The Ophthalmology Department,  Universiti Malaysia Sarawak (UNIMAS), Kuching, Sarawak.

The Ophthalmology Department, Sarawak General Hospital, Kuching, Sarawak, East Malaysia.

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Case 32 Answers

by Dr. Tan Aik Kah & Professor Chua Chung Nen

 

A 39 year-old man with AIDS was referred in early September, 2006 from the medical department because of progressive blurring of vision in both eyes.  He was found to be HIV positive in June 2005 when he developed pulmonary tuberculosis. He was also hepatitis C and  VDRL/TPHA positive (for which he received intravenous penicillin). He developed headache in early June, 2006 and the CD4 counts at the time of admission was 48/ul. A lumbar puncture confirmed the diagnosis of cryptococcal meningitis. He was given 2 days of intravenous amphotericin B but the treatment was suspended because of acute renal failure. The drug was changed to fluconazole. He was given HAART therapy in February 2006, but he defaulted the treatment and did not return for follow up due to financial problem. HAART therapy was restarted while he was hospitalized for the cryptococcal meningitis.


Ocular examinations showed the visual acuity to be counting fingers (CF) in both eyes at 1 metre. There was no relative afferent pupillary defect. Slit-lamp examination revealed normal anterior segment without signs of anterior uveitis. Posterior segment revealed normal retina without signs of cytomegalovirus retinitis. However both optic discs were pale with a cup/disc ratio of 0.8. The intraocular pressure measured 14 in the right eye and 12 in the left eye.

 

 

 

Refraction showed the following results:

RE: -1.50/-0.50/175. BCVA 6/120
LE: -0.50/-1.75/170. BCVA 6/120

 

a. How common is cryptococcal meningitis in AIDS patients?

 

Cryptococcus neoformans is an encapsulated yeast. Of the different varieties, Cryptococcal neoformans var neoformans serotype A accounts for most of the cryptococcal infections in immunocompromised patients.

 

AIDS-associated cryptococcal infections accounts for 80-90% of all patients with cryptococcosis. About 7-15% of patients with AIDS develop cryptococcal infections. The figure is higher in sub-Saharan Africa where 15-30% of  AIDS patients develop cryptococcal disease1,2.

 

Cryptococcal neoformans enters the body via the lungs but the central nervous system is the main site of clinically evident infection. Following pulmonary infection, the fungus disseminates widely and may infect any organ. The organs most often involved including the central nervous system, bones, prostate, eyes and skin. The infection is sensitive to amphotericin B and fluconazole.

 

 

b. What may be responsible for his optic disc appearance?

 

Two possible causes for the optic disc appearance: neurosyphilis and cryptococcal meningitis.

 

Neurosyphilis that occurs in tertiary syphilis may cause optic atrophy but this usually takes decades to occur and is unlikely in this patient.

 

A more likely explanation for the visual loss is the consequence of cryptococcal meningitis.  This has been reported in 1.1% of AIDS patients with the disease3. Several mechanisms have been proposed and this include: damage of the nerves from raised intracranial pressure4, direction of the optic nerve by the cryptococcal fungi which have been observed histologically5, compression of the optic nerve through adhesion, endophthalmitis (not in our case) and cryptococcomas in the optic chiasm (the CT scan in our patient was normal).

 

 

References:

 

1. Selik RM, Chu SY, Ward JW: Trends in infectious diseases and cancers among persons dying of HIV infection in the United States from 1987 to 1992. Ann Intern Med 1995 Dec 15; 123(12): 933-6.

 

2. Mitchell TG, Perfect JR: Cryptococcosis in the era of AIDS--100 years after the discovery of Cryptococcus neoformans. Clin Microbiol Rev 1995 Oct; 8(4): 515-48.

 

3. Rex JH, Larsen RA, Dismukes WE, Cloud GA, Bennett JE. Catastrophic visual loss due to Cryptococcus neoformans meningitis. Medicine (Baltimore). 1993 Jul;72(4):207-24. Review.
 

4. Tan CT. Intracranial hypertension causing visual failure in cryptococcus meningitis. J Neurol Neurosurg Psychiatry. 1988 Jul;51(7):944-6.
 

5. Cohen DB, Glasgow BJ. Bilateral optic nerve cryptococcosis in sudden blindness in patients with acquired immune deficiency syndrome.Ophthalmology. 1993 Nov;100(11):1689-94.