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Yoko Hirohara

Publications and source records attributed to Yoko Hirohara.

15 recordsLinked to original sources
PubMed2004

Age-related changes in ocular and corneal aberrations.

PURPOSE: To compare the ocular and corneal higher-order aberrations (HA) in eyes of different ages. DESIGN: Observational cross-sectional study. METHODS: Sixty-six eyes of 66 normal subjects (age range 4-69 years; average 37.4 +/- 15.4 years) were examined. Wavefront aberrations of the whole eye (ocular) and cornea were measured for the central 4 mm using a Hartmann-Shack aberrometer. RESULTS: Ocular Coma-like aberration (r = 0.270, P =.029), Spherical-like aberration (r = 0.531, P =.001), and total HA(r = 0.431, P =.001) were significantly correlated with age, whereas the corneal aberrations were not significantly correlated. The ocular total HA aberrations increased significantly after age 50 years. CONCLUSIONS: After 50 years of age, ocular aberrations increased abruptly due to the increase of lenticular HA. Customized ablation should be carefully considered, especially in eyes of presbyopic age.

Adolescent↗
PubMed2004

Influence of wavefront aberration and corneal subepithelial haze on low-contrast visual acuity after photorefractive keratectomy.

PURPOSE: To assess low-contrast visual acuity (LCVA) after photorefractive keratectomy in relation to ocular higher-order wavefront aberration and corneal subepithelial haze. DESIGN: Prospective, cross-sectional analysis. METHODS: Photorefractive keratectomy was performed in 51 eyes of 27 subjects with myopic refractive error of -2.0 to -10.5 diopters. Ocular higher-order wavefront aberrations for a 4-mm pupil were measured using Topcon Hartmann-Shack wavefront aberrometer, and the extent of corneal subepithelial haze was quantified with Nidek TSPC-3 hazemeter before and 1 month after photorefractive keratectomy. Low-contrast visual acuity was recorded with Vector Vision CSV-1000LanC10% chart. Total higher-order, third-order (coma-like), and fourth-order (spherical-like) aberrations of the eye were determined. The influence of wavefront aberration and corneal subepithelial haze on LCVA was analyzed. RESULTS: Total higher-order, third-order, and fourth-order aberrations significantly increased by surgery (P < .001, Wilcoxon signed rank test). Photorefractive keratectomy induced a significant increase in corneal haze (P < .01), but no case presented severe corneal haze (grade 3 or greater by Fantes grading). By surgery, LCVA was reduced significantly (P < .001). The logarithm of the minimal angle of resolution LCVA showed a significant correlation with total higher-order aberration (Spearman rank correlation coefficient, r(s) = 0.642, P < .0001). Both third-order (r(s) = 0.618, P < .0001) and fourth-order aberrations (r(s) = 0.552, P < .0001) also significantly correlated with logarithm of the minimal angle of resolution LCVA. There was no correlation between the degree of corneal haze and logarithm of the minimal angle of resolution LCVA (r(s) = 0.094, P = .523). CONCLUSIONS: In eyes with mild to moderate corneal haze after photorefractive keratectomy, deterioration of LCVA is mainly attributable to increases in wavefront aberration, and not to corneal haze.

Adolescent↗
PubMed2004

Light scattering and optical aberrations as objective parameters to predict visual deterioration in eyes with cataracts.

