Measures for preventing recurrence after pterygium surgery.

PURPOSE: To introduce an improved technique of pterygium surgery and to compare postoperative results between this technique and previous techniques. METHODS: In a retrospective survey, the records of 216 consecutive eyes with primary pterygium that underwent surgery by three different techniques were reviewed. The new technique (mini-flap technique) involves making a small excision of the pterygium body, removing the pterygium head by scraping with forceps, applying mitomycin C (MMC), and performing a small conjunctival transposition flap. The previous technique (large-flap technique II) involved making a large excision in the pterygium body, removing the pterygium head with a knife, applying MMC, and performing a large transposition flap. Large-flap technique I is the same as large-flap technique II except for the use of intraoperative MMC. The recurrence rate of each technique was estimated by the Kaplan-Meier life table analysis. RESULTS: The recurrence rates estimated at 1 year after surgery were 15.5% in large-flap technique I, 4.2% in large-flap technique II, and 0% in the mini-flap technique. Large-flap technique II or the mini-flap technique had significantly lower recurrence rates compared with large-flap technique I ( p = 0.02 and p < 0.01, respectively). The mini-flap technique had a significantly lower incidence of conjunctival scarring or granuloma compared with large-flap technique I and large-flap technique II ( p = 0.05 and p = 0.03, respectively.) CONCLUSIONS: The mini-flap technique was useful for preventing recurrence and was technically easier and induced fewer postoperative complications than large-flap techniques I and II.

Effects of pH on contraction and Ca2+ mobilization in vascular smooth muscles of the rabbit basilar artery.

The present study was undertaken to investigate the effects of extracellular pH (pHe) and intracellular pH (pHi) on 5-hydroxytryptamine (5-HT)-induced contraction and Ca2+ mobilization in vascular smooth muscles. Strip preparations of the rabbit basilar artery without endothelium were loaded with 40 microM fura-2-AM and 2 microM BCECF-AM and mounted in an organ bath. The isometric tension was recorded by using a force displacement transducer. Administration of 5-HT caused dose-dependent contraction in the rabbit basilar arteries. Acidification of pHe from 7.40 to 6.90 reduced the 5-HT-induced contraction and [Ca2+]i transients. Alkalinization of pHe from 7.40 to 7.90, on the other hand, enhanced the contraction and elevation of [Ca2+]i. In the other series of experiments, pHi (7.12 in normal PSS) was selectively altered by adding either butyric acid or trimethylamine. Intracellular acidification (pHi = 6.89) and alkalinization (pHi = 7.35) without changes in pHe produced qualitatively similar effects to those caused by extracellular acidification and alkalinization, respectively. Ca-sensitivity, which is defined as Deltatension/Delta[Ca2+]i, was not affected by the alteration of pHe nor pHi. In the Ca2+-free solution, the addition of 5-HT produced transient increases in [Ca2+]i and isometric tension that were much smaller than those in the normal physiological salt solution. The 5-HT-induced responses of [Ca2+]i and tension in the Ca2+-free solution were not affected by acidification nor alkalinization. These results suggest that a 5-HT-induced contraction is significantly modulated by pH through changing the [Ca2+]i transients, and that the change of pHi plays, at least in part, a role in the alteration of 5-HT-induced contraction resulting from acidosis or alkalosis in the rabbit basilar artery.

Measurement of intraocular pressure by both invasive and noninvasive techniques in rabbits exposed to head-down tilt.

This study investigates changes in intraocular pressure (IOP) in rabbits during head-down tilt (HDT), which is commonly used as an experimental model to simulate microgravity. IOP was measured by the needle insertion technique (IOPNEEDLE) and Tono-pen tonometry (IOPTONO-PEN). Although the absolute value of the IOPTONO-PEN was significantly smaller than that of the IOPNEEDLE, a significant correlation (r = 0.99) was observed between them. A linear regression analysis yielded an equation as follows: IOPTONO-PEN = 0. 67 IOPNEEDLE - 0.67. Both the IOPNEEDLE and the IOPTONO-PEN changed depending on the tilt angle. Tilting from horizontal (0 degrees) to 75 degrees head-down increased the IOPNEEDLE and the IOPTONO-PEN by 7.3 +/- 0.8 (mean +/- SEM) mmHg and 4.4 +/- 1.3 mmHg. The IOPNEEDLE elevated from 13.1 +/- 1.3 to 16.9 +/- 1.0 mmHg immediately after the onset of 45 degrees HDT and then gradually declined. The value of the IOPNEEDLE during 8 h of HDT was significantly higher than the value in the control animals, which were kept at the horizontal prone position throughout the experiment. Similar findings were observed in the IOPTONO-PEN. These results suggest that the needle insertion technique and the Tono-pen tonometry are both useful for measuring IOP in rabbits.

Fast oscillations of the electro-oculogram in a series of normal subjects.

Using a newly devised automated electro-oculograph, Nidek EOG-2, the fast oscillations (FOs) of the electro-oculogram were recorded in the 120 eyes of 60 normal subjects. We evaluated the normal means and variability of FO parameters, namely the "Rf" value, which is the average ratio in percentage of the maximum amplitude in the dark period (AD)/the minimum amplitude in the light period (AL), and the "df" value, which is the average difference between AD and AL during the FO measurement. No correlation with age was noted in the "Rf" value, although the lowest mean value of the "df" was detected in the twenties. Regarding sex, the mean levels of the "Rf" and "df" for female subjects were statistically higher than those for male subjects in the younger and global age groups. Some hormonal factor which can stimulate the metabolic activity of the retinal pigment epithelium might have caused this sexual difference.