title: Environmental factors that contribute to upper eyelid ptosis: a study of identical twins.
abstract: BACKGROUND
  Current literature provides little information about the impact of environmental exposures on the severity of acquired blepharoptosis.
  
  
  OBJECTIVE
  The authors assessed environmental factors that may contribute to eyelid ptosis in a population of identical twins.
  
  
  METHODS
  Photographs of 286 sets of twins from a prospectively collected database from 2008 to 2010 were reviewed. The authors identified 96 sets of identical twins (192 individual persons) who had differing severity of ptosis. Digital photographs were analyzed, and the degree of ptosis was measured in each eye of every subject. The external factors that could potentially contribute to blepharoptosis were taken into consideration. The authors then assessed the correlations of 9 different environmental risk factors with ptosis. Generalized linear mixed model were constructed to determine the associations of ptosis measurements with environmental risk factors obtained from the subject survey database.
  
  
  RESULTS
  The mean level of upper eyelid ptosis in the study population was 1.1 mm. The mean difference in ptosis between twins was 0.5 mm. Wearing contact lenses, either hard or soft, was significantly associated with ptosis. The mean ptosis measurement among twins who did not wear contact lenses was 1.0 mm; for those who wore soft contact lenses, the mean was 1.41 mm, and for those who wore hard contact lenses, the mean was 1.84 mm.
  
  
  CONCLUSIONS
  Acquired ptosis is not linked to body mass index, smoking behavior, sun exposure, alcohol use, work stress, or sleep. Wearing either hard or soft lenses was associated with an increased risk of ptosis. These influences are independent of genetic predisposition.
  
  
  METHODS
  3 Diagnostic.
authors: Mr. Satariano and Ms. Zwiebel are Medical Students at Case Western Reserve University, Cleveland, OH. Dr Brown is a Resident Physician and Dr Guyuron is the Chairman, Department of Plastic Surgery, Ohio Plastic Surgery, Case Western Reserve University, Cleveland, OH.
authors: Nicholas
authors: N
authors: Satariano
authors: Mr. Satariano and Ms. Zwiebel are Medical Students at Case Western Reserve University, Cleveland, OH. Dr Brown is a Resident Physician and Dr Guyuron is the Chairman, Department of Plastic Surgery, Ohio Plastic Surgery, Case Western Reserve University, Cleveland, OH.
authors: Matthew S
authors: MS
authors: Brown
authors: Mr. Satariano and Ms. Zwiebel are Medical Students at Case Western Reserve University, Cleveland, OH. Dr Brown is a Resident Physician and Dr Guyuron is the Chairman, Department of Plastic Surgery, Ohio Plastic Surgery, Case Western Reserve University, Cleveland, OH.
authors: Samantha
authors: S
authors: Zwiebel
authors: Mr. Satariano and Ms. Zwiebel are Medical Students at Case Western Reserve University, Cleveland, OH. Dr Brown is a Resident Physician and Dr Guyuron is the Chairman, Department of Plastic Surgery, Ohio Plastic Surgery, Case Western Reserve University, Cleveland, OH.
authors: Bahman
authors: B
authors: Guyuron
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001763:Blepharoptosis / Q000209:etiology*; D003261:Contact Lenses / Q000009:adverse effects*; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D014430:Twins, Monozygotic; D055815:Young Adult