OSLI Retina

May 2020

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286 Ophthalmic Surgery, Lasers & Imaging Retina | Healio.com/OSLIRetina ■ C A S E R E P O R T ■ Night Blindness in a Healthy Middle-Class Child Michael F. Marmor, MD ABSTRACT: How do you clinically approach a night- blind child in a vegetarian family, with no obvious dystrophy and no obvious malnutrition? This case reviews some of the issues, and it reminds us of some of the cautions. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:286-288.] CASE REPORT A 10-year-old girl was referred because of com- plaints of night blindness to her parents, who noted trouble walking at night and the need for extra light under dim conditions. She also had reduced acuity (she did not refract better than 20/60-80), and she had missed a number of Ishihara plates at the referral of- fice. She was from a middle-class vegetarian Indian family and appeared well-nourished, healthy, and in- telligent. Prior examinations by referring physicians all reported normal fundi. As a de-identified retro- spective chart review of one patient, the Institutional Review Board of Stanford University School of Medi- cine waived patient consent. This note complies with the Declaration of Helsinki. DIFFERENTIAL DIAGNOSIS A frequent concern with referrals for night blind- ness in children is rod-cone dystrophy, which may not be obvious in a child's fundus. Systemic syn- dromes seemed unlikely with her good health. She showed no signs of generalized nutritional deficiency and had no history of malabsorption, cystic fibrosis, or gastrointestinal surgery. METHODS A standard clinical exam was performed, adding widefield autofluorescence imaging (Optos, Dun- fermline, United Kingdom) and Cirrus spectral-do- main optical coherence tomography (SD-OCT; Zeiss, Oberkochen, Germany). Electroretinograms (ERGs) were performed according to the ISCEV Standard, 1 using an Espion E3 system (Diagnosys, Lowell, MA). EXAMINATION Her fundus was normal, as were autofluorescence imaging and SD-OCT, including the photoreceptor ellipsoid zone and interdigitation zone marker lines (Figure 1). Visual acuity (VA) was 20/60-80, and color vision was normal with both standard and desaturat- ed Farnsworth D-15 tests. Dark adaptometry was only slightly abnormal with rod threshold elevated (per- haps 0.5 log units), but her ERG (Figure 2) showed marked rod signal loss; 0.01 DA b-wave amplitude was near 50 uV, which is only about a quarter of me- dian for her age. Cone b-waves (LA 3.0) were near 95 uV (two-thirds of typical amplitude for age), but there was no suggestion of b-wave timing delay for either the rods or the cones. This would be atypical From Byers Eye Institute and the Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, California. Originally submitted January 25, 2020. Revision received January 25, 2020. Accepted for publication March 6, 2020. Dr. Marmor reports no relevant financial disclosures. Address correspondence to Michael F. Marmor, MD, Byers Eye Institute at Stanford, 2452 Watson Ct., Palo Alto, CA 94303; email: marmor@stanford. edu. doi: 10.3928/23258160-20200501-06

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