Abstract
Purpose: :
To investigate photoreceptor layer abnormalities and their correlation with visual function in diabetic macular edema (DME), using time-domain optical coherence tomography (OCT)
Methods: :
Digital OCT scans at two visits (baseline and 6 months) were obtained using the Stratus OCT3 (Carl Zeiss Meditec, Dublin, California) by certified imaging technicians from multiples sites in a DRCRnet cohort study of vitrectomy for DME. Subjects with OCT scans (6 radial fast macular scans and high-resolution (512 A scans per B scan) crosshair scans) submitted as hard copy prints at one or both visits were not included in this assessment. The cross hair scans were viewed in gray scale and the presence and continuity of the inner segment- outer segment (IS-OS) junction was evaluated at the center point (CPT) and in the center subfield (CSF) as absent, present but abnormal, and normal.
Results: :
Of the 68 eyes assessed at baseline, IS-OS continuity in the CSF was normal in 7 eyes, abnormal in 34 eyes and absent in 27 eyes. The median visual acuity (VA) score was 75, 62 and 52 letters respectively. This showed statistically significant association of vision with presence of IS-OS junction (Kruskall Wallis test; p=0.003). Similarly, IS-OS at CPT was normal in 19 eyes, abnormal in 24 eyes and absent in 25eyes (Median VA 69, 59 and 49 letters respectively (p=0.001). 66 eyes were graded at both baseline and 6 months and IS-OS status in CSF at both visits were compared. 22 eyes showed improvement at the follow up visit (from absent to abnormal or from abnormal to normal). 38 eyes had no change in IS-OS status and 6 eyes had worsening as compared to baseline. A statistically significant change in VA occurred with the change in IS-OS status, with median of 11 letter improvement in VA in the subset that had improvement of IS-OS and a loss of 21 letters in the subset where IS-OS layer was worse than baseline (p<0.001)
Conclusions: :
IS-OS junction in CSF and CPT can be evaluated from Stratus scans using gray scale digital OCT scans and is significantly associated with concurrent visual function.
Keywords: imaging/image analysis: clinical • clinical research methodology • diabetic retinopathy