Time course of changes in optic nerve head circulation after acute reduction in intraocular pressure

PURPOSE: To study the time course of changes in circulation in the optic nerve head (ONH) after acute reduction in intraocular pressure (IOP) and to evaluate the effects of a calcium antagonist, a nitric oxide synthetase (NOS) inhibitor, indomethacin, and sympathetic nerve amputation on the changes in ONH circulation after reduction of IOP. METHODS: In anesthetized albino rabbits, acute reduction of IOP (acute increase in ocular perfusion pressure [OPP]) was manometrically achieved and normalized blur (NB), a quantitative index of tissue blood velocity obtained with the laser speckle method, was serially monitored for 30 seconds and 60 minutes. The effects of systemic administration of 1 microg/kg per hour nilvadipine (a calcium antagonist), 300 microg/kg Nomega-nitro-l-arginine (l-NAME, a nonselective NOS inhibitor), and 5 mg/kg indomethacin or sympathetic nerve amputation on the changes in NB after reduction of IOP were studied. RESULTS: During changes in IOP from 10 to 40 mm Hg and then back to 10 mm Hg, NB exhibited no significant change. During changes in IOP from 10 to 60 mm Hg and then back to 10 mm Hg, NB initially decreased with an increase in IOP to 60 mm Hg and then increased to baseline level when IOP was returned to 10 mm Hg. In the nilvadipine-treated rabbits, during changes in IOP from 10 to 40 mm Hg and back to 10 mm Hg and during the changes from 10 to 60 mm Hg and back to 10 mm Hg, NB decreased with increase in IOP to 40 or 60 mm Hg and then increased to slightly above the baseline when IOP returned to 10 mm Hg. l-NAME, indomethacin, and sympathetic nerve amputation each had little effect on the time course of change in NB. CONCLUSIONS: ONH circulation was stably maintained after reduction of IOP from 40 to 10 mm Hg but not after that from 60 to 10 mm Hg. The changes in NB after reduction of IOP occurred quickly and were partially impaired with a calcium antagonist, but not with the NOS inhibitor, indomethacin, or sympathetic nerve amputation. These findings suggest the importance of vascular smooth muscle in maintaining stable ONH circulation against reduction of IOP in a fashion nearly independent of NO, endogenous prostaglandins, and the sympathetic nervous system.     

Characteristics of reduction of intraocular pressure after trabeculectomy.

The change in intraocular pressure achieved after 98 trabeculectomy operations performed on 70 patients with primary open-angle glaucoma was analysed. The reduction was proportional to the untreated preoperative pressure, and the results indicated that a first trabeculectomy reduced the intraocular pressure to between 16 and 20 mmHg irrespective of its initial level. Cases which required medical therapy for final pressure control after surgery showed a distribution of initial intraocular pressure similar to those not requiring such therapy. In addition, these cases were reduced to a level of pressure only slightly above the arbitrary figure of 20 mmHg before medical therapy was added, and were therefore considered almost to have reached the normal physiological range. Cases submitted to a second trabeculectomy are discussed, including 2 cases with unexplained acute open-angle glaucoma some months after the first operation.     

Changes in the nerve fiber layer thickness following a reduction of intraocular pressure after trabeculectomy

