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MANAGING OPEN ANGLE GLAUCOMA

Other management considerations

a. Impact of ocular surface disease on management
While dry eye disease is frequently recognized in a large segment of our patient population, we are just learning
about how common it is in the group with and at risk for glaucoma. Not only are some of the primary cases of ocular
surface disease associated with glaucoma, such as chemical or thermal trauma, aniridia and autoimmune conjunc-
tivitis, but the treatments for these conditions may exacerbate glaucoma (e.g. topical steroids increasing IOP) and
vice versa (e.g. preservatives in glaucoma medications exacerbating ocular surface disease). While it is under-
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stood that dry eye disease may be present in 15% of the population, that percentage increases significantly when
looking at the population with glaucoma. 361,362 Estimates vary depending on what parameter is evaluated, but in one
population studied, 59% of those with glaucoma had symptoms of dry eye in at least one eye, 61% had reduced tear
volume on Schirmer test, 78% had reduced tear stability (TBUT), and 65% were noted to have a significant decrease
in tear quality. In another study, severity of ocular surface disease was directly related to elevated IOP, with 63%
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of patients with severe glaucoma and 41% with mild glaucoma exhibiting symptoms of OSD. These numbers need
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to be corroborated by others as the relationship between the comorbidities of ocular surface disease and glaucoma
is only beginning to be elucidated.
It is well established that BAK-containing eye drops are toxic to the ocular surface, yet this preservative remains the
cornerstone of virtually all topical ocular therapeutic agents. BAK is known to be toxic to the conjunctiva, cornea,
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and trabecular meshwork. 364,366,367 In fact, chronic conjunctival inflammation secondary to BAK exposure has been
implicated in reducing the success of glaucoma surgical procedures. Ocular surface disease is related to number
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of glaucoma medications prescribed and duration of glaucoma treatment, both related to BAK exposure. Despite
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newer non-BAK and preservative-free glaucoma medications being developed, lack of uptake of these agents in the
US market has highlighted a need for increased awareness of the significance of treating ocular surface disease in
the management of patients with concomitant glaucoma. Compounding this challenge, certain medications such
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as preservative-free tafluprost are not yet available to our patients in Canada.
Ocular surface disease exacerbated glaucoma is a novel term used to describe those patients with severe OSD who
also have glaucoma that is refractory to medical treatment. These patients respond to medications poorly and
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are more likely to have compromised success during glaucoma filtering procedures. Inflammation, the root of dry
eye disease, is also at the root of glaucoma. The notion of successful glaucoma treatment hinging on successful
maintenance of ocular surface health is new, but makes a great deal of sense. While our knowledge of the increasing
prevalence and impact of dry eye disease is growing quickly, it follows that we need to be far more vigilant about
concurrent disease, elevating the importance of its adequate management, not in spite of but because of the glau-
coma. A shift away from focusing solely on IOP-lowering to the inevitable detriment of the ocular surface must
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occur if ‘preserving visual function … without causing untoward side effects from treatment’ is to be the true focus
in the management of glaucomatous disease. 154
Treatment for the inflammation of ocular surface disease in the presence of glaucoma cannot be ignored. Topical cy-
closporine 0.05% has been shown to have a beneficial effect on the ocular surface in the presence of surface-altering
glaucoma treatments, improving many measurable elements of dry eye disease including symptom questionnaires,
tear stability, tear volume, corneal and conjunctival staining, and corneal morphology. 371

Clinical Recommendations related to ocular surface disease and glaucoma:
• As soon as a patient is identified as being at risk for glaucoma, ocular surface disease parameters should be
included in the clinical assessment (may include the use of standardized questionnaires, measurement of
tear osmolarity, corneal/conjunctival staining, assessment of tear stability).

• Treat the ocular surface disease proactively and aggressively with all available treatments, including agents
that safely target chronic inflammation.

• Once glaucoma is diagnosed, consider the status of the ocular surface in every management decision,
including the initiation of preservative-free formulations and perhaps earlier consideration for SLT.

b. Role of generic medications
While bioequivalence is the only parameter that a generic drug manufacturer needs to demonstrate to prove that

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