• Journal of Biomedical Engineering Research
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• v.40 no.6
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• pp.250-259
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• 2019

Ophthalmic Laser System is widely used in Selective Laser Trabeculoplasty of Open Angle Glaucoma and Ocular Hypertension. Versatile ophthalmic laser system is a medical device with technology that checks the condition of the treatment area by irradiating a continuous laser pulse on the treatment area, and monitoring the microbubble reaction caused by the temperature increase of the melanosome through the ultrasonic signal and the optical signal sensor. It performs selective laser treatment without damaging the photoreceptor by controlling the wavelength of the laser when microbubbles are detected. This study aims to suggest a guideline for evaluating safety, performance and clinical effectiveness of Versatile Ophthalmic Laser System in accordance with the growing technology. International Standards, Regulations, and Clinical Trial Protocols were investigated and analyzed for this study. As a result of this study, the safety, performance and clinical effectiveness test guideline for Versatile Ophthalmic Laser System were proposed. This guideline will ensure the safety and efficacy of Medical device, and furthermore it is expected to be able to promote the development of technology development by supporting a clinical trial plan.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.77-80
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• 2001

The purpose of this work is that by using speckle phenomena of low-level He-Ne laser, it analyzes the movement condition of surface elements on a substance vibrating. The lights from laser reflect against a copper plate and will be shown as speckles on a vibration board. If we vibrate these speckles by sound waves of a speaker installed on the back, the speckles change with various shapes. When a vibration board has a maximum vibration, the frequency becomes a dynamical resonance frequency and we can mark the changes of speckles at that time on a vibration board.

• Journal of Korean Ophthalmic Optics Society
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• v.1 no.1
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• pp.15-22
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• 1996

The fine structure of retinal tissue was studied to investigate on effect of Laser irridation on the ICR mouse with electron microscope. The results obtained were as follows: 1. At the normal groups, the most retinal layers were a complex structure, consisting of several specific cells and nerve fiver. 2. In the increasing time of Laser irridation, each cell layer of retina was not uniform of the structure and band. The visual cells were severely heterochromatin swelling of cytoplasm, irregular shape & heterochromatin of nuclear, and disappear of some cytoplasm. The nucleus and nerve fiber of retinal layer was a very irregular shape, formation of vesicle, not identify of each intercellular boundary. The pigment epithelial cells were not an uniform, a large vesicle formation of cytoplasm, and a condensation & very irregular shape of nucleus.

• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.160-161
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• 2001

A diode laser system has been developed for the refractory glaucoma therapy. The diode lasers have merits in clinical usage including reduction of beam dispersion, higher absorption such as in melanin pigment, and lower complication in treatment. We present the system specification of laser diodes in 810mm with 3W power, which is delivered into the optical fiber core of 600${\mu}{\textrm}{m}$.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.4
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• pp.305-312
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• 2005

In this thesis, Lohmann's algorithm and FFT (fast Fourier transform) are used to synthesize binary-phase holograms. FFT computing is carried out for the calculation of complex wavefronts of $128{\times}128$ sampling points of an object that is numerically specified. Then using the Lohmann's algorithm, the amplitude and the phase of complex wavefronts are encoded in binary holograms on each sampling points. PC (personal computer) and laser printer are used to plot binary-phase holograms and CGH (computer generated holograms) films are obtained from this plot by photographic reduction. Holographic images of numerically specified objects are reconstructed from the He-Ne laser and the inverse Fourier optics system. We estimate the quality of holographic images according to the sampling number, application of random phase, amplitude clipping and bleaching the CGH film. We derive optimized conditions to reconstruct better holographic images and to reduce the speckle noise. FFT and Lohmann's algorithm are implemented with MS Visual BASIC 6.0 for the programming of binary-phase hologram.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.267-273
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• 2006

For this study, we measured heterophoria, Calculated AC/A, Gradient AC/A of pre & post LASIK operation. In case of heterophoria, the results showed that orthophoria 2.78% decreased, exophoria 2.78% increased on pre & post op distance phoria and exophoria 5.55% increased, esophoria 5.55% decreased on pre & post op near phoria. In case of AC/A, Calculated AC/A significantly decreased as 0.36 at AC/A and accommodation decreased as 1.25D (p<0.05). It showed that Gradient AC/A decreased 0.34 and PC/A increased 0.09 but they didn't show significant difference.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.181-186
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• 2000

