EyeNet Magazine


 
Morning Rounds
When Night Falls Fast
By Joseph L. Lin, MD, and Robert L. Lesser, MD
Edited by Thomas A. Oetting, MD
 
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Helen Coates* was having trouble seeing at night. The 57-year-old told us that this problem had become progressively worse over the previous nine months. Indeed, it got bad enough that when it was dark, she needed either a flashlight or somebody to help her get back to a well-lit area. At that point, her family members persuaded Ms. Coates to get her eyes checked.


Ms. Coates’ medical history included idiopathic polyneuropathy, which was previously confirmed by electromyography, and macrocytic anemia of unknown origin, which was diagnosed a year before we saw her. She had no history of hypertension, diabetes mellitus, malabsorption disorders, irritable bowel syndrome, hepatitis or gastric bypass surgery.

Initially, when her macrocytic anemia was diagnosed, the workup found normal vitamin B12, folic acid and liver enzyme levels. In addition, a bone marrow biopsy conducted at the same time found normal cells with no megaloblastic changes and no myelodysplasia.

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We Get a Look

While Ms. Coates told us that she drank a minimal amount of alcohol, she admitted to having poor eating habits, which included far too much junk food and very little meat or vegetables.

The review of systems was significant for anxiety but was otherwise normal. Her family history was significant for a maternal aunt with night blindness.

Ms. Coates’ vision was 20/50 in both eyes. Her IOP by applanation was 12 mmHg in both eyes and her ocular motility was full. Her pupils reacted 3+ with no afferent pupillary defect, her visual fields showed diffuse loss in both eyes (Figs. 1 and 2) and the Amsler grid testing was normal bilaterally. Her color vision by Ishihara plates was 2/15 in both eyes.

Ms. Coates’ slit-lamp exam was normal with no evidence of conjunctival or corneal xerosis, corneal ulceration or keratomalacia. The dilated funduscopic exam showed that she had a vitreous floater in the right eye, and both discs were atrophic temporally with 0.8 cupping. Her macula, vasculature and peripheral retina were normal in both eyes with no signs of retinitis pigmentosa (Figs. 3 to 6).

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Leading Suspects

Retinitis pigmentosa is the most common cause of night blindness. Patients with this genetic condition have progressive nyctalopia; eventually, daytime vision also may be affected.

Vitamin A deficiency is another common cause of night blindness, particularly in developing countries. Foods rich in vitamin A include those of animal origin, such as fish oils, liver and dairy products; in addition, vitamin A precursors can be found in some foods of plant origin, such as carrots, broccoli, oranges, bananas and spinach. Liver disease, various malabsorption syndromes and gastric bypass surgery impacting vitamin A metabolism also can cause nyctalopia.1

With regard to the optic nerve and retina, nyctalopia can be a symptom of glaucoma, X-linked congenital stationary night blindness, gyrate atrophy, Laurence-Moon syndrome, Oguchi disease, optic atrophy, peripheral chorioretinitis, siderosis retinae, cancer-associated retinopathy or hypoxia. Finally, uncorrected myopia may also lead a patient to describe symptoms similar to nyctalopia.

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What’s Your Diagnosis?

INITIAL CLUES. The visual fields showed diffuse loss in both eyes. (Fig. 1, Fig. 2)
ADDITIONAL CLUES: Dilated funduscopic exam showed bilateral optic atrophy with no signs of retinitis pigmentosa. (Fig. 3, Fig. 4, Fig. 5, Fig. 6)

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Lab Results

Ms. Coates’ lab results presented a mixed picture: While her vitamin B12 level was high at 1,700 pg/ml, her vitamin A, folic acid, vitamin C and thiamine levels were low at less than 20 µg/dl, 1.3 ng/ml, 0.12 mg/dl and 44 ng/ml, respectively. The testing confirmed macrocytic anemia, with a hematocrit of 27. Her C-reactive protein was normal at 2.1 mg/l and the liver function tests aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (AP) also were normal, at 8 IU/l, 12 IU/l and 44 IU/l, respectively.

While Ms. Coates refused to undergo an MRI because of claustrophobia, a CT scan of her brain and orbit was unremarkable. Her electroretinogram was flat, and the test for cancer-associated retinopathy antibody was negative.

The Unexpected Emerges

Ms. Coates had profound visual field loss as well as bilateral optic atrophy with no evidence of any pigment retinopathy. It was unclear whether the anemia and the peripheral neuropathy were connected.

She was started on vitamin A supplementation, which produced almost immediate improvement of her nyctalopia. She was then referred to the gastrointestinal service for evaluation for possible malabsorption, celiac or liver disease. But before this workup could take place, she presented to the ER with mental-status changes and an upper GI bleed secondary to liver failure. She was also diagnosed with a distal esophageal ulcer and old gastric lesions.

Although Ms. Coates had vigorously denied abusing alcohol, we learned that she had been a heavy drinker for many years. We were misled not only because both she and her husband had lied about her alcohol abuse but also because the results of her liver function tests were normal. It’s important to note that patients with advanced cirrhosis can have normal or only slightly elevated serum AST or ALT values because hepatocytes that die by apoptosis—as happens in severe cirrhosis—synthesize less AST and ALT.2

When we reviewed her history with other family members, we learned some details about Ms. Coates’ alcohol abuse. She had carried a water bottle filled with vodka in her purse and often drank from a coffee mug filled with liquor at the office. In spite of this, her husband claimed that he did not know she was an alcoholic.

The rest of Ms. Coates’ hospital course was complicated by liver and kidney failure, hepatic encephalopathy and aspiration pneumonia.

Unfortunately, she died within five months of presentation from multiple nosocomial and ventilator-associated pneumonias after being hospitalized for upper GI bleeding complicated by end-stage renal disease and severe cirrhosis.

Our official diagnosis was vitamin A deficiency from alcohol-induced malnutrition and alcoholic liver cirrhosis.

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Looking Back

Initially, Ms. Coates’ medical history suggested that vitamin A deficiency—thanks to her poor diet and a possible malabsorption syndrome—was the likeliest cause of her night blindness. Because of her denial of heavy alcohol intake and her normal liver function tests, cirrhosis was not considered to be a probable cause.

In retrospect, it is important to remember that liver function tests can be unreliable in cases of advanced liver disease.
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* Patient name is fictitious.
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Dr. Lin is an ophthalmology resident and Dr. Lesser is clinical professor of ophthalmology and visual science and of neurology; both are at Yale.
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1 Lieber, C. S. J Am Coll Nutr 1991;10:602–632.
2 Johnston, D. E. Am Fam Physician 1999;59:2223–2230.

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