Shedding new light on diabetic retinopathy with optical coherence tomography

Purpose: To establish whether differences in the assessment of diabetic macular oedema (DME) with either optical coherence tomography (OCT) or stereoscopic biomicroscopy lead to variability in the photocoagulation treatment of DME. Methods: The differences in the assessment of DME with either OCT or stereoscopic bio­ microscopy were analysed by calculating the surface areas and the overlap of retinal thick­ ening. Photocoagulation treatment plans of retinal specialists were compared by evaluat­ ing the number and location of planned laser spots. Results: The threshold for and dosage of photocoagulation differ depending upon whether the basis of retinal thickness diagnosis is clinical observation or OCT. The overlap in laser spot location based on the assessment of DME with OCT or biomicroscopy aver­ ages 51%. Among retinal specialists, the treatment plans differed in the laser spot count by six­ to 11­fold. Conclusion: Diabetic macular oedema photocoagulation treatment threshold and dos­ age of laser spots differ depending on whether thickness assessments are based on ste­ reoscopic slit­lamp biomicroscopy or OCT. In addition, retinal specialists differed in the number and placement of planned laser spots even when given identical information con­ cerning DME and treatable lesions. This variability in the photocoagulation treatment of DME could lead to differences in patient outcome and laser study results.