Efficacy and safety of immediate anterior chamber paracentesis in the treatment of acute primary angle-closure glaucoma: a pilot study

Clinical presentation of acute primary angle closure during the COVID-19 epidemic lockdown

Purpose

This study aimed to investigate the clinical presentation of acute primary angle closure (APAC) during the COVID-19 epidemic lockdown in Wuhan.

Methods

Consecutive patients seeking APAC treatment at the Wuhan Aier Eye Hospital during the 76 days (January 23-April 8, 2020) when the lockdown policy was implemented due to the COVID-19 pandemic were compared to those during the same period the following year (January 23-April 8, 2021), when the lockdown policy was not implemented. The cohorts were compared to assess demographic variables and clinical presentations.

Results

A total of 54 patients (64 eyes) were included in the 2020, compared with 46 patients (51 eyes) in the 2021. Demographic factors were similar between the groups. Significantly more patients developed blindness in the 2020 cohort (21.87%) than in the 2021 cohort (7.84%). Patients in the 2020 showed a longer time from symptom to treatment (241.84 ± 211.95 h in 2020 vs. 121.53 ± 96.12 h in 2021; P = 0.001), higher intraocular pressure at presentation (52.63 ± 12.45 mmHg in 2020 vs. 45.16 ± 9.79 mmHg in 2021; P = 0.001), larger pupil diameter (5.47 ± 1.62 mm in 2020 vs. 4.33 ± 1.27 mm in 2021; P = 0.001), and more glaucomatous optic neuropathy diagnoses [20/64 eyes (31.25%) in 2020 vs. 7/51 eyes (13.73%) in 2021; P = 0.03].

Conclusion

The time between the onset of APAC symptoms and its treatment during the COVID-19 epidemic lockdown was significantly prolonged, which increased the blindness rate of APAC patients.

Mini vitrectomy as an alternative technique for intraocular pressure adjustment in non-drainage scleral buckling

Purpose In non-drainage scleral buckling, anterior chamber paracentesis is usually carried out to decrease intraocular pressure. When the buckling is extensive however, this technique may be inefficient and time consuming. In this study, we tried to determine if a mini 25-gauge pars plana vitrectomy could be used as an efficient and safe alternative procedure to anterior chamber paracentesis for adjusting intraocular pressure during a non-drainage scleral buckling. Methods In this case series, 44 patients with rhegmatogenous retinal detachment (proliferative vitreoretinopathy stage < C) were included. In all cases, a mini 25-gauge pars plana vitrectomy was performed before buckle fixation and repeated if necessary. Complete retinal attachment was defined as the anatomical success. Results Forty-four eyes of 44 patients with mean age of 48.1 ± 18.2 years were included. Silicon buckle nº 276, sponge 505, and sponge 507 were utilized for 7, 34, and 3 eyes, respectively. Intravitreal injection of SF6 gas was performed for 54.5% of the eyes. Mean total time of the operation was 61 ± 16 min and the mean time for vitrectomy was 87 ± 31 s. Complete retinal attachment in 37 and incomplete attachment in 4 eyes were achieved after single operation that was a success rate of 93.2%. One had more than usual vitreous leak at the site of scleretomy and one developed a tiny vitreous hemorrhage at the sclerotomy site. Three sclerotomy sites needed suturing. Conclusion The anatomical outcome and the safety observed in this study were comparable to the current methods reported in the literature. Therefore, if anterior chamber paracentesis fails to adjust intraocular pressure during a non-drainage scleral buckling, performing a small gauge mini vitrectomy is safe and helpful.

Time dependent effects of prolonged hyperglycemia in zebrafish brain and retina

Prolonged hyperglycemia causes long-term vision complications and an increased risk of cognitive deficits. High blood sugar also confers an osmotic load/stress to cells. We assessed behavioral and neurochemical changes in zebrafish brain and retina following prolonged hyperglycemia for 4-weeks or 8-weeks. At each time point, behavior was assessed using 3-chamber choice task and optomotor response; tissue was then collected and levels of inflammatory markers, tight junction proteins, and neurotransmitters determined using Western Blots. After 4-weeks, brain levels of v-rel reticuloendotheliosis viral oncogene homolog A (avian) (RelA; NF-kB subunit), IkB kinase (IKK), and glial fibrillary acidic protein (GFAP) were significantly elevated; differences in zonula occludens-1 (ZO-1), claudin-5, glutamic acid decarboxylase (GAD), and tyrosine hydroxylase (TH) were not significant. In retina, significant differences were observed only for TH (decreased), Rel A (increased), and GFAP (increased) levels. Glucose-specific differences in initial choice latency and discrimination ratios were also observed. After 8-weeks, RelA, GAD, and TH were significantly elevated in both tissues; IKK and GFAP levels were also elevated, though not significantly. ZO-1 and claudin-5 levels osmotically decreased in retina but displayed an increasing trend in glucose-treated brains. Differences in discrimination ratio were driven by osmotic load. OMRs increased in glucose-treated fish at both ages. In vivo analysis of retinal vasculature suggested thicker vessels after 4-weeks, but thinner vessels at 8-weeks. In vitro, glucose treatment reduced formation of nodes and meshes in 3B-11 endothelial cells, suggesting a reduced ability to form a vascular network. Overall, hyperglycemia triggered a strong inflammatory response causing initial trending changes in tight junction and neuronal markers. Most differences after 4-weeks of exposure were observed in glucose-treated fish suggesting effects on glucose metabolism independent of osmotic load. After 8-weeks, the inflammatory response remained and glucose-specific effects on neurotransmitter markers were observed. Osmotic differences impacted cognitive behavior and retinal protein levels; protein levels in brain displayed glucose-driven changes. Thus, we not only observed differential sensitivities of retina and brain to glucose-insult, but also different cellular responses, suggesting hyperglycemia causes complex effects at the cellular level and/or that zebrafish are able to compensate for the continued high blood glucose levels.

