Abstract
PurposeTo explore the relationship between ablation parameters of myopic laser surgery and measurement area of wavefront aberration (WA) with Hartmann-Shack wavefront sensor.Methods58 subjects undergone myopic laser surgeries and 74 uncorrected myopic subjects were enrolled in this experiment. The laser ablation parameters were obtained from surgical records, which included spherical error (Rx), depth, and optical zone (OZ) of ablation. The measured area of WA was tested by the WASCA, and the real pupil size was tested by Pentacam. The corneal eccentricity (E value) and curvature was also measured with the Pentacam. All the measurements were performed under mydriatic condition.ResultsFor uncorrected myopic eyes, the measured area of WA was similar with the real pupil size. But for the corrected eyes, the measured area of WA was smaller than the real pupil size with a mean difference of 0.66 ± 0.54 mm for moderate myopia (t = 6.45, p < 0.0001) and 1.76 ± 0.55 mm for high myopia (t = 18.92, p < 0.0001), but not for mild myopia. The Rx (t = -3.20, p = 0.0017), OZ (t = 64.4, p < 0.0001) and postoperative corneal E value (t = 2.52, p = 0.017) were the independent factors of measured area of WA. Measured area of WA = -0.81*Rx + 1.13*OZ + 0.49*postoperative corneal E value (r2 = 0.997).ConclusionsThe WASCA has a limitation in measuring wavefront aberration over the whole pupil area when it’s used for patients received myopic laser surgery. The measured area is smaller than the real pupil size and depends linearly on ablation depth, optical zone and corneal eccentricity.
Highlights
Wavefront aberrometry has been widely used in both optometry and ophthalmology areas since the modern version of wavefront sensor was introduced into eye research about 20 years ago[1,2]
For the corrected eyes, the measured area of wavefront aberration (WA) was smaller than the real pupil size with a mean difference of 0.66 ± 0.54 mm for moderate myopia (t = 6.45, p < 0.0001) and 1.76 ± 0.55 mm for high myopia (t = 18.92, p < 0.0001), but not for mild myopia
The WASCA has a limitation in measuring wavefront aberration over the whole pupil area when it’s used for patients received myopic laser surgery
Summary
Wavefront aberrometry has been widely used in both optometry and ophthalmology areas since the modern version of wavefront sensor was introduced into eye research about 20 years ago[1,2]. The newly developed wavefront sensor provides capability to assess higher order aberrations of the eye, in addition to the lower order spherical error and astigmatism as measured with conventional refractometry[3,4]. Hartmann-Shack wavefront sensor perhaps is the most widely used technique in clinical offices, due to its fast speed of measurement. The lenslet is optically conjugated with the entrance pupil of the eye, and its function is to sample the whole area of the pupil for the light beam reflected back from a retinal point light source, which was first optically projected onto the retina. The positions of the small image spots are used to analyze the wavefront aberrations of the eye, because deviations of the image spots from their ideal positions are directly proportional to wavefront error of the eye at the corresponding pupil area sampled by the microlenses. It is always desired that the whole pupil area could be sampled so that the wavefront aberrations within the whole pupil area could be measured
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