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.

A Factual Survey on PRK and LASIK in Korea

The surgeons performing photorefractive keratectomy[PRK]and laser in situ keratomileusis[LASIK]and patients got these relatively convenient and effective procedures for correcting myopia are increasing now. Korean Society of cataract and refractive surgery[KSCRS]performed a survey on PRK and LASIK with the members of this society. Seventy-six members replied to questionnaire and fifty answered that they were doing PRK or LASIK. The number of surgeons who had performed more than three hundred cases of PRK or LASIK were twenty-four and seventeen, respectively. The number of surgeons who having done these procedures less than three years were twenty-five and this suggested these operations were much increased recently. Maximum attempted corrections were -5.9 to -6.5 diopter in PRK and -14.4 to -14.9 diopter in LASIK. The surgeons thought reduction of best corrected visual acuity as the complication of LASIK procedure was occurred the incidence of 3.97%[0.1~30%]. Eighty percent of members replied they explained the predictable result and possible complication of operation to their patients by themselves and seventy seven percent of members agreed to the plan that surgeons should do PRK and LASIK with qualification from Korean Ophthalmological Society. We suggest this survey could help performing better procedure by establishing common therapeutic criteria with communication of information and opinion between ophthal-mologist.

Sensitivity and Specificity of Frequency Doubling Perimetry FDPin Early Glaucoma

We evaluated the sensitivity and specificity of Frequency doubling perimetry[FDP]with fourty-nine normal subjects and twenty-six patients of early glaucomatous field change. We regarded Humphrey field analyzer[HFA]30-2 GHT as gold standard. 'True positive 'was regarded as 'outside normal limit 'or P-value of MD or PSD below 0.05 at HFA, 'abnormal 'at FDP P-value of MD or PSD below 0.05. MD of early glaucoma was -5.4 decibel at HFA and -6.61 decibel at FDP, Sensitivity of early glaucoma was 96.1%with FDP and 84.6%with HFA;specificity, 89.7%with FDP and 83.6%with HFA. We could confirm FDP threshold test showed good sensitivity in detecting early glaucoma. Especially, use of PSD increased efficiency of the test.