Daisuke Aizawa

Repeatability, reproducibility, and agreement characteristics of rotating Scheimpflug photography and scanning-slit corneal topography for corneal power measurement

PURPOSE: To evaluate the repeatability, reproducibility, and agreement in anterior, posterior, and in particular the total corneal power of 2 topography devices, rotating Scheimpflug photography and scanning‐slit topography. SETTING: Department of Ophthalmology and Visual Science, Kitasato University Graduate School of Medical Sciences, Sagamihara, Japan. METHODS: Seventeen eyes of 17 subjects (mean age 24.7 years ± 4.1 [SD]) were included in the study. The corneal shapes within the central 3.0 mm were measured with rotating Scheimpflug photography (Pentacam) and scanning‐slit corneal topography (Orbscan II). The within‐rater repeatability and reproducibility of 2 raters and the overall between‐instrument agreement of the measurements were evaluated using intraclass correlation coefficients (ICCs) and the Bland‐Altman method. RESULTS: The repeatability of Scheimpflug photography and scanning‐slit corneal topography was high (ICC, 0.70 to 0.99). Scheimpflug photography outperformed scanning‐slit corneal topography for anterior power, posterior power, and total corneal power. The reproducibility results were similar, with limits of agreement (LoA) consistently narrower for Scheimpflug photography. The between‐instrument agreement was moderate, with LoA around the mean value of total corneal power of 0.46 diopter ranging from 0.032 to 0.889. CONCLUSIONS: The results suggest that repeatability and reproducibility are higher in Scheimpflug photography than in scanning‐slit topography. The agreement between rotating Scheimpflug photography and scanning‐slit topography for total corneal power was moderate.

Clinical outcomes of wavefront-guided laser in situ keratomileusis: 6-month follow-up

Purpose: To evaluate the clinical outcomes 6 months after wavefront‐guided laser in situ keratomileusis (LASIK) for myopia in Japan. Setting: Department of Ophthalmology, Sanno Hospital, Tokyo, Japan. Methods: This prospective study comprised 22 eyes of 12 patients treated with wavefront‐guided LASIK who were available for evaluation at 6 months. The mean patient age was 31.2 years ± 8.4 (SD) (range 23 to 50 years), and the mean preoperative spherical equivalent refraction was −7.30 ± 2.72 diopters (D) (range −2.75 to −11.88 D). In all cases, preoperative wavefront analysis was performed with a Hartmann‐Shack aberrometer and the Technolas® 217z flying‐spot excimer laser system (Bausch & Lomb) was used with 1.0 mm and 2.0 mm spot sizes and an active eye tracker with a 120 Hz tracking rate. The clinical outcomes of wavefront‐guided LASIK were evaluated in terms of safety, efficacy, predictability, stability, complications, and preoperative and postoperative aberrations. Results: At 6 months, 10 eyes had no change in best spectacle‐correct visual acuity and 10 gained 1 or more lines. The safety index was 1.11 and the efficacy index, 0.82. Slight undercorrections were observed in highly myopic eyes. In all eyes, the postoperative refraction tended slightly toward myopia for 3 months and stabilized after that. No complication such as epithelial ingrowth, diffuse lamellar keratitis, or infection was observed. Comparison of the preoperative and postoperative aberrations showed that 2nd‐order aberrations decreased and higher‐order aberrations increased. In the 3rd order, aberrations increased in the high‐myopia group (−6.0 D or worse) and decreased in the low to moderate‐myopia group (better than −6.0 D). Conclusion: Wavefront‐guided LASIK was a good option for refractive surgery, although a longer follow‐up in a larger study is required.

Optical performance in rezoom and array multifocal intraocular lenses in vitro.

PURPOSE To investigate the modulation transfer function (MTF) of two refractive multifocal intraocular lenses (IOLs). METHODS The ReZoom and Array (AMO) multifocal IOLs were evaluated using the OPAL Vector system (Image Science Ltd) and a model eye with a variable aperture (2.1 to 5.5 mm). Modulation transfer functions were evaluated at distant, near, and intermediate (-1.50 diopter defocus) focus lengths. RESULTS The ReZoom IOL distant focus MTF for a 5.1-mm effective diameter was higher than that of the Array IOL. At intermediate distance, the ReZoom lens showed a slight increase compared with the Array. The near focus MTF for the ReZoom IOL began to increase at an effective diameter of 2.1 mm and remained constant for diameters > 3.45 mm. CONCLUSIONS The ReZoom IOL gave better image quality than the Array, particularly at distant focus. To enhance near vision with the ReZoom lens, the desirable real pupil diameter should be at least 3.45 mm.