Efficacy of brinzolamide in the initial management of acute primary angle closure: A randomized controlled trial

WHAT IS KNOWN AND OBJECTIVE?: Since comprehensive medication has an important role in the initial management of patients presenting with acute primary angle closure, it is necessary to analyse the effect of each drug on alleviating the disease. This study aimed to evaluate the intraocular pressure-lowering effect of brinzolamide in the sequential treatment of acute primary angle closure. METHODS: In this randomized double-blind controlled trial, a total of 131 eyes of 125 consecutive patients who presented with their first episode of acute primary angle closure were recruited and received sequential treatment. In this treatment, in the absence of remission, anti-glaucoma drugs, anterior chamber paracentesis and argon laser peripheral iridoplasty are used sequentially. The patients were randomized to receive either brinzolamide or normal saline as a placebo. The primary outcomes were decreased intraocular pressure, success rate and treatment time. RESULTS AND DISCUSSION: There was no statistically significant difference in the decreased level of intraocular pressure between the two groups at 6, 12 or 24 h after the start of treatment (p-values were 0.526, 0.206 and 0.130 respectively). The success rate and treatment time were also not significantly different between the groups. No adverse side effects of brinzolamide were observed in the brinzolamide group. WHAT IS NEW AND CONCLUSION?: In patients with a first episode of acute primary angle closure, brinzolamide did not improve the effectiveness of the sequential treatment for reducing the intraocular pressure levels or shortening the treatment time within the first 24 h of initiating therapy.

Intraocular fluid biomarkers (liquid biopsy) in human diabetic retinopathy

Purpose

This article aims to review the impact of detecting and quantifying intraocular biomarkers (liquid biopsy) in both aqueous and vitreous humor in eyes of people affected by diabetes mellitus.

Methods

This is a detailed review about aqueous and/or vitreous humor sampling in human diabetic eyes for proteomic and/or metabolomic analysis contributing to the understanding of the pathophysiology and treatment effects of diabetic retinopathy.

Results

Aqueous and vitreous humor molecular biomarkers proved to be directly correlated to each other and valuable to study retinal conditions. Moreover, proteomic and metabolomic analysis showed that the biomarkers of neuroinflammation, neurodegeneration, and vasculopathy are detectable in intraocular fluids and that their concentration changes in different stages of disease, and in response to treatment of all diabetic retinopathy aspects, mainly diabetic macular edema and proliferative retinopathy.

Conclusions

Liquid biopsy offers the possibility to improve our knowledge of intraocular eye disease induced by diabetes mellitus. The exact quantification of intraocular biomarkers contributes to the precision medicine approach even in the diabetic retinopathy scenario. The diffusion of this approach should be encouraged to have quantifiable information directly from the human model, which may be coupled with imaging data.

Has the EAGLE landed for the use of clear lens extraction in angle-closure glaucoma? And how should primary angle-closure suspects be treated?

Angle-closure glaucoma is an aggressive condition that causes millions to become blind worldwide. This review explores the use of prophylactic laser peripheral iridotomy (PI) in patients classified as primary angle-closure suspects (PACS), and additionally, the use of clear lens exchange as a primary treatment option in established angle-closure disease with or without glaucoma. As PI has a strong prophylactic effect in fellow eyes of patients who have had an acute attack, its use has been widely adopted in those patients classified as PACS, but with limited evidence to support this. A large randomised trial conducted in China has demonstrated that although PI reduces the risk of incident angle-closure disease, the incidence of disease that would threaten vision was much lower than anticipated. This suggests that the benefit of prophylactic PI is very limited. Health services data shows an association between rising cataract surgical rates and of decreasing rates of acute angle-closure. Age-related growth of the lens is a major component of angle-closure disease. Several studies have shown that clear lens extraction (CLE) effectively lowers IOP in angle-closure. The use of CLE as a primary treatment option has been tested against LPI in the EAGLE study, a large RCT that enroled people with angle-closure and an IOP > 30 mmHg, and those with angle-closure glaucoma. The trial showed CLE to be superior to PI both for IOP control and patient reported quality of life. On these grounds, CLE should be considered for first-line treatment of more advanced angle-closure disease.

Acute primary angle closure-treatment strategies, evidences and economical considerations

Acute primary angle closure requires emergency management that involves a rapid lowering of the intraocular pressure and resolution of relative pupil block - the most common mechanism of angle closure. Emergency strategies for lowering intraocular pressure include medical treatment and argon laser peripheral iridoplasty. Anterior chamber paracentesis and diode laser transcleral cyclophotocoagulation may be considered in special situations. Relative pupil block can be relieved by peripheral laser iridotomy and primary lens extraction; the latter is a more effective treatment according to the results of clinical trials. However, primary lens extraction can be technically demanding in the acute setting. Peripheral laser iridotomy has a role in relieving pupil block and should also be considered in most cases. Lens extraction may be combined with procedures such as goniosynechialysis, trabeculectomy or endoscopic cyclophotocoagulation. In this review, we aim to discuss the available evidence regarding the different treatment modalities. We also discuss the economic consideration, including cost-effectiveness and life expectancy, in the management of acute primary angle closure.

One month of hyperglycemia alters spectral responses of the zebrafish photopic electroretinogram

Prolonged hyperglycemia can alter retinal function, ultimately resulting in blindness. Adult zebrafish adults exposed to alternating conditions of 2% glucose/0% glucose display a 3× increase in blood sugar levels. After 4 weeks of treatment, electroretinograms (ERGs) were recorded from isolated, perfused, in vitro eyecups. Control animals were exposed to alternating 2% mannitol/0% mannitol (osmotic control) or to alternating water (0% glucose/0% glucose; handling control). Two types of ERGs were recorded: (1) native ERGs measured using white-light stimuli and medium without synaptic blockers; and (2) spectral ERGs measured with an AMPA/kainate receptor antagonist, isolating photoreceptor-to-ON-bipolar-cell synapses, and a spectral protocol that separated red (R), green (G), blue (B) and UV cone signals. Retinas were evaluated for changes in layer thickness and for the inflammatory markers GFAP and Nf-κB (RelA or p65). In native ERGs, hyperglycemic b- and d-waves were lower in amplitude than the b- and d-waves of mannitol controls. Alteration of waveshape became severe, with b-waves becoming more transient and ERG responses showing more PIII-like (a-wave) characteristics. For spectral ERGs, waveshape appeared similar in all treatment groups. However, a1- and b2-wave implicit times were significantly longer, and amplitudes were significantly reduced, in response to hyperglycemic treatment, owing to the functional reduction in signals from R, G and B cones. Nf-κB increased significantly in hyperglycemic retinas, but the increase in GFAP was not significant and retinal layer thickness was unaffected. Thus, prolonged hyperglycemia triggers an inflammatory response and functional deficits localized to specific cone types, indicating the rapid onset of neural complications in the zebrafish model of diabetic retinopathy.