PURPOSE: To predict the visual deterioration of eyes with cortical (CC) or nuclear (NC) cataract from objective data on ocular higher-order aberration (HOA) and forward (FLS) and backward light scattering (BLS). SETTING: Osaka University Medical School, Osaka, Japan. METHODS: Twenty-two eyes with mild NC, 41 eyes with mild CC, and 11 normal eyes were examined. Higher-order aberrations were calculated with the Zernike polynomials up to the fourth order from the values obtained by wavefront analysis using the Hartmann-Shack aberrometer. Forward light scattering was calculated from the size of the aberrometer spot images for the central 4 mm, and backward light scattering (BLS) was calculated from the optical density of the Scheimpflug images. The relationship between the area under the log contrast sensitivity function (AULCSF) curve and HOAs, FLS, and BLS was examined. RESULTS: Area under the log contrast sensitivity function was moderately correlated with the HOAs, FLS, and BLS. Multiple linear regression analysis revealed that the AULCSF was predicted by the linear combination of these variables (R(2)=.484, P<.001). Area under the log contrast sensitivity was predicted by BLS and HOA (R(2)=.555) in the NC group and by FLS and HOAs (R(2)=.540) in the CC group. CONCLUSIONS: Loss of contrast sensitivity was predominantly due to BLS and HOA in eyes with NC and FLS and HOA in eyes with CC. Higher-order aberrations, FLS, and BLS, variables that are obtained objectively, can be used to predict quantitatively the visual deterioration in cataractous eyes.

Adult↗
PubMed2004

Wavefront analysis of an eye with monocular triplopia and nuclear cataract.

PURPOSE: To determine whether higher-order aberrations explain patient-reported monocular triplopia. DESIGN: Observational case report. METHOD: A patient complaining of monocular triplopia was examined with a Hartmann-Shack aberrometer to determine whether higher-order wavefront aberrations could account for the triplopia. The patient had a mild nuclear cataract; measurements were made before and after lensectomy. The retinal image was simulated using the Zernike polynomials. RESULT: Spherical aberration (-0.18 microm, 4 mm pupil) and trefoil aberration (-0.16 microm) were increased. The simulated retinal image had a triple configuration similar to the subjective image reported by the patient. After cataract surgery, the subjective triplopia disappeared; spherical, and trefoil aberrations were markedly decreased. CONCLUSION: The monocular triplopia probably stemmed from combined effects of spherical and trefoil aberrations caused by the nuclear cataract.

Adult↗
PubMed2004

Ocular higher-order aberrations and contrast sensitivity after conventional laser in situ keratomileusis.

PURPOSE: To investigate prospectively the relation between induced changes in higher-order aberrations of the eye and changes in contrast sensitivity by conventional laser in situ keratomileusis (LASIK) for myopia. METHODS: In 200 eyes of 110 consecutive patients (mean age, 32.7 +/- 8.4 years) undergoing LASIK, ocular aberrations and contrast sensitivity function were determined before and 1 month after surgery. The amount of myopic correction was 5.2 +/- 2.8 D (range, 1.0-13.0). Ocular higher-order aberrations were measured for a 4-mm pupil using the Hartmann-Shack wavefront analyzer (KR-9000PW; Topcon, Tokyo, Japan). The root mean square (RMS) of the third- and fourth-order Zernike coefficients was used to represent coma- and spherical-like aberrations, respectively. Total higher-order aberrations were calculated as the RMS of the third- and fourth-order coefficients. Contrast sensitivity and low-contrast visual acuity were measured. From the contrast sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated. RESULTS: LASIK significantly improved logMAR best corrected visual acuity (Wilcoxon signed-rank test, P <0.001), but significantly reduced AULCSF (P <0.001) and low-contrast visual acuity (P=0.007). Total higher-order (P <0.001), coma-like (P <0.001), and spherical-like (P <0.001) aberrations were significantly increased after LASIK. The greater the amount of achieved myopia correction was, the more the changes in contrast sensitivity function and ocular higher-order aberrations were. The induced changes in AULCSF by LASIK showed significant correlations with changes in total higher-order (Pearson r=-0.221, P=0.003), coma-like (r=-0.205, P=0.006), and spherical-like (r=-0.171, P=0.022) aberrations. The changes in logMAR low-contrast visual acuity by surgery significantly correlated with changes in total higher-order (r=0.222, P=0.003), coma-like (r=0.201, P=0.007), and spherical-like (r=0.207, P=0.005) aberrations. CONCLUSIONS: Conventional LASIK significantly increases ocular higher-order aberrations, which compromise the postoperative contrast sensitivity function.

Adolescent↗
PubMed2003

Wavefront analysis in eyes with accommodative spasm.

PURPOSE: To investigate changes of spherical aberration in eyes with accommodative spasm. DESIGN: Case reports. METHODS: Four eyes of two patients with accommodative spasm were studied. Ocular spherical aberration was measured with a Hartmann-Shack wavefront aberrometer for the central 4-mm zone. RESULTS: The root mean square values of spherical aberration were negative (-0.086 +/- 0.026 microm root mean square). However, when the spasm of accommodation was cured or treated with a cycloplegic agent, the value shifted toward positivity (0.025 +/- 0.004 microm root mean square). CONCLUSIONS: Excessive accommodative tone is manifested objectively by negative spherical aberration in eyes with accommodative spasm.

Accommodation, Ocular↗
PubMed2002

Effect of tear film break-up on higher-order aberrations measured with wavefront sensor.

PURPOSE: To investigate whether optical wavefront aberrations vary with tear film break-up. DESIGN: Observational case series. METHODS: Higher-order aberrations were examined for 20 eyes of 20 normal subjects with a Hartmann-Shack wavefront sensor before and after tear film break-up. RESULTS: Higher-order aberrations for photopic vision (central 4 mm diameter) after tear film break-up increased 1.44 fold compared to higher-order aberrations before tear film break-up (P =.001, paired t-test). Higher-order aberrations after tear film break-up for scotopic vision (central 6 mm diameter) were also 1.23 times higher than those before break-up (P =.005, paired t-test). CONCLUSION: Wavefront sensing enabled us to evaluate the induced irregular astigmatism caused by tear film break-up quantitatively. Wavefront aberrations should be measured carefully to avoid the effects of tear film break-up, especially in wavefront-guided refractive surgery.

Adult↗
PubMed2002

Changes of ocular aberration with accommodation.

PURPOSE: To study the effect of accommodation on ocular aberrations. DESIGN: Observational case series. METHODS: The ocular aberrations in 33 eyes of 33 young adults were measured with a Hartmann-Shack wavefront aberrometer before and during 3 diopters of accommodation. RESULTS: The root mean square values of wavefront error did not change for a 4-mm and a 6-mm zone; however, spherical aberration changed significantly toward negativity for both the 4-mm zone (P <.001) and 6-mm zone (P =.022). CONCLUSIONS: During accommodation, the significant change in spherical aberration occurs without a change of image quality. Therefore, for customized aberration, it may not be advantageous to eliminate the physiologic spherical aberration for far vision.

Accommodation, Ocular↗
PubMed2002

Higher order wavefront aberrations of cornea and magnitude of refractive correction in laser in situ keratomileusis.

OBJECTIVE: To assess the relation between magnitude of refractive correction and changes in higher order wavefront aberrations of the cornea after laser in situ keratomileusis. DESIGN: Prospective, consecutive, nonrandomized comparative trial (self-controlled). PARTICIPANTS: One hundred eyes of 53 patients with myopia (-2.0 to -13.0 diopters) were included. INTERVENTION: Laser in situ keratomileusis was performed. Videokeratography measurements were conducted before and 1 month after surgery. MAIN OUTCOME MEASURES: The videokeratography data were used to calculate the higher order wavefront aberrations of the cornea for both small (3 mm) and large (6 mm) pupils. RESULTS: For a 3-mm pupil, the surgery significantly increased coma-like (2.4 +/- 1.3-fold, P < 0.001, paired t test) and spherical-like (1.8 +/- 0.9-fold, P < 0.001) aberrations. For a 6-mm pupil, both coma-like (4.4 +/- 3.3-fold, P < 0.001) and spherical-like (9.4 +/- 5.2-fold, P < 0.001) aberrations were significantly increased by surgery. The amount of achieved correction showed significant correlations with the changes in coma-like (Pearson correlation coefficient r = 0.446, P < 0.001) and spherical-like (r = 0.348, P < 0.001) aberrations for a 3-mm pupil, and coma-like (r = 0.566, P < 0.001) and spherical-like (r = 0.693, P < 0.001) aberrations for a 6-mm pupil. The eyes that lost 2 or more lines of baseline spectacle-corrected visual acuity showed significantly larger induced increases in coma-like (P = 0.003, Mann-Whitney U test) and spherical-like (P = 0.009) aberrations for a 3-mm pupil than those that either improved or remained within 1 line of spectacle-corrected visual acuity CONCLUSIONS: Laser in situ keratomileusis, performed using the current algorithms, increases higher order wavefront aberrations of the cornea, dependent on the amount of refractive correction.

