Ability of Scanning Laser Polarimetry (GDx) to Discriminate among Early Glaucomatous, Ocular Hypertensive and Normal Eyes in the Korean Population

We investigated the ability of the GDx-Nerve Fiber Analyzer (NFA) to discriminate between normal and early glaucomatous eyes among Korean individuals by reviewing the medical records of 217 consecutive subjects: 61 early glaucoma patients, 68 ocular hypertensive patients, and 88 normal subjects. GDx parameters were compared using ANOVA. The Receiver Operating Characteristics (ROC) curve for each GDx-NFA variable was used to diagnose each parameter, and Pearson correlation coefficients were calculated to assess the association between GDx-NFA parameters and visual field indices in early glaucoma. The best GDx parameters to discriminate between early glaucomatous and normal subjects were the number, maximum modulation, ellipse modulation and inferior ratio (i.e. area under the ROC curve > 0.8). A value for the Number of equal to or greater than 27 was optimal for detecting early glaucoma, with a sensitivity of 80.3% and specificity of 80.7%. In addition, symmetry was positively correlated with the corrected pattern standard deviation (CPSD) among visual field indices in early glaucoma.

Interocular comparison of nerve fiber layer thickness and its relation with optic disc size in normal subjects

We conducted an investigation of the relation between RNFL thickness and optic disc size along with an interocular comparison of optic disc size, RNFL thickness, and RNFL density in healthy subjects. A total of 64 normal eyes from 32 Korean volunteers were enrolled in this study. A GDx Nerve Fiber Analyzer with software version 2.0.09 was used to image all subjects. Optic disc size was measured by pi x (horizontal radius) x (vertical radius). The RNFL density of each quadrant was calculated by dividing each quadrant integral by the total integral. Optic disc size was positively correlated with the total RNFL thickness (r = 0.615, p < 0.01). Optic disc size and RNFL density were inversely related in the superior quadrant (r = -0.248, p < 0.05). There was a significant positive correlation between optic disc size and RNFL density in the nasal quadrant (r = 0.439, p < 0.01) and the temporal quadrant to a certain degree. A significant positive correlation was found between the right and left eyes in terms of total RNFL thickness in and that of each quadrant. Interocular RNFL density was positively correlated in both the temporal and nasal quadrants. These findings must be considered when one evaluates and compares RNFL measurements between two eyes as is often the case where both eyes are usually affected in the course of glaucomatous RNFL damage.

IOP & Corneal Diameter in Premature Infants

Premature infants may have underdevelopment of multiple organs including ocular structures.Sixty one premature infants of thirty seven weeks-old or younger were examed to note the correlation of intraocular pressure andcorneal diameter with gestational age and birth weight. Following topical anesthesia, intraocular pressure was measured with Tonopen II tonometer and the corneal diameter with caliper.The fundus was examed for the presence of risk factors for retinopathy of prematurity. Average gestational age of the subjects was 30.2 weeks (26~37 weeks), and birth weight was 1419 g (677~3691 g).Thirty five subjects had experienced oxygen therapy, and eleven patients were found to have any stage of retinopathy of prematurity. Average intraocular pressure was 10.8 +/-2.3 mmHg (mean +/-standard deviation), corneal diameter was 8.8 +/-0.5 mm.No significant correlation was found between intraocular pressure or corneal diameter and gestational age or birth weight.The presence of retinopathy of prematurity did not seem to influence the intraocular pressure and corneal diameter. Our results suggested that the growth in uterus did not seem to affect intraocular pressure or corneal diameter in gestational age of 26 to 37 weeks. These normative values may aid ophthalmologists in assesing intraocular pressure and corneal diameter in premature infants.

Cultured Human Retinal Pigment Epithelial Cell Injury Induced by Ultraviolet: Potentiation with Subtoxic Intracellular Zinc Depletion

We studied the mechanism and inhibition of cell death by exposure to UV alone or combination of UV exposure and intracellular zinc depletion with TPEN in cultured human retinal pigment epithelial cells (RPE). Cell death was quantified by measuring LDH release from injured cells. RPE were exposed to UV at 253.7 nm for 1~20 minutes.The 2~5 minutes UV exposure was duration-dependently cytotoxic, whereas 1minute exposure was minimally so.And exposure to TPEN induced concentration-dependent cell death at 1~4 micrometer range ;0.5 micrometer TPEN was minimally toxic.Then, cultures were exposed to varying exposure durations of UV in the absence or presence of 0.5 micrometer TPEN.At any point, the presence of TPEN markedly increased UV toxicity.In contrast, cell membrane-impermeable zinc chelator showed no toxicity.On the other hand, addition of a protein synthesis inhibitor or caspase inhibitor was markedly protective.In addition, RPE injury with exposure to combination of UV 1 min and TPEN 0.25 micrometer was accompanied by TUNEL and Hoechst staining positivity indicating that the toxicity is mainly apoptosis.Electron microscopic examinations revealed that nuclear fragmentation occurred even in sublethal UV or TPEN exposure, suggesting that the injury process already began at these condition consistently with the death being apoptosis. The present study has shown that combination of known risk factors may act synergistically to induce ARMD etc.The RPE injury induced by low dose UV and minimal intracellular zinc depletion was inhibited with protein synthesis inhibitor or caspase inhibitor, so these results suggested the possibility of prevention or treatment of RPE dysfunction.

Visual Acuity and Intraocular Pressure Among Adults Visiting Health Care Center in Seoul

The visual acuity and intraocular pressure were measured and analyzed in 1641 healthy adults visiting AMC health care center. The visual acuity was measured irrespective of wearing glasses and contact lenses with autoacuitometer and we defined this visual acuity as everyday vision. The average everyday vision of better eye was 1.10 in males and 0.96 in females[converted with Han chart:0.95, 0.85; converted with Jin chart: 0.89, 0.78] between 20 and 69 years old. The average everyday vision in males was better than that of females[p<0.01]. The everyday vision was decreased in older subjects. The everyday vision of the subjects under 44 years of age was better than that of over 45 years of age[p<0.01]. The linear equation of the everyday vision according to age was Y=-0.0049X 1.30 in males[R=-0.77], Y=-0.0112X 1.43 in females[R=-0.88][X:age, Y:visual acuity, R:correlation coefficient]. In classification according to occupation, the visual acuity of housewives was low 0.89, but when matched to age &sex it was statistically insignificant. The average intraocular pressure was 13.25+/-2.57 mmHg in males, 12.85+/-2.45 mmHg in females. The IOP of the subjects under 44 years of age was not different from those over 45 years of age[male p=0.31, female p=0.20]. The number of subjects higher than 21 mmHg in intraocular pressure was 21[0.64%].