PURPOSE: To assess changes in the nerve fiber layer thickness after trabeculectomy using scanning laser polarimetry. METHODS: The authors prospectively enrolled 46 eyes from 46 patients with primary open-angle glaucoma in whom intraocular pressure had been reduced by more than 30% after trabeculectomy without significant ophthalmic complications and from whom good quality images were obtained by a scanning laser polarimetry preoperatively and at 3 to 6 months after trabeculectomy. In each enrolled eye, changes in the nerve fiber layer thickness after surgery in the defined ring (1.8 disc diameters) around the optic disc were calculated in 10 degrees intervals (36 sectors in total) and in the following 4 quadrants (the sum of 9 10 degrees sectors): superior, nasal, inferior, and temporal. RESULTS: The mean intraocular pressure was 22.6 +/- 6.9 mm Hg preoperatively and 10.2 +/- 3.7 mm Hg postoperatively (P < 0.01). According to the analyses in every 10 degrees, the postoperative nerve fiber layer thickness was significantly greater than the preoperative nerve fiber layer thickness in the superotemporal region (10-50 degrees) and inferotemporal region (290-340 degrees) of the optic disc (P < 0.05). A stepwise multiple regression analysis showed that only the preoperative mean deviation in the Humphrey visual fields was a significant independent factor associated with changes in the nerve fiber layer thickness in the nasal and inferior quadrants. CONCLUSIONS: The thickness of the nerve fiber layer, as measured by scanning laser polarimetry, may increase after trabeculectomy, especially in the superotemporal and inferotemporal regions, and can be expected in cases in the early stage of glaucoma that have a better mean deviation.     

Optic cup enlargement followed by reduced optic nerve head circulation after optic nerve stimulation.

PURPOSE: To investigate changes in optic nerve head (ONH) circulation, visual evoked potentials (VEPs), and ONH cupping after stimulation of the optic nerve. METHODS: Electrodes were fixed above the optic chiasma in rabbits under general anesthesia. Screw-type electrodes for VEP recording were fixed on the dura. ONH circulation, intraocular pressure (IOP), and blood pressure (BP) were measured after the passage of a current of 0.1 mA for 0.1 second (weak stimulation), 1 mA for 1 second (moderate), 5 mA for 10 seconds (strong), or 25 mA for 10 seconds (severe). Normalized blur (NB), indicative of tissue blood flow and velocity, was measured in the ONH after each stimulation, by using a laser speckle circulation analyzer. Changes in VEP and ocular fundus were also recorded. The ratio of cup area (CA) to disc area (DA) was measured before and 4 weeks after stimulation. After all experiments, the ONH was histologically examined. RESULTS: Weak stimulation increased NB in ONH for 10 minutes, whereas strong or severe stimulation significantly decreased NB for a longer time, in a dose-dependent manner. BP showed no significant change, except with severe stimulation. IOP was not significantly changed. VEP amplitude was reduced 30 minutes after strong stimulation. The CA-to-DA ratio was significantly increased 4 weeks after strong stimulation. In some rabbits, disc hemorrhage occurred, followed by enlargement of disc cupping, with slight gliosis. CONCLUSIONS: Electrical stimulation of the optic nerve changed ONH circulation and VEPs and increased disc cupping. This technique warrants further investigation as an experimental model for normal-tension glaucoma.     

Control of intraocular pressure after trabeculectomy

Control of intraocular pressure (IOP) is the goal of trabeculectomy, and pursuit of this goal does not end with the completion of the surgical procedure. Proper postoperative management of the trabeculectomy patient requires an understanding of possible events that alter IOP and knowledge of the treatments to control IOP. Recent changes in surgical technique, including the use of antimetabolites, have provided new challenges in the postoperative management of trabeculectomy patients. Interventions are described to restore the flow of aqueous to the filtering bleb in the early postoperative period, to manage flat anterior chambers with both high and low intraocular pressures, to manage a failing filtering bleb, and to manage hypotony. Herein we discuss current methods for controlling IOP in the postoperative period.     

Different modes of intraocular pressure reduction after three different nonfiltering surgeries and trabeculectomy

Purpose  

To study the mode of intraocular pressure (IOP) reduction based on correlation with the preoperative IOP after filtering and nonfiltering surgeries.     

