Abstract
Abstract: :
Purpose: To report on the OCT measurement of foveal thickness and interocular asymmetry in normal individuals. Methods: Prospective, cross–sectional study in two hundred eyes of one hundred normal volunteers. All participants were asked to sign for informed consent. All eyes were scanned using the Fast macular thickness protocol in the OCT–III (Zeiss Meditec) software. Analysis was undertaken in the appropriate area of the Macular thickness map protocol using the full 6mm lines of the scan. Central foveal fixation was checked via manual assessment to achieve equal minimum foveal thickness values for the vertical and horizontal meridians. Scans failing this agreement were repeated. Minimum foveal thickness (MFT), central 1 mm average foveal thickness (AFT) and total macular volume (TMV) of both eyes were assessed. The difference in the thickness and volume between the two eyes, ethnic groups, sex, and age groups were all analysed using the student–t test. Results: Of the 100 participants (200 eyes) 67 were women and 33 men, and the mean age was 38.29 years (SD = 11.78). The mean MFT was 171.75µ (SD = 27.29; 95% confidence interval [CI] = 167.94 –175.55), AFT was 206.79µ (SD = 25.13; 95% CI = 203.29 – 210.30), and TMV was 0.161mm3 (SD= 1.97; 95% CI = 0.159 – 0.164). The mean interocular difference of the AFT was 8.29µ (SD= 8.54; 95% CI= 6.59 – 9.98). There was no statistically significant difference in MFT, AFT and TMV between the two eyes of the normal participants. Conclusions: This is the single largest study reporting the normal parameters of the macular thickness in the UK. There was striking symmetry of the AFT between the eyes of each normal individual. The interocular difference of the AFT was much smaller than the range of AFTs measured across normal individuals. Hence, large differences of the AFT between eyes in patients with macular disease may represent a true derangement from normality.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea