference atlas of optic nerve (ON) retinal ganglion cell (RGC) axons could facilitate studies of neuro-ophthalmic diseases by detecting subtle RGC axonal changes. Here we construct an RGC axonal atlas for normotensive eyes in Brown Norway rats, widely used in glaucoma research, and also develop/evaluate several novel metrics of axonal damage in hypertensive eyes.

Methods

Light micrographs of entire ON cross-sections from hypertensive and normotensive eyes were processed through a deep learning-based algorithm, AxoNet2.0, to determine axonal morphological properties and were semiquantitatively scored using the Morrison grading scale (MGS) to provide a damage score independent of AxoNet2.0 outcomes. To construct atlases, ONs were conformally mapped onto an ON "template," and axonal morphometric data was computed for each region. We also developed damage metrics based on myelin morphometry.

Results

In normotensive eyes, average axon density was ∼0.3 axons/µm2 (i.e., ∼80,000 axons in an ON). We measured axoplasm diameter, eccentricity, cross-sectional area, and myelin g-ratio and thickness. Most morphological parameters exhibited a wide range of coefficients of variation (CoV); however, myelin thickness CoV was only ∼2% in normotensive eyes. In hypertensive eyes, increased myelin thickness correlated strongly with MGS (P < 0.0001).

Conclusions

We present the first comprehensive normative RGC axon morphometric atlas for Brown Norway rat eyes. We suggest objective, repeatable damage metrics based on RGC axon myelin thickness for hypertensive eyes.

Translational Relevance

These tools can evaluate regional changes in RGCs and overall levels of damage in glaucoma studies using Brown Norway rats.

Increased incidence of glaucoma medication usage in middle-aged Australian males taking antiretroviral medication - a population-based study

BACKGROUND

To investigate a possible association between glaucoma and the use of anti-retroviral therapy (ART) for HIV in the Australian population.

METHODS

A retrospective review of Australian Pharmaceutical Benefits Scheme data was undertaken from July 2012 to December 2016, inclusive. Three patient groups were compared: those on both topical intraocular pressure (IOP) -lowering medication and ART, those on ART only, and those on IOP-lowering medication only, using the 2016 Australian resident population to estimate prevalence. Odds ratios (95% confidence intervals, [CI]) with Fishers exact test for p values were calculated stratified by age and gender.

RESULTS

The number of prescriptions for topical glaucoma medications in the general Australian population increased progressively by age with a peak prevalence in those aged 80 years and above. Prevalence of ART was highest in males aged 40-49 and 50-59 years (0.41% [CI 0.40, 0.42] and 0.44% [CI 0.43, 0.45], respectively). Our analysis identified an increase in the prescription of IOP-lowering medication in males on ART aged 30-39 (OR 2.23 [CI 1.32, 3.75], p = 0.007) and 40-49 (OR 1.86 [CI 1.42, 2.43], p < 0.001), compared to those not on ART. There were no statistically significant increased odds for females or males aged 50 years or more.

CONCLUSION

Compared with the known increase in glaucoma prevalence with age in the general Australian population, a statistically significant increased prevalence in use of IOP-lowering medications was found in males on ART aged 30-49 years. The mechanism for this is yet to be determined, but possible causes include sequelae of HIV infection, a drug-induced side effect, or increased medical surveillance.

THE THICKNESSES OF CHOROID, MACULAR SEGMENTS, PERIPAPILLARY RETINAL NERVE FIBER LAYER, AND RETINAL VASCULAR CALIBER IN HIV-1-INFECTED PATIENTS WITHOUT INFECTIOUS RETINITIS

PURPOSE

To evaluate choroidal, macular, peripapillary retinal nerve fiber layer (RNFL) thicknesses and retinal vascular caliber alterations in HIV-1-infected patients without opportunistic infections.

METHODS

This cross-sectional study included 45 HIV-1-infected patients and 47 healthy subjects. Spectral domain optical coherence tomography was used for assessment of choroidal, macular, peripapillary RNFL thicknesses and retinal vascular caliber alterations.

RESULTS

The mean CD4 count was 426 ± 226 cells per milliliter and the mean HIV-1 RNA level was 1.8 × 10 ± 3.6 × 10 copies/mL in HIV-infected group. Central inner plexiform, superior photoreceptor, superior and nasal retinal pigment epithelium layers were thinner in HIV-infected patients compared with control subjects (P < 0.05). The differences in sectoral retinal thicknesses lost their significance after Bonferroni correction (P < 0.01). The average thickness of pericentral retina within 3 mm was thinner in the photoreceptor layer in HIV-infected patients compared with control subjects (P = 0.033). The differences in peripapillary RNFL thickness, choroidal thickness, and retinal vascular caliber were not significant between the groups. Choroidal thickness and pericentral outer plexiform were thinner, whereas peripapillary RNFL was thicker in newly diagnosed cases (16 patients) compared with patients having treatment for at least 4 months or longer (27 patients, P < 0.05, Mann-Whitney U test). HIV-1 RNA showed negative correlation with choroidal thickness (r = -0.435, P = 0.003) and positive correlation with peripapillary RNFL in central (r = 0.323, P = 0.032) and superonasal (r = 0.369, P = 0.014) sectors.

CONCLUSION

Choroidal thickness was thinner in newly diagnosed patients compared with patients on treatment. Viral load showed negative correlation with choroidal thickness. Retinal segmental alterations occurred in HIV-infected patients compared with control subjects.

Corneal and Anterior Chamber Morphology in Human Immunodeficiency Virus-1-Infected Patients Without Opportunistic Infections

OBJECTIVES

To evaluate corneal and anterior chamber morphology as measured by Pentacam HR in human immunodeficiency virus (HIV)-infected patients without opportunistic infections and to search for signs of accelerated aging.

METHODS

This prospective study included 41 eyes of 41 HIV-1-infected patients (study group) and 50 eyes of 50 healthy subjects (control group). Specular microscope and Pentacam HR were used for corneal and anterior chamber morphology evaluation. Corneal endothelial cell density (CECD), hexagonal cell ratio, coefficient of variation, corneal thickness, density and volume, maximum keratometry, anterior chamber volume (ACV), and anterior chamber depth (ACD) measurements were recorded for analysis.

RESULTS

The mean CD4 count was 428.3±231.9 (36-950) cells/mL, and the time since diagnosis was 27.5±34.1 months in the study group. The difference in anterior segment parameters was not significantly different between the study and the control groups (P>0.05). Age significantly correlated with CECD (r=-0.436, P=0.004), ACV (r=-0.570, P<0.001), ACD (r=-0.471, P=0.002), and corneal density (r=0.424, P=0.006) in the study group, whereas it did not show a significant correlation with any ocular parameters in the control group (Pearson correlation).

CONCLUSION

Corneal density, CECD, ACV, and ACD showed significant correlation with age in HIV-1-infected patients. Further studies are needed to show whether ocular parameters may serve as useful tools to monitor HIV-related accelerated aging.