Summary: Zebrafish can be used to examine diabetic complications, including vision loss. Here, in zebrafish, we show that prolonged (4 week) hyperglycemia causes an inflammatory response associated with functional deficits localized to specific cone types.

Non-Self-Sealing (Leaky) Anterior Chamber Paracentesis: A New Technique in Managing Postphacoemulsification Intraocular Pressure Rise in Glaucoma and Normal Eyes

Phacoemulsification (phaco) for cataract extraction is 1 of the most commonly performed ophthalmic surgeries. With increasing evidence of significant intraocular pressure (IOP) reduction after phaco, the paradigm for glaucoma treatment has been shifting toward more cataract extraction instead of glaucoma surgery; thus, the population of glaucoma patients undergoing phaco is likely to continue to increase in the coming years. Although the safety of surgery has improved over the years with newer technologies and machines, postoperative IOP spike remains an important condition even after an uneventful operation. Glaucoma patients undergoing phacoemulsification are particularly at risk of further glaucomatous optic nerve damage from the transient yet potentially high pressures after phaco. Common treatments include topical, intracameral, oral, and systemic IOP-lowering medications; postoperative anterior chamber paracentesis (ACP); and so on. No single treatment to date can guarantee effective prevention or control IOP rise in the first 24 hours after phaco. Sometimes, the IOP remains high despite all of the above treatments and the risk for further glaucomatous damage may be unavoidable. In this perspective article, we discuss the incidence, causes, and treatments of IOP rise after phaco and introduce a new technique, a non-self-sealing (leaky) ACP that may be of use in regulating postoperative IOP rise, especially for patients with glaucoma.

The Magnitude of Hypotony and Time Course of Intraocular Pressure Recovery Following Anterior Chamber Cannulation in Nonhuman Primates

Purpose

To determine the magnitude of ocular hypotony and the length of recovery time to 6 and 10 mm Hg IOP following anterior chamber (AC) cannulation.

Methods

Bilateral IOP was recorded 500 times per second via telemetry immediately before, during, and immediately after AC cannulation with a 27-G needle in 10 different sessions at least 2 weeks apart in four male rhesus macaques (nonhuman primates; NHPs) aged 3- to 6-years old. Bilateral IOP was recorded continuously using a proven telemetry system while the NHPs were under general anesthesia during IOP transducer calibration experiments involving manometric control of IOP via AC cannulation, then continuously after the AC needles were removed until IOP recovered to precannulation levels. The change in IOP from baseline to AC cannulation was tested using the signed-rank test. The times necessary for IOP to recover to 6 and 10 mm Hg, respectively, were calculated.

Results

Average precannulation IOP was 11.5 mm Hg and significantly decreased to an average of 2.3 mm Hg immediately following AC needle removal (P = 0.0156). On average, IOP recovered from 2.3 to 6 and 10 mm Hg in 32.4 and 63.7 minutes, respectively. Recovery times of IOP were not affected by repeated AC cannulations every 2 weeks.

Conclusions

Generally, IOP recovers relatively quickly after repeated AC cannulation, and did not result in extended duration hypotony. It is important to consider hypotony in animal experiments and clinical procedures involving AC cannulation and paracentesis when consideration of IOP or its effects is important.

Pressure difference between the anterior chamber and the vitreous cavity in eyes with pupillary block

PURPOSE

The purpose of this study was to measure the pressure difference between the anterior chamber (AC) and the vitreous cavity (VC) in eyes with and without pupillary block.

MATERIALS AND METHODS

Seven vitrectomized porcine eyes were used. Infusion pressures of 10-80 mmHg were generated with a vented gas forced infusion system. Measurements of pressure were obtained with digital manometry connected to 25-gauge catheters from the AC and VC simultaneously. After increasing AC pressure to each target pressure, VC pressure was recorded, and vice versa. Inspection was performed with portable slit-lamp biomicroscopy to identify the development of pupillary block at the end of each experiment.

RESULTS

When the AC pressure was increased, the VC pressure obtained was similar to the AC pressure in all cases. When the VC pressure increased, the AC pressure obtained was similar to that at a VC pressure of less than 50 mmHg. When the VC pressure was increased rapidly to 60, 70, and 80 mmHg, the AC pressures obtained were 57.6 ± 1.0, 64.0 ± 0.8, and 69.6 ± 2.4 mmHg, respectively. Thus, the VC pressures obtained were 1.5, 5.9, and 9.1 mmHg higher than pressures obtained from AC with target pressures of 60, 70, and 80 mmHg, respectively (p = 0.027, 0.001, and 0.001, respectively). Pupillary block was observed in cases where the VC pressure was increased to more than 50 mmHg.

CONCLUSIONS

The AC pressure could be significantly lower than the VC pressure in some eyes with pupillary block.

Diode laser transscleral cyclophotocoagulation followed by phacotrabeculectomy on medically unresponsive acute primary angle closure eyes: the long-term result

Background

To explore the intraocular pressure-lowering effect and complications of diode laser transscleral cyclophotocoagulation (DLTSC) followed by phacotrabeculectomy on medically unresponsive acute primary angle closure eyes.

