Primary Angle-Closure Glaucoma Xử trí

Medical Therapy  

Initial treatment of acute angle-closure is directed towards lowering the IOP to relieve acute symptoms and potential harm of high IOP. This remains the most common method of lowering IOP. Most patients are treated immediately with medications, followed by iridotomy as soon as feasible. In patients with ocular surface disease, consider preservative-free formulations.

Preoperative Medical Therapy  

Preoperative medical therapy serves to lower IOP to relieve the symptoms and signs so that laser iridotomy or iridectomy is possible. Once any angle closure component has been appropriately treated, management is similar to POAG. The IOP lowering mechanisms work by either reducing aqueous production by the non-pigmented epithelium of the ciliary body [eg alpha₂-adrenergic agonists, beta-blockers, carbonic anhydrase inhibitors (CAI)] or increasing outflow pathways or by uveoscleral pathways (eg alpha₂-adrenergic agonists, miotics, prostaglandin derivatives).  

Primary Angle-Closure Glaucoma with Pupillary Block Mechanism  

Reduction of the aqueous production by the use of systemic CAI (eg Acetazolamide), topical alpha₂-selective adrenergic agonists (eg Apraclonidine, Brimonidine), or topical beta-blockers (eg Timolol). Hyperosmotics are the most effective agents (eg oral Glycerol, Mannitol) for the dehydration of the vitreous body. Examples are Glycerol (1-1.5 g/kg PO) and Mannitol (1-1.5 g/kg IV). Patients must be evaluated for kidney or heart disease prior to administration of hyperosmotics. Glycerol may alter blood glucose levels and should not be given to DM patients. Pupillary constriction may be seen from the use of topical parasympathomimetics (eg Pilocarpine 1% or 2%, Aceclidine 2% 2-3 times within 1 hour). Reduction of inflammation may be seen by the use of topical steroids every 5 minutes for 3 times, then 4-6 times daily.  

Primary Angle-Closure Glaucoma with Plateau Iris Mechanism  

Modest pupillary constriction may prevent further angle closure using topical parasympathomimetics (eg Pilocarpine 1%, Aceclidine 2%, Carbachol 0.75%).  

Postoperative Medical Therapy (Intraocular Pressure Control)   

The initial treatment option to lower the IOP is usually topical medications. Medical therapy should start with one drug. If the first choice of treatment has no effect or tachyphylaxis occurs, change the initial therapy rather than adding another drug. Consider balancing between the effectiveness of the medications and the side effects to achieve desired IOP. Pre-treatment baseline IOP values should be considered in the evaluation of efficacy of therapy. In order to maximize patient compliance and adherence, aim to utilize the minimum number of medications with minimum dosing frequency to achieve the target IOP. Surgery may, however, be initially considered in cases where there is severe glaucomatous damage, very high IOP, or concern regarding patient compliance. Systemic medications are only used as a temporary measure.  

Topical Glaucoma Preparations  

Any one or a combination of the following may be used depending on the severity of glaucoma, response to the medication, and ocular and health status of the patient. Always start with the least amount of medication to achieve a therapeutic response. Systemic absorption may take place via the nasal mucosa, which may lead to systemic effects. To minimize this, patients should be taught to apply finger pressure on the medial canthus for 1-2 minutes after instilling the eye drop.







Prostaglandin Analogues  

Example drugs: Bimatoprost, Latanoprost, Latanoprostene bunod, Tafluprost, Travoprost and Unoprostone  

Prostaglandin analogues are generally considered and approved as first-line treatment for reducing IOP. These are the first choices in cases of complete synechial closure. These lower IOP by increasing uveoscleral outflow. The IOP reduction is 25-35%. These appear effective and well tolerated (with few systemic side effects). These are an alternative for patients with contraindications to initial therapy with beta-blockers.  

Beta-blockers  

Example drugs: Betaxolol, Carteolol, Levobunolol, Metipranolol, Timolol  

Beta-blockers have been a traditional choice of therapy as initial IOP-lowering agents due to their effectiveness, low cost, and tolerability. Along with prostaglandin analogues, these are licensed for first- and second-line use. Beta-blockers act by decreasing aqueous humor production. It can reduce IOP to 20-25%. These are associated with few ocular side effects and have a long duration of action, which allows once- or twice-daily dosing. Studies have shown that if a patient is on a systemic beta-blocker, the decrease in IOP with topical beta-blockers is likely to be reduced and, in this case, other drug classes should be considered first.  

