Quick viewing(Text Mode)

The Case of a Teen with Nyctalopia

The Case of a Teen with Nyctalopia

WHAT’S YOUR DIAGNOSIS? MORNING ROUNDS

The Case of a Teen With

ennie Davis,* a 15-year-old with resections, resulting in short gut syn- 1 a history of cystic fibrosis, had drome. Two years prior to our evalua- Jbeen experiencing progressive tion, she had received a liver transplant decreased vision and difficulty with for unspecified liver disease. Her clini- her night vision in both eyes for almost cal course was complicated by low-level three years. chronic rejection. After seeing her primary care physi- The yellow-white deposits in Jennie’s cian, she was referred to our clinic for peripheral raised concerns for a evaluation. fleck retina syndrome. Macular optical coherence tomography (OCT) was per- We Get a Look formed, showing multiple subretinal When we examined Jennie, her best- deposits with photoreceptor disruption corrected visual acuity was 20/40 in her (Fig. 3). (ERG) 2 right eye and 20/50 in her left. In both demonstrated a decreased scotopic eyes, intraocular pressure was normal, response (Fig. 4). and color vision was 11/11 in each eye on testing with Ishihara plates. The Differential Diagnosis anterior segment exam was notable The differential diagnosis of nyctalopia for areas of dryness and early foamy includes common disorders such as un­- plaques on the bilaterally corrected , , and glau- (Fig. 1). coma. The dilated ophthalmoscopic exam Congenital or genetic conditions showed a normal-appearing can also be implicated. These include and macula in both eyes, but both ret­ pigmentosa, congenital station- inas had innumerable yellow-white ary night blindness, , WE GET A LOOK. (1) When we per- punctate deposits which appeared deep , gyrate atrophy, or formed the slit-lamp examination, to the retina and were more pronounced . plaques of foamy spots were visible in the periphery (Fig. 2). Other acquired causes of nyctalopia on both conjunctivas. (2) The dilated include , zinc defic­ ophthalmoscopic exam was note- Further Investigations iency, medications such as thioridazine worthy for numerous yellow-white We further reviewed Jennie’s medical or chloroquine, , or a history of dots in both , particularly in the and surgical history. It included cystic panretinal photocoagulation. periphery. fibrosis–related pancreatic insufficiency, for which she was receiving standard Our Diagnosis pancreatic insufficiency and short gut enzymatic replacement therapy. As a Given the findings of xerosis and fleck syndrome, we placed vitamin A defi- neonate, she had developed meconium , in combination with ciency at the top of our differential. ileus, which necessitated multiple bowel Jennie’s history of cystic fibrosis with We obtained serum vitamin A levels, which measured <5 µg/dL (the reference range for individuals who are 13-17 BY JOHN DEANS, MD, KATHY WHITFIELD, MD, ALICE YANG ZHANG, MD, years old is 14.4-97.7 µg/dL), confirming

Debra Cantrell, OCT-C, COA OCT-C, Cantrell, Debra AND KENNETH L. COHEN, MD. EDITED BY INGRID U. SCOTT, MD, MPH. the diagnosis of vitamin A deficiency.

EYENET MAGAZINE • 37 Discussion Vitamin A consists of a group of lipid- 3 soluble compounds known as retinoic acids. Along with the other fat-soluble vitamins D, E, and K, vitamin A must be acquired through the diet or sup­ plementation. These compounds un-­ dergo emulsification by bile salts in the duodenum and absorption in the ileum before being stored in the liver or adipose tissue. Vitamin A has essential functions in phototransduction, cellular differen- tiation, epithelial maintenance, and 4 immunity. Although vitamin A defi- ciency is commonly associated with malnutrition, our patient’s case high- lights the fact that this condition is not confined to developing nations. Rather, it can occur in any patient with liver, gallbladder, pancreatic, or small-bowel pathology that impairs vitamin A absorption, despite an adequate dietary intake.

