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Takahiro Kiuchi

Bio: Takahiro Kiuchi is an academic researcher from University of Tsukuba. The author has contributed to research in topics: Cornea & Keratomileusis. The author has an hindex of 16, co-authored 33 publications receiving 1198 citations.

Papers
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Journal ArticleDOI
TL;DR: Conventional LASIK significantly increases ocular higher-order aberrations, which compromise the postoperative contrast sensitivity function, and induced changes in AULCSF showed significant correlations with changes in total higher- order (Pearson r=-0.221, P=0.003), coma-like (r-0.201, P =0.007), and spherical-like
Abstract: 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. (Invest Ophthalmol Vis Sci. 2004; 45:3986 –3990) DOI:10.1167/iovs.04-0629

235 citations

Journal ArticleDOI
TL;DR: In post-LASIK eyes, Orbscan II scanning slit topography significantly underestimated corneal thickness, and non-contact specular microscopy gave smaller thickness readings than ultrasonic pachymetry, but these two units showed an excellent linear correlation.
Abstract: Aims: To compare central corneal thickness measurements of three pachymetry devices in eyes after laser in situ keratomileusis (LASIK). Methods: Central corneal thickness was measured in 203 eyes after myopic LASIK. Orbscan II scanning slit topography (Bausch & Lomb), SP-2000P non-contact specular microscopy (Topcon), and ultrasonic pachymetry (Tomey) were used in this sequence. Results: Three devices gave significantly different corneal thickness readings (p r = 0.912, p r = 0.968, p r = 0.933, p Conclusion: In post-LASIK eyes, Orbscan II scanning slit topography significantly underestimated corneal thickness. Non-contact specular microscopy gave smaller thickness readings than ultrasonic pachymetry, but these two units showed an excellent linear correlation.

124 citations

Journal ArticleDOI
TL;DR: The progression of visual field damage in NTG is associated with IOP in the supine position and the magnitude of IOP elevation accompanying postural changes, and results suggest that deterioration inNTG may occur when patients are lying flat during sleep.

104 citations

Journal ArticleDOI
TL;DR: The successful blebs exhibited a large internal fluid-filled cavity, an extensive hyporeflective area, and thicker bleb walls with more microcysts, and the 3-D volume of the intrableb cavity was calculated using3-D CAS OCT.

95 citations

Journal ArticleDOI
TL;DR: Both PRK and LASIK significantly compromised corneal sensation, increased epithelial barrier function, reduced tear secretion, and deteriorated tear film stability (P < .05, Wilcoxon signed-rank test).

91 citations


Cited by
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Journal ArticleDOI
TL;DR: Corneal hysteresis and corneal resistance factor values were significantly lower in keratoconic eyes than in post‐LASIK eyes, and future work is needed to determine whether these differences are useful in detecting keratoconus when other diagnostic tests are equivocal.
Abstract: Purpose To compare the biomechanical properties of normal, post-laser in situ keratomileusis (LASIK), and keratoconic corneas evaluated by corneal hysteresis and the corneal resistance factor measured with the Reichert Ocular Response Analyzer (ORA). Settings Instituto Oftalmologico de Alicante, Vissum, Alicante, Spain. Methods Two hundred fifty eyes were divided into 3 groups: normal (control group), post-LASIK, and keratoconus. The corneal biomechanical properties were measured with the ORA, which uses a dynamic bidirectional applanation process. The main outcome measures were intraocular pressure, corneal hysteresis, and the corneal resistance factor. Results The control group had 165 eyes; the LASIK group, 65 eyes; and the keratoconus group, 21 eyes. In the control group, the mean corneal hysteresis value was 10.8 mm Hg ± 1.5 (SD) and the mean corneal resistance factor, 11.0 ± 1.6 mm Hg. The corneal hysteresis value was lower in older eyes, and the difference between the youngest age group (9 to 14 years) and oldest age group (60 to 80 years) was statistically significant ( P = .01, t test). One month after LASIK, corneal hysteresis and the corneal resistance factor decreased significantly, from 10.44 to 9.3 mm Hg and from 10.07 to 8.13 mm Hg, respectively. In the keratoconus group, the mean corneal hysteresis was 7.5 ± 1.2 mm Hg and the mean corneal resistance factor, 6.2 ± 1.9 mm Hg. There were statistically significant differences in both biomechanical parameters between keratoconic eyes and post-LASIK eyes ( P t test). Conclusions The corneal hysteresis and corneal resistance factor values were significantly lower in keratoconic eyes than in post-LASIK eyes. Future work is needed to determine whether these differences are useful in detecting keratoconus when other diagnostic tests are equivocal.