Time course of the change in optic nerve head circulation after an acute increase in intraocular pressure

PURPOSE: To investigate the time course of changes in optic nerve head (ONH) circulation after an acute increase in intraocular pressure (IOP), by using the laser speckle method, and to evaluate the effects of a calcium antagonist, the nitric oxide synthetase inhibitor, indomethacin, or sympathetic nerve amputation on the response in ONH circulation after an acute increase in IOP. METHODS: In rabbits, the normalized blur (NB) level, a quantitative index of tissue blood velocity in the ONH, was monitored for 60 minutes after an increase in IOP from 20 mm Hg to 40, 50, or 60 mm Hg and for 25 seconds after increase in IOP from 20 mm Hg to 50 or 60 mm Hg with high time resolution. The effects of systemic administration of 1 micro g/kg per hour nilvadipine (a calcium antagonist), 30 mg/kg N(omega)-nitro-L-arginine (L-NAME), or 5 mg/kg indomethacin, or those of sympathetic nerve amputation on the time course of the changes in NB were studied. RESULTS: NB showed a quick recovery within several seconds after increase in IOP to 40 or 50 mm Hg, whereas no or little recovery occurred after an increase to 60 mm Hg. The nilvadipine treatment significantly increased NB at IOP of 20 mm Hg (baseline NB, P = 0.045) and apparently impaired the recovery of NB after the increase in IOP. After L-NAME administration, baseline NB significantly decreased (P = 0.028), and the NB recovery time was slightly but significantly prolonged (P = 0.012). Indomethacin showed no effects on baseline NB or NB recovery. Sympathetic nerve amputation increased baseline NB (P = 0.027), but did not influence NB recovery. CONCLUSIONS: The current results showed a quick recovery response in the ONH circulation after an acute increase in IOP in rabbits. A calcium antagonist impaired the response. Production of nitric oxide or prostaglandins or the sympathetic nervous system is probably not mainly responsible for the reaction.     

复合式小梁切除术治疗非穿透小梁切除术后眼压失控

目的：探讨复合式小梁切除术治疗原发性开角型青光眼行非穿透小梁切除术后眼压失控（眼压升高）的长期疗效与安全性。方法：回顾分析了2006-03/2011-07非穿透小梁切除术治疗原发性开角型青光眼术后眼压失控（眼压升高）再次行小梁切除术的连续随访患者13例25眼。青光眼术后再次眼压异常升高,均属于难治性青光眼,我们采取复合式小梁切除术,对于仅存中心视岛及管状视野患眼,手术在表面麻醉联合球筋膜浸润麻醉下实施。主要检查指标：手术前后眼压、视力、角膜水肿情况、滤过泡特征、前房深浅及其它并发症。结果：随访3mo～5a,非接触眼压测定术前眼压28～52mmHg,术后眼压11.7～18mmHg,术后3mo,眼压为145mmHg,眼压以≤21mmHg为成功标准。术后3mo,视力提高3眼（12%）,视力不变17眼（68%）,视力下降5眼（20%）;术后21眼角膜均变清亮;功能性滤过泡22眼（80%）,有3眼为非功能性滤过泡,眼压再次高于21mmHg,二次进行复合式小梁切除术后眼压控制在21mmHg以下;术后有15眼（60%）出现前房轴深在1.5～2CT间,均自行恢复;术中、术后有10眼（40%）出现不同程度的前房出血,经对症治疗后均已吸收;术后有5例5眼（20%）出现房水闪辉,经散瞳及典必殊滴眼液进行眼局部频点后房水闪辉完全消失,未发生眼内炎等并发症。结论：小梁切除术目前仍是可挽救有视力眼的青光眼最经典、最有效的方法;复合式小梁切除术是原经典手术方式的进一步发展;青光眼术后眼压再次异常升高均属于难治性青光眼,原发性开角型青光眼行非穿透小梁切除术后眼压失控应用复合式小梁切除术再次治疗,证实安全有效,长期疗效满意,是弥补非穿透小梁切除术眼压失控（升高）后有效的治疗措施,并且可以一眼多次手术;有效地保护仅存的视力,维持了一定的视功能;晚期原发性开角型青光眼不适合非透性小梁手术。     

Optic nerve head circulation in untreated ocular hypertension.

AIMS--The laser Doppler technique was used to compare the capillary blood speed measured at localised sites of the optic nerve head in stable, untreated ocular hypertensive patients with that measured in healthy normal subjects. The stereophotogrammetric technique was also used to measure the retinal nerve fibre layer thickness at the disc margin in the eyes of the patients. METHODS--Doppler broadening measurements were made at superior and inferior temporal disc sites in 18 eyes of 10 ocular hypertensive patients and in 12 eyes of seven age and sex-matched normal subjects. RESULTS--On average, Doppler broadening and, hence, capillary blood speed were significantly higher (p = 0.018) in the patients than in the normal subjects. The largest values of Doppler broadening in the patients were measured at sites adjacent to the thinnest retinal nerve fibre layer. Linear regression analysis showed a significant inverse relation (p = 0.0004) between Doppler broadening and nerve fibre layer thickness in left eyes, and a nearly significant relation (p = 0.06) in right eyes. At temporal sites of the optic nerve head there is a compensatory relation between a thinning nerve fibre layer and a locally increasing blood supply to the optic nerve head. CONCLUSION--Together with previous observations of fluorescein filling defects in similar patients, these results indicate that there is spatial heterogeneity of blood flow in the optic nerve head in stable, untreated ocular hypertensive patients.     

Raised intraocular pressure with topical steroids after trabeculectomy

A prospective study of 87 eyes of 52 patients with primary open-angle glaucoma showed a significant steroid-induced rise in intraocular pressure in the 4 weeks after trabeculectomy in 23% of eyes. The steroid response rate was lower (17%) in those eyes that had trabeculectomy without a prior trial of medical therapy than in those who had surgery only after failure of medical therapy (36%), but this difference just failed to reach statistical significance. The responders were not significantly different from the non-responders as regards level of intraocular pressure or severity of visual field loss at diagnosis. The frequency of response was lower than that expected in the normal and in the glaucoma population and fell further in the late post-operative period when only 3 of 8 previously responsive eyes submitted to re-challenge with topical steroids showed persisting responsiveness. Topical steroids may be the commonest cause of high intraocular pressure in the first weeks or even days after trabeculectomy. Decisions about long-term supplementary medical therapy should therfore only be taken several weeks after withdrawal of the post-operative steroid drops.     

青光眼滤过手术后高眼压的临床分析

目的：探讨青光眼患者行小梁切术后发生高眼压(>21mmHg)的常见原因及处理方法。
　　方法：回顾性研究我院2010-07/2014-09青光眼患者行小梁切除术后出现高眼压的病例24眼,分析其常见原因、处理方法。
　　结果：导致术后早期高眼压的因素有：发生滤过泡瘢痕11眼(46%)、滤过内口阻塞4眼(17%)、恶性青光眼3眼(12%)、虹膜切除不合理2眼(8%)、前房积血2眼(8%)、包裹性囊状滤过泡2眼(8%)。经对症治疗后,患者眼压均控制在21 mmHg以下。
　　结论：青光眼行小梁切除术后高眼压是由多因素造成的,术前、术中尽量避免,术后及早发现给予对症处理是手术成功的关键。     

Changes in optic nerve head blood flow after therapeutic intraocular pressure reduction in glaucoma patients and ocular hypertensives

PURPOSE: To detect and quantify changes in optic nerve head (ONH) and peripapillary retinal blood flow by scanning laser Doppler flowmetry (SLDF) in open-angle glaucoma (OAG) and ocular hypertension (OHT) after therapeutic intraocular pressure (IOP) reduction. DESIGN: Prospective, nonrandomized, self-controlled trial. PARTICIPANTS: Twenty patients with OAG and 20 patients with OHT with clinical indications for therapeutic IOP reduction were prospectively enrolled. INTERVENTION: IOP reduction was achieved by medical, laser, or surgical therapy. All patients had IOP reductions more than 20% and a minimum of 4 weeks follow-up. MAIN OUTCOME MEASURES: Blood flow measurements were performed by SLDF analysis software (version 3.3) using Heidelberg Retina Flowmeter images. Statistical evaluations were performed on both groups using a two-tailed distribution paired t test. RESULTS: Twenty patients with OAG had a mean IOP reduction of 37% after treatment. In these patients, mean (+/- standard deviation) rim blood flow increased by 67% (from 158 +/- 79 arbitrary units to 264 +/- 127 arbitrary units, P = 0.001), whereas mean temporal peripapillary retinal flow decreased by 7.4% (P = 0.24), and mean nasal peripapillary retinal flow increased by 0.3% (P = 0.96). Twenty OHT patients had a mean IOP reduction of 33% after treatment. In contrast to the OAG group, neither the mean rim blood flow (7.5% increase from 277 +/- 158 arbitrary units to 298 +/- 140 arbitrary units, P = 0.41) nor the mean temporal (P = 0.35) or nasal (P = 0.88) peripapillary retinal flow changed significantly. CONCLUSIONS: For a similar percentage of IOP reduction, OAG patients had a statistically significant improvement of blood flow in the neuroretinal rim of the ONH, whereas OHT patients did not demonstrate such a change. Peripapillary retinal blood flow, expected to be affected less in glaucoma, remained stable in both groups. In addition to indicating a response to therapy in OAG patients, the reported changes in rim perfusion suggest that ONH autoregulation may be defective in OAG while intact in OHT.     

Long-term effect of phacoemulsification on intraocular pressure after trabeculectomy

PURPOSE: To evaluate the effect of temporal clear corneal phacoemulsification on intraocular pressure (IOP) in eyes that have had trabeculectomy. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: This retrospective study evaluated the IOP in 48 eyes (35 patients) that had temporal clear corneal phacoemulsification after trabeculectomy. The mean interval between trabeculectomy and phacoemulsification was 27 months +/- 21 (SD) and the mean follow-up after phacoemulsification, 23 +/- 12 months. Intraocular pressure and antiglaucoma therapy before cataract surgery and at the end of follow-up were evaluated. For statistical analysis, the paired t test, Wilcoxon test, and chi-square test were used. RESULTS: Thirty-five eyes (73%) preoperatively and 25 eyes (52%) postoperatively were controlled (IOP < 22 mm Hg) without antiglaucoma therapy. The difference was statistically significant (P =.04, chi-square test). At the end of follow-up, the increase in mean IOP (1.6 mm Hg) and in mean number of antiglaucoma medications (0.4) was statistically significant (P =.002 and P =.05, respectively). CONCLUSIONS: Temporal clear corneal phacoemulsification after trabeculectomy was followed by a slight but statistically significant increase in IOP and the need for antiglaucoma medication after 2 years. However, the impairment in IOP control is comparable to that in the natural course of trabeculectomy.     

非穿透小梁手术后高眼压的早期房角镜检查

目的观察非穿透小梁手术后高眼压的房角及小梁前弹力膜滤过窗的改变。方法对5例(5眼)开角型青光眼住院行非穿透小梁手术术后早期发生高眼压者,早期行前房角镜检查。结果1眼小梁后弹力膜过厚滤过不畅,4眼术区房角滤过窗阻塞,其中2眼周边虹膜与术区小梁后弹力膜相接触阻塞滤过窗,1眼前房积血术区前房角见血凝块,1眼巩膜减压液腔内积血。治疗后术区前房角滤过窗口重新开放眼压降至正常范围。结论术后早期高眼压与内部阻塞因素有关,早期非常规情况下的前房角镜检查,对分析判断早期高眼压的原因有十分重要的作用。     

青光眼小梁切除术后激光断线控制眼压的观察

目的 观察Nd∶YAG激光切断巩膜瓣缝线控制青光眼小梁切除术后眼压的效果.方法 利用Nd∶YAG激光电离爆破效应切断巩膜瓣缝线,控制青光眼小梁切除术后眼压.结果 Nd∶YAG激光切断巩膜瓣缝线后,滤过增强,眼压明显下降,视力提高,无手术并发症出现.结论 采用Nd∶YAG激光切断巩膜瓣缝线以增加滤过,控制青光眼小梁切除术后的眼压,可以取得良好的效果.     

