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    Diagnosing and managing patients with narrow angles

    Proper gonioscopy can significantly affect visual outcome

     

    Angle OCT and ultrasound biomicroscopy are useful adjunct imaging tools but may not reveal important characteristics such as peripheral anterior synechiae and should not replace gonioscopic evaluation. Note that these adjunct tests do not yield information about the amount of pigment in the trabecular meshwork.

    Angle OCT imaging is also helpful in monitoring angle position status post treatment as well as for patient education.

    Treatment and management

    In cases of identified acute angle closure, the first line of treatment is to reduce IOP in order to prevent glaucomatous optic neuropathy. This may be accomplished by using fast-acting topical glaucoma medications such as beta blockers, alpha agonists, carbonic anhydrase inhibitors, and pilocarpine.11

    With the exception of pilocarpine, these medications work to reduce the aqueous production quickly—pilocarpine constricts the pupil and helps widen the angle. It should be noted that if a secondary angle closure such as phacomorphic glaucoma is suspected, pilocarpine should not be used because it may narrow the angle further. Pilocarpine may also worsen an angle closure due to uveal effusion because it facilitates vascular permeability. Prostaglandins may not be as effective in immediate IOP reduction but should be used if no alternative or additional medications are available.

    The medications may be instilled every 10 to 30 minutes and should be continued until the IOP has been reduced to under 30 mm Hg. As with any treatment, optometrists should be aware of systemic conditions and potential contraindications with these medications. These include but are not limited to asthma, chronic obstructive pulmonary disease (COPD), kidney disease, and allergies.

    Related: Medically managing glaucoma

    In urgent or nonresponsive IOP, systemic carbonic anhydrase inhibitors (two 250-mg tablets po in one dose) may be given but are contraindicated in secondary angle closure induced by topiramate.14

    If secondary inflammation is present, topical steroids should be initiated.

    Indentation gonioscopy may also be performed with a smaller lens such as a four-mirror lens. Applying pressure to the central cornea may drive the iris posteriorly, allowing the angle to open.

    Once the IOP is controlled, the next step is to reverse the mechanism of angle closure. Laser peripheral iridotomy (PI) has been the definitive treatment for ACG due to pupillary block as well as a preventative treatment in narrow angle suspects. A PI establishes an alternative route for aqueous flow between the anterior and posterior chambers and allows for the iris to return to a neutral position.

    The PI may be placed superior, inferior, or at 3o’clock on the peripheral iris and is typically performed with a YAG laser. In some cases, the IOP remains elevated despite a patent PI, as seen with retro illumination. This is thought to be the result of prolonged irido-trabecular contact, resulting in long-term damage to the trabecular meshwork. Most patients who undergo PI will require additional intervention for either IOP lowering or improvement of visual acuity.5,10,11

    Even though PI is a minimally invasive procedure, complications may develop as a result, although unlikely. These include the risk of cataract progression, hyphema, peaked pupil, monocular diplopia, retinal detachment, and permanent vision loss.5

    An alternative approach for managing PACG is surgical lens extraction, as used in managing age-related cataracts. Age-related growth of the lens plays a major part in the mechanisms leading to primary angle-closure glaucoma, and lens extraction is used routinely in patients with coexisting cataract.10

    The effectiveness of early lens extraction for the treatment of primary angle-closure glaucoma (EAGLE) study is a step in determining the efficacy and safety of this treatment in people with primary angle-closure glaucoma without cataract. The results, released in 2016, showed that the study has achieved its primary aim to demonstrate that initial clear-lens extraction would be associated with better quality of life, lower IOP, and less need for glaucoma surgery at 36 months than standard care.19

    Despite these results, we still lack predictive factors that would better enable clinicians to identify individuals who are more likely to benefit from clear-lens extraction as a first line treatment. The decision should be made carefully after thorough evaluation and discussion with individual patients.

    Narrow angle suspect

    In cases of angle closure or ACG, the treatment and management process is relatively step-wise and direct—reduce the IOP and address the underlying cause.

    What about the asymptomatic patient with anatomically narrow angles? If he has no history of intermittent attacks or optic disc damage, what is the best management? Not everyone with narrow angles will go on to develop angle closure.

    Related: How oral and dental hygiene plays a role in glaucoma

    Ultimately there is no one method of management in these scenarios. Careful and accurate gonioscopy is essential in correctly evaluating the angle and identifying additional risk factors such as peripheral anterior synechiae. If synechiae are present with no other findings, a PI may be warranted. Dilating these patients on a case by case basis due to their increased possibility of undiagnosed glaucoma is an important component of their ocular care. Avoid using combinations of drugs that stimulate both the dilator and sphincter muscles as these will maximize the pupil block. Monitoring post-dilation IOP for any changes greater than approximately 5 mm Hg will help proactively identify any pressure spikes and allow for timely treatment. An iatrogenic angle-closure attack occurring in a managed and well-controlled environment can actually be turned to the patient’s advantage. The likelihood of acute angle-closure producing visual debilitation is far greater when the attack is unsupervised, where there is an average delay of 3.5 days before patients present for attention.11 If no pressure spike or angle closure event occurs, consider having the patient return in a few weeks to repeat gonioscopy and/or additional imaging. Ultimately, educating the patient on signs and symptoms of angle closure will be your best tool going forward as well as discussing prophylactic options available for all narrow angle patients.

     

    References

    1. World Health Organization. Global Data on Visual Impairments 2010. Geneva: World Health Organization, 2012. Available at: http://www.who.int/blindness/GLOBALDATAFINALforweb.pdf?ua=1. Accessed 8/25/17.

    2. Foster PJ, Johnson GJ. Glaucoma in China: how big is the problem? Br J Ophthalmol. 2001 Nov;85(11):1277-82. 


    3. Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol. 2006 Mar;90(3):262-7.


    4. Varma DK, Kletke S, Rai AS, Ahmed IIK. Proportion of undetected narrow angles or angle closure in cataract surgery referrals. Can J Ophthalmol. 2017 Aug;52(4):366-372.

    5. Cumba RJ, Nagi KS, Bell NP, Blieden LS Chuang AZ, Mankiewicz KA, Feldman RM. Clinical outcomes of peripheral iridotomy in patients with the spectrum of chronic primary angle closure. ISRN Ophthalmol. 2013 Jun 26;2013:828972.

    6. Friedman DS. Epidemiology of angle-closure glaucoma. J Curr Glaucoma Pract. 2007 May-Aug;1(1):1-3.

    7. Varma DK, Simpson SM, Rai AS, Ahmed IIK. Undetected angle closure in patients with a diagnosis of open-angle glaucoma. Can J Ophthalmol. 2017 Aug;52(4):373-378.

    8. Quigley HA. Angle-Closure glaucoma: concepts and epidemiology. Glaucoma Today. Available at: http://glaucomatoday.com/2009/08/GT0709_08.php/. Accessed 12/15/17.

    9. Foster PJ, Buhrmann R, Quigley HA, Johnson GJ. The definition and classification of glaucoma in prevalence surveys. Br J Ophthalmol. 2002 Feb;86(2):238-42.

    10. Azuara-Blanco A, Burr J, Ramsay C, Cooper D, Foster PJ, Friedman DS, Scotland G, Javanbakht M, Cochrane C, Norrie J; EAGLE study group. Effectiveness of early lens extraction for the treatment of primary angle-closure glaucoma (EAGLE): a randomised controlled trial. Lancet. 2016 Oct 1;388(10052):1389-1397.

    11. Fricke TR, Mantzioros N, Vingrys AJ. Management of patients with narrow angles and acute angle-closure glaucoma. Clin Exp Optom. 1998 Nov-Dec;81(6):255-266.

    12. Varma D, Adams WE, Phelan PS, Fraser SG. Viscogoniolasty in patients with chronic narrow angle glaucoma. Br J Ophthalmol. 2006 May;90(5):648-9.

    13. Coleman AL, Yu F, Evans SJ. Use of gonioscopy in Medicare beneficiaries before glaucoma surgery. J Glaucoma. 2006 Dec;15(6):486-93.

    14. Vagheri N, Wajda BN, Calvo CM et al. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease (7th ed.). 2017. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins.

    15. Foster PJ, Aung T, Nolan WP, Machin D, Baasanhu J, Khaw PT, Alsbirk PH, Lee PS, Seah SK, Johnson GJ. Defining ‘‘occludable’’ angles in population surveys: drainage angle width, peripheral anterior synechiae, and glaucomatous optic neuropathy in east Asian people. Br J Ophthalmol. 2004 Apr;88(4):486-90.

    16. Lachkar Y, Bouassida W. Drug-induced acute angle closure glaucoma. Curr Opin Ophthalmol. 2007 Mar;18(2):129-33.

    17. Acharya N, Nithyanandam S, Kamat S. Topiramate-associated bilateral anterior uveitis and angle closure glaucoma. Indian J Ophthalmol. 2010 Nov-Dec;58(6):557-9.

    18. Asrani SG, Foster PJ, Palmberg PF, Ritch R. MD Roundtable: Expert Tips for Assessing the Narrow Angle. Available at: https://www.aao.org/eyenet/article/md-roundtable-expert-tips-assessing-narrow-angle?january-2015. Accessed 8/25/17.

    19. Chan P, Tham C. Commentary on effectiveness of early lens extraction for the treatment of primary angle-closure glaucoma (EAGLE). Annals Eye Science. Available at: http://aes.amegroups.com/article/view/3677. Accessed 12/15/17.

    Rachel Grant, OD, FAAO
    Dr. Rachel Grant received her Doctor of Optometry degree in 2012 from Southern California College of Optometry. She completed a ...

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