Here’s another reason why dry eye disease (DED) deserves our attention: The tear film-air interface provides 75% of the refractive power of the eye.¹ Align that with the other reasons DED requires treatment — its presence affects preoperative planning, surgical outcomes and patient satisfaction² — and that requirement could be called a mandate.

DED has been divided into four subtypes: aqueous tear deficiency (ATD); blepharitis/meibomian gland dysfunction (MGD), also known as evaporative; goblet cell/mucin deficiency; and exposure-related dysfunctional tear syndrome. There are also masqueraders, or coconspirators, of DED such as: superior limbic keratoconjunctivitis, topical medication toxicity, Thygeson’s superficial punctate keratitis, mucous fishing syndrome, contact lens-related toxicity, allergic conjunctivitis, conjunctivochalasis, chemical toxicity and floppy eyelid syndrome.³ Nonobvious or obvious anterior basement membrane dystrophy can become more clinically relevant after cataract surgery, and other mechanical diseases like Salzmann’s nodular degeneration should be carefully evaluated for upon slit lamp examination.

The Prospective Health Assessment of the Cataract Patient’s Ocular Surface (PHACO) study found that 87% of patients scheduled for cataract surgery had clinical findings of dry eye but were asymptomatic.⁴

WHAT DED DOES

DED can impact the preoperative planning of your cataract surgery. An irregular ocular surface can result in topographical aberrations, such as irregular mires, that create artificially steeper Ks and irregular astigmatism. Treating seemingly higher levels of astigmatism can cause an overcorrection and possibly lead to flipping the axis postoperatively.

Cataract surgery itself can exacerbate pre-existing dry eye. Inciting factors include: prolonged intraoperative microscopic light exposure, grooved corneal tunnel incisions, denervation of the cornea, topical anesthesia and drops containing preservatives, such as benzalkonium chloride.^5-7 Also, femtosecond-assisted limbal relaxing incisions (LRIs) create intrastromal incisions without disturbing the epithelium, preserving tear film stability and offering patient comfort, unlike penetrating limbal relaxing incisions.⁸ In a study by Kasetsuwan et al., which analyzed the incidence of postoperative dry eye one week following phacoemulsification, 68.4% had reduced TBUT, 11.9% had a diminished Schirmer 1 score without anesthesia, and 9.8% had dry eye based on the Ocular Surface Disease Index (OSDI) score.⁹

ESTABLISHING AND MANAGING DED

There are myriad methods to assess dry eye subjectively. Visual-function questionnaires are useful tools. The OSDI is a 12-item questionnaire that rapidly assesses and categorizes DED severity into normal, mild, moderate and severe, based on a scoring algorithm. The score is scaled from 0-100 with higher values indicating more severe disease; values ≥ 13 indicate DED.¹⁰ (For more DED diagnostics, see page 24.)

After establishing the diagnosis of dry eye and classifying the subtype(s), the next step is to outline its management (Table 1, page 22).³ Artificial tears are indicated for all subtypes of DED. They lubricate the surface, remove debris, reduce elevated pro-inflammatory mediators, dilute a hyperosmolar tear film and supplement deficient components of the tear film.³ For those with moderate to severe dry eye, it is recommended to use preservative-free artificial tears at least four times per day. While artificial tears provide improvement of subjective symptoms and objective findings, they will not resolve dry eye on their own for the majority of patients.

The first-line treatments for DED (ATD, MGD and goblet/mucin deficiency) are artificial tear supplements and topical anti-inflammatories (Table 1).³ Anti-inflammatory therapies have been proven to be efficacious for moderate to severe evaporative dry eye and ATD. Topical cyclosporine A (Restasis, Allergan) 0.05% works by inhibiting cytokine production from activated T lymphocytes, reducing conjunctival goblet cell loss and epithelial apoptosis. An early response can be observed at six weeks; however, it may take at least six months to see an improvement. Donnenfeld et al. studied the effects of cyclosporine compared to preservative-free artificial tears (PFAT) following phacoemulsification and implantation of multifocal IOLs. They found that the cyclosporine group had an improved mean uncorrected distance visual acuity (UCDVA) of 20/25 compared to the artificial tear group with mean UCDVA of 20/30 (P=0.45). Mean best-corrected distance visual acuities (CDVA) were 20/20 in the cyclosporine group compared to 20/25 in the PFAT group (P=0.005). They also noted improved contrast sensitivity, conjunctival staining and TBUT.¹¹