Transconjunctival suture adjustment for initial intraocular pressure control after trabeculectomy

PURPOSE: In an experimental human eye model of trabeculectomy, scleral flap suture adjustment allows predictable control of intraocular pressure (IOP). This approach had not previously been described in clinical use; we present a case series with the application of this technique. METHODS: A prospective, non-comparative interventional case series of consecutive patients undergoing trabeculectomy. Forty trabeculectomies were performed using a 3 mm x 4 mm scleral flap with two apical adjustable 10-0 nylon sutures under a fornix-based conjunctival flap. Intraoperatively the scleral flap sutures were tied tightly to appose the edges of the flap. All trabeculectomies were augmented with antimetabolite intraoperatively. On day one, patients with an IOP greater than 15 mm Hg had their suture tension adjusted to lower their IOP to a target range (10 to 15 mm Hg). Major outcome measures were IOP before and after adjustment and success at last follow-up (IOP < or = 15 mm Hg on no glaucoma medication and no clinically significant complications) without and with adjunctive needling. Other outcomes measured were postoperative complications, bleb needling, final bleb morphology, and visual acuity change from pre-operation to final follow-up. RESULTS: Average day one IOP was 14.8 mm Hg (standard deviation (SD) 7.8). Fourteen patients had a day one IOP over 15 mm Hg and underwent suture adjustment, lowering IOP to between 10 and 15 mm Hg. (Mean post adjustment IOP was 10.7 mm Hg (SD 3.6)). One patient had a conjunctival tear intraoperatively. Four patients had transient wound leaks. No patients had shallow anterior chambers. All but four had diffuse blebs at last follow-up. Success rate without any further surgical intervention was 75%, and success rate with adjunctive needling was 100%. The mean duration of follow-up was 6.3 months (range 1-12 months). CONCLUSION: The approach of tying scleral flap sutures tightly with transconjunctival adjustment of sutures if the IOP is greater than 15 mm Hg on day one allows excellent control of early postoperative IOP.     

Immediate postoperative intraocular pressure measurements after trabeculectomy with releasable sutures

BACKGROUND: To assess the practicality of same-day intraocular pressure (IOP) review following trabeculectomy with releasable sutures. It is a prospective observational case series study. METHODS: 40 eyes of patients undergoing inpatient trabeculectomy for glaucoma optic neuropathy. IOP measurement at 2, 4, 8, 12 and 24 h following trabeculectomy with releasable sutures. Slit-lamp microscopy documenting surgical complications. RESULTS: Three patients required intervention within the first 24 h and four patients at 24 h because of raised IOP. Investigating pressure outcomes of low (<8 mmHg) and high (>21 mmHg) the sensitivity and specificity of IOP assessments at 2, 4, 8 and 12 h were compared with a 'gold standard' of IOP at 24 h postoperatively. False negative results persist at time periods for low IOP and are absent for high IOP only at 8 h postoperatively. There is a marked change in IOP over the first 24-h period in some patients, both from high to low and from low to high levels. CONCLUSIONS: Same-day review of trabeculectomy is not a practical proposition as a policy for a unit with present operative techniques. Indeed the finding of transient high pressures during the first 24 h in some cases suggests that in those patients for whom there is concern (mainly those with severe disc cupping at the time of surgery) at least one IOP check during the first 24 h postoperatively may be warranted in addition to the 24-h postoperative check.