Special Feature
Visual Disturbances in Patients With AIDS
By Frederic Kauffman, MD
In north america, there are approximately 900,000 HIV-positive persons and more than 30,000,000 throughout the world.1 With the recent advent of combination drug therapy in HIV-positive patients, the disease is managed more and more on an outpatient basis, and patients appear to have an improved quality of life. As patients live longer, however, and as our understanding of the disease improves, more and more complications are being recognized. Ocular complications of HIV infection occur in as many as 70% of patients and clearly represent a significant form of patient morbidity.2 Although uncommon as presenting manifestation of AIDS, such complications often are infectious in origin and may be the first indication of systemic infection.
In order to evaluate properly the AIDS patient with visual complaints, it is imperative to have a basic understanding of eye anatomy and the visual axis. The sclera is a tough fibrous layer that protects the intraocular contents and serves as a firm attachment for the extraocular muscles. The avascular cornea is innervated by the ophthalmic division of the trigeminal nerve and serves as the major refractive medium of the eye. The uveal tract, consisting of the iris, ciliary body, and choroid is the vascular pigmented coat. The ciliary muscle changes the shape of the lens, making it more convex and increasing its refractive power, pulling the ciliary body forward. The colored iris attaches to the anterior surface of the ciliary body, dividing the space between the lens and the cornea into anterior and posterior chambers. Dilation and constriction of the pupil by the iris serves to control the amount of incoming light, and during accommodation restricts light to the center of the lens, thereby reducing spherical aberration. The retina is the photoreceptor portion of the eye, with the fovea centralis serving as the area for the most distinct vision. The optic nerve is approximately 3 mm medial to the fovea. Its central optic disc is insensitive to light (i.e., the blind spot) and is the site of entrance for the central retinal artery, a branch of the ophthalmic artery. The inner nervous layer of the retina, in contact with the vitreous, is supplied with blood by the central retinal artery; the outer pigmented surface that contains the rods and cones is supplied by choroidal capillaries. Retinal viability is dependent on both blood sources. Venous drainage is accomplished by the central retinal vein that generally accompanies the corresponding branches of the central retinal artery. The aqueous humor, the vitreous body, and the lens are the refractive portions of the eye. The aqueous humor provides nourishment to the lens and cornea, is secreted by the ciliary processes, and is drained out of the anterior chamber via the canal of Schlemn into a venous sinus. The vitreous body maintains the shape of the eyeball posterior to the lens, keeping the retina flush against the wall of the eye. Finally, Figure 1 illustrates the visual axis, the various sites of lesions that may occur along the optic pathway, and associated visual field defects.3
In any patient with a visual complaint, proper diagnosis and treatment is predicated on the performance of an accurate and focused history and physical examination. Tables 1 and 2 list the pertinent aspects of the eye history and physical exam.
Table 1
Eye history-visual impairment
· Past ocular trauma/surgery
· Pre-existing visual impairment
· Glasses/contacts
· Trauma vs. non-trauma
· Time of onset
· Diplopia/field defect/blurred vision
· Redness/pain/discharge
· Patient treatment
· General medical history
The ocular manifestations of AIDS have been classified into four major categories: 1) benign AIDS retinal microangiopathy; 2) opportunistic infections; 3) ocular neoplastic lesions; and 4) neuro-ophthalmic lesions.4 The frequency of ocular manifestations has an inverse correlation with the number of CD4 lymphocytes, and as such, serves as a marker of immune system decline in AIDS patients.5 Most of this discussion will focus on the first two categories, which represent the majority of clinically-significant entities. (See Table 3.)
