• Journal of Korean Ophthalmic Optics Society
• /
• v.15 no.3
• /
• pp.275-280
• /
• 2010

Propose: Due to the rapid growth of medical technologies and the increasing population of older people, we investigated clinical status of ocular dimensions and visual acuity for pre and post cataract surgeries of people over age 90. Methods: From March 2007 to February 2009, we investigated eighty-two eyes of forty-eight patients who had undergone cataract surgeries at an ophthalmic clinic (Ansung, Kyungi-do), investigated maximum corrected vision, axial length, anterior chamber depth and accompanied ocular diseases before and after the surgeries based on the collected data. Results: As patients aged, axial length unchanged but anterior chamber depth decreased over all due to the increase of intraocular lens thickness, and men tended to have a higher degree than women. Seventy-one (86.6%) of eighty-two eyes showed improved corrected vision than before surgeries and forty-three (52.4%) eyes could see more than visual acuity of 0.5. Conclusions: Patients with the systemic disease and accompanied ocular disease showed low vision less than 0.5 after cataract surgery compared to same healthy age peoples. But the others improved correction visual acuity more than 0.5, so the cataract surgery was surely necessary for people over 90 years old and also the presence of ocular disease could have a great influence on correction visual acuity.

• Journal of Korean Ophthalmic Optics Society
• /
• v.18 no.3
• /
• pp.341-346
• /
• 2013

Purpose: The purpose of this study was to evaluate whether a relationship exists between head posture and phoria, and usefulness in examining habitual head posture. Methods: Twenty two subjects (20 males and 2 females, mean age $23.6{\pm}2.7$ years) with abnormal phoria from participants randomized were enrolled in this study. For all subjects, testing included case history, cover test, refraction, phoria and vergence test. Habitual head posture (head posture, head tilt and face turn) was measured by Impression IST, and observed by examiners. Results: The abnormal head posture was revealed in some subjects with abnormal phoria. Spearman' correlation ($\rho$=0.524, p=0.045) showed significant correction between face turn and phoria at distance in 15 subjects with prism prescription. No significant relationship between head posture and phoria was found in subjects with abnormal phoria. The objective measurement and subjective observation of head posture showed insignificant correction but there was a distinct difference. The former was detail and the latter was discriminate. Conclusions: Presence of abnormal head posture was found in phoric subjects. The results indicate the need to observe habitual head posture at all major positions of gaze in phoria.

• Journal of Korean Ophthalmic Optics Society
• /
• v.18 no.3
• /
• pp.279-289
• /
• 2013

Purpose: To evaluate the changes of refractive power when worn soft contact lenses were temporarily removed. Methods: 91 soft contact lens wearers (15 males and 76 females; total 182 eyes) from 17 to 39 years of age (average: $24{\pm}4.8$ years) were participated. Objective and subjective refraction, and corneal radius were measured at 0, 30, 60 and 90 min after lens removal. The changes in refractive power were evaluated between measurements over time. The other parameters such as types of lenses, fitting and wearing conditions were also assessed. Results: Objective refraction, subjective refraction and corneal radius were significantly changed according to measured time (p<0.0001). A moderate myopic shifts was observed at the beginning (30 min after lens removal) and a slight myopic shift at the late of measurement (60 min to 90 min after lens removal). There are no significant differences between lens types, fitting states, wearing time, wearing days and sleeping time in the previous day. However, there was significant interaction in changes for corneal radius between measuring time and lens type (p=0.017), fitting state (p=0.019), and sleeping time prior to the test (p=0.010). Conclusions: Time to reach refractive and corneal radius stability after contact lens removal revealed at least more than 60 min, regardless of types of lenses, fitting and wearing conditions. Therefore, refraction for correction should be performed after waiting for more than that time as possible.

• Journal of Korean Ophthalmic Optics Society
• /
• v.14 no.1
• /
• pp.23-29
• /
• 2009

Purpose: To investigate request for optical shop startup education of ophthalmic optics students as a basic source for startup education. Methods: Total of 287 students' from three ophthalmic optics college in Kyung-gi region was surveyed and analyzed the data using SPSS analysis. Results: Most students didn't have experience of optical shop startup business education (94.4%). However, the request of startup education was very high (89.9%) and there was significant difference according to grade (p<0.01). The most wanted education for the student who want to opening a shop was a lecture related to finding best place for the shop. For importances of select a site and purchasing information of frame, lens, contact lens in startup education were significant difference according to correction of visual acuity (p<0.001, p<0.05) and optician family present (p<0.05, p<0.001). For importance of customer management and publicity activities was significant difference according to correction of visual acuity (p<0.05). Conclusions: For request of optical shop startup education was very high and need to having startup education.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.6
• /
• pp.3208-3229
• /
• 2017

Rectification is an essential procedure for simplifying the disparity extraction of stereo matching algorithms by removing vertical mismatches between left and right images. To support real-time stereo matching, studies have introduced several look-up table (LUT)- and computational logic (CL)-based rectification approaches. However, to support high-resolution images, the LUT-based approach requires considerable memory resources, and the CL-based approach requires numerous hardware resources for its circuit implementation. Thus, this paper proposes a multi-level accumulation-based rectification method as a simple CL-based method and its circuit implementation. The proposed method, which includes distortion correction, reduces addition operations by 29%, and removes multiplication operations by replacing the complex matrix computations and high-degree polynomial calculations of the conventional rectification with simple multi-level accumulations. The proposed rectification circuit can rectify $1,280{\times}720$ stereo images at a frame rate of 135 fps at a clock frequency of 125 MHz. Because the circuit is fully pipelined, it continuously generates a pair of left and right rectified pixels every cycle after 13-cycle latency plus initial image buffering time. Experimental results show that the proposed method requires significantly fewer hardware resources than the conventional method while the differences between the results of the proposed and conventional full rectifications are negligible.