Alpha₂-selective Adrenergic Agonists  

Example drugs: Apraclonidine, Brimonidine  

Alpha₂-selective adrenergic agonists act by reducing aqueous humor production and increasing uveoscleral outflow. The IOP reduction is 20-25%. These may be given 1 hour prior to surgery or immediately afterwards to reduce the magnitude and frequency of acute postoperative IOP spikes and decrease bleeding due to the vasoconstrictor effect. Brimonidine exhibits highly selective alpha₂-agonism (1000:1 over alpha₁ agonism). Their selectivity results in the absence of both mydriasis and vasoconstriction. Long-term use of Apraclonidine is limited due to tachyphylaxis and increased risk of allergy with time.

Carbonic Anhydrase Inhibitors (CAI)  

Example drugs: Brinzolamide, Dorzolamide  

Carbonic anhydrase inhibitors reduce IOP by inhibition of carbonic anhydrase, resulting in decreased aqueous humor production. The IOP reduction is 20%.  

Parasympathomimetics  

Example drugs: Carbachol, Demecarium, Ecothiophate, Pilocarpine  

Parasympathomimetics lower IOP by decreasing resistance to aqueous humor outflow from the anterior chamber and increasing trabecular outflow. They may, however, reduce uveoscleral outflow, which may cause a paradoxical rise in IOP in patients with severely compromised trabecular outflow. The IOP reduction is 20-25%. These have fewer systemic side effects than beta-blockers but more significant ocular side effects. Long-term post-op use of Pilocarpine may be given to patients with plateau iris syndrome, ie angle remains narrow despite a patent laser iridotomy.  

Hyperosmotic Agents  

Example drug: Topical Glycerol  

Hyperosmotic agents may be given in cases of acute angle-closure attacks in the presence of an edematous cornea. The IOP reduction is 15-30%. Glycerol can cause irritation when given topically, and a local anesthetic may be given before application of glycerol to the cornea to reduce the likelihood of a painful response.  

Rho Kinase Inhibitor  

Example drug: Netarsudil  

Rho kinase inhibitor lowers IOP by increasing outflow of aqueous humor through the expansion of the juxtacanalicular connective tissue and dilating the episcleral veins. The IOP reduction is 20-25%.    

Systemic Glaucoma Preparations  

Oral Carbonic Anhydrase Inhibitors (CAI)  

Example drugs: Acetazolamide, Methazolamide  

Oral carbonic anhydrase inhibitors lower IOP by decreasing aqueous production through inhibition of carbonic anhydrase. The IOP reduction is 30-40%. These may be given pre-operatively to acute angle-closure or severe glaucoma patients to prevent IOP spikes. These are for short-term use only due to their systemic side effects.  

Hyperosmotic Agents  

Example drugs: Glycerol, Isosorbide, Mannitol  

Hyperosmotic agents dehydrate and reduce vitreous volume. These are the most effective agents to control acutely elevated IOP. The IOP reduction is 15-30%. These are for short-term use in cases where a large, rapid reduction in the IOP is required. Prior to use, patients must be evaluated for heart and kidney disease due to their potential to increase blood volume.  

Adjunctive Medical Therapy  

The medications may be combined with each other or serve as additional therapy to surgical treatment. Drugs belonging to the same class should not be combined. Additional drugs should be used only to achieve target IOP.  

Fixed Combination Topical Therapy  

Fixed combination topical therapy is used as an adjunctive therapy given to patients who fail to achieve their target IOP with monotherapy. This offers a convenient and simple dosing regimen and is preferred over the use of 2 separate agents. When available, fixed combination drugs may be preferable to 2 separate agents, which may improve compliance due to reduced dosing schedules. Generally, superior IOP-lowering efficacy is seen in combination therapy with agents from different classes than using the individual components alone. In employing fixed combination treatment, use agents that have both shown individual efficacy (but as individual agents, were insufficient in reaching the target IOP). Do not combine 2 drugs with the same mechanism of action.

Patient Education  

Instruct patients to avoid medicines that cause pupillary dilatation and induce an AACC (eg decongestants, adrenergic agents, anticholinergics, antipsychotics, antidepressants, and motion sickness medications). Teach patients how to properly instill eye drops (intervals, lid closure, punctal occlusion). Do punctal occlusion and eyelid closure for at least 3 minutes. If ≥2 drops are to be instilled, wait at least 5 minutes between drops. Demonstrate the preferred method and ensure the patient can do it.  