Because it takes time to reap the full benefits of cyclosporine, several clinicians have found using an NSAID or topical steroid helps with the burning and stinging¹² of cyclosporine until the induction period is complete. Topical loteprednol QID can be used for two weeks to begin subjectively and objectively improving the ocular surface for preoperative measurements while waiting for anti-inflammatory medications to take effect.¹³

Lifitegrast (Xiidra, Shire) 5.0% is the newest FDA- approved medication for DED. It is an intracellular adhesion molecule-1 (ICAM) decoy that blocks the binding interaction of lymphocyte function-associated antigen-1 (LFA-1). This inhibits T-cell recruitment, activation and proinflammatory cytokine release associated with DED. Studies involving lifitegrast have shown improvement in dry eye symptoms by day 14.¹⁴ Irritation and discomfort can occur with application; the most common nonocular side effect is dysgeusia.

Warm compresses and eyelid scrubs such as Avenova (NovaBay Pharmaceuticals) or OcuSoft scrubs (OCuSOFT) are also first-line therapies for MGD. Other options include LipiFlow (J&J Vision), which uses thermal pulsation to liquefy and express meibum; it works well preoperatively. Clinical studies have shown improvements in OSDI scores and meibomian secretion scores. However, LipiFlow is not for everyone, including patients who do not have sufficient glands to perform a lid expression; at least six lower lid glands, open to some degree, are generally required.¹⁵

Punctal plugs are another useful tool with improved corneal staining, prolonged TBUT, decrease in tear osmolarity and increase in goblet cell density. Contraindications include allergies to plug material, nasolacrimal duct obstruction and canaliculitis or dacryoadenitis. It has been suggested that clinical ocular surface inflammation is a contraindication because it can cause prolonged contact of abnormal tears containing proinflammatory cytokines with the ocular surface.¹⁶ However, it is reasonable to treat your patient with an anti-inflammatory for several weeks prior to inserting a punctal plug.

Tetracyclines, such as doxycycline, are used for their anti-inflammatory properties. They inhibit matrix metalloproteinases and collagenases. Clinical studies of oral tetracycline agents found a significant improvement of reported symptoms and ocular inflammation/irritation. However, a five-day course of azithromycin (500 mg for day one, then 250 mg for the remaining four days) showed greater improvements in ocular surface staining, redness and shorter duration of treatment compared to doxycycline 200 mg once a day.^17,18

Omega-3 fatty acids and other nutritional supplements have been found to be useful in ATD and MGD. There were significant improvements in OSDI scores and objective evaluations of corneal smoothness in those taking supplements of gamma-linolenic acid and omega-3 fatty acids in patients with moderate to severe dry eye compared to placebo. Studies regarding optimal dosage and formulation are ongoing.^3,19

CONCLUSION

DED is a critical component of patient satisfaction and optimal surgical outcomes. It consists of multiple subtypes that overlap with each other. DED is often overlooked due to many patients being asymptomatic and will likely worsen following cataract surgery. After implementation of your initial treatment plan, it is a good idea to wait four to six weeks before reassessing and augmenting the plan. If the patient is still symptomatic, you can continue to expand upon the plan with additional therapies until the right combination is found. When dealing with an unhappy postoperative patient, remember the “big three” — DED, residual refractive error and posterior capsule opacification.²⁰ It is important to diagnose and treat DED preoperatively while it’s still “the patient’s problem.” If diagnosed postoperatively, then it becomes the doctor’s problem. Treating DED can be challenging, but thankfully there are many diagnostic and therapeutic tools to help our patients. OM

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About the Authors

Nichelle Warren, MD, is a PGY-3 ophthalmology resident at the Medical University of South Carolina. She is interested in pursuing a cornea fellowship with particular interest in refractive surgery and corneal transplant. You may reach her at warrenni@musc.edu.

Karolinne Maia Rocha, MD, PhD, is director of the Cornea Service, Storm Eye Institute, Medical University, South Carolina, Charleston, S.C. Contact her at 843-792-8100 or karolinnemaia@gmail.com.

Financial disclosure: Dr. Rocha is a consultant for J&J Vision, B + L and Alcon. Dr. Warren has no financial interest related to this article.