Methods

Nine eyes of nine medically unresponsive acute primary angle closure patients were enrolled. All the patients underwent cyclophotocoagulation followed by phacotrabeculectomy to control the prolonged acute attack. Data were recorded prospectively and then analyzed retrospectively. The reduction in intraocular pressure, improvement of vision and the complications were evaluated.

Results

After DLTSC, the IOP of all the patients were reduced, but all were above 21 mmHg under topical anti-glaucoma medications. After phacotrabeculectomy, the IOP of all the patients was decreased. At the final visit, the vision of all the patients was improved and the IOP of all the patients was below 21 mmHg without anti-glaucoma medications. There were no complications during the DLTSC and phacotrabeculectomy. Uveitis was the common complications after the both procedures, which were resolved by medication treatment.

Conclusion

Diode laser transscleral cyclophotocoagulation followed by phacotrabeculectomy is an alternative procedure to control the intraocular pressure of medically unresponsive acute primary angle closure eyes with few complications.

Effect of anterior chamber paracentesis on initial treatment of acute angle closure

OBJECTIVE

To compare anterior chamber paracentesis (ACP) with standard medical management of acute primary angle closure (APAC).

DESIGN

Prospective study.

PARTICIPANTS

Patients with APAC and intraocular pressure (IOP) ≥ 50 mm Hg were enrolled.

METHODS

Patients were randomized to receive ACP and medical treatment (group 1) or medical management alone (group 2).

RESULTS

There were 26 patients (mean age 69.3 ± 10.4 years, 31 eyes) in group 1 and 28 patients (mean age 67.0 ± 9.7 years, 30 eyes) in group 2. The IOP in group 1 was significantly lower at 15 minutes, 30 minutes, and 1 hour after treatment (p < 0.05). At 1, 2, and 24 hours after treatment, visual acuity was significantly better in group 1 than in group 2. At each time point after treatment, the grade of corneal edema was not different between the groups. Pain score at 1 and 2 hours after treatment was significantly lower in group 1 than in group 2; however, no difference was noted at 24 hours after treatment. The mean follow-up period in group 1 was 16.1 ± 1.3 months and in group 2 was 15.6 ± 1.4 months (p = 0.803). At last follow-up, IOP, pupil size, number of eyes with nonreactive pupils, and centre endothelial cell counts were not different; however, visual acuity was significantly better in group 1 (0.43 ± 0.06 logMAR vs 0.74 ± 0.10 logMAR, p = 0.007).

CONCLUSIONS

Immediate ACP is a safe and effective for rapidly lowering IOP, and is associated with better visual acuity than medical treatment alone.

Management algorithms for primary angle closure disease

In contrast to primary open angle glaucoma, preventive interventions in primary angle closure disease (PACD) can sometimes be definitive. Data from randomized, controlled trials - and where this is not available - principles grounded in known biology, biological plausibility, logic, preferred practice and personal experience have been synthesized to develop explicit clinical algorithms for management of the spectrum of PACD. The mainstay of first-line intervention is usually a laser iridotomy: a commonly necessary but sometimes insufficient manoeuvre in PACD. The crucial stepwise considerations after iridotomy are: whether the angle is open or closed; whether the IOP can be medically controlled; the extent of PAS, and the presence of visually significant cataract. Indication for subsequent interventions--which may include iridoplasty, cataract surgery, trabeculectomy or phacotrabeulectomy--are herein based on an arbitrary threshold (180 degrees) for angle opening and extent of PAS following initial treatment.

Anterior chamber paracentesis and pH values in patients with acute primary angle closure

BACKGROUND

To assess the efficacy and safety of anterior chamber paracentesis (ACP) and the changes in pH values in eyes with acute primary angle closure (APAC).

METHODS

This retrospective case-control study involved 22 patients with APAC who underwent ACP (study group) and 21 patients with APAC who did not undergo ACP (control group). Intraocular pressure (IOP) and visual acuity were measured before treatment and 15 min and 24 h after treatment in both groups. The pH of aqueous humor was measured immediately after ACP in the study group.

RESULTS

A total of 43 eyes in 43 patients were reviewed. The IOP 15 min after ACP (23.3 ± 9.6 mmHg) and 24 h after ACP (21.6 ± 12.0 mmHg) were significantly lower than that before ACP (58.6 ± 12.9 mmHg). The IOP 15 min after ACP was significantly lower than the IOP 15 min after conventional treatment (55.4 ± 10.3 mmHg). Visual acuity recovery was achieved earlier after ACP than after conventional treatment. Hyphema after ACP was noted in one eye. The mean pH of the aqueous humor in APAC was 6.99 ± 0.35. The pH of the aqueous humor significantly correlated with the duration of acute IOP elevation and the IOP before ACP.

CONCLUSIONS

ACP is an effective and safe procedure. The pH of aqueous humor is lower in eyes with APAC of longer duration and in eyes with higher IOP at presentation.

Aqueous Humor Levels of TGF-β2 and TNF-α in Indonesian Eyes With Acute Primary Angle Closure

PURPOSE

To measure aqueous humor levels of TGF-β2 and TNF-α in Indonesian eyes with acute primary angle closure (APAC) and to investigate their relationship to response to treatment.

DESIGN

A prospective observational study.

METHODS

On presentation, aqueous humor samples were taken from APAC eyes by paracentesis. All APAC eyes then underwent laser peripheral iridotomy (LPI). Two weeks following LPI, trabeculectomy was performed if the intraocular pressure (IOP) was still high. Alternatively, phacoemulsification was performed in cases of normal IOP. Aqueous humor samples were taken again at the time of both surgical procedures. Age-matched cataract patients were included as a control group. Cytokine samples were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Forty-three Indonesian APAC subjects were recruited in this study. The mean presenting IOP was 56.4 ± 0.52 mmHg and 53% underwent trabeculectomy. Comparison of the APAC eyes to the control group showed there was a significant difference in the mean levels of TGF-β2 (2007.7 ± 827.2 pg/mL vs 466.1 ± 219.3 pg/mL, p < 0.001) and TNF-α (0.714 ± 0.33 pg/mL vs 0.228 ± 0.16 pg/mL, p < 0.001). There was no significant difference in the presented TGF-β2 and TNF-α levels between the trabeculectomy and phacoemulsification groups (p:0.391 and p:0.494). Between presentation and surgery in the trabeculectomy subgroup, both cytokine levels appeared to be significantly different (p < 0.035 and p < 0.038).

