Abstract
Purpose :
Ultra-widefield (UWF) retinal imaging has proved useful in diagnosis of disease where visualization of the periphery is vital. A slit-scanning ophthalmoscope can be used to measure peripheral refraction [Everett, et al., IOVS 59.9 (2018): 2148-2148] faster and with more ease-of-use than current commercial systems, such as open-field autorefractors. Peripheral refraction is important in cases of myopia and UWF imaging can provide a suitable way to extend the typical range of measurement. We performed a prospective study in order to investigate the feasibility of the use of UWF imaging to extend the range of measurement of peripheral refraction.
Methods :
Four subjects ranging from -12.25D to -0.50D spherical equivalent were tested on a widefield slit-scanning ophthalmoscope (CLARUS™ 500, ZEISS, Dublin, CA). The internal fixation target was moved to enable data capture over multiple overlapping 90° fields. Prototype software was used to calculate the vertical component of peripheral refraction over each field, co-register the fields based on matching of fundus features, and then merge them together in order to derive peripheral refraction over 130° along the horizontal meridian.
Results :
UWF peripheral refraction measurements provided an extended view of peripheral refraction for emmetropic and myopic subjects. Figure 1 displays an example of UWF absolute peripheral refraction in a myopic eye. Figure 2 shows the relative peripheral refraction along the full horizontal meridian (averaged over a vertical extent of 1°) for each of the four subjects. All curves show the characteristic of relative hyperopia peripherally. Subjects 053 and 243, the most myopic subjects, both show this effect more drastically than the only mildly myopic 298 and 873.
Conclusions :
A slit-scanning ophthalmoscope is capable of providing UWF measurements of peripheral refraction. This method could further the study of myopia development and progression through analyzing effects of refraction in the far periphery.
This is a 2020 Imaging in the Eye Conference abstract.