Contrast sensitivity function and ocular higher-order wavefront aberrations in normal human eyes.
ABSTRACT To investigate the relation between contrast sensitivity function and ocular higher-order wavefront aberrations in normal human eyes.
Prospective observational case series.
Three hundred seven eyes of 161 normal subjects, ranging in age from 15 to 60 years (30.9+/-8.0 [mean +/- standard deviation]).
Ocular higher-order aberrations were measured for a 4-mm pupil using the Hartmann-Shack wavefront analyzer. The root-mean-square of the third- and fourth-order Zernike coefficients was used to represent comalike and spherical-like aberrations, respectively. We measured contrast sensitivity, low-contrast visual acuity (VA), and letter contrast sensitivity. From the contrast sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated. Pupil diameter in a photopic condition was recorded using a digital camera.
Multiple linear regression analysis revealed that comalike aberration (P = 0.002) was significantly associated with AULCSF, but spherical-like aberration (P = 0.200), age (P = 0.185), and photopic pupil diameter (P=0.252) were not. Comalike aberration showed a significant correlation with low-contrast VA (P<0.001), but spherical-like aberration (P = 0.293), age (P = 0.266), and pupil diameter (P = 0.756) did not. Comalike aberration was found to be significantly associated with letter contrast sensitivity (P<0.001), but spherical-like aberration (P=0.082), age (P = 0.370), and pupil diameter (P = 0.160) were not.
In normal human eyes, comalike aberration of the eye significantly influences contrast sensitivity function.
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ABSTRACT: To evaluate a digital photography method of pupil size estimation over a broad range of illumination conditions and to compare this method with common clinical techniques. College of Optometry, Ohio State University, Columbus, Ohio, USA. Two examiners measured the pupil diameter in 45 right eyes at 3 illumination levels: <0.63 lux (dark), 5 lux (dim), and 1000 lux (bright). Estimation by infrared video recording, the reference standard, was compared with measurements by digital photography, ruler, semicircular templates, and the Colvard pupillometer. Masked graders measured pupil size from infrared video recordings and digital photographs. The repeatability of the measurement method determined by the mean intraclass correlation coefficients was highest for video recording across conditions (0.86-0.97), followed by digital photography (0.76-0.94), Colvard pupillometry (0.63-0.82), ruler (0.71-0.85), and templates (0.70-0.83). An analysis of variance showed a significant difference in pupil size by method (P<.001). All methods except digital photography estimated smaller pupil sizes under dark and dim illumination than infrared video measurements (all P<.01). Under bright illumination, the ruler measurements were significantly smaller (-0.15 mm) and the Colvard pupillometer measurements were greater (+0.30 mm) than the reference (P<.01). The 95% limits of agreement (LoA) between examiners were smallest for video measurements at all light levels. The remaining measures ranked from best to worst by 95% LoA were digital photography, Colvard pupillometry, ruler, and templates. Estimation of pupil size by digital photography was more repeatable and accurate than estimates by common clinical techniques over a wide range of illumination. Although not as quick as other methods, digital photography is relatively inexpensive, permits lasting documentation, and allows independent grading suitable for clinical research purposes.Journal of Cataract [?] Refractive Surgery 02/2004; 30(2):381-9. · 2.53 Impact Factor
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ABSTRACT: To investigate whether corneal wavefront aberrations vary with aging. One hundred two eyes of 102 normal subjects were evaluated with videokeratography. The data were decomposed using Taylor and Zernike polynomials to calculate the monochromatic aberrations of the cornea for both small (3-mm) and large (7-mm) pupils. For a 3-mm pupil, the amount of total aberrations (Spearman rank correlation coefficient r(s) = 0.145; P = 0.103) and spherical-like aberrations (r(s) = -0.068; P = 0.448) did not change with aging, whereas comalike aberrations exhibited a weak but statistically significant correlation with age (r(s) = 0.256; P = 0.004). For a 7-mm pupil, total aberrations (r(s) = 0.552; P < 0.001) and comalike aberrations (r(s) = 0.561; P < 0.001) significantly increased with aging, but spherical-like aberrations showed no age-related changes (r(s) = 0.124; P = 0.166). Simulated pupillary dilation from 3 mm to 7 mm caused a 38.0+/-28.5-fold increase in the total aberrations, and the extent of increases significantly correlated with age (r(s) = 0.354; P < 0.001). Pupillary dilation influenced the comalike aberrations more in the older subjects than in the younger subjects (r(s) = 0.243; P = 0.006), but such age dependence was not found for spherical-like aberrations (r(s) = 0.141; P = 0.115). Comalike aberrations of the cornea correlate with age, implying that the corneas become less symmetrical along with aging. Spherical-like aberrations do not vary significantly with aging. Pupillary dilation markedly increases wavefront aberrations, and those effects are more prominent in older subjects than in younger subjects.Investigative Ophthalmology & Visual Science 06/1999; 40(7):1351-5. · 3.44 Impact Factor
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ABSTRACT: Refractive surgery induces optically abrupt changes in shape in the midperiphery of the cornea. The abruptness of this change is in part dependent on the magnitude of the surgically induced refractive change. Therefore, the optical aberrations of the cornea, as quantified by wavefront variance (WFV), may be expected to increase as the surgically induced change in the refraction increases. It is the purpose of this study to test the hypothesis that as the surgery-induced change in refraction increases, so does the WFV of the cornea. Fourteen radial keratotomy (RK) patients and seven normal patients served as subjects. Measurements were made before and 2 years after RK surgery. To quantify the WFV of the cornea, we used corneal topography measurements to calculate the surgically induced change in corneal WFV with respect to two different reference surfaces, a sphere and the presurgical cornea. To quantify the surgically induced change in the equivalent spherical correction (ESC), cycloplegic refractions were performed. The measurements were summarized by regressing the surgically induced change in the WFV against the surgically induced change in the ESC. For large pupils (7 mm diameter), the correlation between the change in the WFV referenced to a sphere and the change in the ESC was significant (p < 0.0001, r2 = 0.745) and dominated by fourth order aberrations. Similar results were found for the surgical lens. For small pupils (3 mm diameter), the effects were markedly reduced. (1) As the magnitude of the surgically induced refractive change increases so does the WFV of the cornea, particularly for large pupils. (2) The increase in corneal WFV for large pupils is dominated by fourth order aberrations. (3) The increase in corneal WFV is consistent with reported decreases in visual function (contrast sensitivity and low contrast visual acuity), particularly for large pupil diameters in combination with large surgically induced changes in refractive error.Optometry and Vision Science 10/1996; 73(9):585-9. · 1.90 Impact Factor