The effect of YAG laser anterior capsulotomy on prostaglandin concentration in aqueous humor

The YAG (yttrium aluminum garnet) laser has been recommended for anterior capsulotomies. One major complication is elevated intraocular pressure. We report a study of the biochemical content of the aqueous humor after a YAG laser anterior capsulotomy. We analyzed 6-keto-prostaglandin F1 alpha, thromboxane B2 and protein concentrations in the aqueous humor of human eyes. The average values of protein, 6-keto-prostaglandin F1 alpha, and thromboxane B2 in the control eyes were 81.3 +/- 14.0 mg/dL, 17 +/- 30 pg/mL, and 10 +/- 10 pg/mL, respectively. These values were elevated to 182.4 +/- 81.3 mg/dL, 401 +/- 55 pg/mL, and 576 +/- 148 pg/mL, respectively, after YAG laser anterior capsulotomy. The samples with a moderate level of 6-keto-prostaglandin F1 alpha (less than 300 pg/mL) had negligible changes of thromboxane. The elevation of thromboxane was obvious only when prostaglandin levels rose above 300 pg/mL.     

Nd:YAG激光前囊膜光切术后眼压和角膜厚度变化与房水内MDA含量的关系

目的：探讨Ｎｄ：ＹＡＧ激光前囊膜光切术后眼压升高和角膜内皮损伤的发生机制,观察丹参和维生素Ｅ在其中的保护作用。方法：２４兔（４８只眼）随机分为４组,其中药物组激光手术前后应丹参和维生素Ｅ。观察兔眼Ｎｄ：ＹＡＧ激光前囊膜光切术后２、１２、２４、４８小时的眼压和角膜厚度变化以及房水丙丙二醛（ｍａｌｏｎｄｉａｌｄｅｈｙｄｅ,ＭＤＡ）含量的改变。结果：激光术后眼压升高,角膜增厚、并伴随房水内ＭＤＡ含量明显     

Nd:YAG激光晶状体前囊膜切除术后房水内丙二醛变化与眼压的关系

探讨Ｎｄ：ＹＡＧ激光晶状丛前囊膜切除术后暂时性眼压升高的发生机制,观察丹参和维生素Ｅ对眼压升高的影响。方法２４只兔随机分为４组,药物且激光手术前后应用丹参和维生素Ｅ。定期观察激光术后眼压和房水内丙二醛含量的变化。结果激光术后发生暂时性眼升高并伴随房水内ＭＤＡ含量明显增加。药物组术后房水内ＭＤＡ含量无明显增加并且术后性眼压升高的幅度明显降低。结论激光前囊膜切除术后暂时性眼压升高与术后房水内ＭＤＡ含量     

The effect of neodymium: YAG laser capsulotomy on aqueous humor dynamics in the monkey eye

The creation of a posterior capsulotomy utilizing a neodymium:YAG (Nd:YAG) laser is often followed by an increase in the intraocular pressure (IOP). In order to study the cause of this pressure rise, six eyes of three cynomolgus monkeys underwent extracapsular cataract extraction followed 2 to 3 months later by Nd:YAG laser capsulotomy. Eyes were evaluated clinically and examined histopathologically at 1 hour, 3 hours, 1 day, 3 days, 1 week, and 1 month after laser treatment. Although IOP did not increase after laser capsulotomy, outflow facility was decreased 80% from baseline levels at 3 hours, at 3 hours, 1 day, and 3 days. After laser treatment, the anterior chamber and meshwork contained fibrin, lens material, inflammatory cells, pigmented macrophages, erythrocytes, and free pigment. Most of these elements had cleared the meshwork by 1 month.     

玻璃体切割术后前房氧含量变化研究

目的 观察兔眼玻璃体切割(玻切)术后前房氧含量的变化,探讨玻切术后发生白内障的可能机制.方法 40只兔随机分为A、B,C、D四组,每组10只兔.A组为空白对照组,其前房氧分压和氧含量作为基线值;B组为玻切术中充填平衡盐溶液(BSS)组;C组为玻切术中充填惰性气体(C_3F_8)组;D组为玻切术中充填硅油组.采用血气分析法分别测量A组及B、C、D三组术后1d、3d、7d、1月、3月前房氧分压,根据Henry定律计算氧含量.结果 前房氧分压和氧含量基线值分别为(4.90±0.06)kPa、(1.24±0.01)μl/ml;B、C两组术后各时间段的氧分压和氧含量均高于基线值(P<0.05);D组术后1d、3d、7d、1月的氧分压和氧含量高于基线值(P<0.05),3月时氧分压和氧含量回落至基线值.结论 玻切术后,玻璃体腔填充物不同,前房氧含量的变化不同;前房氧含量的增加,在一定程度上可能促进了术后白内障的形成.     

Determination of the aqueous humor volume by three-dimensional mapping of the anterior chamber

In this study involving 12 patients planned for routine cataract surgery, we used the topography of the anterior chamber depth and the corneal diameter obtained from Orbscan II data to calculate the aqueous humor volume. Prior to the surgical procedure, a small amount of fluorescein was injected into the anterior chamber and an aqueous humor sample was taken, from which the aqueous humor volume could be calculated by fluorometry. The volumes obtained from Orbscan II data were validated by the fluorometric measurements and compared to three theoretical formulas for aqueous humor volume calculation. The aqueous humor volume calculations based on the Orbscan II data aligned better to the fluorometric values (R(2) = 0.890) than the values obtained by Heim's formula (R(2) = 0.677), Brubaker's formula (R(2) = 0.671), and Schenker's formula (R(2) = 0.585), or the assumption of a constant aqueous humor volume.     

Effect of oxygen on aqueous humor dynamics in rabbits

A study was made in albino rabbits of the effect on aqueous humor dynamics of 100% oxygen, administered by face mask. A mean decrease in intraocular pressure of 4.9 mm Hg was found. This was accompanied by a decrease in episcleral venous pressure of 4.5 mm Hg. Anterior chamber aqueous humor flow decreased transiently after oxygen administration but returned to pre-oxygen levels after about 60 min. It was concluded that the sustained decrease in intraocular pressure which was caused by oxygen was secondary to the decrease in episcleral venous pressure and not to a decrease in the production of aqueous humor.     

Quantification of nitric oxide and cytokines in rabbit aqueous humor after neodymium:YAG laser capsulotomy

PURPOSE: The purpose of this study was to evaluate the presence of nitric oxide (NO) and cytokines such as interleukin 1 beta, interleukin 2 receptor (IL-2R), interleukin 6 and tumor necrosis factor alpha on aqueous humor after neodymium:YAG (Nd:YAG) laser posterior capsulotomy. METHODS: Fifteen rabbits (30 eyes) with dense posterior capsule opacities underwent Nd:YAG capsulotomy 4 months after phacoemulsification cataract surgery. After general and topical anesthesia, Nd:YAG capsulotomy was performed using an equal number of shots and power setting on all eyes. Aqueous humor specimens were collected from each eye preoperatively and at 12, 24 and 48 h after the surgery to determine NO and cytokine levels. RESULTS: The levels of NO and cytokines except IL-2R were significantly high as compared to preoperative levels in all eyes at 12 and 24 h postoperatively (p < 0.05). Although the levels of NO and cytokines were higher than preoperative levels at 48 h, the differences were not statistically significant (p > 0.05). CONCLUSION: These findings suggest that NO and cytokines appear to be potential inflammatory mediators in the occurrence of early inflammation following Nd:YAG posterior capsulotomy.