|Year : 2023 | Volume
| Issue : 1 | Page : 89-91
Nyctalopia in alcoholic liver disease–induced vitamin A deficiency: Can serum retinol levels be relied upon?
Ramya R Nadig1, Himanshu Kashyap1, Rajesh Nagarajan2, Rajiv Raman1
1 Shri Bhagwan Mahavir Vitreoretinal Services, Medical Research Foundation, Sankara Nethralaya, Chennai, Tamil Nadu, India
2 Vision Research Foundation, Sankara Nethralaya, Chennai, Tamil Nadu, India
|Date of Submission||28-Jul-2022|
|Date of Acceptance||07-Sep-2022|
|Date of Web Publication||20-Jan-2023|
Shri Bhagwan Mahavir Vitreoretinal Services, Medical Research Foundation, Sankara Nethralaya, 18 College Road, Chennai - 600 006, Tamil Nadu
Source of Support: None, Conflict of Interest: None
We report a case of a 52-year-old man with diminution of vision in both eyes at night for 15 days with mild retinal pigment epithelium changes at the macula and a tessellated background on fundus examination. Given his history of chronic alcohol consumption and jaundice two weeks back, vitamin A deficiency was contemplated. Electroretinogram (ERG) showed diminished responses. Serum retinol was 17 μg/dl. On supplementation with vitamin A, symptoms improved and ERG was normal; however, serum retinol levels were still low at 8.98 μg/dl. Thus, serum retinol does not necessarily indicate response to treatment, and ERG is necessitated in such cases.
Keywords: Electroretinogram, night blindness, serum retinol, vitamin A deficiency
|How to cite this article:|
Nadig RR, Kashyap H, Nagarajan R, Raman R. Nyctalopia in alcoholic liver disease–induced vitamin A deficiency: Can serum retinol levels be relied upon?. Indian J Ophthalmol Case Rep 2023;3:89-91
|How to cite this URL:|
Nadig RR, Kashyap H, Nagarajan R, Raman R. Nyctalopia in alcoholic liver disease–induced vitamin A deficiency: Can serum retinol levels be relied upon?. Indian J Ophthalmol Case Rep [serial online] 2023 [cited 2023 Feb 1];3:89-91. Available from: https://www.ijoreports.in/text.asp?2023/3/1/89/368180
Vitamin A (retinol) is a lipid-soluble compound that plays a key role in the visual cycle. The present knowledge on it was enriched by the work of Dowling and Wald who elucidated on “capacity for sight under variable levels of light.” Their studies explicated the need for adequate functioning of “three integrative parts of the eye: the pupil, the rods and cones, and rhodopsin in the rods” for night vision.
Rhodopsin is crucial for night vision. Various nutrients are required in the regeneration of rhodopsin, including proteins, vitamins, and minerals like zinc which significantly affect the metabolism of vitamin A. Although poor dietary intake is the cause in underdeveloped countries, in developed countries nyctalopia due to vitamin A deficiency occurs in cases of chronic alcoholism and cirrhosis that lead to impaired liver function.
Deficiency causes varied ocular manifestations, the earliest being night blindness. Therefore, a high index of suspicion to detect the deficiency and start early treatment are essential. This can reverse ocular complications prior to permanent vision loss.
Monitoring the changes in ERG in a case of vitamin A deficiency (VAD)-associated night blindness aids in demonstrating functional recovery.
| Case Report|| |
A 52-year-old man presented with diminution of vision in both eyes at night for 15 days. Best-corrected visual acuity (BCVA) in the right eye was 6/7.5, N6 and in the left eye was 6/12, N8. Both eyes revealed mild retinal pigment epithelium changes at the macula and a tessellated background on fundus examination [Figure 1]a. Color vision was normal. Visual fields showed low reliability.
