"En face" OCT imaging of the IS/OS junction line in type 2 idiopathic macular telangiectasia.
OBJECTIVE
We investigated abnormalities of the photoreceptor inner/outer segment (IS/OS) junction layer viewed "en face" and their functional correlates in type 2 idiopathic macular telangiectasia (type 2 MacTel).


METHODS
Segmentation and "en face" imaging of the IS/OS lines in spectral domain optical coherence tomographic (SD-OCT) volumes were performed manually. Mesopic retinal sensitivity thresholds were determined using a Nidek MP1 microperimeter. "En face" SD-OCT images and microperimetric data were superimposed over images of the fundus. Retinal structure and characteristics of type 2 MacTel were analyzed, and associations of structural changes with function were investigated.


RESULTS
We examined 49 eyes of 28 patients (mean age 62.6 ± 9.4 years). Total IS/OS break area ranged from 0.04 to 2.23 mm² (mean 0.63 mm², SD 0.53 mm²) and 0.03 to 1.49 mm² (mean 0.49 mm², SD 0.42 mm²) in right and left eyes, respectively. A correlation between fellow eyes was present (Spearman correlation ρ = 0.770, P < 0.01). An assessment of the repeatability of IS/OS lesion area measurements (n = 19 eyes) revealed an intra-class correlation coefficient of 0.99 (95% confidence interval [CI] of 0.975-0.996). Retinal areas corresponding to an IS/OS break showed a mean retinal sensitivity of 8.3 ± 5.8 and 8.7 ± 5.7 decibels (dB) in right and left eyes, respectively. Mean sensitivity over retinal areas outside the lesion was significantly higher, 17.0 ± 3.3 and 16.7 ± 3.6 dB in right and left eyes, respectively (paired t-test, P < 0.01). Mean aggregate retinal sensitivity loss was 33.5 ± 30.4 dB (n = 40), correlating well with IS/OS lesion area (Pearson correlation coefficient = 0.848, P < 0.01).


CONCLUSIONS
"En face" OCT imaging of the IS/OS junction layer provides a functionally relevant method for assessing disease severity in type 2 MacTel.
The Reading Centre, Department of Research and Development, Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK. Ferenc.Sallo@moorfields.nhs.uk
Ferenc B
FB
Sallo
Tunde
T
Peto
Catherine
C
Egan
Ute E K
UE
Wolf-Schnurrbusch
Traci E
TE
Clemons
Mark C
MC
Gillies
Daniel
D
Pauleikhoff
Gary S
GS
Rubin
Emily Y
EY
Chew
Alan C
AC
Bird
D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058456:Retinal Telangiectasis / Q000175:diagnosis* / Q000503:physiopathology; D012684:Sensory Thresholds / Q000502:physiology; D041623:Tomography, Optical Coherence / Q000379:methods*; D014792:Visual Acuity / Q000502:physiology