Abstract
Purpose :
Autorefractors typically measure over a limited range of visual field angles. Retinal imaging, particularly ultra-widefield (UWF) imaging, has demonstrated utility in visualizing the periphery. UWF slit-scanning ophthalmoscopes can measure peripheral refraction over a wider field of view (FOV) and are faster and easier to use than open-field autorefractors. A prospective study was performed to examine UWF imaging feasibility to extend peripheral refraction measurement range to a full 130°.
Methods :
A modified widefield slit-scanning ophthalmoscope (CLARUS™ 500, ZEISS, Dublin, CA) with prototype software was used to test 5 subjects with spherical equivalent refractions ranging from -12.25D to 0.00D. In order to capture overlapping 90° fields, images were acquired with the internal fixation at central position, and then with ±20° offsets along each meridian. The vertical component of refraction over the full FOV was determined from the slit-scan data. Fundus features were used to co-register and merge the fields, resulting in a 130° peripheral refraction map.
Results :
An extended view of UWF peripheral refraction was obtained for emmetropic and myopic subjects. In Fig 1, a sample UWF absolute peripheral refraction map is shown. In Fig 2, relative peripheral refraction along the full nasal/temporal and superior/inferior meridians is displayed. These measures were computed from an average of 1° strip for each subject. Most myopic subjects show characteristic relative peripheral hyperopia along the nasal/temporal meridian and relative myopia along the superior/inferior meridian. Lid/lash artifacts prevented a full range of measurements in superior/inferior regions.
Conclusions :
This study demonstrated a capability of providing data on an unprecedented FOV. Peripheral refraction measurements acquired on myopic eyes followed established trends. Consistent with literature, this study showed hyperopia increases more in the nasal/temporal field than in the superior/inferior field. This measurement technique could be useful for enhancing research in the field of myopia.
This is a 2021 ARVO Annual Meeting abstract.