title: Evaluation of Choroidal Thickness and Volume during the Third Trimester of Pregnancy using Enhanced Depth Imaging Optical Coherence Tomography: A Pilot Study.
abstract: BACKGROUND
  During pregnancy the maternal choroid is exposed to the multiple haemodynamic and hormonal alterations inherent to this physiological condition. These changes may influence choroidal anatomy. In this study a quantitative assessment of overall choroidal structure is performed, by constructing a 3-dimensional topographic map of this vascular bed.
  
  
  OBJECTIVE
  To compare the thickness and volume of the maternal choroidal in the third trimester of pregnancy with that of an age-matched control group of women.
  
  
  METHODS
  Twenty-four eyes of 12 pregnant women in the last trimester and 12 age-matched healthy controls (24 eyes) were included. Optical coherence tomography in enhanced depth imaging mode was used to construct maps of the choroid of the macular area. Choroidal thickness and volume were automatically calculated for the 9 subfields defined by the Early Treatment Diabetic Retinopathy Study (ETDRS). A comparative analysis between the two groups was performed using the two-way ANOVA test.
  
  
  RESULTS
  The average thickness of the choroid for the entire ETDRS area of the pregnant group was 295.15 ±42.40μm and 271.56 ±37.65μm in the control group (p=0.051). The average choroidal volume was 8.05 ±1.12mm(3) and 7.46 ±1.03mm(3), respectively (p=0.067). Although the choroid of the pregnant group had larger thickness and volume in all subfields compared to the control group, this difference was statistically significant only in three regions - the central subfield, minimum foveal thickness and inferior inner macula (p<0.05).
  
  
  CONCLUSIONS
  Our study suggests that in the third trimester of pregnancy the choroid may be subjected to physiological changes in structure. Whether these changes are a result of hormonal and/or haemodynamic adaptations of pregnancy remains to be studied.
authors.affiliation: Department of Ophthalmology, Centro Hospitalar Vila Nova de Gaia/Espinho , Portugal .
authors.forename: Renata T
authors.initials: RT
authors.lastname: Rothwell
authors.affiliation: Department of Ophthalmology, Centro Hospitalar Vila Nova de Gaia/Espinho , Portugal .
authors.forename: Dália M
authors.initials: DM
authors.lastname: Meira
authors.affiliation: Department of Ophthalmology, Centro Hospitalar Vila Nova de Gaia/Espinho , Portugal .
authors.forename: Marisa A
authors.initials: MA
authors.lastname: Oliveira
authors.affiliation: Department of Ophthalmology, Centro Hospitalar Vila Nova de Gaia/Espinho , Portugal .
authors.forename: Lígia F
authors.initials: LF
authors.lastname: Ribeiro
authors.affiliation: Department of Ophthalmology, Centro Hospitalar Vila Nova de Gaia/Espinho , Portugal .
authors.forename: Sofia L
authors.initials: SL
authors.lastname: Fonseca
keywords: Choroid; Choroidal volume; OCT