Neuroretinal Degeneration in HIV Patients Without Opportunistic Ocular Infections in the cART Era

Subtle structural and functional retinal abnormalities, termed 'HIV-associated Neuroretinal Disorder (HIV-NRD)', have been reported in HIV patients receiving combination antiretroviral therapy (cART), without infectious retinitis or any apparent fundus abnormalities otherwise. In this review, we provide an overview of studies investigating HIV-NRD in HIV patients without opportunistic ocular infections in the cART era, and try to elucidate underlying mechanisms and associated risk factors. Most studies focused on patients with severe immune-deficiency and demonstrated that patients with nadir CD4 counts<100 cells/μL are most at risk for neuroretinal damage, with a thinner retinal nerve fiber layer, subtle loss of color vision and/or contrast sensitivity, visual field deficits, and subnormal electrophysiological responses. In contrast, alterations in retinal vascular calibers and retinal blood flow were not associated with nadir CD4 counts, but instead with detectable viremia, suggesting a role for (chronic) inflammation in microvascular damage. Although the alterations in visual function are subtle, they can lead to difficulties in activities, such as reading or driving, thereby affecting quality of life. Since HIV has become a chronic disease, its long-term effects with respect to visual function loss become more important, as is recently emphasized by a longitudinal study, reporting that AIDS patients with HIV-NRD have higher risks of developing bilateral visual impairment and even blindness than patients without HIV-NRD. The question remains whether patients with high (>350 cells/μL) nadir CD4 counts and well-suppressed HIV infection on cART remain at risk for HIV-NRD, as this group constitutes a growing part of the aging HIV-infected population.

Incidence and long-term outcomes of the human immunodefıciency virus neuroretinal disorder in patients with AIDS

PURPOSE

Patients with AIDS have an abnormality of retina/optic nerve function, manifested as decreased contrast sensitivity (in the absence of ocular opportunistic infections or media opacity), abnormalities on automated perimetry, and loss of retinal nerve fiber layer, even among those with good visual acuity, termed the "human immunodeficiency virus (HIV) neuroretinal disorder." The objectives of this study were to determine the prevalence, incidence, risk factors, and outcomes of HIV neuroretinal disorder.

DESIGN

Prospective cohort study.

PARTICIPANTS

A total of 1822 patients with AIDS without ocular infections or media opacities.

METHODS

Patients with HIV neuroretinal disorder were identified by a contrast sensitivity <1.50 log units in either eye in the absence of ocular opportunistic infections or media opacity.

MAIN OUTCOME MEASURES

Incidence of HIV neuroretinal disorder, mortality, visual impairment (visual acuity ≤20/50), and blindness (≤20/200) on logarithmic visual acuity charts.

RESULTS

Sixteen percent of participants had HIV neuroretinal disorder at enrollment. The estimated cumulative incidence by 20 years after AIDS diagnosis was 51% (95% confidence interval [CI], 46-55). Human immunodeficiency virus neuroretinal disorder was more common in women and African Americans. Risk factors for HIV neuroretinal disorder included hepatitis C infection, low CD4+ T cells, and detectable HIV RNA in the blood. Patients with HIV neuroretinal disorder had a 70% excess mortality versus those without it, even after adjusting for CD4+ T cells and HIV load (hazard ratio [HR], 1.7; 95% CI, 1.3-2.1; P < 0.0001). Patients with HIV neuroretinal disorder had increased risks of bilateral visual impairment (HR, 6.5; 95% CI, 2.6-10.6; P < 0.0001) and blindness (HR, 5.9; 95% CI, 2.8-13.7; P = 0.01) versus those without HIV neuroretinal disorder.

CONCLUSIONS

Human immunodeficiency virus neuroretinal disorder is a common finding among patients with AIDS, and it is associated with an increased mortality and an increased risk of visual impairment. Successful antiretroviral therapy decreases but does not eliminate the risk of HIV neuroretinal disorder.

Visual function assessment in simulated real-life situations in HIV-infected subjects

Visual function abnormalities are common in people living with HIV disease (PLWH) without retinitis, even after improvement in immune status. Abnormalities such as reduced contrast sensitivity, altered color vision, peripheral visual field loss, and electrophysiological changes are related to a combination of retinal dysfunctions, involving inner and outer retinal structures. The standard protocol for testing vision performance in clinical practice is the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. However, this method poorly correlates with activities of daily living that require patients to assess visual stimuli in multiple light/contrast conditions, and with limited time. We utilized a novel interactive computer program (Central Vision Analyzer) to analyze vision performance in PLWH under a variety of light/contrast conditions that simulate stressful and real-world environments. The program tests vision in a time-dependent way that we believe better correlates with daily living activities than the non-timed ETDRS chart. We also aimed to correlate visual scores with retinal neuro-fiber layer thickness on optical coherence tomography. Here we show that visual acuity is more affected in PLWH in comparison to HIV-seronegative controls in varying contrast and luminance, especially if the nadir CD4+ T-cell count was lower than 100 cells/mm³. Visual impairment reflects the loss of retinal nerve fiber layer thickness especially of the temporal-inferior sector. In PLWH the ETDRS chart test led to better visual acuity compared to the Central Vision Analyzer equivalent test, likely because patients had indefinite time to guess the letters. This study confirms and strengthens the finding that visual function is affected in PLWH even in absence of retinitis, since we found that the HIV serostatus is the best predictor of visual loss. The Central Vision Analyzer may be useful in the diagnosis of subclinical HIV-associated visual loss in multiple light/contrast conditions, and may offer better understanding of this entity called “neuroretinal disorder”.

Association between retinal nerve fiber layer thickness and abnormalities of vision in people with human immunodeficiency virus infection

PURPOSE

To investigate relationships between contrast sensitivity (CS), color vision, and retinal nerve fiber layer (RNFL) among people with human immunodeficiency virus (HIV) infection; to evaluate the effect of time since diagnosis of HIV infection on RNFL thickness.

DESIGN

Noninterventional cross-sectional study.

METHODS

We evaluated 102 eyes of 57 HIV-infected individuals without ocular opportunistic infections. Peripapillary RNFL thickness was determined with spectral-domain optical coherence tomography in 4 quadrants. CS was measured with the Pelli-Robson technique (expressed as logCS); color vision was measured with the Lanthony desaturated 15-hue technique (expressed as color confusion index [C-index], with higher scores indicating worse color vision). Correlations between values were assessed using Spearman correlation coefficients.

RESULTS

Median RNFL thickness (average of 4 quadrants) was 102.9 μm (range, 75.0-134.7 μm). Median logCS was 1.90 (range, 1.25-1.95). Median C-index was 1.58 (range, 0.96-4.07). Temporal RNFL thickness was correlated with logCS (r=0.295, P=.003) and C-index (r=-0.338, P=.0005). Time since diagnosis of HIV infection was shorter for those with thick average RNFL than for those with thin average RNFL (P=.18).

