At the completion of this article, the reader should be able to:
• Understand the impact of ocular surface disease (OSD) on glaucoma management
• Improve skills in educating patients about the iStent implantation
procedure, discussing the risks and benefits and addressing patient concerns
• Understand the importance of individualised peri-operative care plans that address both glaucoma management and OSD treatment
Dr Alex Ioannidis
MBBS FRCOPHTH FRANZCO
Vision Eye Institute
Images: Alex Ioannidis
DR ALEX IOANNIDIS explores the intersection of two critical aspects of glaucoma care: the peri-operative contributions of skilled optometrists and the impact of ocular surface disease in glaucomatous patients. He also discusses how, when necessary, surgical solutions can alter the patient’s trajectory – often succeeding under the auspices of collaborative care.
Ocular surface disease (OSD) presents a multifaceted challenge in the management of glaucoma, often complicating treatment strategies and affecting patient comfort and adherence. At the same time, the peri-operative care of patients undergoing interventions like iStent implantation requires meticulous attention to detail to ensure optimal outcomes. Integrating the management of OSD with peri-operative optometric care is crucial for enhancing treatment efficacy and patient satisfaction in glaucoma management.
The impact of OSD
OSD is a multifactorial disorder of the conjunctival epithelium, cornea, lacrimal, and meibomian glands that results in either deficient or inappropriate tear production. OSD can lead to decreased visual acuity and result in significant ocular discomfort.¹
OSD can occur in conjunction with many other ocular conditions and often co-exists with glaucoma due to the current use of medications used to treat the condition. At present, 11% of the five million Americans over 50 who have dry eye disease also have glaucoma.2
Topical medical therapy is the most common initial treatment for glaucoma, and 49-59% of glaucoma patients on topical anti-glaucomatous medications have some form of OSD.3 OSD in these patients can be a pre-existing condition that is exacerbated by topical therapy or a novel disease that manifests after initiation of topical glaucoma therapy.
Topical glaucoma medications can cause significant morbidity with patients complaining of a burning sensation, irritation, itching, tearing, skin pigmentation and decreases in visual acuity often within three months of medication initiation.4
Furthermore, untreated primary open angle glaucoma (POAG) patients have a higher risk of OSD in part due to a 22% lower basal tear turnover rate in comparison to patients without glaucoma.5
The resulting OSD in patients with glaucoma can lead to poor medication compliance from the associated symptoms. This can lead to cessation of therapy by the patient without informing the physician resulting in elevation of IOP and disease progression.
In addition, OSD is also linked to a higher rate of failure in filtration glaucoma surgery.
Thus, management of OSD in glaucomatous patients is important when trying to reduce further ocular morbidity and to improve the success of glaucoma therapy.
Case 1
A 69-year-old female patient with unilateral POAG presented complaining of chronic conjunctival injection and irritation. Her condition was stable based on serial VF testing and OCT analysis of the optic nerves.
Her IOP was measured at 18 mmHg on GAT. Her glaucoma was being treated with latanoprost nocte in the left eye. On this last review, she was found to have developed a cataract and was keen to explore her options on reducing the drop burden on her ocular surface – and to become drop free if possible.
Clinical examination revealed significant skin pigmentation and conjunctival injection of the left eye (Figures 1 and 2).
Cataract surgery was performed in combination with implantation of the iStent inject system in the trabecular meshwork. Her postoperative IOP was 14 mmHg and the latanoprost drops were ceased in the left eye. Within a month there was a marked improvement in the appearance of her conjunctiva with resolution of the symptoms of irritation.
Her forniceal conjunctiva ceased to be injected (Figure 3).
Case 2
The chronic use of medications to lower IOP can have other unintended consequences when it comes to the management of the ocular surface.
The use of prostaglandin analogues has also been associated with local tissue atrophy in the orbit – a type of orbitopathy – reported to occur with a number of prostaglandin analogues in current circulation.6 This can result in deepening of the orbital sulcus due to the loss of adipose and connective tissue in that area (Figures 4 and 5).
Case 3
Corneal toxicity secondary to chronic medication use is another area where the iStent inject system can make a significant difference eliminating the gritty and stinging sensation that is associated with drop installation.
The main culprit in these cases with benzalkonium chloride (BAK) which acts as a preservative in glaucoma medications. BAK has been shown to strongly induce the expression of inflammatory mediators in the lens epithelial cells compared with latanoprost or timolol.
The Blue Mountains Eye Study and Ocular Hypertension Treatment Study both suggested higher rates of cataract formation in those with antiglaucoma therapy. Miyake conducted studies that suggested that BAK preserved drops prior to cataract surgery increased the risk of cystoid macular oedema.
Chronic BAK exposure has been associated with significant ocular surface toxicity, often manifesting as a diffuse punctate keratopathy (Figure 6).
Once iStent inject surgery has been performed – as in this case – and BAK is eliminated from the ocular surface, significant improvement of the overall corneal health is seen with resolution of the signs (Figure 7).
The use of microtrabecular shunts such as the iStent inject system from Glaukos has been revolutionary in the management of mild-to-moderate stable glaucoma.
