title: Fixation in patients with juvenile macular disease.
abstract: OBJECTIVE
  The instability of fixation with central scotoma has been mainly studied in patients with age-related macular diseases (MDs). However, early macular lesions can lead to different characteristics of fixation. The aim of this work was to study fixation in patients with juvenile MD.
  
  
  METHODS
  Eye movements of 10 patients and 10 controls were monitored during fixation. Visual fields were assessed by static perimetry to determine the extent of the field defects. Eye movements were separated into saccades and drifts, with fixation stability assessed by bivariate contour ellipse area (BCEA). To quantify the number and location of preferred retinal loci (PRL), the kernel density estimator and expectation maximization for mixtures of gaussians were used.
  
  
  RESULTS
  Patients have worse fixation stability than controls and large BCEAs resulted in more than one PRL. It was found that central field defects (10 degrees) have negative correlation with the size of BCEA. In addition, the meridian of saccades during fixation was correlated with the meridian inter-PRL.
  
  
  CONCLUSIONS
  Patients with juvenile MDs have large BCEAs, frequently associated with two PRL. Similar results had been found for patients with age-related MDs. Also, the meridian of involuntary saccades during fixation was found to be correlated with the location of PRLs, suggesting a useful role of these movements in alternating between them.
authors.affiliation: Department of Physics, University of Minho, Braga, Portugal. macedo@fisica.uminho.pt
authors.forename: António Filipe
authors.initials: AF
authors.lastname: Macedo
authors.forename: Sérgio Miguel Cardoso
authors.initials: SM
authors.lastname: Nascimento
authors.forename: Augusto Oliveira Silva
authors.initials: AO
authors.lastname: Gomes
authors.forename: André Teixeira
authors.initials: AT
authors.lastname: Puga
mesh_terms: D000328:Adult; D017668:Age of Onset; D005133:Eye Movements; D005260:Female; D005403:Fixation, Ocular; D006801:Humans; D008266:Macula Lutea; D008297:Male; D008875:Middle Aged; D016011:Normal Distribution; D012164:Retinal Diseases / Q000453:epidemiology / Q000503:physiopathology*; D014794:Visual Fields