CONCLUSIONS

Both worse CS and worse color vision are correlated with thinning of the temporal RNFL, with possible threshold effects. Increased prevalences of abnormal CS and abnormal color vision in this population are therefore likely attributable to neuroretinal compromise. This pattern of structural and functional losses may reflect preferential damage to small-caliber axons in the maculopapillary bundle, possibly associated with mitochondrial dysfunction, providing a potential disease mechanism for HIV-associated "neuroretinal disorder."

Effect of host genetics on incidence of HIV neuroretinal disorder in patients with AIDS

Approximately 10%-15% of patients with AIDS but without ocular opportunistic infections will have a presumed neuroretinal disorder (HIV-NRD), manifested by reduced contrast sensitivity and abnormal visual fields. The loss of contrast sensitivity often is sufficient to impair reading speed. To evaluate the effect of host genetics on HIV-NRD, we explored validated AIDS restriction gene variants CCR5Delta32, CCR2-64I, CCR5 P1, SDF-3'A, IL-10-5'A, RANTES -403A, RANTES -28G, RANTES-In1.1C, CX3CR1-249I, CX3CR1-280M, IFNG-179T, MDR1-3435T, and MCP-1364G, each of which has been implicated previously to influence HIV-1 infection, AIDS progression, therapy response, and antiviral drug metabolism, and an IL-10 receptor gene, IL-10R1, in the Longitudinal Study of the Ocular Complications of AIDS cohort. In European Americans (cases = 55, controls = 290), IL-10-5'A variant and its promoter haplotype (hazard ratio = 2.09, confidence interval. 1.19 to 3.67, P = 0.01), in African Americans (cases = 54, controls = 180), RANTES-In1.1C and the associated haplotype (hazard ratio = 2.72, confidence interval.: 1.48 to 5.00, P = 0.001), showed increased HIV-NRD susceptibility. Although sample sizes are small and P values do not pass a strict Bonferroni correction, our results suggest that, in European Americans, an IL-10-related pathway, and, in African Americans, chemokine receptor ligand polymorphisms in RANTES are risk factors for HIV-NRD development. Clearly, further studies are warrented.

Melanopsin retinal ganglion cells are resistant to neurodegeneration in mitochondrial optic neuropathies

Mitochondrial optic neuropathies, that is, Leber hereditary optic neuropathy and dominant optic atrophy, selectively affect retinal ganglion cells, causing visual loss with relatively preserved pupillary light reflex. The mammalian eye contains a light detection system based on a subset of retinal ganglion cells containing the photopigment melanopsin. These cells give origin to the retinohypothalamic tract and support the non-image-forming visual functions of the eye, which include the photoentrainment of circadian rhythms, light-induced suppression of melatonin secretion and pupillary light reflex. We studied the integrity of the retinohypothalamic tract in five patients with Leber hereditary optic neuropathy, in four with dominant optic atrophy and in nine controls by testing the light-induced suppression of nocturnal melatonin secretion. This response was maintained in optic neuropathy subjects as in controls, indicating that the retinohypothalamic tract is sufficiently preserved to drive light information detected by melanopsin retinal ganglion cells. We then investigated the histology of post-mortem eyes from two patients with Leber hereditary optic neuropathy and one case with dominant optic atrophy, compared with three age-matched controls. On these retinas, melanopsin retinal ganglion cells were characterized by immunohistochemistry and their number and distribution evaluated by a new protocol. In control retinas, we show that melanopsin retinal ganglion cells are lost with age and are more represented in the parafoveal region. In patients, we demonstrate a relative sparing of these cells compared with the massive loss of total retinal ganglion cells, even in the most affected areas of the retina. Our results demonstrate that melanopsin retinal ganglion cells resist neurodegeneration due to mitochondrial dysfunction and maintain non-image-forming functions of the eye in these visually impaired patients. We also show that in normal human retinas, these cells are more concentrated around the fovea and are lost with ageing. The current results provide a plausible explanation for the preservation of pupillary light reaction despite profound visual loss in patients with mitochondrial optic neuropathy, revealing the robustness of melanopsin retinal ganglion cells to a metabolic insult and opening the question of mechanisms that might protect these cells.

Structural and functional assessment in HIV-infected patients using optical coherence tomography and frequency-doubling technology perimetry

PURPOSE

To assess retinal nerve fiber layer (RNFL) and macular thickness using optical coherence tomography (OCT) on HIV-infected patients without ocular manifestations and to correlate these findings with frequency-doubling technology perimetry (FDT).

DESIGN

Cross-sectional study.

METHODS

setting: Single center. study population: Seventy-three patients (146 eyes) with clinically normal examination classified in 3 groups: group A, HIV-infected patients with CD4 count <100 cells/mm(3) for at least 6 months; group B, HIV-infected patients with CD4 count >100 cells/mm(3) since diagnosis; and group C, HIV-negative control subjects. observation procedures: Fast RNFL and fast macula scan strategies on Stratus OCT and Humphrey Matrix 24-2 full-threshold program. main outcome measures: OCT RNFL and macular thicknesses and FDT indices (mean deviation [MD], pattern standard deviation [PSD], and glaucoma hemifield test [GHT]).

RESULTS

Group A had a significantly thinner average RNFL, temporal outer macula, and inferior outer macula thicknesses when compared to groups B and C (P < .05). Statistically significant differences were observed in the FDT MD between groups A and C (P = .034) and in PSD in group A compared to groups B and C (P = .011). Eyes of HIV patients with GHT and PSD results outside normal confidence limits had thinner average RNFL thickness measures than eyes with results within normal limits in the same group of patients (P < .05).

CONCLUSIONS

HIV-infected patients with low CD4 count have a significant RNFL and macular thinning. Functional loss detected by FDT is related to RNFL thinning in HIV-infected patients.

Mitochondrial haplogroups are associated with risk of neuroretinal disorder in HIV-positive patients

Although highly active antiretroviral therapy has improved survivorship dramatically and decreased the incidence of cytomegalovirus retinitis among patients with AIDS, other ophthalmic complications continue to occur. One complication observed in approximately 12% of HIV-infected patients is a presumed neuroretinal disorder (NRD), manifested as decreased contrast sensitivity and associated with vague subjective complaints of hazy vision. Pathologically, patients with AIDS even without ocular opportunistic infections have loss of optic nerve axons, suggestive of mitochondrial dysfunction. We explored whether variation in mitochondrial DNA was associated with time to NRD in HIV-infected patients in the Longitudinal Study of Ocular Complications of AIDS cohort. Within the Western European, or "N", mitochondrial DNA macrohaplogroup, haplogroup J, was associated with 80% decrease in the risk of progression to NRD during the study (hazard ratio = 0.20, P = 0.039) and suggested an independent association with protection against NRD in a cross-section of all patients taken at enrollment (1.5% vs. 8.9% in patients with vs. without haplogroup J, respectively, P = 0.05). These data suggest that mitochondrial genotype may influence propensity to develop HIV-associated NRD in patients with AIDS.