CONCLUSIONS

This study showed the aqueous humor levels of TGF-β2 and TNF-α appeared high at presentation but decreased subsequently, with no difference detected between groups with persistently high IOP and those with normalized IOP.

Breakdown of the blood-ocular barrier as a strategy for the systemic use of nanosystems

Several drug delivery systems have been proposed to overcome physiological barriers, improving ocular bioavailability. Systemic routes are seldom used due to the blood-ocular barrier. Novel drug delivery systems based on nanotechnology techniques have been developed to overcome ocular physiological barriers. This non-systematic review suggests the utilization of a transitory blood-ocular breakdown to allow the access of drugs by nanotechnology drug delivery systems via the systemic route. We discuss the possible ways to cause the breakdown of the blood-ocular barrier: acute inflammation caused by intraocular surgery, induced ocular hypotony, and the use of inflammatory mediators. The suitability of use of the systemic route and its toxic effects are also discussed in this article.

Effects of pegaptanib injections on intraocular pressure with and without anterior chamber paracentesis: a prospective study

PURPOSE

To investigate how prophylactic anterior chamber paracentesis affects the intraocular pressure (IOP) after intravitreal pegaptanib injections.

METHODS

In this prospective study, 41 eyes of 41 patients receiving intravitreal pegaptanib injections were randomly assigned either to receive anterior chamber paracentesis prior to the injection (Group A, 20 patients, n = 35 injections) or not (Group B, 21 patients, n = 38 injections). IOP was measured before the pegaptanib injection (T0) and 2 min (T1), 30 min (T2) and 1 week (T3) after the injection. A four-point scale was used to evaluate the subjective pain experienced during the procedure.

RESULTS

The mean IOP at T1 was 15.3 ± 7.5 mmHg in group A and 47.1 ± 24.1 mmHg in group B (difference -31.85 mmHg, 95% Confidence interval -40.13 to -23.56; p < 0.0001). In 45% of the injections without paracentesis, IOP was higher than 50 mmHg 2 min after the pegaptanib injection. No significant difference in IOP was observed at T0, T2 and T3 between the two study groups. The mean pain scores did not differ significantly (0.97 in group A versus 1.32 in group B; p = 0.08).

CONCLUSIONS

The results suggest that prophylactic anterior chamber paracentesis helps to prevent the high postoperative IOP spike without causing patients any additional pain.

Conventional and emerging treatments in the management of acute primary angle closure

The management of acute primary angle closure is directed at lowering the intraocular pressure and relieving pupil block. Conventional treatment involves the use of medical treatment and laser peripheral iridotomy, respectively, as a means for achieving these aims. Newer therapeutic strategies have been described that are potentially useful adjuncts or alternatives to conventional treatment. Emerging strategies that lower intraocular pressure include anterior chamber paracentesis, as well as laser procedures such as iridoplasty and pupilloplasty. A possible alternative to relieving pupil block is lens extraction, and may be combined with adjunctive measures such as goniosynechiolysis and viscogoniosynechiolysis. Trabeculectomy has a limited role in the acute setting. This review paper reviews the current evidence regarding conventional and newer treatment modalities for acute primary angle closure.

Cyclodiode laser in the treatment of acute angle closure

AIM

To describe the outcome of using diode laser transscleral cyclophotocoagulation (cyclodiode laser) as a safe technique in managing acute angle closure refractory to conventional treatment.

METHODS

This is a retrospective case series from two ophthalmic units in the United Kingdom. Five patients with acute angle closure refractory to medical and laser treatment underwent cyclodiode laser treatment. Demographic information, symptoms, medical and surgical treatment, visual outcomes, and intraocular pressure (IOP) control were recorded.

CASE REPORTS

All five patients had symptomatic acute angle closure. Conventional management, including topical and systemic medical treatment, laser iridotomy and laser iridoplasty, did not achieve adequate IOP control or relieve symptoms. Emergency cyclodiode laser treatment was performed within 2-23 days of presentation. All patients subsequently required lensectomy at a later date. At final follow-up (6-14 months), all patients had visual acuity of 6/12 or better with well-controlled IOPs (≤ 17 mm Hg). Only one patient was on topical treatment. One patient developed a persistent low-grade anterior uveitis.

DISCUSSION

Cyclodiode laser is a safe alternative to emergency lensectomy or trabeculectomy in cases of acute angle closure, which do not respond to treatment.

Sustained elevation of extracellular ATP in aqueous humor from humans with primary chronic angle-closure glaucoma

While the death of retinal ganglion cells in glaucoma is frequently associated with an elevation of intraocular pressure (IOP), the mechanisms connecting the two processes remain unclear. Extracellular ATP is released throughout the body in response to mechanical deformations. We have previously shown that patients with an acute rise in IOP have an elevated concentration of ATP in the anterior chamber. In the present study we ask whether ATP levels remain increased in patients with chronic elevations of IOP. The concentration of ATP in samples of aqueous humor obtained from patients with primary chronic angle-closure glaucoma (PCACG) was compared with that from control cataract patients whose IOP was normal. The mean ATP concentration in aqueous humor was 14-fold higher for PCACG samples than for control. ATP levels were correlated with IOP and the cup-to-disk ratio (C/D ratio). Brief treatment of Timolol, Alphagan, Pilocarpine and/or Azopt did not affect the rise in ATP concentration. In conclusion, sustained elevations in extracellular ATP levels accompany the chronic elevation of IOP in chronic glaucoma. As numerous ocular tissues express purinergic receptors, an increased extracellular ATP may have diverse physiological and pathophysiological effects.