Adult↗
PubMed2002

Wavefront aberrations measured with Hartmann-Shack sensor in patients with keratoconus.

OBJECTIVE: To compare the ocular wavefront aberrations of normal and keratoconic eyes and to describe the characteristics of the higher-order aberrations in eyes with keratoconus. DESIGN: Prospective case control and observational study. PARTICIPANTS: Thirty-five keratoconic eyes and thirty-eight normal controls. METHODS: Higher-order aberrations in refraction were measured with a wavefront sensor, and those aberrations resulting from the cornea were evaluated by videokeratographic data. MAIN OUTCOME MEASURES: Coma-like (S(3 + 5)), spherical-like (S(4 + 6)), and total (S(3 + 4 + 5 + 6)) higher-order aberrations in both refraction and the cornea. RESULTS: The mean +/- standard deviation of S(3 + 5) (1.88 +/- 1.16), S(4 + 6) (0.70 +/- 0.55), and S(3 + 4 + 5 + 6) (2.03 +/- 1.23) in refraction (6-mm diameter, root mean square, micro m) were significantly higher in the keratoconic eyes than in normal controls (0.26 +/- 0.10, 0.19 +/- 0.10, 0.34 +/- 0.11, respectively; Mann-Whitney U test, P = 0.001). Coma-like aberrations were 2.32 times larger than spherical-like aberrations in keratoconic eyes. CONCLUSIONS: The increase of ocular higher-order aberrations in keratoconic eyes results from an increase of corneal higher-order aberrations. Coma-like aberrations were dominant compared with spherical-like aberrations in keratoconic eyes. Wavefront sensing will enable us not only to evaluate the quality of vision but also to differentiate keratoconic eyes from normal eyes by analyzing the characteristics of the higher-order aberrations.

Adult↗
PubMed2002

Wavefront analysis of higher-order aberrations in patients with cataract.

PURPOSE: To determine local refractive changes and higher-order aberrations in patients with nuclear or cortical cataract. SETTING: Osaka University Medical School, Osaka, Japan. METHODS: Wavefront analysis of both ocular and corneal aberrations was performed with the Hartmann-Shack aberrometer in 2 patients, a 22-year-old woman with bilateral developmental nuclear cataract and a 68-year-old woman with mild bilateral cortical cataract. RESULTS: Case 1 showed a delay in the wavefront that caused a myopic shift in the central pupillary area in both eyes, associated with the nuclear cataract. The spherical-like aberration (right eye, 36%; left eye, 21%) was greater than the coma-like aberration in both eyes. Case 2 showed an advancement of the wavefront that caused a hyperopic shift, especially in the lower temporal pupillary area, that was associated with the cortical cataract. The coma-like aberration (right eye, 63%; left eye, 52%) was greater than the spherical-like aberration in both eyes. The polarity of the third-order spherical aberration was negative in Case 1 and positive in Case 2. Corneal higher-order aberrations were small and had a different distribution than ocular higher-order aberrations in both patients. CONCLUSIONS: The Hartmann-Shack aberrometer was useful in detecting local refractive changes and higher-order aberrations in patients with mild cataract. The polarity and the absolute value of ocular higher-order aberrations may be useful parameters to characterize eyes with cataract.

Adult↗
PubMed2002

Apparent accommodation and corneal wavefront aberration in pseudophakic eyes.