Multifocal electroretinography in HIV-positive patients without infectious retinitis

PURPOSE

To evaluate early changes in the central retinal response in human immunodeficiency virus (HIV)-positive patients without infectious retinitis using multifocal electroretinography (mfERG).

DESIGN

Case control study.

METHODS

We evaluated three cohorts: HIV-negative controls and two groups of HIV-positive patients separated according to their nadir CD4 counts (>or= 100 cells/mm(3) and < 100 cells/mm(3) for a minimum of six months). mfERG first-order kernels (FOKs) and second-order kernels (SOKs) were analyzed separately by areas of rings, quadrants, and individual hexagons for each cohort.

RESULTS

Of 103 hexagon locations of FOK results, there were no significant differences in amplitudes of P1 and N1 across the groups (.05 < P < .50), although there was a trend for an overall reduction in the amplitudes. Similarly, latency N1 did not differ (.28 < P < .95). There were significantly delayed latencies of P1 between cohorts across 103 hexagons in both kernels. SOK results also showed significant delay in latencies of P1 and a trend of reduced P1 amplitudes across studied locations among cohorts (.24 < P < .08).

CONCLUSIONS

The results demonstrate widespread delay in latency in HIV-positive patients, especially in those with prolonged low (below 100 cells/mm(3)) CD4 nadir counts. These findings suggest early diffuse dysfunction of the inner retina results from severe HIV disease even in the HAART era.

AIDS and ophthalmology: the first quarter century

PURPOSE

To describe changes in the acquired immunodeficiency syndrome (AIDS) epidemic that are important to ophthalmologists, to provide an overview of issues relevant to current evaluation and treatment of human immunodeficiency virus (HIV)-related eye disease, and to identify problems related to the eye and vision that require continued study.

DESIGN

Literature review and commentary.

METHODS

Selected articles from the medical literature and the author's clinical and research experiences over 25 years were reviewed critically.

RESULTS

The AIDS epidemic has had a profound impact on ophthalmology since the ophthalmic manifestations of AIDS were first described in 1982. The introduction of highly active antiretroviral therapy (HAART) has markedly reduced the incidence of cytomegalovirus (CMV) retinitis, but has not eliminated new cases altogether. Treatment strategies for CMV retinitis have evolved over the past decade. Current issues of importance include choice of initial anti-CMV drugs; time at which anti-CMV drug treatment is discontinued in patients who achieve immune recovery; strategies for monitoring patients at risk for disease reactivation; and management of complications (retinal detachment, immune recovery uveitis). Attention also is being directed to the problem of visual disturbances (reduced contrast sensitivity, altered color vision, visual field abnormalities) that can occur in HIV-infected individuals without infectious retinopathies.

CONCLUSIONS

Ocular disorders associated with HIV disease remain important problems in the United States, despite HAART, and increasingly are important worldwide. The approach to management of CMV retinitis has evolved from short-term treatment of a preterminal infection to the long-term management of what has become a chronic disease. Many challenges remain to be addressed.

Vision function in HIV-infected individuals without retinitis: report of the Studies of Ocular Complications of AIDS Research Group

PURPOSE

To evaluate the prevalence and risk factors for vision loss in patients with clinical or immunologic AIDS without infectious retinitis.

DESIGN

A prospective, multicenter cohort study of patients with AIDS.

METHODS

One thousand three hundred and fifty-one patients (2,671 eyes) at 19 clinical trials centers diagnosed with AIDS but without major ocular complications of HIV. Standardized measurements of visual acuity, automated perimetry, and contrast sensitivity were analyzed and correlated with measurements of patients' health and medical data relating to HIV infection. We evaluated correlations between vision function testing and HIV-related risk factors and medical testing.

RESULTS

There were significant (P<.05) associations between measures of decreasing vision function and indices of increasing disease severity, including Karnofsky score and hemoglobin. A significant relationship was seen between low-contrast sensitivity and decreasing levels of CD4+ T-cell count. Three percent of eyes had a visual acuity worse than 20/40 Snellen equivalents, which was significantly associated with a history of opportunistic infections and low Karnofsky score. When compared with external groups with normal vision, 39% of eyes had abnormal mean deviation on automated perimetry, 33% had abnormal pattern standard deviation, and 12% of eyes had low contrast sensitivity.

CONCLUSIONS

This study confirms that visual dysfunction is common in patients with AIDS but without retinitis. The most prevalent visual dysfunction is loss of visual field; nearly 40% of patients have some abnormal visual field. There is an association between general disease severity and less access to care and vision loss. The pathophysiology of this vision loss is unknown but is consistent with retinovascular disease or optic nerve disease.

Laser Scanning Confocal Ophthalmoscopy and Polarimetry of Human Immunodeficiency Virus Patients Without Retinopathy, Under Antiretroviral Therapy

PURPOSE

Confocal laser scanning ophthalmoscopy (HRT; Heidelberg retinal tomograph II) and scanning laser polarimetry (GDx-variable corneal compensator [VCC]) were used to investigate whether early indicators of retinal nerve fiber layer (RNFL) thickness loss could be observed in patients infected with the human immunodeficiency virus (HIV) that had no associated retinopathy or optic neuropathy and were concomitantly receiving antiretroviral medications.

METHODS

HRT and GDx-VCC parameters obtained from a group of 13 HIV-positive subjects (n=26 eyes) on antiretroviral therapy examined with HRT, with a subgroup of six subjects (n=12 eyes) examined with both HRT and GDx-VCC, were compared with those of a matched HIV-negative control cohort (13 subjects, n=26 eyes) examined with HRT, with a subgroup of five subjects (n=10 eyes) examined with both HRT and GDx-VCC. We employed generalized estimating equations for statistical analysis.

RESULTS

Reduced mean values for the HRT height variation contour (p<0.045) and HRT mean RNFL thickness (p<0.023) were observed in HIV-positive subjects controlling for age, sex, and race. A significantly reduced mean value corresponding to the GDx-VCC superior maximum (p<0.014) and inferior maximum (p<0.016) were also observed for the HIV-positive cohort analyzed controlling for age, sex, and race.

CONCLUSION

HRT and GDx-VCC indicators of RNFL thickness appear to be significantly reduced in HIV-positive subjects without retinopathy or optic nerve disease using antiretroviral medication, suggesting RNFL loss occurs in this population of HIV-positive patients. The lack of correlation between CD4 counts, viral load, number of antiretroviral medications used, or years from diagnosis of HIV and RNFL thinning, suggests that possibly other factors associated with HIV infection may contribute to the apparent RNFL thickness loss.

Longitudinal study of the ocular complications of AIDS: 2. Ocular examination results at enrollment

OBJECTIVE

To report the clinical features on eye examination of patients with AIDS in the era of highly active antiretroviral therapy (HAART).