Surgically induced astigmatism after posterior chamber phakic intraocular lens implantation

Aim: To assess astigmatism induced after phakic intraocular lens (Visian ICL, STAAR Surgical) implantation. Methods: Seventy-three eyes of 47 patients undergoing ICL implantation through a horizontal 3.0 mm clear corneal incision were retrospectively examined. The amount of corneal astigmatism before and 3 months after surgery using an automated keratometer (ARK-700A, Nidek) and corneal topography (ATRAS995, Carl Zeiss Meditec) were quantitatively investigated. The surgically induced astigmatism was assessed by vector analysis using the Holladay-Cravy-Koch formula. Results: The corneal astigmatism was significantly increased from 1.10 (0.51) dioptres (D) to 1.44 (0.57) D using the keratometer (Wilcoxon signed-rank test, p<0.001). It was also significantly increased from 1.16 (0.53) D to 1.45 (0.57) D using corneal topography (p<0.001). On the other hand, the manifest astigmatism was significantly decreased from 0.93 (0.60) D to 0.72 (0.58) D (p<0.001). The surgically induced astigmatism was 0.45 (0.26) D at an axis of 93.3° using the keratometer and 0.49 (0.26) D at an axis of 98.0° using corneal topography. Conclusions: ICL implantation induces corneal astigmatism through a with-the-rule astigmatic shift of approximately 0.5 D, which was small but not negligible for candidates for refractive surgery.

A case of late-onset diffuse lamellar keratitis 12 years after laser in situ keratomileusis

Laser in situ keratomileusis (LASIK) is an effective means of correcting refractive errors but there may be some postoperative complications. Diffuse lamellar keratitis (DLK), a relatively common complication after LASIK, is characterized by an infl ammatory cellular response at the interface, usually within 1 week of surgery. We present herein a case of DLK with an extremely delayed onset, occurring 12 years after LASIK, necessitating intensive steroidal treatment to avoid subsequent visual disturbances.

Time Course of Accommodation After Implantable Collamer Lens Implantation

PURPOSE To assess the time course of accommodative function after Implantable Collamer Lens (ICL) implantation and to investigate the relationship between patient age and accommodation in ICL-implanted eyes. DESIGN Prospective, nonrandomized clinical trial. METHODS We prospectively examined 69 eyes of 40 consecutive patients with myopic refractive errors of -3.25 to -22.75 diopters (D) who were undergoing ICL implantation. We assessed the amplitude of accommodation using an accommodometer before and one, three, six, and 12 months after surgery. We also investigated its relationship with patient age. RESULTS The accommodation was 6.36 +/- 3.94 D (mean +/- standard deviation) before surgery and 4.89 +/- 2.72 D, 4.98 +/- 2.67 D, 5.16 +/- 2.72 D, and 5.72 +/- 2.85 D at one, three, six, and 12 months after surgery, respectively. The variance of data was statistically significant (P = .02, repeated-measures analysis of variance). Multiple comparisons demonstrated significant differences between measurements made before surgery and at one month after (P = .004, Fisher least significant difference test), before surgery and at three months after (P = .007), and before surgery and at six months after (P = .01). There was a significant correlation between patient age and accommodation before (Pearson correlation coefficient, r = -0.665; P < .001) and one year after (r = -0.803; P < .001) ICL implantation. CONCLUSIONS Accommodation was impaired transiently in the early postoperative periods, and then recovered gradually over time, indicating that transient dysfunction of the ciliary muscles by ICL fixation may occur after ICL implantation even if the crystalline lens remained intact. As patients aged, the amplitude of accommodation became significantly smaller not only in normal eyes but also in ICL-implanted eyes.

Late-onset Diffuse Lamellar Keratitis

BACKGROUND Diffuse lamellar keratitis (DLK) is marked by the presence of diffuse or multifocal infiltrates confined to the laser in situ keratomileusis(LASIK) interface. These infiltrates are culture-negative, and the etiology is thought to be noninfectious. Most cases of DLK occur within the first week or two following surgery. CASE We describe two cases of diffuse lamellar keratitis that occurred 3 months after LASIK. These patients were treated with intensive topical corticosteroids. RESULTS We treated the patients with topical corticosteroids, with rapid improvement in patient symptoms, visual acuity, and slit-lamp biomicroscopy. CONCLUSION DLK may occur three months after LASIK.