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BLOG: A healthy ocular surface is required for surgery
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Cataract surgery patients have come to expect what can be considered life-changing refractive outcomes.
When patients have ocular surface disease (OSD), however, treatment to improve and ultimately optimize corneal health is required before the procedure can take place. Postoperatively, untreated OSD can cause poor visual quality, fluctuating vision and ocular discomfort, ultimately undermining the surgery and leaving the patient unhappy.
It is in the best interest of patients to delay cataract surgery until the ocular surface has been optimized. Although they will be initially disappointed, patients will appreciate the wait once educated to understand the key role corneal health plays in the accuracy of the preoperative measurements.
Make it as easy as 1-2-3
There are three keys to simplifying one's approach to identifying OSD and targeting treatments to the appropriate components of this multifactorial disease: osmolarity, inflammation and meibomian gland function. Point-of-care diagnostic tests addressing these dry eye hallmarks can be implemented by the work-up technician and used to pinpoint the diagnosis, educate patients and facilitate a therapeutic strategy.
Tear film. Tear hyperosmolarity is considered to be the core mechanism of dry eye, triggering a cascade of signaling events in surface epithelial cells. Even the mildest abnormality can equate to significant discomfort and visual symptoms. The TearLab Osmolarity System provides an objective measure of osmolarity using a small 50-mL sample of tears. A cut-off of 308 mOsm/L or an intereye difference greater than 8 mOsm/L is a highly sensitive measure (Craig et al.; Lemp et al.; Sambursky, Davitt et al.).
Inflammation. The stressed epithelial cells can produce matrix metalloproteinases (MMP)-9. These proteolytic enzymes destabilize the tear film by breaking down tight junctions and facilitating inflammatory cell migration. MMP-9 is elevated in the tears of patients with dry eye disease, and the levels have been shown to correlate with examination findings in terms of disease severity (Lemp et al.; Sambursky, Davitt et al.; Sullivan et al.; Potvin et al.; Sambursky and O’Brien). InflammaDry (Quidel) is a highly accurate test that recognizes elevated levels of MMP-9 in tear fluid samples taken from the palpebral conjunctiva. The normal range of MMP-9 levels in human tears is 3 ng/mL to 41 ng/mL (Sambursky and O’Brien).
Meibomian glands. Meibomian gland dysfunction is present in 86% of patients, making meibography an indispensable part of identifying disease and targeting treatment (Craig et al., Lemp et al., Nichols et al.). With a noninvasive device like the LipiScan (Johnson & Johnson Vision), practitioners can see atrophy and gland dropout. These images, along with results from the other point-of-care tests, make for powerful tools when it comes to getting patients on board with the next steps for their treatment.
First line of attack
To restore tear film homeostasis, the Tear Film & Ocular Surface Society Dry Eye Workshop II lists therapy options organized in a stepwise fashion (Craig et al.). For example, the OSD patients with elevated MMP-9 indicating inflammation will likely require prescription therapy, and topical antibiotic or antibiotic-steroid combinations can be considered if there is anterior blepharitis, along with lid hygiene products that include hypochlorous acid.
A majority of dry eye disease patients have meibomian gland dysfunction (Nichols et al.), necessitating lid disease treatments along with physical heating and expression of the meibomian glands. LipiFlow (Johnson & Johnson Vision) applies localized heat to the meibomian glands to improve meibum mobility during a bilateral, 12-minute, in-office procedure.
Two new device-based meibomian gland dysfunction treatments that also use the application of heat are Alcon's iLux system and TearCare from Sight Science.
Don’t forget the questionnaires
Physicians should implement questionnaires such as Standardized Patient Evaluation of Eye Dryness or the Ocular Surface Disease Index to capture subjective information about patients’ dry eye disease and the condition’s overall impact on their daily life. Patients who score at an established threshold can then automatically receive point-of-care tests.
An aggressive, strategic and straightforward approach to OSD treatment for presurgical patients will ensure they cross the finish line boasting about their visual results – even if they have a slight delay along the way!
References:
Blackie CA, et al. Cornea. 2009;doi:10.1097/ICO.0b013e318191b870.
Craig JP, et al. Ocul Surf. 2017;doi:10.1016/j.jtos.2017.08.003.
Lemp M, et al. Am J Ophthalmol. 2011;doi:10.1016/j.ajo.2010.10.032.
Nichols KK, et al. Invest Ophthalmol Vis Sci. 2011;doi:10.1167/iovs.10-6997a.
Potvin R, et al. Clin Ophthalmol. 2015;doi:10.2147/OPTH.S95242.
Sambursky R, Davitt W, et al. Cornea. 2014;doi:10.1097/ICO.0000000000000175.
Sambursky R, O’Brien TP. Curr Opin Ophthalmol. 2011;doi:10.1097/ICU.0b013e32834787bb.
Schiffman RM, et al. Arch Ophthalmol. 2000;118(5):615-621.
Sullivan B, et al. Invest Ophthalmol Vis Sci. 2010;doi:10.1167/iovs.10-5390.