Fluorophotometric and tonometric evaluation of ocular effects following aqueocentesis performed with needles of various sizes in dogs

OBJECTIVE

To measure ocular effects (blood-aqueous barrier breakdown and intraocular pressure [IOP]) following aqueocentesis performed with needles of various sizes in dogs.

ANIMALS

28 healthy adult dogs.

PROCEDURES

24 dogs underwent unilateral aqueocentesis (24 treated eyes and 24 contra-lateral untreated eyes); 25-, 27-, or 30-gauge needles were used in 3 treatment groups (n = 8/group). Four dogs were untreated controls. Aqueocentesis was performed during sedation and topical anesthesia. Anterior chamber fluorophotometry was performed before and after aqueocentesis on day 1. On days 2 through 5, sedation and fluorophotometry were repeated. Intraocular pressure was measured with a rebound tonometer at multiple time points.

RESULTS

Aqueocentesis resulted in blood-aqueous barrier breakdown detected via fluorophotometry in all treated eyes, with barrier reestablishment by day 5. On day 2, the contralateral untreated eyes of all 3 groups also had significantly increased fluorescence. Use of a 25-gauge needle resulted in a significant increase in treated eyes' anterior chamber fluorescence on days 3 and 5 as well as a significant increase in IOP 20 minutes following aqueocentesis, compared with the other treatment groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Aqueocentesis performed with a 25-gauge needle resulted in the greatest degree of blood-aqueous barrier breakdown and a brief state of intraocular hypertension. Use of a 27- or 30-gauge needle is recommended for aqueous paracentesis. A consensual ocular reaction appeared to occur in dogs following unilateral traumatic blood-aqueous barrier breakdown and may be of clinical importance.

Predominant cone photoreceptor dysfunction in a hyperglycaemic model of non-proliferative diabetic retinopathy

Approximately 2.5 million people worldwide are clinically blind because of diabetic retinopathy. In the non-proliferative stage, the pathophysiology of this ocular manifestation of diabetes presents as morphological and functional disruption of the retinal vasculature, and dysfunction of retinal neurons. However, it is uncertain whether the vascular and neuronal changes are interdependent or independent events. In addition, the identity of the retinal neurons that are most susceptible to the hyperglycaemia associated with diabetes is unclear. Here, we characterise a novel model of non-proliferative diabetic retinopathy in adult zebrafish, in which the zebrafish were subjected to oscillating hyperglycaemia for 30 days. Visual function is diminished in hyperglycaemic fish. Significantly, hyperglycaemia disrupts cone photoreceptor neurons the most, as evidenced by prominent morphological degeneration and dysfunctional cone-mediated electroretinograms. Disturbances in the morphological integrity of the blood-retinal barrier were also evident. However, we demonstrate that these early vascular changes are not sufficient to induce cone photoreceptor dysfunction, suggesting that the vascular and neuronal complications in diabetic retinopathy can arise independently. Current treatments for diabetic retinopathy target the vascular complications. Our data suggest that cone photoreceptor dysfunction is a clinical hallmark of diabetic retinopathy and that the debilitating blindness associated with diabetic retinopathy may be halted by neuroprotection of cones.

Incisional surgery for angle closure glaucoma

Angle closure glaucoma remains a major challenge for ophthalmologists. The three main challenges in the treatment of angle closure glaucoma are, firstly, to achieve rapid reduction of intraocular pressure in acute angle closure glaucoma, secondly, to prevent progression to chronic angle closure glaucoma, and thirdly, to manage established chronic angle closure glaucoma. Incisional surgery for angle closure glaucoma is typically required when laser surgery and/or medical therapy fail to control the intraocular pressure or control progressive synechial closure. The role for surgical iridectomy and emergency trabeculectomy in the modern management of acute angle closure glaucoma is diminishing. Trabeculectomy, goniosynechialysis, cyclodestructive procedures, and glaucoma implant are effective surgical options for chronic angle closure glaucoma, but none of them have been shown to be more effective than the others with proper comparative clinical trials. Trabeculectomy and goniosynechialysis are often combined with cataract extraction, which appears to offer additional pressure-control benefits to patients with chronic angle closure glaucoma.

Angle-closure glaucoma: the role of the lens in the pathogenesis, prevention, and treatment

Primary angle-closure glaucoma is a major cause of blindness worldwide. It is a disease of ocular anatomy that is related to pupillary-block and angle-crowding mechanisms of filtration angle closure. Eyes at increased risk for primary angle-closure are small with decreased axial length, anterior chamber depth, and filtration angle width, associated with a proportionately large lens. Angle-closure glaucoma afflicts Asian and Eskimo eyes more frequently than eyes in other races with similar predisposing dimensions. The treatment of primary angle closure addresses its causal mechanisms. Laser peripheral iridotomy equalizes the anterior and posterior pressures and widens the filtration angle by reducing the effect of pupillary block. Argon laser peripheral iridoplasty contracts the iris stroma to reduce angle crowding and is helpful for some affected eyes. Lensectomy dramatically widens the angle and eliminates pupillary block. Clinical reports of lensectomy with posterior chamber intraocular lens implantation in the treatment of acute, chronic, and secondary angle-closure glaucoma describe very favorable results. The appropriate role for lensectomy in the management of primary angle closure, however, remains unproven. Prospective, randomized clinical trials are ongoing to determine the value and comparative risks and efficacy of lensectomy versus medical therapy, laser peripheral iridotomy, laser iridoplasty, and filtration procedures for the treatment of acute and chronic primary angle closure and for the prevention of chronic angle-closure glaucoma, both after and in place of laser peripheral iridotomy.

Corneal indentation in the early management of acute angle closure

PURPOSE

To describe in detail corneal indentation (CI) in the management of a series of patients treated for acute angle closure (AAC).

DESIGN

Retrospective, consecutive, noncomparative case series.

PARTICIPANTS

Seven consecutive patients (8 eyes) referred to the authors with the diagnosis of AAC. Patients presented to the Prince of Wales Hospital, Randwick, or to the private practices of the authors.

