Published papers

Background: To investigate the peripheral optical quality and its relationship with axial elongation, myopic progression in Japanese children. Methods: Twenty-nine Japanese children, ages 10 to 12 years old, with baseline refraction from +0.75D to -5.5 D, were included and followed for 9 months. The central and peripheral point spread functions (PSFs; 0, 10, 20, 30 nasally) were obtained at 0.25 D steps around ±2.5 D of best-focus PSF (BF-PSF) using double-pass PSF system. Modulation transfer function (MTF) area of the BF-PSF was calculated from BF-PSF to represent the peripheral optical quality. Relative peripheral defocus (RPD), the refraction of anterior/posterior focal lines, MTF area, and their correlations with myopia progression were analyzed. Results: The average refractive change in 9 months was -0.5 ± 0.8 D. The change in axial length was significantly positively correlated with the amount of myopic progression (P = 0.0058) and RPD (P = 0.0007, 0.0036 and 0.0040, at 10, 20, 30 respectively) at the initial visit, but did not correlate with the peripheral MTF area. Myopic progression of more than 0.5 D with axial elongation was observed in seven children (MP group). The RPDs at 20 and 30 in the MP group were significantly more hyperopic than in the non-MP group (P = 0.002 and 0.007), whereas there was no significant difference in axial length, and central and peripheral MTF area between the MP and non-MP groups. MP group had more hyperopic focal lines compared with non-MP group at 20 and 30. Conclusion: These results suggest that the progression of axial myopia in children is associated with hyperopic RPD and refraction of focal lines, not with peripheral optical quality. © 2013 Springer-Verlag Berlin Heidelberg.

Purpose: To evaluate the early results of laser in situ keratomileusis (LASIK) using a new ablation program, Optimized Aspherical Transition Zone (OATZ). Methods: The results at 3 months after surgery in 16 eyes of 8 patients who underwent LASIK using the OATZ program (OATZ group) for myopia or myopic astigmatism were compared with those in 40 eyes of 22 patients who underwent LASIK using the conventional program (Conventional group). Results: There was no significant difference in postoperative uncorrected visual acuity, best-corrected visual acuity, or refraction (spherical equivalent) between the 2 groups. Contrast sensitivity and contrast visual acuity were also comparable between the groups. The safety index and the efficacy index were 0.94 and 0.71 in the OATZ group and 1.00 and 0.85 in the Conventional group, respectively. The proportion of eyes with postoperative coma-like, spherical, and higher-order aberrations in the OATZ group was significantly smaller than the proportion in the Conventional group. Conclusions: In this study, the early results of LASIK using the OATZ program were good. Further investigations into the usefulness of the OATZ program should be conducted using various settings for optical zone, transitional zone, and profile number.

Purpose: To evaluate the predictability of intraocular lens (IOL) power calculation after phototherapeutic keratectomy (PTK). Methods: In this study, 12 eyes of 8 patients who underwent cataract surgery after PTK (PTK group), and 63 eyes of 55 patients who underwent only cataract surgery (control group) were compared. The main outcome measure was the difference between the target and actual refraction achieved 1 month after cataract surgery. IOL power was determined using 4 measurements for the PTK group: standard keratometric power, total optical power and total axial power (central 3mm) analyzed using a slit-scan corneal topographic analysis system, and pre-PTK measurements of keratometric power. Results: Measurements of corneal power by the 4 different methods in the PTK group did not differ significantly, nor did errors in postoperative refractive power differ for the different methods. The refractive errors after cataract surgery were within ±1.0 D of the targeted value in about 50% of the PTK groups using any measurement method, and all of the predicted values were lower than values in the control group. There was no significant difference in predictability of achieving the target refraction as a function of the 4 different keratometric values used to calculate IOL power. Conclusions: The predictability of IOL power needed to achieve postoperative refraction within a target range is lower for eyes undergoing both PTK and cataract surgery than for eyes undergoing cataract surgery alone, which suggests that informed consent to cataract surgery with IOL implantation should include the information that the range of possible refractive error after cataract surgery is greater in eyes that have undergone PTK.

