title: Unilateral negative electroretinogram presenting as photophobia.
abstract: We aimed to describe four cases with an acquired unilateral negative electroretinogram (ERG) and severe unilateral photophobia and assess the underlying pathology.
  
  
  
  We performed a retrospective chart view of the four cases by visiting two independent hospitals.
  
  
  
  Over the last 10 years, a 65-year-old man, 71-year-old woman, 68-year-old man, and 73-year-old woman presented to the hospitals with unilateral photophobia. Symptom onset was relatively obvious in all the patients. Comprehensive examinations, including visual acuity and visual field assessment, optical coherence tomography, and fluorescein angiography, showed minimal change in the eye with photophobia. However, only in the affected eye, the mixed rod-cone response in full-field ERG showed a markedly electronegative pattern, namely the amplitude of a-wave was preserved and larger than that of b-wave, and the rod and cone responses were very low. In fact, the cone responses were almost absent in all four patients. ERG findings indicate dysfunction of both rod and cone visual pathways, and the preserved a-wave in the mixed rod-cone ERG suggests that the disturbance of the rod visual pathway exists in post-photoreceptors. Moreover, although multifocal ERG showed a very low amplitude in the entire area, the preservation of the responses was detected to some extent only in the center. These symptoms and examination findings remained unchanged for more than 4 years.
  
  
  
  Four patients with acquired unilateral negative ERG associated with severe photophobia showed similar clinical findings. To our knowledge, no known disorders can explain these conditions.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo, Kyoto, 606-8507, Japan.
authors.forename: Ai
authors.initials: A
authors.lastname: Kido
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo, Kyoto, 606-8507, Japan. kenboo@kuhp.kyoto-u.ac.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Ogino
authors.affiliation: Aichi Medical University, Nagakute, Aichi, Japan.|Yanagida Eye Clinic, Shizuoka, Japan.
authors.forename: Yozo
authors.initials: Y
authors.lastname: Miyake
authors.affiliation: Yanagida Eye Clinic, Shizuoka, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yanagida
authors.affiliation: Department of Instrumental Analysis, Research Center for Human and Environmental Science, Shinshu University, Nagano, Japan.
authors.forename: Takanobu
authors.initials: T
authors.lastname: Kikuchi
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo, Kyoto, 606-8507, Japan.
authors.forename: Nagahisa
authors.initials: N
authors.lastname: Yoshimura
mesh_terms: D000368:Aged; D004596:Electroretinography / Q000379:methods*; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D008297:Male; D020795:Photophobia / Q000503:physiopathology*; D020419:Photoreceptor Cells, Vertebrate; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology
keywords: Normal fundus; Peripheral cone–rod dysfunction; Unilateral negative ERG; Unilateral photophobia