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Dry eye needs to be evaluated, managed before ocular surgery
Dry eye is a multifactorial disease of the tear film and ocular surface resulting in symptoms of discomfort, visual disturbance and tear film instability with potential ocular surface damage. It is accompanied by increased tear film osmolarity and ocular surface inflammation. This definition, given by the Dry Eye WorkShop in 2007, forms the basis of our understanding of dry eye. It also gives guidelines regarding grading of dry eye and treatment strategies for each grade of severity.
When it comes to ocular surgeries, managing dry eye in the perioperative period plays an important role in having a good outcome and a happy patient. Most of the patients that we operate for cataract are elderly with pre-existing minimal dry eye or a component of conjunctivochalasis, both of which can get worse after surgery. Apart from the routine use of a dry eye questionnaire and clinical evaluation with Schirmer’s test, corneal staining and tear breakup assessment to diagnose dry eye, newer modalities of investigations are now being used.
Hyperosmolarity plays an important role in the pathogenesis of dry eye. The advent of instruments to measure it in a simple and repeatable manner using the TearLab osmometer has allowed surgeons to include it in their preoperative and postoperative assessment of patients undergoing ocular surgery, especially cataract and LASIK. The need to measure tear film dynamics such as tear breakup time in a noninvasive manner, the tear meniscus height and quantifying the meibomian gland function using the meibography application in machines such as the Oculus Keratograph, or the assessment of the lipid layer of tears using LipiView technology (TearScience) is being attempted in centers that have access to this expensive equipment. Tear proteomics is another area with increased interest, and assessing the profile of inflammatory mediators in dry eye can give us a clue to the severity and can help in further understanding the disease. Recently, InflammaDry (RPS) a rapid in-office diagnosis kit, has been made available to ascertain the levels of MMP-9 in tears. The quality of vision of patients with dry eye can be assessed using instruments based on the double-pass aberrometry principle. Although the objective scatter index (OSI) can be affected even by cataract, the change in OSI over a period of a couple of minutes or before and after application of lubricants will help us understand the contribution of dryness to a patient’s poor quality of vision.
Preoperatively, looking for and treating dry eye appropriately with lubricants, omega-3 fatty acid supplements, systemic doxycycline and/or low-dose steroids or topical cyclosporine form an important part of the preoperative assessment. If the dry eye is severe, we might need to consider starting autologous serum drops to improve the ocular surface health before surgery; however, because they have to be compounded fresh, there is a potential risk for contamination, and use is reserved for very severe cases and when the patient can come for a regular follow-up. The other option would be to consider occlusion of the puncta on a temporary or permanent basis before the surgery based on severity. Dry eyes can also alter the keratometry/topographic values we use for IOL calculation. Priming patients preoperatively about their dry eye level and explaining the steps taken to improve it before planning cataract surgery helps them better deal with the minimal increase in postoperative dryness.
Intraoperatively, the use of Apidine (povidone-iodine, Appasamy Associates) before surgery, the excess use of topical anesthetic drops and exposure to microscope light, and the neurotrophic change due to corneal incisions contribute to the postoperative dryness and ocular surface staining/damage. Intraoperatively, adequately coating the ocular surface with viscoelastic material and reducing the microscope light are advisable. Also, because ocular surface colonization by microorganisms might be more prominent in a dry eye as compared with a normal eye, postoperative use of preservative-free antibiotics is preferred.
Postoperatively, the patient will need to be closely followed to ensure adequate health of the ocular surface. It is preferable to put the patient on preservative-free medications as much as possible in the postoperative period. There are reports of increased or faster ocular surface stability using topical cyclosporine or omega-3 fatty acids, especially in post-LASIK eyes.
To conclude, a patient with dry eyes who undergoes ocular surgery needs a meticulous evaluation of his tear film and ocular surface status before surgery. The dryness and ocular surface need to be treated so they are as normal as possible before attempting surgery, and these patients need a closer follow-up postoperatively until the ocular surface stabilizes.
References:
Bron AJ, et al. Ocul Surf. 2014;doi:10.1016/j.jtos.2014.02.002.
Cetinkaya S, et al. BMC Ophthalmol. 2015;doi:10.1186/s12886-015-0058-3.
International Dry Eye Workshop. Ocul Surf. 2007;doi:10.1016/S1542-0124(12)70081-2.
Jee D, et al. J Cataract Refract Surg. 2015;doi:10.1016/j.jcrs.2014.11.034.
For more information:
Dennis S.C. Lam, MD, FRCOphth, can be reached at State Key Laboratory in Ophthalmology, Sun Yat-Yen University, 54 South Xianlie Road, Guangzhou 510060, People’s Republic of China; email: dennislam.gm@gmail.com.
Disclosure: Srinivasan and Lam report no relevant financial disclosures.