Purpose: To determine whether staining of the lens capsule with trypan blue 0.1% and indocyanine green (ICG) 0.5% diminishes with time and whether it differs between the anterior and posterior capsules. Setting: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan. Methods: Crystalline lenses removed from porcine eyes were stained for 10 seconds with 0.1 mL of trypan blue 0.1% or indocyanine green 0.5%. They were then placed in distilled water and observed for the persistence of staining over time. In a second experiment, the anterior chamber and internal aspects of the anterior capsule and internal and vitreous aspects of the posterior capsule were gently irrigated with 0.1 mL of trypan blue 0.1% or ICG 0.5%. After 10 seconds, the capsules were irrigated with distilled water and the staining intensities were compared. Results: Staining was not diminished 30 seconds, 5 minutes, or 1 hour after application of either dye. No difference was evident in staining intensity or diminution with time between the anterior and posterior capsules, but the external aspects were stained more than the internal aspects with both dyes. Trypan blue produced more intense staining than ICG. Conclusions: Since the intensity of capsule staining in the intact lens did not change during a 1-hour immersion in water, capsule dyes may not dissipate fully during cataract surgery. As possible long-term adverse effects have not been ruled out, capsule dyes should be used in a low concentration for a short exposure time. © 2004 ASCRS and ESCRS.

The single-pass modulation transfer function (MTFsgl) is an important numerical parameter that can help elucidate the performance and some processes of the human visual system. In previous studies, the MTF sglwas calculated from double-pass point spread function (PSF) measurements. These measurements include a depolarized reflection component from the retina that introduces a measurement artifact, and they require long acquisition times to allow averaging to reduce speckle. To solve these problems, we developed a new ocular PSF analysis system (PSFAS) that uses polarization optics to eliminate the depolarized retinal reflection component, and a rotating prism to increase measurement speed. Validation experiments on one patient showed that the MTFsglmeasured by PSFAS agrees closely with the MTF calculated from contrast sensitivity measurements. A simulated retinal image was calculated by convolution of Landolt rings with the calculated single-pass PSF provided by the PSFAS. The contrast characteristic then was calculated from the simulated retinal images. These results indicate that the MTF sglobtained using the PS-FAS may be a reliable measure of visual performance of the optics of the eye, including the optical effects of the retina. The simulated retinal images and contrast characteristics are useful for evaluating visual performance. © 2004 Society of Photo-Optical Instrumentation Engineers.

We developed a new point spread function (PSF) analysis system (PSFAS) to study the optical system of the human eye. An infrared point light source is projected on the retina, then the single-pass modulation transfer function (MTF) is derived from the image of incoherent polarized reflection double-pass PSF measured by PSFAS: The retinal images and the contrast characteristics of various sized Landolt's rings then are simulated with the single-pass PSF calculated by the single-pass MTF. The visual acuity (VA) is predicted from the retinal images. The single-pass MTF and the contrast characteristics of aged subjects were clearly lower than those of a young subject in mid-frequency, though the cut-off frequency was similar in the two subjects. The predicted VA from the simulated retinal images agreed with the actual VA in normal subjects and in those with myopic astigmatism. This becomes a useful system for elucidating the optical characteristics of the human eye. In addition, the visual simulation obtained using this system is clinically useful for objectively evaluating visual function.

