Ark 700a

The uncorrected and corrected visual acuities of both eyes were measured with a Landolt ring chart at 5 m. The refractive errors were determined by an autorefractometer and keratometer (ARK-700A; Nidek, Gamagori, Japan). The visual acuity was measured according to the standard of the International Organization for Standardization.¹⁶ The decimal BCVA was converted to the logarithm of the minimum angle of resolution (logMAR) units for statistical analyses. To describe the age-specific BCVA, subjects were divided into five age groups, viz., ≤74 years, 75–79 years, 80–84 years, 85–89 years, and ≥90 years.
Subjects with a BCVA of <20/40 (>0.3 logMAR units) in the better seeing eye, the criterion of vision reduction used in the Blue Mountains Eye Study,^{7 (link)} was classified as being visually impaired. Blindness was defined as a BCVA in the better seeing eye of <3/60 based on the World Health Organization standards.

The right eyes of eight New Zealand white adult rabbits weighing 2.5 kg to 3.0 kg were used for the experiments. All animals used in this study were treated according to the guidelines of the Association for Research in Vision and Ophthalmology. And this study was approved by the Ethics Committee of the Eye & ENT Hospital, Fudan University, Shanghai, China. Prior to the experiments, the animals were examined with a slit lamp to rule out clinically observable ocular diseases. The manifest refraction was determined using the autorefractor (ARK-700A; NIDEK Co., Ltd., Aichi, Japan) and recorded as spherical equivalent (SE). Corneal power was determined using a corneal topography system (ZEISS, Model 995).
Follow-up examinations were performed with topical anesthesia at postoperative 7, 30, and 180 days.

Before surgery, and 3 months and 1, 4, 8, and 12 years after surgery, we assessed the following parameters: logMAR of uncorrected distance visual acuity (UDVA), logMAR of corrected distance visual acuity (CDVA), manifest refraction (spherical equivalent), intraocular pressure (IOP), and endothelial cell density, and keratometric readings, in addition to the usual slit-lamp biomicroscopic and funduscopic examinations. The safety index was determined as mean postoperative decimal CDVA/mean preoperative CDVA and the efficacy index as mean postoperative decimal UDVA/mean preoperative CDVA. Preoperatively, we measured the mean keratometric readings using an autorefractometer (ARK-700A, Nidek, Gamagori, Japan) and the central corneal thickness using an ultrasound pachymeter (DGH-500, DGH Technologies, Exton, US), the IOP using a noncontact tonometer (KT-500, Kowa, Tokyo, Japan), and the endothelial cell density using a noncontact specular microscope (SP-8800, Konan, Nishinomiya, Japan). Experienced optometrists performed at least 3 consecutive measurements in all subjects, and we used the average value for statistical analysis.

Experienced optometrists used a Snellen chart at a distance of 5 m to measure visual acuity, and an automated refractometer (ARK-700A, Nidek, Gamagori, Japan) as a starting point for a full manifest refraction. The grade of nuclear sclerosis of the crystalline lens was assessed by cataract specialists according to the Emery-Little classification. For subgroup analysis, the cataract type was divided into 3 subgroups (nuclear sclerosis, cortical, and posterior subcapsular cataract), based on slit-lamp biomicroscopy after mydriasis. Since it was challenging to exactly classify the type of cataract, we determined as cases those subjects who presented with advanced forms of 1 of the 3 cataract types, regardless of the concomitant presence of the remaining 2 cataract types.

A total of 2377 unrelated Japanese individuals were recruited from Yokohama City University, Okada Eye Clinic, and Aoto Eye Clinic in Yokohama, Kanagawa Prefecture, Japan. Corneal curvature radii were measured in horizontal and vertical meridians with autorefractors (ARK-730A, [NIDEK, Aichi, Japan], ARK-700A [NIDEK], and KP-8100P [TOPCON, Tokyo, Japan]). The keratometric index of 1.3375 was used to convert the radius of corneal curvature in millimeters into a corneal power in diopters (D). Corneal cylinder power was calculated as the difference in diopters between the steepest and flattest medians. According to previous studies^{9 (link),11 (link)}, we defined individuals with mean corneal cylinder power ≤  − 0.75 D across both eyes as corneal astigmatism cases (n = 1535), while controls were defined as mean corneal cylinder power >  − 0.75 D across both eyes (n = 842). This study did not include individuals who had a previous history of ocular surgery or any ocular condition that may affect the accuracy of keratometry. The study details were explained to all participants, and written informed consent was obtained from all participants. The study methodology adhered to the tenets of the Declaration of Helsinki and was approved by the Ethics Committee of Yokohama City University School of Medicine (approval number: A150122004; approval date: 06/02/2015).

Visual acuity. The refractive error (spherical equivalent) was determined by an auto refractometer and keratometer (ARK-700A, Nidek, Aichi, Japan). The data of the refractive errors were used as useful references to obtain the best-corrected visual acuity (BCVA). The uncorrected and the BCVA of both eyes were measured with a Landolt ring chart at 5 m by well-trained orthoptists. To obtain the BCVA, orthoptists used corrective lenses placed in trial frames for each participant. A VI was defined as BCVA worse than 20/40 in the better-seeing eye for the statistical analyses. This cut-off BCVA corresponded to the American Association of Ophthalmology categorization of a visual impairment which was defined as the distance BCVA worse than 20/40 in the better-seeing eye [26 ]. The decimal BCVA was converted to the logarithm of the minimum angle of resolution (logMAR) units for the statistical analyses.