title: The IS/OS junction layer in the natural history of type 2 idiopathic macular telangiectasia.
abstract: OBJECTIVE
  To document the progression of a break in the photoreceptor inner segment/outer segment (IS/OS) junction layer and its functional correlates over time in the natural history of type 2 idiopathic macular telangiectasia (type 2 MacTel).
  
  
  METHODS
  Patients with at least 1 year of follow-up were selected from the MacTel Study. En face images were created by manual segmentation of the IS/OS junctional line in volume scans acquired using a spatial-domain optical coherence tomography retinal imaging unit. Retinal sensitivity thresholds were determined using a retinal microperimeter unit. Aggregate retinal sensitivity loss within IS/OS lesions was calculated. Changes over time in an area of IS/OS defects and retinal sensitivity were analyzed.
  
  
  RESULTS
  thirty-nine eyes of 23 patients (mean age: 62.3 ± 9.2 years) were analyzed. Mean follow-up time was 1.9 years (range: 1-3 years). Mean IS/OS break area at baseline was 0.575 mm(2) (SE = 0.092, 95% confidence interval [CI]: 0.394-0.756 mm(2)). The cluster-adjusted mean annual progression rate in IS/OS break area was 0.140 mm(2) (SE = 0.040, 95% CI: 0.062-0.218 mm(2), P < 0.001). Mean aggregate retinal sensitivity loss was at baseline 28.56 dB (SE = 5.43, 95% CI: 17.32-39.80 dB, n = 28), a positive correlation with IS/OS lesion area was present (P < 0.001). The mean annual rate of change in aggregate sensitivity loss was 5.14 dB (SE = 1.51, 95% CI: 2.19-8.10 dB, P < 0.001, n = 37), a significant correlation with lesion area increase was found (P = 0.006).
  
  
  CONCLUSIONS
  Both IS/OS break area and rate of enlargement correlate with aggregate retinal sensitivity loss in type 2 MacTel. En face OCT imaging of the IS/OS layer provides a functionally relevant method for documenting disease progression in type 2 MacTel.
authors.affiliation: Department of Research and Development, Moorfields Eye Hospital, London, United Kingdom. Ferenc.Sallo@moorfields.nhs.uk
authors.forename: Ferenc B
authors.initials: FB
authors.lastname: Sallo
authors.forename: Tunde
authors.initials: T
authors.lastname: Peto
authors.forename: Catherine
authors.initials: C
authors.lastname: Egan
authors.forename: Ute E K
authors.initials: UE
authors.lastname: Wolf-Schnurrbusch
authors.forename: Traci E
authors.initials: TE
authors.lastname: Clemons
authors.forename: Mark C
authors.initials: MC
authors.lastname: Gillies
authors.forename: Daniel
authors.initials: D
authors.lastname: Pauleikhoff
authors.forename: Gary S
authors.initials: GS
authors.lastname: Rubin
authors.forename: Emily Y
authors.initials: EY
authors.lastname: Chew
authors.forename: Alan C
authors.initials: AC
authors.lastname: Bird
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D055211:Retinal Photoreceptor Cell Inner Segment / Q000502:physiology*; D055214:Retinal Photoreceptor Cell Outer Segment / Q000502:physiology*; D058456:Retinal Telangiectasis / Q000175:diagnosis* / Q000503:physiopathology; D012684:Sensory Thresholds / Q000502:physiology; D013997:Time Factors; D041623:Tomography, Optical Coherence / Q000379:methods*; D014792:Visual Acuity / Q000502:physiology