The Effect of Axial Length on the Variability of Stratus Optical Coherence Tomography

PURPOSE: To evaluate the effect of axial length on the variability of retinal nerve fiber layer (RNFL) thickness measurements using the Stratus optical coherence tomography (OCT) in normal and glaucomatous eyes. METHODS: We measured the RNFL thickness in 474 subjects using the Stratus OCT twice during the same day. Axial length was measured with the IOLMaster, and refractive error was the absolute value of the spherical equivalent measured with an auto ref-keratometer. Standard deviation in overall mean RNFL thickness was used as the dependent variable to identify significant correlations. RESULTS: Long axial length affected the variability in the RNFL thickness value by stratus OCT at the temporal quadrant (p = 0.006) and clock-hour sector 9 (p = 0.001). Refractive error also affected the variability of the RNFL thickness value by stratus OCT at the temporal quadrant (p = 0.025) and clock-hour sector 9 (p = 0.024). CONCLUSIONS: It is clinically significant that longer axial length demonstrates greater variability in temporal area as detected by OCT, a measurement which correlates with the preferably damaged position in the myopic glaucoma eye.

The Effect of Various Factors on Variability of Retinal Nerve Fiber Layer Thickness Measurements Using Optical Coherence Tomography

PURPOSE: To evaluate the effects of various factors on the variability of retinal nerve fiber layer (RNFL) thickness measurements using the Stratus optical coherence tomography (OCT) in normal and glaucomatous eyes. METHODS: Four hundred seventy-four subjects (103 normal eyes and 371 glaucomatous eyes) were scanned to determine the RNFL thickness measurements using the Stratus OCT. Measurements were obtained twice during the same day. The standard deviation (SD) was used to compare the variability in RNFL thickness measurements of the normal subjects to that of the glaucomatous patients. Multivariate regression analysis was used to evaluate which covariates were independent predictors of SD in overall mean RNFL thickness. RESULTS: The mean SD of all RNFL thickness measurements was larger in the glaucoma group except in one sector. In the multivariate regression analysis, the average signal strength (SS) and the relative SS change (difference in SS between initial and repeat scans, divided by initial SS) were independent predictors of the SD in the RNFL thickness measurements (partial R2 = 0.018, 0.013; p = 0.016, 0.040, respectively). CONCLUSIONS: Glaucomatous eyes tend to be more variable than normal eyes in RNFL thickness measurement using the Straus OCT. The average SS and the relative SS changes appear to correlate with the variability in RNFL thickness measurement. Therefore, the results of the RNFL analysis should not be interpreted independently of these factors.

The Result of Byon's Test in Incomplete Nasolacrimal Duct Obstruction

PURPOSE: To assess the threshold of draining capacity, we performed Byon's test in patients complaining epiphora with incomplete nasolacrimal duct obstruction. METHODS: We measured the draining capacity by using Mclntyre R cannula in 54 patients (98 eyes) from February to December 2000. Through the cannula inserted to lacrimal sac we instilled distilled water for 1 minute at the height of 1.3 meter, then we counted the amount of fluid dropped. RESULTS: The mean values of draining capacity were 2.42+/-0.92 cc/min in men, 2.20+/-0.90 cc/min in women (2.25+/-0.91 cc/min in total). These were lower than normal value by about 48% and the difference was statistically significant (P<0.0001). The highest values in each group were 3.53 cc/min in men, 3.45cc/min in women. Epiphora developed when the draining capacity decreased under the 79% of normal capacity. CONCLUSIONS: This study supports the previous theory that incomplete nasolacrimal duct obstruction may progress to complete obstruction. We hope for another convenient and accurate method for quantitative measurement of lacrimal drainage capacity which will be positioned as a basic test of ophthalmology.

The effect of Hydrogen Peroxide and Ascorbic Acid on Proliferation and Morphology of Lens Epithelial Cells

PURPOSE: The therapeutic effects of amniotic membrane transplantation (AMT) contain anti-fibrosis, anti-inflammation and facilitation of epithelialization. Thus we investigated whether applying of amniotic membrane (AM) ointment could get the same effect as AMT. METHODS: Alkali burn was induced by applying 6 mm round filter paper which was soaked with 1 N NaOH, onto the central cornea for 60 seconds on both eyes of 10 white rabbits. Then we applied AM ointment on one eye and base ointment on the other eye, four times a day for 1 week. The corneas were harvested for histopathologic studies at 1 day and 3 weeks. Corneal opacity and thickness were measured in 3 days and 1, 2, 3 weeks. RESULTS: In the AM ointment applicated group, the number of the infiltrated PMNs (polymorp-honuclear cells) and apoptotic keratocytes were significantly less than that of the control group (P<0.05). The degree of lipid peroxidation and myofibroblast differentiation were less than those of the control group. Corneal opacity and corneal edema were less in AM ointment group than control group. CONCLUSIONS: AM ointment application after alkali burn is beneficial to reduce inflammation, keratocyte apoptosis and lipid peroxidation, and is considered to suppress corneal haze by these effects. Therefore, this report may be a basic study for the AM ointment research to treat recalcitrant keratitis.

Transmission Electron Microscopic Findings of the Normal and Mature Cataractous Lenses

PURPOSE: Phacoemulsification is now a well-established technique for the surgical treatment of soft cataractous lens, hard lenses being considered less suitable. We have been examined noraml and mature cataractous lenses by transmission electron microscopy. METHODS: A soft cataractous lens and a normal lens were extracted from cadavers. In addition, four hard cataractous and a soft cataractous lenses were extracted from five patients who underwent extracapsular cataract extraction. RESULTS: In transmission electron microscopic investigation of normal lens and soft and hard cataractous lenses, the normal lenses showed classical ball-and-socket inter- digitations and relatively regular arrangement of fiber cell. In soft mature cataracts, disruptions of fiber cell morphology including numerous ball-and-socket interdigitations, abrupt continuities in fiber cell membranes and high amplitude of undulating membranes were present. In the hard cataractous lenses, the fiber cell morphology was severely damaged. The interfibrous spaces were more compact and irregular than soft mature cataracts. CONCLUSIONS: The large amount of irregular undulating membranes and flattening of fiber cells increases the condenssness of hard cataracts, and makes phacoemulsification less suitable.

Efficacy of Colorado Needle in Lid Surgery

Eyelid has rare infection and good wound healing due to rich blood supply, but often lead to excessive bleeding during surgery. Thus, bleeding control in time of operation is very important to secure operation field and minimize subcutaneous hemorrhage and edema after operation. Retrospectively, we analized intra- and post-operative complications of 92 patients who had undergone eyelid surgeries by one operator using Colorado patients who had undergone eyelid surgeries by one operator using Colorado dissection needle attached to monopolar electrocautery from March to October 1997. there were 49 patients of epiblepharon or entropion, 16 patients of ptosis, 10 patients of dermatochalasis and 17 patients of blepharoplasty. In all 92 patients who had be used with Colorado needle neither complications nor side effects were developed. Therefore, we consider that the colorado needle monopolar electrocautery is an useful instrument in eyelid surgery.