Comparison of OCT and HRT Findings Among Normal, Normal Tension Glaucoma, and High Tension Glaucoma

PURPOSE: To evaluate the relationship between optic disc and retinal nerve fiber layer (RNFL) measurements obtained with the optical coherence tomography (OCT) and the Heidelberg retina topography (HRT) in normal, normal tension glaucoma (NTG), and high tension glaucoma (HTG). METHODS: Normal, NTG and HTG subjects who met inclusion and exclusion criteria were evaluated retrospectively. One hundred seventy eyes of 170 patients (30 normal, 40 NTG, and 100 HTG) were enrolled. Complete ophthalmologic examination, HRT, OCT, and automated perimetry were evaluated. RESULTS: Disc area, cup area and cup/disc area ratio measured with HRT were significantly different between NTG and HTG (all p0.05). Mean deviation and corrected pattern standard deviation measured by automated perimetry was significantly correlated with mean and inferior RNFL thickness in both NTG and HTG (Pearson's r, p<0.05). Mean RNFL thickness/disc area ratio was significantly larger in HTG than NTG (35.21+/-18.92 vs. 31.30+/-10.91, p=0.004). CONCLUSIONS: These findings suggest that optic disc and RNFL damage pattern in NTG may be different from those of HTG.

Pulsatile Ocular Blood Flow in Healthy Koreans

PURPOSE: To determine the normal reference range of pulsatile ocular blood flow (POBF) values in healthy Korean subjects and to find out the factors that may affect them. METHODS: A total of 280 eyes of 280 normal subjects were included in this study. Best corrected visual acuity (BCVA), intraocular pressure (IOP), axial length, POBF, systemic blood pressure, and pulse rate were measured. The mean, standard deviation, range, and the 5th and 95th percentiles of POBF were calculated, and the influences of various parameters to POBF were determined by multiple regression analyses. RESULTS: The mean POBF value was 766.0+/-221.6 microliter/min in men and 1021.1+/-249.5 microliter/min in women. The 5th and 95th percentiles for POBF values were 486.0 microliter/min and 1140.0 microliter/min in men and 672.0 microliter/min and 1458.0 microliter/min in women. The POBF values were significantly influenced by gender, mean blood pressure, pulse rate, and axial length. CONCLUSIONS: Even though the POBF values were influenced by gender, BP, and axial length, we could define the normal reference range of POBF in healthy Koreans.

Mesopic Contrast Sensitivity Functions in Amblyopic Children

This study both measured and compared the mesopic contrast sensitivity function and the visual acuity in both normal and amblyopic eyes from amblyopic children using an ACV (visual acuity analyzer). Twenty one amblyopic children (mean age, 8.48 years; S.D., 1.68 years), 11 strabismic amblyopes and 10 anisometropic amblyopes, were tested. Based on a display of the standard optotypes, the minimal contrast level, at which the optotypes were correctly read for all sizes of displays from a distance of 1m, was measured. The contrast ranged from 1% to 99% and the spatial frequencies ranged from 0.6 to- 30cpd using a Landolt ring composed of low (0.6- 2.9 c.p.d.), intermediate (3.0 - 12.9 c.p.d.) and high level (13.0- 30.0 c.p.d.) frequencies. As the visual acuity decreased, the mesopic contrast sensitivity function decreased along the contrast sensitivity axis. However, the peak sensitivity was noted at the same spatial frequencies. A comparison between the normal eye and the corresponding amblyopic eye showed that under mesopic conditions, the contrast sensitivity functions decreased more in the intermediate spatial frequencies than in the other spatial frequencies. The mesopic contrast sensitivity function decreased in the amblyopic eyes, which suggests the possibility of its use an adjunct to an evaluation of amblyopia.

Eye Movement Recording using Computer Image Recognition Technique

PURPOSE: To describe that Computer image recognition technique is more accurately and less invasive than other methods, which using contact lens with a search probe or electrodes for record of eye movements. METHODS: A reference marker which was infrared was attached to the center of the forehead of the patients and the infrared light was illuminated to both eyes. Video image sequences were recorded using digital CCD camera and the captured image frames (640 X 480) were processed using a image analysis program. From which each image frame captured, pupil area was saperated using difference of brightness in pupil and iris. And then the pupil center was determined by calculating the center-of-mass of black pixels to meet the pupil threshold criteria. RESULTS: In a post-processing process, we could acquire horizontal and vertical eye position and velocity data. Inverse fast fourier transformation(FFT) and digital filtering algorithm were applied to filter out noise due to limited resolution of the CCD camera and sampling rates. Experimental result showed that the system could detect about 0.2mm positional location and 30Hz horizontal and vertical eye movements simultaneously. CONCLUSIONS: We could accurately measure and record two dimensional eye movements of patients (horizontal and vertical simultaneously) in real time with some head movements.

Postoperative Refractive Error in Combined Operation of Vitrectomy and Intraocular Lens Implantation

PURPOSE: To compare the actual and expected refractive errors of intraocular lens (IOL) implantation with vitrectomy in various conditions. METHODS: One hundred sixty-five eyes were divided into five groups: Group 1 had cataract extarction and IOL implantation only, Group 2 had cataract extraction and IOL implantion after vitrectomy, Group 3 had cataract extraction and implantation of an IOL with vitrectomy, Group 4 had cataract extraction and IOL implantaion with vitectomy and scleral encircling, and Group 5 had cataract extraction and IOL implantaion with vitrectomy and intraocular gas injection. The actual and expected refractive errors of IOL implantation were compared. RESULTS: Mean myopic shift was 0.15 diopter for group 1, 0.22 diopter for group 2, 0.20 diopter for group 3, 1.40 diopter for group 4, 0.91 diopter for group 5. CONCLUSIONS: Vitrectomy alone has no influence on refractive error but when scleral encircling or intraocular gas injection were performed with vitectomy, there were statistically significant myopic shifts.