Abstract
Purpose::
Optical coherence tomography (OCT) is a sensitive tool to detect small thickness and volume changes of the macula. However, the physiologically occurring symmetry of foveal thickness and macular volumetric measurements is unknown. Therefore, we aimed to find the cutoff point for normal symmetry of OCT measurements in the macula.
Methods::
48 healthy volunteers participated in the study (mean age: 41 years, 21-90 years). Standard macular mapping was performed in a radial line pattern followed by macular map analysis by StratusOCT (Carl Zeiss Meditec, Dublin, CA, USA) in both eyes. Central foveal thickness (FT) and macular volume were recorded with a diameter of 3,45 mm and 6,0 mm (MV3 and MV6, respectively), and the difference between the two eyes was calculated. Statistical analysis was performed by Statistica 6.0 software (Statsoft Inc., Tusla, OK, USA). The cutoff point for normal symmetry was determined as mean difference+2SD.
Results::
The difference in FT between two eyes was 7,15±6,19 µm (mean±SD), while the differences for MV3 and MV6 were 0,039±0,043 mm3 and 0,095±0,08 mm3, respectively (mean±SD). There was a significant negative correlation between age and both MV3 and MV6 (p<0,05, r=-0,23 and p<0,001, r=-0,41, respectively) while FT was not correlated with age.
Conclusions::
We could demonstrate that macular thickness and volume data obtained by StratusOCT show a high degree of symmetry. According to our data, the cutoff point for FT difference among two eyes is 19,53 µm, while the cutoff points for MV3 and MV6 difference are 0,105 mm3 and 0,255 mm3, respectively. We also showed that macular volume decreases with age, which is most probably because of apoptosis occurring in the retina. Our results may help to improve the detection of early macular changes as assessed by StratusOCT.
Keywords: macula/fovea • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina