Tetsuro Oshika

Comparison of corneal wavefront aberrations after photorefractive keratectomy and laser in situ keratomileusis.

PURPOSE To compare changes in the corneal wavefront aberrations after photorefractive keratectomy and laser in situ keratomileusis. METHODS In a prospective randomized study, 22 patients with bilateral myopia received photorefractive keratectomy on one eye and laser in situ keratomileusis on the other eye. The procedure assigned to each eye and the sequence of surgery for each patient were randomized. Corneal topography measurements were performed preoperatively, 2 and 6 weeks, 3, 6, and 12 months after surgery. The data were used to calculate the wavefront aberrations of the cornea for both small (3-mm) and large (7-mm) pupils. RESULTS Both photorefractive keratectomy and laser in situ keratomileusis significantly increased the total wavefront aberrations for 3- and 7-mm pupils, and values did not return to the preoperative level throughout the 12-month follow-up period. For a 3-mm pupil, there was no statistically significant difference between photorefractive keratectomy and laser in situ keratomileusis at any postoperative point. For a 7-mm pupil, the post-laser in situ keratomileusis eyes exhibited significantly larger total aberrations than the post-photorefractive keratectomy eyes, where a significant intergroup difference was observed for spherical-like aberration, but not for coma-like aberration. This discrepancy seemed to be attributable to the smaller transition zone of the laser ablation in the laser in situ keratomileusis procedure. Before surgery, simulated pupillary dilation from 3 to 7 mm caused a five- to six-fold increase in the total aberrations. After surgery, the same dilation resulted in a 25- to 32-fold increase in the photorefractive keratectomy group and a 28- to 46-fold increase in the laser in situ keratomileusis group. For a 3-mm pupil, the proportion of coma-like aberration increased after both photorefractive keratectomy and laser in situ keratomileusis. For a 7-mm pupil, coma-like aberration was dominant before surgery, but spherical-like aberration became dominant postoperatively. CONCLUSIONS Both photorefractive keratectomy and laser in situ keratomileusis increase the wavefront aberrations of the cornea and change the relative contribution of coma- and spherical-like aberrations. For a large pupil, laser in situ keratomileusis induces more spherical aberrations than photorefractive keratectomy. This finding could be attributable to the smaller transition zone of the laser ablation in the laser in situ keratomileusis procedure.

Adhesion of lens capsule to intraocular lenses of polymethylmethacrylate, silicone, and acrylic foldable materials: an experimental study

AIMS To investigate the adhesion characteristics of several intraocular lenses (IOLs) to the simulated and rabbit lens capsule. METHODS Adhesive force to bovine collagen sheets was measured in water with polymethylmethacrylate (PMMA), three piece silicone, and acrylic foldable IOLs. In rabbit eyes, phacoemulsification and IOL implantation were performed. Three weeks later, adhesion between the anterior/posterior capsules and IOL optic was tested, and the capsule was examined histologically. RESULTS The mean adhesive force to the collagen sheet was 1697 (SD 286) mg for acrylic foldable, 583 (49) mg for PMMA, and 0 mg for silicone IOLs (p=0.0003, Kruskal–Wallis test). Scores (0–5) of adhesion between rabbit anterior capsule and IOL optic were 4.50 (0.55) for acrylic foldable, 3.20 (0.84) for PMMA, and 0.40 (0.55) for silicone IOLs (p=0.004). Scores between rabbit posterior capsule and IOL optic displayed a similar tendency; 4.50 (0.84) for acrylic foldable, 3.00 (1.00) for PMMA, and 0.40 (0.55) for silicone IOLs (p=0.021). Histological observation indicated that the edge of IOL optic suppressed the migration of lens epithelial cells towards the centre of the posterior capsule. This inhibitory effect was most pronounced with acrylic foldable IOL and least with silicone IOL. CONCLUSIONS The acrylic foldable IOL adhered to the lens capsule more than the PMMA IOL, and the silicone IOL showed no adhesiveness. These differences seem to play a role in preventing lens epithelial cells from migrating and forming posterior capsule opacification.

Two year clinical study of a soft acrylic intraocular lens

Purpose: To assess the efficacy and safety of a soft acrylic intraocular lens (IOL) in small incision cataract surgery. Methods: Sixty‐four eyes of 64 patients (mean age 71.0 ± 7.7 [SD] years) who had phacoemulsification and implantation of a soft acrylic IOL were followed for 2 years. Results: At day 1, 96.9% of patients had corrected visual acuity of 20/40 or better, and 50.0% had 20/20 or better. At 2 years postoperatively, 100% had 20/40 or better, and 86.3% had 20/20. Surgically induced keratometric cylinder remained quite stable throughout the 2 year follow‐up period, with axis‐based astigmatism of ±0.3 diopters. Flare intensity measured with the laser flare‐cell meter was less than that with other type of IOLs measured, including poly(methyl methacrylate) and silicone. Neodymium:YAG laser capsulotomy was performed in seven cases (11.1 %) without causing damage to the optic. No other postoperative complications were encountered. Conclusion: Soft acrylic IOLs have clinically apparent advantages in small incision cataract surgery.