410 citations

01 Jan 1993
TL;DR: The research indicates that fluent reading rates can be attained with a restricted field of view, as little as four characters, however, attainment of fluent reading levels requires that print size and contrast should be several times threshold and the diameter of a central scotoma should be less than 22°.
Abstract: We have applied research on the visual psychophysics of reading to low vision assessment. Research on different aspects of the reading process found that reading rate rather than reading comprehension is more sensitive to variations in a subject’s visual functioning or the stimulus properties of print. The research identified four different visual factors that significantly affect reading rate: (1) acuity reserve [print size relative to acuity threshold], (2) contrast reserve [print contrast relative to contrast threshold], (3) field of view [number of letters visible], and (4) in cases of maculopathy, central scotoma size. Our research indicates that fluent reading rates can be attained with a restricted field of view, as little as four characters. However, attainment of fluent reading levels requires that print size and contrast should be several times threshold and the diameter of a central scotoma should be less than 22°. Although important clinical studies are lacking, we derived specific visual requirements for different reading rates from published experimental research to provide a starting point and to illustrate how visual requirements could be derived, even with poor correlations. Research has made significant progress toward the development of a comprehensive low vision assessment that will allow the practitioner to identify visual impediments to reading, other than reduced visual acuity. Having more fully characterized a visual impairment, the practitioner may tailor devices or interventions to the individual’s needs and capabilities.

349 citations

Journal ArticleDOI
TL;DR: The fundamental limitations and advantages of time-domain and Fourier-domain interferometric detection methods are discussed, and new perspectives on functional imaging with the use of state-of-the-art high-speed OCT technology are demonstrated.
Abstract: In the past decade we have observed a rapid development of ultrahigh-speed optical coherence tomography (OCT) instruments, which currently enable performing cross-sectional in vivo imaging of biological samples with speeds of more than 100,000 A-scans/s. This progress in OCT technology has been achieved by the development of Fourier-domain detection techniques. Introduction of high-speed imaging capabilities lifts the primary limitation of early OCT technology by giving access to in vivo three-dimensional volumetric reconstructions on large scales within reasonable time constraints. As result, novel tools can be created that add new perspective for existing OCT applications and open new fields of research in biomedical imaging. Especially promising is the capability of performing functional imaging, which shows a potential to enable the differentiation of tissue pathologies via metabolic properties or functional responses. In this contribution the fundamental limitations and advantages of time-domain and Fourier-domain interferometric detection methods are discussed. Additionally the progress of high-speed OCT instruments and their impact on imaging applications is reviewed. Finally new perspectives on functional imaging with the use of state-of-the-art high-speed OCT technology are demonstrated.

345 citations

Journal ArticleDOI
TL;DR: Evidence-based treatment of neurotrophic corneal diseases includes using neuroregenerative (blood component-based and neurotrophic factors), neuroprotective, and ensconcing (bandage contact lens and amniotic membrane) strategies and avoiding anti-inflammatory therapies, such as cyclosporine and corticosteroids.

339 citations

Journal ArticleDOI
TL;DR: Intacranial pressure may play an important role in the development of POAG and NTG and in preventing the progression of OHT toPOAG and in protecting against the pathogenesis of glaucoma.
Abstract: PURPOSE To compare intracranial pressure (ICP) in subjects with primary open-angle glaucoma (POAG), normal-tension glaucoma (NTG; subset of POAG), and ocular hypertension (OHT) with that in subjects with no glaucoma.

331 citations