Benign AIDS Retinal Microangiopathy
Cotton wool spots (retinal nerve fiber infarcts), microaneurysms, and retinal hemorrhages make up the microangiopathic changes frequently seen in AIDS patients. Nearly 67% of AIDS patients have been found to have these changes, whereas only 40% of patients with AIDS-related complex and less than 2% of asymptomatic HIV-positive patients have such changes.4 Underlying risk factors for AIDS do not appear to influence prevalence of this microangiopathy.4 No cause of this entity is known. Though infectious etiologies have been speculated, pathogens and pathogenic antigens have not been isolated from the eyes of these patients.6 AIDS retinal microangiopathic findings tend to come and go, most frequently are seen in the posterior retinal pole, are not accompanied by iritis or vitritis and usually are not associated with visual complaints. However, color-vision and contrast-sensitivity testing has demonstrated a significant decrease in color discrimination and contrast thresholds in these patients, indicating dysfunction of the macula or optic nerve.7 No specific therapy is required for patients found to have retinal microangiopathy, but this finding in patients without known retinal disease (e.g., diabetic retinopathy) warrants HIV testing.8
Table 2
Eye physical exam
· Visual acuity/visual fields
· Lids-position/contour/color/swelling
· Pupils-equality/shape/reactivity/accommodation
· Extraocular movements
· Anterior segment-cornea/conjunctiva/anterior chamber/iris/lens
· Intraocular pressure
· Fundus-optic disc/retinal vessels/retinal background
· Orbit-symmetry/proptosis/tenderness/crepitence
Opportunistic Ocular Infections
Cytomegalovirus (CMV) Retinitis. CMV retinitis occurs in nearly 30% of AIDS patients, generally as a late manifestation of disease.4 The virus spreads via cell to cell transfer resulting in peripheral or central scotoma, and diminished visual acuity if the fovea is affected.8 Late in the course of the disease retinal detachment may occur, even with appropriate antiviral therapy. With infection of the optic nerve or macula, total blindness may occur. Due to its frequency and symptomatology, CMV retinitis is the most clinically significant AIDS-related ocular complication. Ophthalmoscopic evaluation reveals cotton wool spots and variable degrees of retinal hemorrhage which progress over time. Disease generally is unilateral, but may progress to the opposite eye if antiviral therapy is not instituted. Slit lamp evaluation reveals little to no iritis or vitritis. Treatment consists of induction and maintenance gancyclovir or foscarnet, which prevents retinal spread of the infection but does not restore function of infected areas.8-10 Acyclovir is ineffective in non-toxic doses.
Herpes Zoster Ophthalmicus (HZO). HZO occurs in approximately 4% of AIDS patients, and along with herpes simplex virus may cause acute retinal necrosis, uveitis, vitritis, ocular pain, and variable degrees of visual loss. Treatment with acyclovir results in resolution of the infection and prevention of spread to the opposite eye. However, despite therapy, necrotic holes in the region of retinitis can result in retinal detachment in up to 85% of patients.8 In addition, outer retinal necrosis may result in vascular and optic disc atrophy, progressing to loss of all light perception within days. Unfortunately, outer retinal necrosis and its devastating effects are not amenable to therapy.8
Toxoplasma Chorioretinitis (TC). Caused by the parasite Toxoplasma gondii, TC occurs infrequently in AIDS patients, though greater than 50% of patients with TC have associated toxoplasmic encephalitis.11 Photophobia and floaters are common symptoms, along with decreased visual acuity if the macula is involved. Examination reveals retinal necrosis that preferentially affects the central retina and macula, along with single yellow-white oval lesions associated with satellite scars. Anterior uveitis, cataracts, and glaucoma may also be seen. If untreated, blindness ultimately ensues. Treatment includes pyrimethamine, and sulfadiazine or clindamycin, with or without steroids.8
Pneumocystis Carinii Choroiditis. Pneumocystis carinii choroiditis is a rare condition typically found in AIDS patients treated with inhaled pentamidine. Its presence usually heralds the presence of systemic infection. Symptoms are minimal, and examination reveals yellow choroidal lesions. Treatment includes several months of trimethoprim-sulfamethoxazole.8
Ocular Syphilis. Ocular syphilis may present in a multitude of fashions, including symptomatic floaters, decreased visual acuity, and photophobia. The typical lesions of secondary syphilis may also be noted. During an ophthalmologic exam, any of the following may be seen: loss of eye lashes, conjunctivitis, iritis, vitritis, retinitis, papillitis, and optic neuritis.2 Ocular syphilis typically is accompanied by neurosyphilis, and treatment with penicillin is indicated.