• The Journal of Korea Robotics Society
• /
• v.7 no.2
• /
• pp.120-128
• /
• 2012

The loop closure problem is one of the most challenging issues in the vision-based simultaneous localization and mapping community. It requires the robot to recognize a previously visited place from current camera measurements. While the loop closure often relies on visual bag-of-words based on point features in the previous works, however, in this paper we propose a line-based method to solve the loop closure in the corridor environments. We used both the floor line and the anchored vanishing point as the loop closing feature, and a two-step loop closure algorithm was devised to detect a known place and perform the global pose correction. We propose an anchored vanishing point as a novel loop closure feature, as it includes position information and represents the vanishing points in bi-direction. In our system, the accumulated heading error is reduced using an observation of a previously registered anchored vanishing points firstly, and the observation of known floor lines allows for further pose correction. Experimental results show that our method is very efficient in a structured indoor environment as a suitable loop closure solution.

• Journal of KIISE:Computing Practices and Letters
• /
• v.14 no.3
• /
• pp.291-295
• /
• 2008

In this paper, we propose an input image reduction method to solve the problems of Radon transform which is a line structure analysis tool to correct a rotated object through a vision system. First we extract an object image removed background from the input image. Then we also select a reduced object image as a final input mage of Radon transform from the object image by considering slope. Finally we extract a rotated angle by using Radon transform with the final input image and correct the rotated object with the angle. In experimental results, we could improve the process time of about 64%, reduce the memory space of about 18% and make progress the line detection rate of about 18%.

• Journal of Korean Ophthalmic Optics Society
• /
• v.17 no.1
• /
• pp.53-58
• /
• 2012

Purpose: The purpose of this study was to predict the amount of astigmatism through logMAR visual acuity by Jin's chart at best vision spherical power and to compare availability of astigmatism expectation by Jin's and beam project chart. Methods: LogMAR and decimal visual acuity were measured for 150 college students and visual acuity and compared the amount of astigmatism under full correction. Results: Jin's chart was showed marked differences at least more than 0.25 D intervals per line than beam project chart. Correlation with the amount of astigmatism was higher the logMAR visual acuity r = 0.8578 than decimal visual acuity r = -0.7199. Conclusions: LogMAR visual acuity at best vision spherical power was able to predict to amount of astigmatism and Jin's chart was easier than beam project chart to predict difference of each lines.

• Journal of Korean Ophthalmic Optics Society
• /
• v.18 no.4
• /
• pp.549-554
• /
• 2013

Purpose: To determine the minimal illumination for visual acuity with the decimal vision chart and individual difference with varying contrast and illumination. Methods: Landolt's vision chart with 10 different grade of contrast was made. Minimal illumination was measured for 69 eyes using 100% contrast vision chart. Minimal contrast for identifying the chart was measured in conditions of the minimal illumination and 230 lx, respectively. Results: Minimal illumination was gradually increased with decrease of the chart size. Mean of minimal illumination to identify the 1.0 visual acuity was $74.39{\pm}25.90$ lx with range of 17~107 lx. In conditions of the minimal illumination and 230 lx, the minimal contrast for identifying the chart were gradually increased with decrease of the chart size in both conditions, the those deviation for 69 eyes was also increased. Conclusions: For refractive correction, examiners need to consider the individual difference for identifying the visual chart according to illumination and contrast.

• Journal of Veterinary Clinics
• /
• v.25 no.4
• /
• pp.292-294
• /
• 2008

The purpose of this study was to evaluate the cause of lens luxation and to determine the frequency of vision loss, glaucoma, cataract, and corneal edema before and after intracapsular lens extraction (ICLE). The medical records of 8 dogs underwent ICLE for the correction of anterior lens luxation at the Veterinary Medical Teaching Hospital of Seoul National University from August 2005 to September 2007 were reviewed. The most frequently affected breed was Miniature Poodle (n = 3). The mean age was $10.8{\pm}2.1$ years. Preoperatively, 5 eyes (67.5%) with anterior luxation had secondary glaucoma, 7 eyes (87.5%) had vision loss, and all eyes (100.0%) had corneal edema. Four weeks after ICLE, 6 eyes (75.0%) had normal intraocular pressure (IOP), and 4 eyes (50.0%) regained vision. Corneal edema was reduced after ICLE in all eyes, but still remained in 4 eyes. It was considered that ICLE was beneficial in the management of anterior lens luxation, but the eyes without glaucoma before ICLE had more favorable prognosis than eyes with.