INTERVENTION

Seven patients (8 eyes) underwent CI as part of their early management for AAC.

MAIN OUTCOME MEASURES

Reduction in intraocular pressure (IOP), symptoms of AAC and pain relief.

RESULTS

Of the 7 patients, complete data were available for 6. The IOP was significantly reduced (P<0.05) and 3 of 4 patients with severe acute pain reported early resolution of pain after CI. The average reduction in IOP was 20.9 mmHg (range +1 to -45). All patients subsequently underwent definitive management with laser peripheral iridotomies or lensectomy using phacoemulsification. Three patients treated acutely with CI without any medical agents had a mean IOP reduction of 21 mmHg (range, 20-23) after indentation.

CONCLUSIONS

Corneal indentation is a rapid, portable, and effective method of reducing elevated IOP in the setting of AAC. It can be performed with instrumentation that is readily at hand and allows for rapid pain relief. This reduction in IOP improves corneal clarity and permits further definitive management of the patient with AAC.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Acute increase of intraocular pressure releases ATP into the anterior chamber

Throughout the body, mechanical perturbations are transduced into neurochemical signals by the release of ATP from non-neuronal cells. As an increased intraocular pressure (IOP) can initiate mechanical changes, we hypothesized that extracellular levels of ATP might be increased in the anterior chamber of human patients with primary acute angle closure glaucoma (PAACG). ATP levels in aqueous humor samples were determined using the luciferin-luciferase assay. Samples were obtained from 18 controls scheduled for cataract extraction and from 14 subjects with angle closure glaucoma during paracentesis. All subjects with angle closure glaucoma had remarkably elevated levels of ATP in their aqueous humor. The mean ATP concentration was ninefold higher for patients with angle closure glaucoma than for control. The concentration of ATP was correlated with IOP levels, further supporting a causal relationship. ATP levels were not influenced by the duration of the PAACG attack, suggesting the rate of ATP release was sustained. We conclude that increased IOP leads to increased levels of extracellular ATP in the anterior chamber. This elevated ATP may contribute to the extreme pain experienced by subjects with angle closure glaucoma, and may serve as a source of elevated adenosine in the anterior chamber.

Efficacy and safety of intravenous injection of lidocaine in the treatment of acute primary angle-closure glaucoma: a pilot study

AIMS

To study the safety and effectiveness of a combination of both intravenous injection of lidocaine and intraocular pressure-lowering medications, in the intraocular pressure control and relief of symptoms of refractory acute primary angle-closure glaucoma (PACG).

METHODS

Five consecutive patients with their first attack of acute PACG, with intraocular pressure > or = 45 mmHg and a failure to release from the attack under antiglaucomatous medications for 4 hours, were recruited into the study. On presentation, each patient received topical pilocarpine and timolol, and systemic acetazolamide and mannitol as primary treatment. Then the patients accepted 2% lidocaine by intravenous injection at dose of 0.8 mg/kg in concert with antiglaucomatous medications. The intraocular pressures after intravenous injection at 30 minutes, and then at 1, 2, 4, 12, and 24 hours, were documented by applanation tonometry. Symptoms, visual acuity, intraocular pressure, corneal edema, angle status on gonioscopy, pupillary size, and reaction were also measured.

RESULTS

Six eyes of five patients seen with acute PACG were recruited. The mean intraocular pressure was reduced from 50.83 +/- 5.34 mmHg to 39.5 +/- 3.45 mmHg at 30 minutes after intravenous injection, and then to 33.3 +/- 3.56 mmHg at 1 hour, and 24.55 +/- 5.09 mmHg at 2 hours after intravenous injection. The mean intraocular pressure was less than 21 mmHg at 4 hours and beyond. There was instant symptomatic relief for all patients. No complications were encountered.

CONCLUSIONS

From this preliminary study, intravenous injection of lidocaine seems to be safe and effective in controlling intraocular pressure and eliminating symptoms in acute PACG. But the exact efficacy and safety need further investigation in large case studies.

Current approaches to the management of acute primary angle closure

PURPOSE OF REVIEW

Recent advances in the management of acute primary angle closure include argon laser peripheral iridoplasty, immediate anterior chamber paracentesis, and cataract or lens extraction by phacoemulsification. This review summarizes current thoughts on the role of these treatment modalities.

RECENT FINDINGS

Argon laser peripheral iridoplasty has been shown to be superior to treatments using combined topical and systemic medications in controlling intraocular pressure in acute primary angle closure. Immediate paracentesis has been shown to be very effective for aborting the condition. This is a good alternative for suitable cases and especially in settings in which laser equipment is not readily available. Cataract or lens extraction by phacoemulsification appears to be promising in preventing progression to chronic angle closure glaucoma after acute primary angle closure.

SUMMARY

Surgical trials are underway to examine the role of cataract/lens extraction in post-acute primary angle closure. This technique has the potential to prevent recurrence of the condition and progression to chronic angle closure glaucoma. With existing and upcoming new data on managing acute primary angle closure, it is hopeful that a more optimal treatment algorithm will be established soon.

Anterior chamber paracentesis in patients with acute elevation of intraocular pressure

PURPOSE

The purpose was to evaluate the efficacy and the safety of anterior chamber paracentesis (ACP) in acute elevation of intraocular pressure (IOP).

METHODS

We prospectively enrolled 20 patients who presented with acute unilateral elevation of IOP above 50 mmHg. IOP was measured before, 10 min, and 1, 7 and 30 days after ACP. The outcome at 1 year was available in 19 patients.

RESULTS

The patients included 14 cases of primary acute angle-closure attacks and six cases of secondary glaucoma. IOP decreased from 53.4 +/- 4.2 mmHg to 24.1 +/- 12.5 mmHg at 10 min, to 18.2 +/- 11.1 mmHg at 24 h, and to 16.4 +/- 10.7 mmHg 7 days after ACP. ACP combined with antiglaucomatous medications provided immediate relief of symptoms in all cases and improvement of corneal oedema in 17 cases. We noted three failures in secondary glaucoma. We performed a laser peripheral iridotomy (LPI) in 14 patients and a surgical procedure in 17 eyes. No complications related to ACP were observed.