We see that the chronic use of drops has a detrimental effect on the ocular surface of these patients resulting in secondary morbidity which can be quite significant but also can result in poor adherence to management protocols.
It’s advantageous to offer this cohort of patients access to the iStent inject system reducing or eliminating the drop burden and thus achieving better outcomes and disease management.
Peri-operative considerations for optometrists
The involvement of an optometrist in the peri-operative care of patients undergoing iStent implantation is crucial for enhancing patient outcomes through comprehensive care and education of the patient and collaboration with the referring ophthalmologist.
Optometrists play a significant role in both the pre-operative and post-operative phases, ensuring patients are well-informed, prepared and supported throughout the process. Below are key peri-operative considerations for optometrists to keep in mind:
PRE-OPERATIVE PHASE
1. Initial assessment and referral
• Screening for glaucoma: conduct thorough eye examinations to diagnose glaucoma and evaluate its severity.
• Patient education: informing the patient about glaucoma and discussing the range of treatment options, including the potential benefits of iStent implantation.
• Referral to ophthalmologist: optometrists play a key role in identifying suitable candidates for iStent and referring them to an ophthalmologist for further evaluation and surgical planning.
2. Management of Ocular Surface Disease (OSD)
• Treat dry eye and OSD: address the ocular surface issues that may arise due to glaucoma medication.
• Patient education on OSD: educate patients on how to manage dry eye symptoms and how iStent implantation can help to maintain ocular surface health.
3. Pre-surgical counselling
• Explain the procedure: optometrists should educate their patients about what to expect during iStent implantation, including the steps of the surgery and its benefits.
• Discuss risks and benefits: provide balanced information on the potential outcomes, such as reduced intraocular pressure and potential decrease in medication use.
• Address patient concerns: answer any questions and alleviate fears or misconceptions about the surgery.
4. Medication management
• Medication review: adjust existing glaucoma medications if necessary, coordinating with the attending ophthalmologist regarding any changes.
POST-OPERATIVE PHASE
1. Immediate post-operative care
• Monitor healing: assess the surgical site for signs of infection, inflammation or other complications during initial follow-up visits.
• Intraocular pressure monitoring: regularly check intraocular pressure to ensure the iStent is functioning effectively.
2. Long-term follow-up
• Ongoing IOP monitoring: the optometrist will continuously monitor intraocular pressure to detect any changes or need for further intervention.
• Visual field testing: visual field tests are recommended to track the patient’s visual health and detect any progression of glaucoma.
• Optic nerve evaluation: after iStent implantation, OCT evaluation of the retinal nerve fibre layer (RNFL) can provide valuable information about the structural changes in the optic nerve head and RNFL.
3. Medication Adjustments
• Glaucoma medication review: adjust glaucoma medications as needed
• Coordinate with ophthalmologist: maintain open communication with the ophthalmologist to ensure a cohesive treatment plan and make necessary adjustments.
4. Patient Education and Support
• Post-operative instructions: provide clear instructions on post-operative care, including activity restrictions, medication adherence and signs of complications.
• Lifestyle advice: offer guidance on lifestyle modifications that can support overall eye health and glaucoma management.
By considering these peri-operative aspects of care for patients undergoing iStent implantation, optometrists can ensure coordinated care that enhances patient outcomes and satisfaction.
Conclusion
The iStent inject offers a procedural option that can streamline patient care in glaucoma management. Optometrists, as primary eyecare providers, play a crucial role in identifying suitable candidates for this procedure and educating them about its potential benefits.
The safety profile of the iStent inject makes it a viable option for early surgical intervention in patients with mild-to-moderate glaucoma, often in conjunction with cataract surgery. Optometrists can engage in collaborative care by assessing patients for iStent inject candidacy, conducting pre-operative assessments and providing patient education.
A collaborative approach ensures that patients are well-informed and have realistic expectations about the procedure. Post-operatively, optometrists monitor patients’ intraocular pressure and manage medications, working closely with ophthalmologists
to optimise outcomes.
Ultimately, the optometrist’s involvement in the peri-operative care of iStent inject patients contributes to comprehensive and coordinated management, which can improve patient outcomes.
More reading
Ménière’s disease: a primer for optometrists
Accommodation disorders: Recognising, assessing and managing
Dry eye: Patient identification, product formulation and therapy escalation
References
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2. Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol. 2006; 90(3):262–267.
3. Leung EW, Medeiros FA, Weinreb RN. Prevalence of ocular surface disease in glaucoma patients. J Glaucoma. 2008; 17(5):350–355.
4. Rossi GC, Scudeller L, Rolle T, Pasinetti GM, Bianchi PE. From benzalkonium chloride- preserved latanoprost to polyquad-preserved travoprost: A 6-month study on ocular surface safety and tolerability. Expert Opin Drug Saf. 2015; 14(5):619–623.
5. Kuppens EV, van Best JA, Sterk CC, de Keizer RJ. Decreased basal tear turnover in patients with untreated primary open-angle glaucoma. Am J Ophthalmol. 1995; 120(1):41– 46.
6. Inoue K, Shiokawa M, Wakakura M, Tomita G. Deepening of the upper eyelid sulcus