PURPOSE: To assess the relationship between apparent accommodation in pseudophakic eyes, multifocal corneal effects, and wavefront aberrations of the cornea. METHODS: In 102 eyes of 86 patients who had undergone phacoemulsification and posterior chamber intraocular lens implantation, the amount of apparent accommodation was measured with an accommodometer. The degree of corneal multifocality was determined on the corneal topography by measuring the maximum and minimum corneal refractive powers within the pupillary area. Wavefront aberrations of the cornea were calculated by expanding the height data of the corneal topography into Zernike polynomials for individual pupil size. The influence of higher-order aberration on the retinal image quality was simulated by computing the point-spread function (PSF) and modulation-transfer function (MTF) from the aberration function. RESULTS: There was a significant positive correlation between the amount of apparent accommodation and corneal multifocality (Pearson correlation coefficient, r = 0.451, P < 0.001). The coma-like aberration showed a significant positive correlation with the amount of apparent accommodation (r = 0.440, P < 0.001), but the spherical-like aberration did not (r = 0.001, P = 0.993). Among the coma-like aberrations, the component representing vertically asymmetrical distribution of corneal refractive power with greater refraction located in the lower part of the eye was most relevant to apparent accommodation. Computer simulation of PSF and MTF indicated that a focus shift of 0.5 D deteriorated the retinal image significantly more in eyes without higher-order aberrations than in eyes with a moderate amount of coma-like aberrations. CONCLUSIONS: Coma-like aberration of the cornea, along with corneal multifocality, contributes to apparent accommodation in pseudophakic eyes.

Accommodation, Ocular↗
PubMedDate not supplied

Progression of pellucid marginal degeneration and higher-order wavefront aberration of the cornea.

PURPOSE: To report the time course of changes in corneal wavefront aberrations in a patient with pellucid marginal degeneration. CASE: A 59-year-old man with pellucid marginal degeneration was followed-up annually with slit-lamp microscopy and videokeratography for 11 years. The anterior corneal height data of the videokeratography were expanded into the set of orthogonal Zernike polynomials to calculate wavefront aberrations for the central 3-mm cornea. OBSERVATIONS: Although the patient complained of gradual deterioration of vision, there was no evident sign of disease progression on slit-lamp examination and visual acuity measurement. Color-coded maps of videokeratography showed slight deterioration over time, but no remarkable and decisive changes were seen. Coma-like aberration displayed a gradual, but apparent increase with a 1.67-fold worsening (0.473 microm to 0.792) during the 11-year follow-up period. Spherical-like aberration remained almost stable throughout the observation period. There were no obvious changes in crystalline lens and retina. CONCLUSIONS: The results suggest that increases in coma-like aberrations of the cornea reflect the subclinical progression of pellucid marginal degeneration over the years.

Corneal Diseases↗
PubMedDate not supplied

Effect of aging on ocular light scatter and higher order aberrations.

PURPOSE: To study the effect of aging on ocular light scatter and higher order aberrations in humans. METHODS: Seventy-six eyes of 76 normal subjects who had refractive errors but no ocular disease were studied. Their age ranged from 4 to 69 years (mean 34.8 +/- 5.8 yr). Both light scatter and total higher order aberrations were simultaneously and quantitatively measured by a Hartmann-Shack sensor for the central 4-mm-diameter pupil. Higher order aberrations were calculated from the Zernike polynomials up to the 4th order. The amount of light scatter was estimated by using the diameter of the point spread functions (PSFs) of the Hartmann images. A correction was made for the effect of the aberrations on the width of the images. Linear regression analysis was performed to investigate the effect of aging on light scatter and total higher order aberrations. RESULTS: A significant correlation was found between scatter and age (Spearman rank correlation coefficient, r = 0.501, P = .001). Also, the total higher order aberrations increased significantly with age (r = 0.323, P = .005). The total higher order aberration and scatter index were not statistically significantly correlated (r = 0.184, P = .112). CONCLUSIONS: These results indicate that scatter was better correlated with age than higher order aberrations.

Adolescent↗