title: The pupil light reflex in Leber's hereditary optic neuropathy: evidence for preservation of melanopsin-expressing retinal ganglion cells.
abstract: OBJECTIVE
  To investigate the pupillary light reflex (PLR) of patients with severe loss of vision due to Leber's Hereditary Optic Neuropathy (LHON) in the context of a proposed preservation of melanopsin-expressing retinal ganglion cells (mRGCs).
  
  
  METHODS
  Ten LHON patients (7 males; 51.6 ± 14.1 years), with visual acuities ranging from 20/400 to hand motion perception and severe visual field losses, were tested and compared with 16 healthy subjects (7 males; 42.15 ± 15.4 years) tested as controls. PLR was measured with an eye tracker and the stimuli were controlled with a Ganzfeld system. Pupil responses were measured monocularly, to 1 second of blue (470 nm) and red (640 nm) flashes with 1, 10, 100, and 250 cd/m² luminances. The normalized amplitude of peak of the transient PLR and the amplitude of the sustained PLR at 6 seconds after the flash offset were measured. In addition, optical coherence topography (OCT) scans of the peripapillary retinal nerve fiber layer were obtained.
  
  
  RESULTS
  The patient's peak PLR responses were on average 15% smaller than controls (P < 0.05), but 5 out of 10 patients had amplitudes within the range of controls. The patients' sustained PLRs were comparable with controls at lower flash intensities, but on average, 27% smaller to the 250 cd/m² blue light, although there was considerable overlap with the PLR amplitudes of control. All patients had severe visual field losses and the retinal nerve fiber layer thickness was reduced to a minimum around the optic disc in 8 of the 10 patients.
  
  
  CONCLUSIONS
  The PLR is maintained overall in LHON patients despite the severity of optic atrophy. These results are consistent with previous evidence of selective preservation of mRGCs.
authors.affiliation: Instituto de Psicologia, Universidade de São Paulo, São Paulo, Brazil. almoura_oft@yahoo.com.br
authors.forename: Ana Laura A
authors.initials: AL
authors.lastname: Moura
authors.forename: Balázs V
authors.initials: BV
authors.lastname: Nagy
authors.forename: Chiara
authors.initials: C
authors.lastname: La Morgia
authors.forename: Piero
authors.initials: P
authors.lastname: Barboni
authors.forename: André Gustavo Fernandes
authors.initials: AG
authors.lastname: Oliveira
authors.forename: Solange R
authors.initials: SR
authors.lastname: Salomão
authors.forename: Adriana
authors.initials: A
authors.lastname: Berezovsky
authors.forename: Milton Nunes
authors.initials: MN
authors.lastname: de Moraes-Filho
authors.forename: Carlos Filipe
authors.initials: CF
authors.lastname: Chicani
authors.forename: Rubens
authors.initials: R
authors.lastname: Belfort
authors.forename: Valerio
authors.initials: V
authors.lastname: Carelli
authors.forename: Alfredo A
authors.initials: AA
authors.lastname: Sadun
authors.forename: Donald C
authors.initials: DC
authors.lastname: Hood
authors.forename: Dora Fix
authors.initials: DF
authors.lastname: Ventura
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029242:Optic Atrophy, Hereditary, Leber / Q000503:physiopathology*; D010775:Photic Stimulation / Q000379:methods; D012025:Reflex, Pupillary / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000378:metabolism* / Q000473:pathology; D017299:Rod Opsins / Q000378:metabolism*; D041623:Tomography, Optical Coherence; D000099210:Melanopsin
chemical_list: D017299:Rod Opsins; D000099210:Melanopsin
keywords: LHON; OCT; ganglion cells; melanopsin; pupillometry