Purpose: To evaluate the efficacy and safety of an ozonated solution used as a preoperative disinfectant and to irrigate the corneal flap in laser in situ keratomileusis. Methods: In normal human eyes, the rates of positive bacterial culture before and after irrigation were compared for 3 kinds of solutions: a 1:16 solution of povidone-iodine, a hypotonic-ozonated solution, and an isotonic-ozonated solution. In white rabbit eyes, the conjunctival fomix of the eye was irrigated with one of the 3 solutions before a corneal flap was made. Then the flap was irrigated with one of these 3 solutions: a hypotonic-ozonated solution, an isotonicozonated solution, or a balanced salt solution (BSS). The degree of corneal epithelial damage, the degree of edema in the flap after irrigation, and postoperative wound healing were compared in rabbit eyes exposed to the 3 solutions. Results: In human eyes, all 3 solutions were effective preoperative disinfectants. In rabbit eyes, the degree of corneal damage was more severe in the eyes irrigated with povidone iodine solution than in those irrigated with other solutions. There was no noticeable difference in the degree of flap edema after irrigation under the flap or in wound healing among eyes irrigated with BSS or an ozonated solution. Conclusions: An ozonated solution is an effective preoperative disinfectant and causes less corneal damage than a povidone iodine solution. An isotonic ozonated solution could be used to irrigate under the corneal flap during laser in situ keratomileusis.

PURPOSE: To examine the long-term occurrence and course of Elschnig pearl (string of pearls) formation along neodymium:YAG (Nd:YAG) laser posterior capsulotomy margins. SETTING: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan. METHODS: The clinical records of eyes having an Nd:YAG posterior capsulotomy to treat posterior capsule opacification after cataract surgery were retrospectively reviewed. Kaplan-Meier and Cox proportional hazards analysis were performed. RESULTS: Among 201 eyes, string of pearls developed in 139 (69.2%). The mean follow-up after the Nd:YAG posterior capsulotomy was 32.1 months +/- 25.3 (SD). At 2 years, the cumulative probability of developing string of pearls was 77.0% (95% confidence interval [CI], 70.6%-83.4%), after which it reached a plateau. Among the 139 eyes, 100 had sufficient data to be reviewed to assess the long-term outcome (mean follow-up from Nd:YAG posterior capsulotomy, 43.7 +/- 26.0 months). A second Nd:YAG posterior capsulotomy was performed in 18 eyes (18.0%) to treat progression of string of pearls, typically within 2 years after the initial Nd:YAG capsulotomy. The string of pearls disappeared spontaneously in 31 eyes (31.0%). The probability of disappearance was 80.4% (95% CI, 63.4%-97.4%) 8 years after the Nd:YAG posterior capsulotomy. Cox proportional hazards analysis identified no factor significantly favoring the disappearance of the string of pearls. CONCLUSIONS: String of pearls was a common complication after Nd:YAG laser posterior capsulotomy. About 20% of cases were progressive and required a second capsulotomy; however, most regressed over several years.

Purpose: To examine the long-term occurrence and course of Elschnig pearl (string of pearls) formation along neodymium:YAG (Nd:YAG) laser posterior capsulotomy margins. Setting: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan. Methods: The clinical records of eyes having an Nd:YAG posterior capsulotomy to treat posterior capsule opacification after cataract surgery were retrospectively reviewed. Kaplan-Meier and Cox proportional hazards analysis were performed. Results: Among 201 eyes, string of pearls developed in 139 (69.2%). The mean follow-up after the Nd:YAG posterior capsulotomy was 32.1 months ± 25.3 (SD)(SID). At 2 years, the cumulative probability of developing string of pearls was 77.0% (95% confidence interval [CI], 70.6%-83.4%), after which it reached a plateau. Among the 139 eyes, 100 had sufficient data to be reviewed to assess the long-term outcome (mean follow-up from Nd:YAG posterior capsulotomy, 43.7 ± 26.0 months). A second Nd:YAG posterior capsulotomy was performed in 18 eyes (18.0%) to treat progression of string of pearls, typically within 2 years after the initial Nd:YAG capsulotomy. The string of pearls disappeared spontaneously in 31 eyes (31.0%). The probability of disappearance was 80.4% (95% CI, 63.4%-97.4%) 8 years after the Nd:YAG posterior capsulotomy. Cox proportional hazards analysis identified no factor significantly favoring the disappearance of the string of pearls. Conclusions: String of pearls was a common complication after Nd:YAG laser posterior capsulotomy. About 20% of cases were progressive and required a second capsulotomy; however, most regressed over several years. © 2002 ASCRS and ESCRS.