Assessment of the Heidelberg Retina Tomograph in the detection of sight-threatening diabetic maculopathy.
OBJECTIVE
To assess the potential role of the Heidelberg Retina Tomograph (HRT) in screening for sight-threatening macular oedema in diabetes.


METHODS
One hundred and thirty-one eyes of 81 consecutive diabetic patients who fitted the inclusion criteria were included in the study. On HRT, the volume above the reference plane bound within a 2 mm diameter circle centred at the fovea was measured. The volumetric indices were compared with the mean measurement index in a group of 20 age-matched controls (mean score = 1, mean +2 SD score = 1.8). We also assessed the sensitivity of the subjective analysis of the intensity image and the addition of the three-dimensional map to the intensity image for detecting macular oedema and clinically significant macular oedema (CSMO).


RESULTS
One hundred and twelve eyes of 71 patients had a corrected Snellen visual acuity of 6/9 or better. When considering eyes with 6/9 or better vision only, the system's sensitivity for detecting CSMO was 58.33% 'per eye' examined, and 81.82% 'per patient' examined using a cut-off volumetric index of 1.8. In our study eyes with 6/9 or better vision, we found a 21% prevalence of CSMO. The predictive values of a positive test were 38.89% and 45% (cut-off score 1.8, 'per eye' and 'per patient' respectively) for CSMO. The predictive values of a negative test were 86.84% and 90.48% (cut-off score 1.8, 'per eye' and 'per patient' respectively) for CSMO.


CONCLUSIONS
The volumetric assessment of diabetic maculopathy by HRT is a potentially useful method for screening eyes at risk. A larger group of patients with a greater number of eyes with minimal or no maculopathy is required to establish the specificity of this technique.
Zambarakji
H J
HJ
Department of Ophthalmology, Queen's Medical Centre, University Hospital, Nottingham, UK.
Butler
T K
TK
Vernon
S A
SA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000601:surgery; D005260:Female; D006801:Humans; D017075:Laser Coagulation; D008268:Macular Degeneration / Q000175:diagnosis* / Q000601:surgery; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D019721:Ophthalmoscopes; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014054:Tomography / Q000295:instrumentation*; D015351:Vision Screening / Q000295:instrumentation; D014792:Visual Acuity