|Figure 1: (a) Color Fundus photo of a 52-year-old patient at initial presentation. (b) Color fundus photo of the same patient at the subsequent visit|
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Given his history of chronic alcohol consumption and jaundice two weeks back, vitamin A deficiency was contemplated. The patient was investigated for serum vitamin A levels and was found to be reduced at 17 μg/dl (normal being 30–80 μg/dl). A full-field ERG performed according to ISCEV Standards demonstrated absent scotopic responses to dim flash dark adapted (DA) 0.01, reduced A and B wave amplitudes for DA 3.0 and DA 10.0 tests, and significant reduction in oscillatory potential amplitudes. Reduced B wave amplitudes in light adapted (LA) 3.0 and 3.0 Hz flicker were also seen [Figure 2]a.
|Figure 2: (a) Full-field ERG of a 52 year-old patient at initial presentation. (b) Full-field ERG of the same patient at the subsequent visit|
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Thus, it was established that the patient had alcoholic liver disease–induced vitamin A deficiency which caused acquired night blindness. He was advised vitamin A supplementation of 25000 IU orally daily for a month.
On follow-up, patient was symptomatically better. BCVA in both eyes were 6/6, N6 with a fundus picture similar to the initial visit [Figure 1]b. A repeat full-field ERG showed normal responses [Figure 2]b. However, serum vitamin A levels were still low at 8.98 μg/dl.
| Discussion|| |
Chronic liver diseases are mostly coupled with vitamin A deficiency. The vitamin A status can be assessed by measuring the serum retinol concentration. A study on “The vitamin A spectrum” stated that concentration of serum retinol below 0.5 μmol/L (14 μg/dL) could point toward deficiency, whereas levels more than 1.4 μmol/l (39.2 μg/dl) were suggestive of normal dark adaptation and therefore normal vitamin-A-dependent retinal function. On analyzing the results of a patient, Wachtmeister et al. discovered that “a serum retinol level above 0.7 μmol/L (19.6 μg/dL) predicts a normal or close to normal dark-adapted rod threshold.”
In our case, we observed abnormal ERG at 17 μg/dl when the patient had an acute episode of jaundice and thus compromised liver stores.
The serum retinol concentration is maintained by the circulating retinol from hepatic stores; therefore the levels of serum retinol may be normal even when the total body stores are low. Thus, the total vitamin A status is not reflected appropriately by the serum retinol levels.
Abbott-Johnson et al. showed “no significant correlation between DA thresholds and biochemical parameters (vitamin A, RBP, vitamin A/RBP ratio and zinc)”. The authors also stated that in spite of no demonstrable changes in retinol levels, there was considerable improvement in DA and it may have been due to storage of retinyl ester in the retina. The retinal pigment epithelium-choroid complex has the maximum concentration of vitamin A next only to liver, and this could effectively act as a buffer for the retina against hypovitaminosis.
It was found that daily oral vitamin A supplements of 3300 μg was associated with significant (P < 0.05–0.005) improvement in dark adaptation and retinol-binding protein. Thus, the authors implied that supplementation of vitamin A stimulates retinol binding protein release from the liver which in turn enhances the transport and delivery of retinol to peripheral tissues like the retina. This may act as a significant factor in the improvement of vitamin A status and associated night blindness in patients with cirrhosis.
In our patient, liver function was impaired at initial visit which led to decrease in serum retinol levels. However, the improvement in the ERG with decrease in vitamin A levels post supplementation led us to hypothesize that with the improvement in liver function, the protein component (like retinol-binding protein) improved which caused more binding of vitamin A and an acute phase of probable decrease in the free serum retinol level.
A WHO report states that ERG has high relevance, credibility, comparability, time sensitivity and information in assessing night blindness. Thus, ERG monitoring is most reliable and indicative of response to supplementation.
| Conclusion|| |
Thus, it can be concluded that in a case of nyctalopia due to alcoholic liver disease–induced vitamin A deficiency, ERG monitoring is of utmost importance as serum retinol monitoring does not necessarily indicate response to treatment.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]