DESIGN

Cohort study.

PARTICIPANTS

Patients with AIDS, age > or = 13 years.

METHODS

Ophthalmologic examination, contrast sensitivity, visual fields, and laboratory testing at enrollment.

MAIN OUTCOME MEASURES

Eye examination findings at enrollment.

RESULTS

As of March 31, 2003, 1632 participants with AIDS were enrolled. Evidence of intraocular inflammation was substantially more common among patients with cytomegalovirus (CMV) retinitis or other major ocular complications than among those without, as were the complications of infection and inflammation, including cataracts, pseudophakia, macular edema, and epiretinal membrane. Among patients with CMV retinitis, macular edema and epiretinal membrane formation were most common among patients with long-standing retinitis and immune recovery. Patients with newly diagnosed retinitis had eye examination findings similar to those reported in the pre-HAART era. Visual impairment (<20/40) in the better-seeing eye was present in 9.2% of patients with CMV retinitis, 41.4% of patients with other major ocular complications (primarily ocular opportunistic infections), and only 0.6% of patients with no major ocular complication (P<.0001). Although patients without major ocular complications generally had good visual acuity, approximately 9.8% of eyes and 6.6% of participants had contrast sensitivity loss sufficient to impair reading speed.

CONCLUSIONS

In the HAART era, CMV retinitis and other ocular opportunistic infections are associated with intraocular inflammation, structural ocular complications, and visual impairment. Patients with newly diagnosed CMV retinitis have eye examination findings similar to those seen in the pre-HAART era.

Immunodetection of human immunodeficiency virus type 1 (HIV-1) Vpr in brain tissue of HIV-1 encephalitic patients

Human immunodeficiency virus (HIV) encephalitis (HIVE), the most severe neurological complication associated with HIV-1 infection, leads to the onset of HIV-1-associated dementia (HAD). Several HIV-1 viral proteins have been implicated in HIVE-associated neurodegeneration. HIV-1 viral protein R (Vpr), a virion associated gene product known to induce apoptosis in nonproliferating cells, including neurons, is thought to contribute to the neuropathogenesis associated with HIVE. Though current research suggests that Vpr plays a significant role in neuropathogenesis, the presence of Vpr in the brain tissue of HIVE patients has not been assessed. Using a panel of HIVE patient brain tissue, the authors have shown that Vpr is present in detectable amounts in both the basal ganglia and frontal cortex of all HIVE brain tissue samples tested. Double immunofluorescence indicated that Vpr was found in the macrophages and neurons, but not in the astrocytes, of HIVE patients. These results for the first time show the presence of Vpr in vivo and further support the role of Vpr in neuropathogenesis.

Optic nerve axonal pathology is related to abnormal visual evoked responses in AIDS

Electrophysiological studies in subjects with HIV/AIDS demonstrate subtle changes in the visual pathway even in the absence of visual symptoms. But the pathological correlate of the electrophysiological abnormalities is largely unknown. This study attempts to correlate pathological changes in the retina and intraorbital portion of optic nerve in four drug naïve patients of AIDS caused by HIV-1 clade C, who had abnormalities in the visual evoked potentials recorded antemortem. Three had no visual complaints and one patient had sudden loss of vision in the right eye. In all four patients, the visual evoked potentials disclosed variable prolongation of P100 latencies. Histologically axonal cytoskeletal breakdown and depletion in the optic nerves was the cardinal finding with variable myelin loss, even in the absence of overt visual dysfunction, or infective retinitis. The axonal loss was maximal in the symptomatic case. Retinal ganglion cell depletion was seen in only two patients. Sectoral infiltration of the optic nerve by cryptococci and Cryptococcal choroiditis was the only opportunistic infection to involve the eye. Axonal pathology in the optic nerve appears to be related to the abnormalities recorded in visual evoked potentials even in the absence of overt clinical symptoms. Opportunistic infections could be contributing to the axonal pathology in the optic nerve in patients with AIDS.

Objective analysis of retinal damage in HIV-positive patients in the HAART era using OCT

PURPOSE

To assess retinal nerve fiber layer (RNFL) thickness in patients with human immunodeficiency virus (HIV) disease without cytomegalovirus retinitis (CMV).

DESIGN

A case-control study.

METHODS

The study included 113 eyes of 65 patients in one center. Thickness of RNFL along a 3.4-mm-diameter circle centered on the optic nerve head was evaluated using third-generation optical coherence tomography. Patients in group A (39 eyes of 22 patients) were human immunodeficiency virus-negative control subjects. Group B (36 eyes of 18 patients) was composed of HIV patients with no history of CMV retinitis and CD4 counts consistently above 100. Group C (38 eyes of 25 patients) comprised HIV patients with no history of CMV retinitis but a history of CD4 count less than 100 at some point lasting for at least 6 months.

RESULTS

The average RNFL thicknesses in groups A, B, and C were 103.33 +/- 8.50 microm, 103.30 +/- 9.28 microm, and 90.10 +/- 12.50 microm, respectively. Group C had significantly thinner overall RNFL than either of the groups A and B (Tukey-Kramer). This difference was most prominent in temporal, superior, and inferior retinal areas. No difference was in nasal retinal area, nor between groups A and B in any of the areas.

CONCLUSIONS

Significant RNFL thinning occurs in HIV patients without CMV retinitis and with low CD4 counts compared with the same subgroup of patients with CD4 count increased to above 100 and HIV-negative control subjects. Third-generation OCT may be useful in diagnosis of early subclinical HIV-associated visual functional loss.

Neuro-ophthalmological disorders in HIV infected subjects with neurological manifestations

AIMS

To determine the frequency and features of neuro-ophthalmological manifestations in neurologically symptomatic HIV infected patients and to assess whether or not the visual evoked potential (VEP) features in these patients differ from those of neurologically asymptomatic HIV infected patients.

METHODS

Neuro-ophthalmological evaluation was performed in 166 neurologically symptomatic confirmed HIV positive patients, of whom 75 with normal ophthalmological examination were further studied by means of VEPs. The VEPs values were compared to those obtained from 53 other confirmed HIV positive subjects with neither ophthalmological nor neurological manifestations, who served as a comparison group and to the references values of our laboratory.

RESULTS

An abnormal neuro-ophthalmological examination was noted in 99/166 patients (60%). Eye movement disorders were present in 99 patients (51%). Visual field defects were detected in 39% of the patients. Optic neuropathy was noted in 31%, papilloedema in 27% and ocular motor nerve palsies in 26% of the patients. Toxoplasmosis and cryptococcosis were the most frequent associated pathologies, though in some patients the HIV itself was the presumed cause. VEPs were abnormal in 57% and 42% of patients with and without neurological manifestations, respectively. Compared to asymptomatic patients, symptomatic patients had a significantly increased mean latency; however, both groups had significant increase in mean latency compared to reference values.