Table 3
Prevalence of ocular manifestations in AIDS4
|
|
|
| · Benign AIDS retinal microangiopathy |
|
| · Opportunistic ocular infections |
|
| · Ocular neoplasms |
|
| · Neuro-ophthalmic lesions |
|
Cryptococcal Meningitis. Forty percent of patients with cryptococcal meningitis have involvement of the visual system.2 Patients may present with visual field loss due to involvement of the optic nerves or optic tracts; cranial nerve palsies (cranial nerves 3, 4, 6, or 7); evidence of choroiditis; and optic nerve swelling.2
Ocular Neoplasms
Kaposi's Sarcoma. Eyelid and conjunctival involvement are common in Kaposi's sarcoma, though rarely does it affect visual function. Eyelid lesions characteristically are purple, flat, or raised. Lesions of the conjunctiva are bright red and may be associated with subconjunctival hemorrhage.6 Lesions need not be treated except for cosmetic purposes in which case radiation, chemotherapy, or surgical excision may be useful.2
Orbital Lymphoma. A rare event, orbital lymphoma may present with proptosis, pain, diplopia, and periorbital edema. Occasionally it is associated with central nervous system lymphoma.2
Neuro-ophthalmic Lesions
Patients with AIDS frequently develop neurologic complications that may be associated with ocular signs and symptoms. For instance, space-occupying lesions from CNS toxoplasmosis or lymphoma may give rise to visual field defects, and cryptococcal meningitis may result in cranial nerve palsies, nystagmus, and cortical blindness. Overall, such ocular findings have a prevalence of 8%, and their presence warrants consideration for a primary central nervous system cause.4
Summary
Recognition of the wide variety of ophthalologic pathology in patients with AIDS is critical to ultimate preservation of patient well being. Many of the etiologies of visual complaints are treatable, with preservation of visual function the ultimate goal. Unfortunately, many of these disorders occur in the latter stages of illness. Though not curable, AIDS is still a disease in which preventing visual morbidity will have a great effect on patient quality of life.
References
1. Cunningham ET, Margolis TP. Ocular manifestations of HIV infection. N Engl J Med 1998;339:236-244.
2. Gariano RF, et al. Ocular examination and diagnosis in patients with the acquired immunodeficiency syndrome. West J Med 1993;158:254-262.
3. Snell R, Smith M. The eye and orbit. In: Snell R and Smith M. Clinical Anatomy for Emergency Medicine. St Louis: Mosby; 1993:265.
4. Jabs DA, et al. Ocular manifestations of acquired immune deficiency syndrome. Ophthalmology 1989; 96:1092-1099.
5. Rothenhaus TC, Polis MA. Ocular manifestations of systemic disease. Emerg Med Clinics N Am 1995; 13:607-630.
6. Heinemann MH. Ophthalmic problems. Med Clinics N Am 1992;76:83-97.
7. Quiceno JI, et al. Visual dysfunction without retinitis in patients with acquired immunodeficiency syndrome. Am J Ophthalmology 1992;113:8-13.
8. D'Amico DJ. Diseases of the retina. N Engl J Med 1994;331:95-106.
9. Whitley RJ, et al. Guidelines for the treatment of cytomegalovirus diseases in patients with AIDS in the era of potent antiviral therapy. Arch Intern Med 1998; 158:957-969.
10. Drew WL, et al. Oral gancyclovir as maintenance treatment for cytomegalovirus retinitis in patients with AIDS. N Engl J Med 1995;333:615-620.
11. Culbertson WW. Infections of the retina in AIDS. International Ophthalmol Clin 1989;29:108-118.
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