Etiology and Epidemiology Vitamin A deficiency is the leading cause of preventable childhood blind- ness worldwide. The World Health Or- ganization estimated that in 2013, the deficiency affected approximately one- FURTHER INVESTIGATIONS. When developing our differential, we ordered OCT third of children aged 6-59 months, and an ERG. (3) Macular OCT reveals subretinal deposits and photoreceptor disrup- with higher rates in sub-Saharan Africa tion. (4) ERG tracings demonstrate a decreased scotopic response. (48%) and South Asia (44%).1 In the developed world, vitamin A is conjunctival and corneal xerosis. In Complications deficiency is much rarer but may occur the absence of vitamin A, which has The associated with in fat malabsorption conditions such as vital functions in epithelial maturation, vitamin A deficiency represents a spec- cystic fibrosis, celiac disease, primary there is a loss of mucin-secreting con- trum of disease. The earliest findings of biliary cirrhosis, small-bowel Crohn’s junctival goblet cells. This will result conjunctival dryness with Bitot’s spots disease, and short gut syndrome, as well in tear film disruption and dryness. and corneal punctate epithelial erosions as after bariatric surgery. It may also Bitot’s spots are a classic associated may progress to peripheral corneal be seen with hepatic cirrhosis, most finding (see the foamy spots in Fig. 1). ulcers or keratomalacia with full-thick- commonly due to alcoholism, and in These triangular patches of xerosed ness liquefactive necrosis of the . patients following severely restricted conjunctiva represent areas of squa- Blindness may result from scar forma- diets by choice or as a result of mental mous metaplasia with overlying keratin tion and/or corneal decompensation. health conditions. debris mixed with Corynebacterium xerosis. The gas that is produced by Confirming the Diagnosis What the Ophthalmologist this bacterium accounts for the foamy Vitamin A deficiency is a clinical Should Look For appearance of these lesions. diagnosis; however, additional testing Nyctalopia is the earliest and most Finally, vitamin A deficiency can may be beneficial for confirmation. For common symptom of vitamin A defi- cause a fleck retinopathy, as shown in adults, a serum vitamin A level of <30 ciency. This occurs due to an insufficient Figs. 2 and 3. The cause and compo- µg/dL is suggestive but not diagnostic, supply of the chromophore 11-cis retinal, sition of these small, white peripheral as serum levels do not fully reflect which is a derivative of vitamin A and subretinal dots is not yet known, but hepatic vitamin A stores and may be a necessary constituent of the visual they may represent areas of photo­ depressed in protein-deficiency states.1,3 pigment . receptor damage or lipofuscin accu­ -binding protein (RBP) levels 2 The next ophthalmic manifestation mulation. may also be measured. The reference BS. Esquejo-Leon, Lyn Rona COA; OCT-C, Cantrell, Debra OCT-C; Sean Grout,

38 • MAY 2020 range is 30 to 75 mg/L, and a serum ret- treated with a beta carotene–based sup- blindness, xerophthalmia, and retinop- inol:RBP ratio of <0.8 suggests vitamin plement. However, this treatment did athy. Treatment is oral or intramuscular A deficiency. Conjunctival impression not improve her symptoms or vitamin vitamin A supplementation. cytology may be considered; histology A levels, which suggested that she could shows squamous metaplasia of the not convert beta carotene to retinol *Patient name is fictitious. conjunctival epithelium and goblet cell in her gut because of prior bowel 1 https://data.unicef.org/topic/nutrition/vitamin- loss. Further evaluation of nyctalopia or resections. Therefore, her therapy a-deficiency. Accessed March 11, 2020. xerophthalmic may also include was changed to retinyl palmitate, a 2 Chow CC, Mieler WF. Retin Cases Brief Rep. ERG, OCT, fluorescein angiography, preformed type of vitamin A. Because 2014;8(3):164-166. and visual fields. zinc is a necessary cofactor of RBP, she 3 Krishna U et al. EyeNet. 2016;20(12)35-36. aao. was started on zinc supplementation org/eyenet/article/management-of-bitot-s-spots. Treatment as well. Accessed Feb. 13, 2020. Vitamin A deficiency is treated with With the above regimen, Jennie’s 4 World Health Organization. Vitamin A supple- high-dose oral or intramuscular vitamin serum vitamin A recovered to a normal ments: a guide to their use in the treatment and A supplementation. Dose adjustments level of 17.0 µg/dL. Her nyctalopia prevention of vitamin A deficiency and xeroph- are required for infants and pregnant resolved, as did her yellow-white de- thalmia. 2nd ed. 1997. www.who.int/nutrition/ women.4 Topical retinoic acid (0.1%) posits. We performed OCT and found publications/micronutrients/vitamin_a_ may serve as adjunctive therapy in cases that her macula had normalized, but deficiency/9241545062/en/. Accessed Feb. 13, 2020. of xerosis, as healing may be delayed the patient did not return for repeat 5 McLaughlin S et al. Eye (Lond). 2014;28(5):621- several days from the start of systemic ERG. 623. therapy. Nyctalopia improves or resolves within 48 hours of treatment, and Conclusion Dr. Deans is chief resident of ; retinopathy has been shown to resolve Vitamin A deficiency is the leading pre- Dr. Whitfield and Dr. Zhang are both assistant within eight months.2 ventable cause of professors of ophthalmology; and Dr. Cohen is worldwide, but it can also occur in the the Sterling A. Barrett Distinguished Professor Our Patient’s Course developed world in patients with fat Ophthalmology. All four are at the University of Jennie was referred to the nutritional malabsorption or liver disease.5 Oph- North Carolina at Chapel Hill. Financial disclo- services department. She was initially thalmic manifestations include night sures: None.

The 19th Annual Downeast Ophthalmology Symposium OCTOBER 2-4, 2020 EyeNet Bar Harbor, Maine Gives You the Full Picture Poll-topping, digestible For further information, contact: coverage of all things Shirley Goggin Maine Society of ophthalmologic Eye Physicians and Surgeons P.O. Box 190

 Manchester, ME 04351

EyeNetFEBRUARY 2018 207-445-2260

MIGS Roundup [email protected] New Options, Trends, and Caveats Visit Us Online aao.org/eyenet

Facial Transplants Maximizing Periocular Results Write to Us DMEK Enters the Mainstream

OPINION Why Consensus Statements Matter [email protected] www.maineeyemds.com

EYENET MAGAZINE • 39

2018.eyenet.QTR.indd 1 2/27/18 10:30 AM

Top View