Influence of Overnight Orthokeratology on Axial Elongation in Childhood Myopia

PURPOSE This prospective study was conducted to assess the influence of overnight orthokeratology (OK) on axial elongation in children, with those wearing spectacles as controls. METHODS One hundred five subjects (210 eyes) were enrolled in the study. The OK group comprised 45 patients (90 eyes, age 12.1 ± 2.5 years, mean ± SD; OK group) who matched the inclusion criteria for OK. The control group comprised 60 patients (120 eyes, 11.9 ± 2.0 years) who also matched the inclusion criteria for OK but preferred spectacles for myopia correction. Axial length was measured at baseline and after 2 years using ocular biometry, and the changes were evaluated and compared between the groups. RESULTS Ninety-two subjects (42 and 50 in the OK and control groups, respectively) completed the 2-year follow-up examinations. At baseline, the spherical equivalent refractive error was -2.55 ± 1.82 and -2.59 ± 1.66 D, and the axial length was 24.66 ± 1.11 and 24.79 ± 0.80 mm in the OK and control groups, respectively, with no significant differences between the groups. The increase in axial length during the 2-year study period was 0.39 ± 0.27 and 0.61 ± 0.24 mm, respectively, and the difference was significant (P < 0.0001, unpaired t-test). CONCLUSIONS OK suppressed axial elongation in myopic children, suggesting that this treatment can slow the progression of myopia to a certain extent.

Changes in anterior and posterior corneal curvatures in keratoconus.

OBJECTIVE To quantitatively evaluate the changes in anterior and posterior corneal curvatures of eyes with keratoconus. DESIGN Case-control retrospective and observational study. PARTICIPANTS Thirty-one patients who were clinically diagnosed to have unilateral or bilateral keratoconus and 18 normal subjects. INTERVENTION The anterior and posterior topographies were obtained using scanning-slit videokeratography and assessed by Fourier series harmonic analysis. MAIN OUTCOME MEASURES Quantitative descriptors of the topography data, spherical power, regular astigmatism, and irregular astigmatism (asymmetry and higher order irregularity) components were compared between the anterior and posterior surfaces and among groups of clinically diagnosed keratoconus (33 eyes), keratoconus suspect (13 eyes), and normal subjects (36 eyes). RESULTS Spherical power (P = 0.0003, Mann-Whitney U test with Bonferronis correction of P values), regular astigmatism (P = 0.0166), and asymmetry (P = 0.0031) of the anterior surface were significantly greater in the keratoconus eyes than in the normal controls. For the posterior surface, spherical power (P<0.0001), regular astigmatism (P = 0.0143), asymmetry (P< 0.0001), and higher order irregularity (P = 0.0032) of the keratoconus group were significantly greater than those of the control group. The keratoconus suspect eyes, when compared with the normal controls, showed a significantly greater amount of spherical power (P = 0. 0166) and asymmetry (P<0.0001) in the anterior surface and spherical power (P <0.0001), regular astigmatism (P = 0.0244), asymmetry (P<0.0001), and higher order irregularity (P = 0.0276) in the posterior surface. All refractive components demonstrated statistically significant correlations between the anterior and posterior surfaces (P<0.0001, Spearmans rank correlation). CONCLUSIONS Not only the anterior but also the posterior corneal curvature is affected in keratoconus. These changes are observed from the early stage of this disorder.

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.

Factors affecting the forward shift of posterior corneal surface after laser in situ keratomileusis

PURPOSE To evaluate the anteroposterior movement of the corneal back surface after laser in situ keratomileusis (LASIK). DESIGN Retrospective noncomparative case series. PARTICIPANTS One hundred ninety-six eyes of 120 subjects with myopic refractive errors of -2.0 to -12.5 diopters. INTERVENTION LASIK was performed. Corneal topography of the posterior corneal surface was obtained with the scanning slit topography system before and 1 month after surgery. MAIN OUTCOME MEASURES The amount of forward shift of the posterior corneal surface was determined. Multiple regression analysis was used to assess the factors that affect the forward shift of the posterior corneal surface. RESULTS After surgery, the posterior corneal surface displayed mean forward shift of 40.9 +/- 24.8 micrometer. Explanatory variables relevant to the forward shift of corneal posterior surface were, in the order of magnitude of influence, the amount of laser ablation (partial regression coefficient B = 0.561, P < 0.0001), preoperative corneal thickness (B = -0.176, P = 0.00096), and preoperative intraocular pressure (B = 1.676, P = 0.0053). Preoperative refraction and achieved myopic correction showed collinearity with the amount of laser ablation. CONCLUSIONS LASIK induces a forward shift of the cornea. Eyes with thinner corneas, higher intraocular pressure, and higher myopia requiring greater laser ablation are more predisposed to the anterior shift of the cornea.