CONCLUSION

Neuro-ophthalmological manifestations are common in neurologically symptomatic HIV infected patients. Subclinical dysfunction in the visual pathways is a common phenomenon in both HIV infected patients with and without neurological symptoms, but neurologically symptomatic patients seem to have more damage in their visual pathways.

Delayed diagnosis of HIV infection in ophthalmic practice

The introduction of potent antiretroviral drug combinations has transformed human immunodeficiency virus/acquired immunodeficiency disease syndrome (HIV/AIDS) from an intractable and rapidly fatal disease to a chronic manageable illness with prolonged life survival for many patients. This paper discusses the ophthalmic and medical histories of two young female patients who presented with 'atypical' optic neuropathy and toxoplasma gondii retinochoroiditis and were later found to be HIV infected. We discuss the need for increased vigilance in the ophthalmic community for suspecting HIV infection to allow optimal management of the ophthalmic and systemic manifestations of the disease spectrum associated with HIV/AIDS.

Posterior segment manifestations of HIV/AIDS

The ocular posterior segment manifestations of AIDS may be divided into four categories: retinal vasculopathy, unusual malignancies, neuro-ophthalmologic abnormalities, and opportunistic infections. Microvasculopathy is the most common manifestation. Opportunistic infections, particularly cytomegalovirus retinitis and progressive outer retinal necrosis, are the most likely to result in visual loss due to infection or subsequent retinal detachment. Diagnosis and treatment are guided by the particular conditions and immune status of the patient.

The relationship between AIDS retinal cotton wool spots and neuropsychological impairment in HIV-positive individuals in the pre-highly active antiretroviral therapy era

PURPOSE

To determine the relationship between AIDS retinal cotton wool spots (CWS) and neuropsychological impairment in HIV-positive individuals in the pre-HAART (highly active anti-retroviral therapy) era and the association between AIDS-related retinal CWS and neuropsychological impairment in HIV-positive patients not treated with HAART.

METHODS

A case-control analysis of prospectively acquired data in HIV-infected individuals who underwent prospective and longitudinal evaluations of retinal findings as well as neuropsychological testing was performed. Individuals underwent prospective retinal ophthalmic examinations with fundus photography of any retinal lesions. They also underwent periodic neuropsychological testing. The occurrence of retinal CWS was analyzed in relationship to neuropsychological impairment.

RESULTS

Thirty individuals with CWS were compared to 6o matched control AIDS patients. There was no association between either global clinical neuropsychological impairment or impairment in any of the five major domains tested and retinal CWS. There was an association between beta-2 microglobulin and CWS as well as an association between low CD4 T-cell count and the presence of retinal CWS.

CONCLUSIONS

We found no association between retinovascular disease and neurocognitive impairment in this case-control study. Retinal CWS in HIV disease are related to higher serum beta-2 microglobulin levels and lower CD4 T-cell counts, suggesting that these lesions are related to HIV disease progression but may be caused by a pathological process independent of CNS disease.

7-Chlorokynurenate Ameliorates Neuronal Injury Mediated by HIV Envelope Protein gp120 in Rodent Retinal Cultures

Prior studies with in vitro model systems have suggested that at least part of the neurological manifestations of AIDS may stem from neuronal injury involving the HIV-1 coat protein gp120. This form of neuronal damage is most probably mediated indirectly by a complex set of cellular interactions among macrophages, astrocytes, and neurons, resulting in a final common pathway of overstimulation of N-methyl-d-aspartate (NMDA) receptors. We studied the neuroprotective effect from gp120-induced neuronal injury of an antagonist of the glycine site of the NMDA receptor, 7-chlorokynurenate. In identified rat retinal ganglion cells in culture, we found that 50 microM 7-chlorokynurenate significantly abrogated the injury engendered by 20 pM gp120. Addition of 300 microM exogenous glycine prevented this protective effect of 50 microM 7-chlorokynurenate. These data suggest that glycine site antagonists of the NMDA receptor may have therapeutic potential for ameliorating neuronal damage associated with gp120.

Retinal nerve fiber layer evaluation in human immunodeficiency virus-positive patients

PURPOSE

To determine the effect of human immunodeficiency virus (HIV) infection on topographic measures of the optic disk and the retinal nerve fiber layer.

METHODS

A cross-sectional study at the Acquired Immunodeficiency Syndrome (AIDS) Ocular Research Unit at the University of California, San Diego. Retinal nerve fiber layer thickness at the optic nerve head was evaluated using the Heidelberg Retinal Tomograph, a confocal scanning laser tomograph in 38 HIV-positive and 24 age-matched HIV-negative subjects.

RESULTS

HIV-positive patients without CMV retinitis showed significant differences from HIV-negative normal controls in a number of measures of the retinal nerve fiber layer. This indicated a loss of retinal ganglion cells in HIV-positive patients without retinitis. HIV-positive patients with CMV retinitis were worse in most measurements than both HIV-negative controls and HIV-positive patients without CMV.

CONCLUSIONS

Significant thinning of the retinal nerve fiber layer occurs in HIV-positive patients without infectious retinopathy, and there are further changes in the optic disk associated with CMV retinitis. Confocal scanning laser tomography may be of use in the diagnosis of early HIV-associated visual function loss.

Sensory evoked potentials in SIV-infected monkeys with rapidly and slowly progressing disease

Human immunodeficiency virus (HIV-1) infects the central nervous system (CNS) early in the course of disease progression and leads to some form of neurological disease in 40-60% of cases. Both symptomatic and asymptomatic HIV-infected subjects also show abnormalities in evoked potentials. As part of an effort to further validate an animal model of the neurological disease associated with lentiviral infection, we recorded multimodal sensory evoked potentials (EPs) from nine rhesus macaques infected with passaged strains of SIVmac (R71/E17), prior to and at 1 month intervals following inoculation. The latencies of forelimb and hindlimb somatosensory evoked potentials (SEP) and flash visual evoked potentials (VEP) were measured. Within 14 weeks of inoculation, all but two animals had progressed to end-stage disease (rapid progressors). The two animals with slowly progressing disease (AQ15 and AQ94) had postinoculation life spans of 109 and 87 weeks, respectively. No significant changes were observed in evoked potentials recorded during the control period or at any time in the animals with slowly progressing disease. However, all of the monkeys with rapidly progressing disease exhibited increases in latency for at least one evoked potential type. The overall mean increases in somatosensory and visual evoked potential peak latencies for the rapid progressors were 22.4 and 25.3%, respectively. For comparison, the changes in slow progressors were not significant (1.8 and -1.9%, respectively). These results, coupled with our previous finding of slowed motor evoked potentials in the same cohort of macaques (Raymond et al.: J Neurovirol 1999;5:217-231), demonstrate a broad and somewhat variable pattern of viral injury to both sensory and motor system structures, resembling the findings in HIV-infected humans. These results coupled with our earlier work demonstrating cognitive and motor behavioral impairments in the same monkeys support the use of the SIVmac-infected rhesus macaque as a model of AIDS-related neurological disease.

Neuronal injury associated with HIV-1: approaches to treatment

Mounting evidence suggests that cognitive dysfunction developing as a result of HIV-1 infection is mediated at least in part by generation of excitotoxins and free radicals in the brain. This syndrome is currently designated HIV-1-associated cognitive/motor complex, was originally termed the AIDS Dementia Complex, and for simplicity, is called AIDS dementia in this review. Recently, brains of patients with AIDS have been shown to manifest neuronal injury and apoptotic-like cell death. How can HIV-1 result in neuronal damage if neurons themselves are only rarely, if ever, infected by the virus? Experiments from several different laboratories have lent support to the existence of HIV- and immune-related toxins in a variety of in vitro and in vivo paradigms. In one recently defined pathway to neuronal injury, HIV-infected macrophages and microglia, or immune-activated macrophages and astrocytes (activated by the shed HIV-1 envelope protein, gp120, or other viral proteins and cytokines), appear to secrete excitants and neurotoxins. These substances may include arachidonic acid, platelet-activating factor, free radicals (NO. and O2.-), glutamate, quinolinate, cysteine, amines, and as yet unidentified factors emanating from stimulated macrophages and reactive astrocytes. A final common pathway for neuronal susceptibility is operative, similar to that observed in stroke and several neurodegenerative diseases. This mechanism involves excessive activation of N-methyl-D-aspartate (NMDA) receptor-operated channels, with resultant excessive influx of Ca2+ and the generation of free radicals, leading to neuronal damage. With the very recent development of clinically tolerated NMDA antagonists, there is hope for future pharmacological intervention.

Visual dysfunction in HIV-positive patients without infectious retinopathy

Persons with HIV disease are susceptible to various manifestations of retinal damage, such as infectious retinopathies (e.g., cytomegalovirus [CMV] retinitis and toxoplasmosis) and noninfectious complications (microangiopathic infarctions or cotton-wool spots [CWS]); CWS being quite common in AIDS patients. Until recently, little research focused on noninfectious ocular pathology in HIV disease. These disorders may all affect normal functioning of the visual system while funduscopic examination results appear normal. A review of the psychophysical changes, color and contrast sensitivity, peripheral visual function, electrophysiologic and morphologic changes, the relationship of vision loss and neuropsychological changes, postretinal damage, and imaging capabilities cast important new light on quality of life issues and vision function for all HIV/AIDS patients regardless of CD4 count, other measures of wellness, or treatment protocols. Entopic perimetry, a low-cost psychophysical technique screening test, allows sensitive and specific identification of very peripheral areas of visual field loss. The authors recommend its implementation and use by primary care providers, particularly for early detection of retinal damage when funduscopic examination results may appear normal.

Molecular basis of glutamate toxicity in retinal ganglion cells

Loss of retinal ganglion cells (RGCs) is a hallmark of many ophthalmic diseases including glaucoma, retinal ischemia due to central artery occlusion, anterior ischemic optic neuropathy and may be significant in optic neuritis, optic nerve trauma, and AIDS. Recent research indicates that neurotoxicity is caused by excessive stimulation of receptors for excitatory amino acids (EAAs). In particular, the amino acid glutamate has been shown to act as a neurotoxin which exerts its toxic effect on RGCs predominantly through the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor. NMDA-receptor-mediated toxicity in RGCs is dependent on the influx of extracellular Ca2+. The increase in [Ca2+]i acts as a second messenger that sets in motion the cascade leading to eventual cell death. Glutamate stimulates its own release in a positive feedback loop by its interaction with the non-NMDA receptor subtypes. Ca(2+)-induced Ca2+ release and further influx of Ca2+ through voltage-gated Ca2+ channels after glutamate-induced depolarization contribute to glutamate toxicity. In vitro and in vivo studies suggest that the use of selective NMDA receptor antagonists or Ca2+ channel blockers should be useful in preventing or at least abating neuronal loss in the retina. Of particular importance for future clinical use of NMDA receptor antagonists in the treatment of acute vascular insults is the finding that some drugs can prevent glutamate-induced neurotoxicity, even when administered a few hours after the onset of retinal ischemia.

Morphological consequences of myelination in the human retina

Intraretinal myelination of ganglion cell axons occurs in about 1% of humans and when observed ophthalmoscopically, appears as a white or opaque patch within the fiber layer. Previous studies of myelinated retinal tissue have largely been conducted at the light microscopic level. Three retinae with intraretinal myelination and one normal retina were obtained post-mortem and prepared for electron microscopy. The present study showed that myelinated patches in the human retina contained a mixture of unmyelinated and myelinated axons. Within this population of myelinated axons were structures which were abnormal and there were obvious signs of axonal and myelin sheath degeneration within the myelinated patches. Outside these myelin patches the retina appeared normal without signs of degeneration indicating that post-mortem degeneration prior to fixation could not account for all of the degenerative changes observed. The lack of significant numbers of macrophages and lymphocytes indicated that there was no concomitant inflammatory process within the myelin patches. The myelination present within these eyes appeared to be due to the anomalous location of oligodendrocytes. Both unmyelinated and myelinated axons had larger diameter than axons measured within normal areas of the retina or those within the optic nerve.

An immunohistochemical study of TNF-alpha in optic nerves from AIDS patients

PURPOSE

Both in vitro and in vivo studies have implicated a role for tumor necrosis factor (TNF-alpha) in the pathology of demyelinating diseases. The purpose of this study was to address the hypothesis that TNF-alpha is a mediator of AIDS-related optic nerve injury and to determine the cell types involved in the proliferation of TNF-alpha in the AIDS optic nerve.

METHODS

Ten optic nerves from seven patients with AIDS, and three from persons who were HIV negative were stained, using the indirect immunoperoxidase method. Six of the ten AIDS optic nerves were positive for cytomegalovirus (CMV), but the remainder did not have abnormal fundus findings.

RESULTS

In all the optic nerves from AIDS patients with or without CMV retinitis, the vast majority of astrocytes stained strongly for TNF-alpha. Microglial cells (MPS-derived macrophages) varied from not staining to staining strongly positive for TNF-alpha. However, oligodendrocytes were not labeled positively for TNF-alpha. Some endothelial cells also stained for TNF-alpha. Examination of normal optic nerves and controls did not reveal any cell type that stained positively for TNF-alpha.

CONCLUSIONS

The present study supports the contention that TNF-alpha is a major mediator of AIDS-associated optic neuropathy. HIV infection induces the production of TNF-alpha in macrophages and astrocytes, which probably causes demyelination and other neuronal damage.

Analysis of visual dysfunctions in HIV-positive patients without retinitis

PURPOSE

To investigate visual dysfunctions in ophthalmoscopically normal human immunodeficiency virus (HIV)-positive patients and to correlate the results to the stage of HIV disease and neuropsychological status.