CONCLUSION

ACP is a safe and effective procedure for acute elevation of IOP in acute primary primary angle-closure but only remains an add-on therapy to usual treatments. However, this technique must be evaluated in larger series.

Phacoemulsification and Goniosynechialysis in the Management of Unresponsive Primary Angle Closure

PURPOSE

To evaluate the effectiveness of phacoemulsification and goniosynechialysis (PEGS) in managing acute and subacute primary angle closure unresponsive to conventional therapy.

MATERIALS AND METHODS

Retrospective series of patients of six glaucoma-trained surgeons with primary angle closure that did not respond to medical management, Nd:YAG laser peripheral iridotomy, or argon laser peripheral iridoplasty.

RESULTS

A total of twenty-one patients with an average age of 65.6 years were included. Underlying mechanism of angle closure included pupillary block (n = 18) and plateau iris (n = 3). Average intraocular pressure (IOP) immediately prior to PEGS was 40.7 mm Hg, and mean follow-up time after PEGS was 11.7 months. PEGS decreased mean IOP by 25 mm Hg (62%), and mean number of medications from 3.8 pre-surgery to 1.7 post-surgery (55%). Mean LogMar visual acuity improved after PEGS, from 0.64 to 0.44 (Paired t test t = 4.120 P = 0.001). Subsequent trabeculectomy was necessary in one case (5%).

CONCLUSIONS

Phacoemulsification with goniosynechialysis may be an effective treatment option for primary angle closure unresponsive to conventional therapy.

Angle-closure glaucoma in East Asian and European people. Different diseases?

In contrast to the pattern of disease in Europeans, primary angle closure has a higher prevalence and tends to be asymptomatic in East Asians. The higher prevalence is attributed to differences in anterior chamber and angle anatomy. Several studies suggest that central anterior chamber depth is shallower in East Asians than in Europeans, although this is not universally accepted. It is debated whether pupil block is the predominant mechanism of angle closure in Asian people. Meaningful comparison between studies is currently hindered by differences in patient selection, examination technique, and case definition; however, the major scientific deficiency is the paucity of prospective followup data to give an insight into natural history of the disease. This review examines the data on prevalence, risk factors, and mechanism of angle closure. Special consideration is given to limitations of methodology in research to date, with the intention of developing more robust data in future studies.

Glaucoma management in developing countries: medical, laser, and surgical options for glaucoma management in countries with limited resources

PURPOSE OF REVIEW

Most people affected by glaucoma live in developing countries. Recent trials and reports provide sound evidence for management of glaucoma. This review extrapolates relevant articles to the developing world.

RECENT FINDINGS

The predictive value of gonioscopy for progression of primary angle closure suspects (PACS) to primary angle closure (PAC) is only 22% (95% CI: 9.80-34.2). PACS are not uncommon; laser peripheral iridotomy (LPI) is neither indicated nor feasible for all. Twenty-eight and a half percent of PAC progress to primary angle closure glaucoma; the number needed to treat (NNT) for LPI to prevent progression is only 4. Laser peripheral iridoplasty controls acute angle closure glaucoma (AACG) faster than medical therapy alone. Primary lens extraction has also been suggested as treatment for AACG after control of the acute attack. A 5-year NNT for ocular hypertension (OH) of 20 is too high to allow treatment of all OH. High-risk OH and primary open angle glaucoma (POAG) have an NNT of 5 to 6 and merit treatment. Latanoprost and brimonidine are effective in lowering IOP in Asian eyes with POAG, but primary surgical therapy may be a more viable option. For cataract and coexistent glaucoma requiring filtration, trabeculectomy combined with the Blumenthal technique of cataract surgery may be as effective as trabeculectomy combined with phacoemulsification.

SUMMARY

The principles of glaucoma management should be the same the world over. Considering the paucity of resources and competing opportunity costs, countries with limited resources have to extrapolate available information in a sensible and cost-effective manner.

Angle-closure glaucoma: impact, etiology, diagnosis, and treatment

PURPOSE OF REVIEW

Recent studies underscore the importance of angle-closure glaucoma (ACG) as a cause of world blindness. A major contribution in assessing the true impact of this disease has been an article estimating the number of persons with occludable angles, angle closure, and blindness from ACG in China as 28.2 million, 9.1 million, and 1.7 million, respectively. Although these numbers are based on data from Singapore and Mongolia, which may be applied to China only with caution, they emphasize the blinding potential of ACG, which is three times as likely to be associated with blindness as open-angle glaucoma (OAG).

RECENT FINDINGS

Recent reports in the Chinese literature on ACG prevalence suffer from definitional problems that would appear to lead to systematic overestimates of ACG prevalence and underestimates of OAG prevalence. Nonetheless, data from studies by Chinese investigators further emphasize the strong association between ACG and blindness, with fully 16% of subjects with ACG blind in one report-a far higher proportion than for OAG in China and elsewhere. The importance of topiramate as a cause of secondary angle closure has recently been understood, in part, because of a series of 19 such cases reported by investigators at the Food and Drug Administration.

SUMMARY

Angle closure in this setting appears to be caused by uveal effusion and anterior rotation of the ciliary body with resultant closure of the angle. The condition is not always responsive to laser iridectomy, and elimination of the causative agent appears to be critical. Ultrasonic biomicroscopy is a potential new diagnostic modality for ACG, allowing the measurement of novel parameters, such as the angle opening distance (AOD) at 500 microm (AOD 500). The efficacy of such parameters in improving screening for ACG can only be established by prospective studies of potentially at-risk eyes. A number of novel treatments for AC and angle closure have recently been proposed, including cataract extraction, paracentesis, and argon laser iridoplasty. As with proposed new diagnostic modalities, the efficacy of these treatments remains to be demonstrated with prospective studies, ideally organized in a controlled, randomized fashion.