Abstract
Purpose::
To determine the prevalence of tilted optic discs and it relationship with myopic refractive error and axial length in adult Chinese individuals in Singapore
Methods::
This study was a population-based, cross-sectional survey of adult Chinese persons aged 40 to 81 years residing in Tanjong Pagar district, Singapore. Axial ocular dimensions were measured using an A-scan ultrasound device. Noncycloplegic refraction was measured with an auto refractor and further refined subjectively. Colour optic disc stereo photographs were taken with a mydriatic fundus camera. From the disc photographs, maximum, minimum, vertical and horizontal disc diameters were measured. The angle of tilt was also measured and defined as the angle between the maximum disc diameter and the horizontal disc diameter. All measurements were made with the Bersoft Image Measurement software (version 5.0, Buenos Aires, Argentina). Disc ovality was assessed using the ratio of minimum to maximum disc diameter. (Index of tilt) A tilted optic disc was defined as a disc with an index of tilt less than 0.75.
Results::
488 subjects had their optic disc parameters measured, and their mean age was 58.8 +/-11.1 years. The prevalence of tilted optic discs was 2.9%. The mean tilt ratio was 0.881 +/- 0.064. The mean spherical equivalent was -0.39 +/-2.77 dioptres and the mean axial length was 23.14 +/- 1.32 mm. Greater index of tilt correlated with greater myopia (p<0.01) and greater axial length (p<0.01). Tilted discs were present in 20.8% of eyes with myopia compared with 5.9% of eyes with no myopia (p<0.01). Age did not have any significant association with tilt ratio or the prevalence of tilted disc.
Conclusions::
Tilted optic disc was a fairly common finding in the adult Chinese population and was strongly associated with myopia and axial length.
Keywords: optic disc • myopia