Corneal thickness measurements: scanning-slit corneal topography and noncontact specular microscopy versus ultrasonic pachymetry ☆

Purpose: To compare central corneal thickness measurements taken with 3 pachymetry systems: Orbscan scanning‐slit corneal topography/pachymetry, Topcon SP2000P noncontact specular microscopy, and Tomey ultrasonic pachymetry. Setting: Multicenter study, Tokyo, Japan. Methods: In 216 healthy eyes of 114 subjects, scanning‐slit topography, noncontact specular microscopy, and ultrasonic pachymetry were used in that sequence to record central corneal thickness. In another 20 healthy eyes of 13 subjects, 2 sets of measurements were repeated for each pachymetry to assess repeatability. Results: The mean central corneal thickness was compatible between scanning‐slit topography (546.9 &mgr;m ± 35.4 [SD]) and ultrasonic pachymetry (548.1 ± 33.0 &mgr;m); however, noncontact specular microscopy gave a significantly smaller mean (525.3 ± 31.4 &mgr;m) than the other 2 tests (P<.001, Tukey multiple comparison). There were significant linear correlations between scanning‐slit topography and noncontact specular microscopy (r = 0.846, P<.001), noncontact specular microscopy and ultrasonic pachymetry (r = 0.897, P<.001), and ultrasonic pachymetry and scanning‐slit topography (r = 0.852, P<.001). Noncontact specular microscopy tended to show the best repeatability; however, the difference was not statistically significant (P = .663, repeated‐measure analysis of variance). Conclusions: Corneal thickness readings were comparable between scanning‐slit topography and pachymetry; noncontact specular microscopy gave significantly smaller values. The measurements of the 3 methods showed significant linear correlations with one another. All methods provided acceptable repeatability of measurements.

Psychometric properties of the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25), Japanese version.

BackgroundThe importance of evaluating the outcomes of health care from the standpoint of the patient is now widely recognized. The purpose of this study is to develop and test a Japanese version of the National Eye Institute Visual Function Questionnaire (NEI VFQ-25).MethodsA Japanese version was developed with a previously standardized method. The questionnaire and optional items were completed by 245 patients with cataracts, glaucoma, or age-related macular degeneration, by 110 others before and after cataract surgery, and by a reference group (n = 31). We computed rates of missing data, measured reproducibility and internal consistency reliability, and tested for convergent and discriminant validity, concurrent validity, known-groups validity, factor structure, and responsiveness to change.ResultsBased on information from the participants, some items were changed to 2-step items (asking if an activity was done, and if it was done, then asking how difficult it was). The near-vision and distance-vision subscales each had 1 item that was endorsed by very few participants, so these items were replaced with items that were optional in the English version. For example, more than 60% of participants did not drive, so the driving question was excluded. Reliability and validity were adequate for all subscales except driving, ocular pain, color vision, and peripheral vision. With cataract surgery, most scores improved by at least 20 points.ConclusionWith minor modifications from the English version, the Japanese NEI VFQ-25 can give reliable, valid, responsive data on vision-related quality of life, for group-level comparisons or for tracking therapeutic outcomes.

Wavefront Analysis in Eyes With Nuclear or Cortical Cataract

PURPOSE To compare the higher-order aberrations of the oculus (whole eye) and cornea in eyes with mild cortical or nuclear cataract and to estimate the effect of ocular higher-order aberrations on the loss of contrast sensitivity using wavefront analysis. DESIGN Observational case series. METHODS Six eyes of four patients with mild nuclear cataract, 18 eyes of 14 patients with mild cortical cataract, and nine eyes of nine normal patients were examined. Wavefront aberrations of the oculus and cornea for central 6 mm diameter were measured using the Hartmann-Shack (HS) aberrometer. Higher-order aberrations were calculated with Zernike polynomials up to sixth order. The relationship between average lens density (ALD) measured by the Scheimpflug camera and the ocular total higher-order aberration (OTHA) was investigated. The relationship between contrast sensitivity (CS) and the OTHA or ALD was also examined. RESULTS The OTHA was significantly larger in cataracts compared with normal subjects, while corneal total higher-order aberration did not differ between cataracts and normal subjects. The polarity of spherical aberration was negative in all eyes with nuclear cataract while positive in all eyes with cortical cataract. The correlation between ALD and OTHA was not significant in eyes with cataracts. The CS highly correlated with OTHA while it moderately correlated with ALD. CONCLUSIONS The HS aberrometer is useful to objectively evaluate the deterioration of images in eyes with mild cataract and it revealed that the polarity of spherical aberration was different between nuclear and cortical cataract. It was also suggested that in mild nuclear or cortical cataract, not only light scattering, but also optical aberration of the lens contributes to the loss of contrast sensitivity.