title: Choroidal thickness profile in Retinitis Pigmentosa - Correlation with outer retinal structures.
abstract: OBJECTIVE
  To compare the choroidal thickness (CT) of subjects with Retinitis Pigmentosa (RP) with age-matched healthy subjects and to correlate the visual acuity with retinal parameters including central macular thickness (CMT), inner segment/outer segment junction (IS/OS junction) integrity, external limiting membrane (ELM) integrity and choroidal thickness in subjects with RP.
  
  
  METHODS
  Eighty-eight eyes (69 patients) with typical RP and 188 eyes of 104 healthy subjects were enrolled between September 2012 and January 2013. All subjects underwent a comprehensive ocular examination including choroidal imaging using enhanced depth imaging with spectral domain optical coherence tomography. Outcome measures were CT difference between RP and age-matched healthy subjects; and correlation of various factors such CMT, IS/OS junction integrity, ELM integrity, and CT with visual acuity.
  
  
  RESULTS
  Among RP subjects, mean age was 31.39 ± 13.4 years with a mean BCVA of 0.99 ± 0.94 logMAR. Mean spherical equivalent was -0.6 ± 1.6D. Mean CMT was 148.48 ± 119 μm. Mean subfoveal CT was 296.9 ± 72 μm. Mean IS/OS and ELM integrity was 42.2 ± 46.6% and 43.75 ± 45.7%, respectively. The mean age was 40.0 ± 13.5 years with a mean spherical equivalent of 0.18 ± 0.6D for the normal age-matched healthy group. Mean subfoveal CT was 283.1 ± 47.8 μm. CT at various locations in patients of various ages in the RP group did not show any statistical significant difference (P = ≫0.05) in comparison with age-matched healthy subjects. On multivariate regression, ELM percentage integrity had the strongest association with best corrected visual acuity, followed by IS/OS junction percentage integrity. Subfoveal choroidal thickness had very weak correlation with visual acuity as well other retinal parameters. There was a significant difference in the outer retinal structure integrity (p = 0.002) and CMT (p = 0.02) between the eyes with good (⩾20/200) and poor vision (<20/200), but not in subfoveal choroidal thickness (p = 0.3).
  
  
  CONCLUSIONS
  Our study results did not show any significant difference in choroidal thickness between subjects with RP and age-matched healthy subjects. Choroidal thickness correlated better with the age but not with the vision or outer retinal structures in eyes with RP. Outer retinal structure integrity and CMT had a better correlation with visual acuity.
authors.affiliation: Smt. Kanuri Santhamma Retina Vitreous Centre, L.V. Prasad Eye Institute, Kallam Anji Reddy Campus, L.V. Prasad Marg, Banjara Hills, Hyderabad 500 034, Andhra Pradesh, India.
authors.forename: Jay
authors.initials: J
authors.lastname: Chhablani
authors.affiliation: Smt. Kanuri Santhamma Retina Vitreous Centre, L.V. Prasad Eye Institute, Kallam Anji Reddy Campus, L.V. Prasad Marg, Banjara Hills, Hyderabad 500 034, Andhra Pradesh, India.
authors.forename: Ganesh Babu
authors.initials: GB
authors.lastname: Jonnadula
authors.affiliation: L.V. Prasad Eye Institute, Kode Venkatadri Chowdary Campus, Tadigadapa, Vijayawada 521137, Andhra Pradesh, India.
authors.forename: P
authors.initials: P
authors.lastname: Srinivasa Rao
authors.affiliation: Smt. Kanuri Santhamma Retina Vitreous Centre, L.V. Prasad Eye Institute, Kallam Anji Reddy Campus, L.V. Prasad Marg, Banjara Hills, Hyderabad 500 034, Andhra Pradesh, India.
authors.forename: Amarnath
authors.initials: A
authors.lastname: Venkata
authors.affiliation: Smt. Kanuri Santhamma Retina Vitreous Centre, L.V. Prasad Eye Institute, Kallam Anji Reddy Campus, L.V. Prasad Marg, Banjara Hills, Hyderabad 500 034, Andhra Pradesh, India.
authors.forename: Subhadra
authors.initials: S
authors.lastname: Jalali
keywords: Choroidal thickness; ELM junction; IS/OS junction; RP; Retinitis Pigmentosa