The complicated ins and outs of paediatric glaucoma
Early detection and diagnosis are key for these young patients
As a new parent, I now understand why parents constantly worry parents about their children. Will they be happy and healthy? Will they have any developmental delays? What if they fall and hurt themselves? What if they are bullied? The possibilities are endless, but as an eye care provider I also worry about conditions that could cause vision loss.
Paediatric glaucoma is one of these conditions that, although rare, can cause irreversible vision loss and leave children visually impaired if not treated in a timely and adequate manner. Primary congenital glaucoma accounts for 50% to 70% of all paediatric glaucoma, and its prevalence is approximately one in 10,000 births.1 Other types of paediatric glaucoma can be acquired (eg, through trauma, intraocular surgery) or secondary to a systemic condition, such as Sturge-Weber syndrome, or ocular anomaly, such as aniridia.
Being knowledgeable about and competent with the signs and symptoms of paediatric glaucoma, specifically primary congenital glaucoma, is important.
According to the American Academy of Ophthalmology, only 25% of primary congenital glaucoma is present at birth, but it can develop anytime during the first year of life.2 Common symptoms that parents may notice are epiphora, blepharospasm and photophobia, but these can be missed or confused with other conditions such as a nasolacrimal duct obstruction. Some signs to look for when examining infants with suspected primary congenital glaucoma are clouding of the cornea (corneal oedema) secondary to elevated IOP. It often accompanies breaks in the Descemet membrane known as Haab striae. This elevation in the IOP also causes enlargement of the cornea in one or both eyes. In an infant younger than 12 months, a corneal diameter of greater than 12 mm is considered enlarged.3
Comprehensive care
A complete ophthalmic exam of a patient who may have glaucoma should include IOP, funduscopic exam and cycloplegic refraction. The clinician also should initially assess the infant’s general appearance and visual behaviour. Are they visually engaged? Are they exploring the room? Are they mobile? Do their eyes appear normal and clear or are they cloudy in appearance? Do both eyes look in the same direction? Is there any presence of nystagmus?
After completing a thorough history and observing the patient’s interactions, visual assessment should be completed. This can include whether each eye fixes and follows a toy or object. It should be checked whether a newborn blinks to light response. Teller cards or LEA Gratings paddles could be used for quantitative visual acuity.
The examination of the cornea is crucial to determine the clarity, size and any abnormalities of the anterior segment. This can be completed with the parent holding the infant with their face in a handheld slit lamp, or with an external 20-D lens with external light source if the child will cooperate (Figure 1).
IOP assessment can be difficult to obtain but is vital to the exam. IOP can be completed via iCare, Goldmann applanation tonometry (the gold standard) or Tono-Pen. Central corneal thickness with pachymetry can supply more information but adjusting IOP secondary to pachymetry is not recommended because of other factors affecting corneal thickness (corneal scarring, corneal oedema, etc). A funduscopic exam with the binocular indirect ophthalmoscope allows evaluation of the optic nerve for a progressive increase in cupping or asymmetric cup to disc ratio of 0.2 μm or more secondary to elevated IOP.3 Along with optic nerve changes from an elevated IOP, there can be an associated elongation of the eyeball. This could result in an associated large myopic shift or progressive high myopia associated with primary congenital glaucoma highlighting why a cycloplegic dilation is essential.4
If it is determined that an infant has two or more of the above signs of glaucoma, then an urgent referral to a paediatric ophthalmologist is crucial with the diagnosis of primary congenital glaucoma. Unfortunately, medication management of primary congenital glaucoma does not show sustained efficacy as primary treatment and these patients often require surgical management, which is why the paediatric ophthalmologist needs to be involved quickly. Glaucoma medication, either topical or oral, can be used for temporary treatment prior to surgery to aid in clearing corneal oedema for better ocular examination and surgical intervention. After surgical intervention, topical treatment may be implemented as an adjunctive therapy for aided control of IOP.
Medication management
When considering starting infants on topical or oral medication for eye pressure, there are some systemic considerations that could be lethal if not prescribed correctly. Adverse reactions can also present atypically in children, and because they are not able to communicate symptoms and parents may not readily recognise them, close monitoring is important.
β-Blockers such as timolol can provide a 20% to 25% IOP reduction. It is typically prescribed at 0.1% or 0.25% in smaller children because of the risk of bronchospasms and bradycardia. β-Blockers should be avoided in patients with reactive airways. When unable to avoid, selective betaxolol should be considered in patients with asthma. Carbonic anhydrase inhibitors offer a 25% reduction with topical medication and 40% reduction in IOP with oral medication. The topical form is systemically safer and better tolerated but not as effective. When prescribing carbonic anhydrase inhibitors, it is important to avoid in patients with compromised corneas and sulfa drug allergies.
Metabolic acidosis, poor feeding and minimal to no weight gain are systemic concerns with oral acetazolamide (Diamox) and even possible with topical treatment in newborns so it should be avoided when possible. α-Agonists such as brimonidine can cause a 2– to 6–mm Hg reduction in IOP but should be avoided in small children and infants because of potential central nervous system suppression. In infants and children less than 40 lb, it can cause bradycardia, hypotension, hypothermia, hypotonia and apnea. Apnea has an even higher incidence if paired with a β-blocker such as timolol. Therefore, brimonidine should be avoided in all small children because of the potentially fatal adverse events of the medication.
Prostaglandins can provide a 25% to 30% reduction in IOP and have minimal adverse events. Prostaglandins can result in increased eyelash growth and eye redness, so if only using it in one eye it may be worth mentioning to the parent. Prostaglandins should be avoided when inflammatory properties present, such as with uveitic glaucoma (Figure 2).5,6
Combination drops are convenient for the patient and parent, especially when more than one medication is required to manage IOP, but they are considered off label for use in children. Because of the risk of adverse events, there are limited options for combination drops; brimonidine is present in brimonidine 0.2%/timolol 0.5% (Combigan; Allergan/AbbVie) and brinzolamide 1%/brimonidine 0.2% (Simbrinza; Alcon).
Conclusion
It is the role of the primary eye care provider to diagnose disease in these patients and urgently refer them when necessary to reduce the potential amount of vision loss and optic nerve damage. Early detection can be key in preventing these patients from requiring low-vision services. Management of IOP reduction can be very tricky given risk of systemic adverse events and often requires surgical interventions. Effective communication with the ophthalmologist and building trust can aid in the primary eye care provider’s ability to treat these patients and better care for our paediatric patients.
Samantha Rosen, OD, is a paediatric optometrist at Helen DeVos Children’s Hospital in Grand Rapids, Michigan, US. Dr Rosen has no financial disclosures.
References
1. Karmel M. Childhood glaucoma: the challenges inherent in treating a vulnerable population. EyeNet. 2016;45-49.
2. Okorie A, Madu A. Diagnosis and treatment of primary congenital glaucoma. American Academy of Ophthalmology. 2010. Accessed May 1, 2023.
https://www.aao.org/eyenet/article/diagnosis-treatment-of-primary-congenital-glaucoma
3. Bagheri N, Wajda B, Calvo C, Durrani A, eds. The Wills Eye Manual. Lippincott Williams & Wilkins; 2016.
4. Mandal AK, Chakrabarti D, Chakrabarti R. Primary congenital glaucoma—pathogenesis, clinical features, diagnosis, differential diagnosis and management. In: Ramakrishnan R, Krishnadas R, Robin AL, Khurana M, eds. Diagnosis and Management of Glaucoma. 1st ed. Jaypee Brothers Medical Publishers; 2013:442-450.
5. Dorkowski M, Williamson J, Rixon A.
A guide to applying IOP-lowering drugs. Review of Optometry. 2018;155(7):24.
6. Giaconi JAA, Coppens G, Zeyen T. Paediatric glaucoma: glaucoma medications and steroids. 2nd ed. Springer; 2016:481-486. Pearls of Glaucoma Management. doi:10.1007/978-3-662-49042-6_51