The setup of the moir$\acute{e}$ deflectometry using the virtual grating was done, so the convergence and divergence of a pencil of ray was determined. The light source was He-Ne laser(3mW). The focal length of the first lens, the second lens being 18 mm, 250 mm respectively was used for the setup of the beam expander. The optics of the moir$\acute{e}$ deflectometry determining the vergence was used a diffraction grating(pitch = $1.6{\mu}m/line$) and a front flat reflection mirror. The effective focal length of the trial lens set was measured and compared with the theoretical value.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.181-188
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• 1998

In order to examine the legibility of the Hangul letters which is a syllabic, the three kind of visual charts were made of the ninety eight($14{\times}7$) Hangul Gothic type letters by the laser printer. These Hangul letters were constructed with the 13 consonant letters which are 'ㄱ, ㄴ, ㄷ, ㄹ, ㅁ, ㅂ, ㅅ, ㅇ, ㅈ, ㅋ, ㅌ, ㅍ, ㅎ', and the 6 vowel letters which are 'ㅏ, ㅓ, ㅗ, ㅜ, ㅡ, ㅣ'. The two examination methods were used, One is the discriminating the letters on the visual chart by men having 1.5 visual acuity. The other is the using the laser printer's resolution. Obtained data by these examination methods are the minimum readable size values of the letters and the maximum readable distance values from the reader to the objects. From these data the relative legibility of the Hangul letters were calculated, where the letter ㄱ was chosen for the standard. This resultant data were analyzed. In this result, the mean legibility of these Hangul letters descended in the order of 'ㄱ, ㄴ, ㅅ, ㄷ, ㅈ, ㅇ, ㅁ, ㅋ, ㅌ, ㅍ, ㅎ' Which are the consonant letters being in these letters. And the mean legibility descended in 'ㅣ, ㅡ, ㅏ, ㅗ, ㅓ, ㅜ' order. The mean legibility is dependent on used consonant letter more then on used vowel.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.35-39
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• 2003

The display technology on the retina is the key role in inspecting the condition of the patients. 2-dimensional retina image is widely used in the eye examination as of today. Recently, 3-dimensional retina image ones have been introduced to this area, but the quality of the image is not fully satisfied to the operator. For the purpose of developing 3-D retina imaging instrument, the optimization of a 3-D retina imaging system using Code-V tool was investigated in this thesis. He-Ne laser having the wavelength 632.8 nm was used to make a power source to detect the retina. Several lenses and mirrors installed on sledge which were developed to perform focus control on 3-D device were designed to make a beam focusing and direct line. Polygon scanner having 24 mirror facets and galvanometer making tilting movement were utilized to make a 2-D laser plane. Also, design of eye ball had been fulfilled to see the focus of the 2-D plane. Reflected ray from retina detected on the sensor array with the same path. All cognitive components were optimized for aberration correction in order to focus on retina. Results of optimization were compared to those of initial designed optics system. On the basis of above results, the result of third aberration has been corrected to stable values to the optical system. MTF evaluating the resolution of an image has been closely correlated to the diffraction limit and PSF indicating the strength distribution of an image has shown the SR value as 0.9998 having high performance. The possibility of new and powerful 3-D retina image instrument was verified by simulating each component of the instrument by Code-V.

• Journal of the Optical Society of Korea
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• v.18 no.2
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• pp.151-155
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• 2014

Although various ophthalmic imaging methods, including fundus photography and optical coherence tomography, have been applied for effective diagnosis of ocular diseases with high spatial resolution, most of them are limited by shallow imaging penetration depth and a narrow field of view. Also, many of those imaging modalities are optimized to provide microscopic anatomical information, while functional or cellular information is lacking. Compared to other ocular imaging modalities, photoacoustic imaging can achieve relatively deep penetration depth and provide more detailed functional and cellular data based on photoacoustic signal generation from endogenous contrast agents such as hemoglobin and melanin. In this paper, array-based ultrasound and photoacoustic imaging was demonstrated to visualize pigmentation in the eye as well as overall ocular structure. Fresh porcine eyes were visualized using a real-time ultrasound micro-imaging system and an imaging probe supporting laser pulse delivery. In addition, limited photoacoustic imaging field of view was improved by an imaging probe tilting method, enabling visualization of most regions of the retina covered in the ultrasound imaging.