Communicate to the patient and family the importance of compliance since glaucoma is a chronic disease that requires continuous patient cooperation for successful management. Advise patients with a family history of PACD to undergo regular eye screening examinations for this condition. Inform patients at risk for acute angle-closure about its symptoms and instruct them to notify immediately should these symptoms occur. Provide them with educational materials about PACD. 

Laser Peripheral Iridotomy  

Laser peripheral iridotomy is a definitive treatment for acute and chronic angle-closure glaucoma with a pupillary block component. This is a preferred surgical treatment due to its favorable risk-benefit ratio. It relieves pupil block and can prevent the formation of PAS. In angle-closure with plateau iris mechanism, peripheral laser iridotomy will help confirm the diagnosis and will eliminate the pupillary block component, if present. This should only be done once corneal edema (if present) or an AACC attack has been medically cleared. This is also indicated in suspected cases of angle closure due to posterior mechanisms or plateau iris to eliminate any possible pupillary block component.  

Prophylactic iridotomy is also indicated in the fellow eye, if it is similarly predisposed (if the chamber angle is anatomically narrow), to prevent an attack. This is effective as a preventive measure in patients at moderate to high risk of experiencing an acute attack. Argon laser iridotomy has a superior closure rate than neodymium: yttrium-aluminum-garnet (Nd:YAG) laser. Possible complications include visual disturbances (eg glare, spots, halos, lines, shadows), temporary blurring of vision, intra-op bleeding, transient elevation of IOP, inflammation, localized lens opacities, and posterior synechiae. Rarely, it may cause cystoid macular edema, retinal damage, malignant glaucoma, decompression retinopathy, retinal and subhyaloid hemorrhage, and Descemet’s membrane detachment. Postoperative management includes checking the IOP 30 minutes-2 hours after the surgery and repeat by 24-48 hours. Repeat gonioscopy to check for PAS and/or plateau iris configuration. Check the patency of the peripheral iridotomy.

Peripheral Iridectomy  

Peripheral iridectomy has been largely replaced by iridotomy in recent years. This is an alternative to laser iridotomy when an acute attack cannot be broken or when the cornea fails to clear sufficiently for laser iridotomy to be performed. The advantages are that it can be done even when the cornea is cloudy and permits deepening of the anterior chamber, breaking newly formed PAS. The risks are similar as with other invasive ocular surgeries.  

Laser Peripheral Iridoplasty  

Laser peripheral iridoplasty contracts the peripheral iris, resulting in the widening of the anterior chamber angle and the re-opening of the appositionally closed segments. This stretches the iris and deepens the chamber angle to reduce the risk of progressive synechial closure. This can be used to eliminate appositional angle closure caused by nonpupillary block mechanisms. This may be done prior to laser iridotomy when an acute attack cannot be broken, and the cornea is cloudy or hazy. This may be performed, in addition to iridotomy, in cases of iris plateau configuration and when the angle remains narrow despite a patent laser iridotomy (plateau iris syndrome). Complications include iris atrophy and non-dilatable pupil (established), mild iritis, mydriasis, IOP spikes, and corneal endothelial burns.  

Lens Extraction with Intraocular Lens Implant  

Lens extraction with intraocular lens implant significantly widens the anterior chamber angle in angle-closure glaucoma and in eyes with narrow, occludable angles based on various studies. This is helpful in cases where either the lens thickness or anterior position is thought to be the main mechanism involved in the acute episode of angle-closure. Recent data suggest that cataract and clear lens extraction may be more effective at controlling IOP than traditional therapy.

Anterior Chamber Paracentesis  

Anterior chamber paracentesis may be done prior to laser iridotomy when an acute attack cannot be broken and the cornea is too cloudy or hazy. This provides rapid symptom relief and prevents further damage to the optic nerve and TM from the acutely elevated IOP. This may be used in cases that are refractory to medical management and have no access to laser.  

Goniosynechialysis  

Goniosynechialysis restores drainage function through mechanical lysis of adhesions that lead to angle scarring. Scarring that is present for <1 year tends to have better results.  

Phacotrabeculectomy, Trabeculectomy, Phacoemulsification  

Phacotrabeculectomy, trabeculectomy, and phacoemulsification reduce IOP and need for antiglaucoma agents and increase ACD. Phacoemulsification results in less post-op complications. Trabeculectomy may be needed in asymptomatic chronic angle closure with a pressure of >35 mmHg, >6 clock hours of PAS, and/or established glaucomatous optic neuropathy.