METHODS

Fifty-one randomly selected eyes (26 right, 25 left) of 51 HIV-positive patients with visual acuity measurements of 20/20 or better and no ophthalmoscopically detectable disorders were prospectively examined using achromatic and short-wavelength automated perimetry, color vision testing, and contrast sensitivity testing. CD4+ T-lymphocyte count, presence of systemic infection, hemoglobin, hematocrit, serum beta 2-microglobulin levels, and results of neuropsychological testing were also analyzed.

RESULTS

On achromatic automated perimetry, 21.6% (11/51) of patients performed abnormally according to the mean defect and 27.5% (14/51) according to the Glaucoma Hemifield Test; 29.4% (15/51) performed abnormally on short-wave-length automated perimetry according to the mean defect and 23.5% (12/51) according to the Glaucoma Hemifield Test. On contrast sensitivity, 5.9% (3/51) of patients performed abnormally in the 1.5-cycles per degree (cpd) line, 2.0% (2/51) in the 3-cpd line, 23.5% (12/51) in the 6-cpd line, 25.5% (13/51) in the 12-cpd line, and 33.3% (17/51) in the 18-cpd line. On the Farnsworth-Munsell 100-hue test, 29.4% (15/51) of patients performed abnormally. After correction for multiple correlations, two statistically significant correlations were found: sum of log contrast sensitivity with achromatic automated perimetry and sum of log contrast sensitivity with the Farnsworth-Munsell 100-hue test.

CONCLUSIONS

A significant percentage of HIV-positive patients with visual acuity of 20/20 or better and no ophthalmologic evidence of retinitis performed abnormally on visual psychophysical tests. The severity of visual dysfunction was not correlated with the stage of HIV infection or the degree of neuropsychological dysfunction.

Apoptosis in development and disease of the nervous system: II. Apoptosis in childhood neurologic disease

The loss of cells in the human nervous system has long been known as the hallmark of incurable degenerative disease. Recent studies that began with attempts to understand cell loss during normal development have now begun to contribute to our understanding of the process of pathological cell loss. In many neurodegenerative conditions, it has become clear that apoptosis, or programmed cell death, plays a role in the diminution of cell number. In the cases of human immunodeficiency virus-associated encephalopathy and several of the hereditary neurodegenerative disorders, triggers and mediators of this process have been identified. This identification is not only the first step toward treatment of such disorders, but it also raises the possibility of exploiting this information to design targeted apoptosis-based therapies for tumors of the nervous system.

Ophthalmic complications of HIV infection

HIV retinopathy, a noninfectious microangiopathy, is the most common ocular manifestation of HIV infection. Opportunistic infections, neoplasms, neuro-ophthalmic lesions, and drug-induced lesions may also cause ocular problems. Opportunistic ocular infections, particularly CMV retinitis, are a major cause of morbidity in patients with AIDS. Because of the underlying chronic and progressive immune dysfunction, the ocular symptoms, signs, clinical course, and treatment are often atypical and severe, requiring protracted medical therapy.

Visual field loss in HIV-positive patients without infectious retinopathy

PURPOSE

To determine the extent of vision loss in a cross-sectional study of HIV-positive individuals who had no infectious retinopathy.

METHODS

Visual field loss was determined by computerized achromatic automated perimetry and short-wavelength automated perimetry in both eyes in 65 HIV-positive individuals without infectious retinopathy and in one randomly selected eye each in 57 age-matched normal controls. Results were analyzed using the global index of mean defect and the Glaucoma Hemifield Test, and significance was determined through analysis of variance, chi-square, and Tukey-Kramer tests.

RESULTS

We found that HIV-positive patients, compared with age-matched HIV-negative controls, demonstrated significant (at least P < .01) localized defects as well as an increased mean defect. The HIV-positive patients also had a significantly greater number of defective points, especially on short-wavelength automated perimetry, even while ophthalmoscopic examination and fundus photographs suggested that the retinas were normal.

CONCLUSIONS

There is a significant loss of visual function in HIV-positive individuals that is not the result of infectious retinopathies. The finding by short-wavelength perimetry of more severe defects suggests that the vision defects are not caused by attentional or other suprachiasmatic problems because the neurologic difficulty of both achromatic and short-wavelength perimetry is similar. The effects of this vision loss on the daily living and occupational tasks of this population require further study.

The coat protein gp120 of HIV-1 inhibits astrocyte uptake of excitatory amino acids via macrophage arachidonic acid

The human immunodeficiency virus coat protein gp120 injures central mammalian neurons both in vitro and in vivo, and this observation may contribute, at least in part, to the neurological dysfunction associated with the acquired immunodeficiency syndrome. Recent work suggests that gp120 mediates neuronal damage predominantly via an indirect route involving activation of brain macrophages. We have previously shown that the stimulation of N-methyl-D-aspartate receptors by excitatory amino acids is essential for the neuronal injury observed with gp120. Here we show that gp120 impairs astrocyte uptake of excitatory amino acids and the excess glutamate thus engendered may contribute to the increased neuronal damage. We also studied the mechanism whereby gp120 inhibits the uptake of excitatory amino acids by astrocytes. We present data suggesting that at least one pathway involves a direct effect of gp120 on macrophages, which in turn release arachidonic acid, a known inhibitor of excitatory amino acid uptake by astrocytes. Our findings suggest that the observed effects on glia and neurons of gp120 may be secondary, at least in part, to its initial activation of macrophages.

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.

Apoptotic neurons in brains from paediatric patients with HIV-1 encephalitis and progressive encephalopathy

The pathogenesis of human immunodeficiency virus type 1 (HIV-1) associated dementia in adults involves neuronal loss from discrete areas of the neocortex and subcortical regions, but the mechanism for neuronal death is poorly understood. Gene-directed cell death resulting in apoptosis is thought to be a normal feature of neuronal development, but little is known about neuronal apoptosis in disease states. We investigated whether HIV-1 infection of the central nervous system is spatially associated with apoptosis of neurons. Using an in situ technique to identify newly cleaved 3'-OH ends of DNA as a marker for apoptosis, we demonstrate the presence of apoptotic neurons in cerebral cortex and basal ganglia of children that had HIV-1 encephalitis with progressive encephalopathy. Furthermore, an association was observed between the localization of apoptotic neurons and perivascular inflammatory cell infiltrates containing HIV-1 infected macrophages and multinucleated giant cells. Apoptotic neurons and p24-positive macrophages were observed infrequently in cerebral cortex and basal ganglia in children with HIV-1 infection without encephalitis or clinical encephalopathy. In nine control (HIV-1 negative) brains, ranging from the first post-natal month of life to 16.5 years of age, infrequent neuronal apoptosis was observed in three cases. These findings suggest that neuronal apoptosis is unlikely to be associated with post-natal development except in early post-natal germinal matrix, and that it may instead represent the end result of specific pathological processes, such as HIV-1 encephalitis.