Article

A clean ocular surface is a must anymore

The surgeon who doesn’t assess a patient’s ocular surface prior to surgery risks a suboptimal outcome.

Patients who have dry eye or whose eyes are marginally compensated prior to surgery are likely to have more severe symptoms postoperatively.

Preoperatively, an unhealthy tear film can interfere with the quality and accuracy of measurements and may result in dissatisfied patients postoperatively. Assessment, preparation and optimization of the ocular surface are critical prerequisites to refractive cataract surgery.

As we live in a world of advancing technology with exceedingly high patient expectations, today’s refractive cataract specialist needs to consider testing for ocular surface disease (OSD) a pre-emptive strike.

Several factors contribute to exacerbation of ocular surface disease after surgery. Damage to the corneal nerves when the incision or flap is created can lead to a reduction in corneal sensitivity and neurotrophic dry eye. A decrease in tear function postoperatively may increase tear osmolarity with a subsequent rise in concentration of pro-inflammatory cytokines and matrix metalloproteinase-9 (MMP-9) in the tear film.1 Toxicity from preservatives in the drops used after surgery can also exacerbate dry eye disease.

There is no way of predicting the risks or severity of postrefractive dry eye preoperatively, but pre-existing OSD is a known risk factor for postoperative dry eye, corneal staining, bothersome dry eye symptoms, prolonged corneal hypoesthesia and delayed visual recovery.2,3 Once patients at risk for severe dry eye after refractive cataract surgery are identified, then, with effective management, surgical outcomes and patient satisfaction can be optimized.

RISK FACTORS TO LOOK FOR

Risk factors for chronic dry eye after either cataract or refractive surgery include female gender, Asian ethnicity, contact lens use/intolerance, diabetes and, in the case of refractive surgery, higher refractive errors requiring deeper stromal ablation.3 Keep in mind that any type of refractive procedure can exacerbate pre-existing dry eye. Some feel that there may be more risk with a lamellar procedure due to severing of the corneal nerves and less risk with surface ablations because they leave the nerves intact.

Dry eye disease is extremely prevalent, especially in elderly patients slated for cataract surgery. Trattler et al reported that 87% of patients scheduled for cataract surgery were diagnosed with dry eye disease, yet a minority had a previous diagnosis of dry eye.4 Hyperosmolar patients had greater variability in K readings and IOL power calculations compared with patients whose osmolar readings were normal.5

These inconsistent keratometry readings due to dry eye disease can significantly impact results, especially in patients with premium presbyopic lenses. In addition to unpredictable preoperative measurements, an unhealthy tear film can also cause delayed healing and suboptimal results postoperatively.

PRE-EMPTING THE PROBLEM

Several steps can be taken to reduce the incidence and severity of dry eye postoperatively. Careful patient history should be obtained, including inquiries about systemic conditions such as collagen-vascular or cicatrizing disease and inquiries about dry eye symptoms. Many patients looking to have laser vision correction (LVC) who have become intolerant to their contact lenses could have dry eye disease.

Dry eye disease is a leading cause of contact lens intolerance, and these patients frequently turn to refractive surgery as an alternative to wearing contact lenses. Any mention of contact lens intolerance should suggest the probability of underlying dry eye disease. These patients are at higher risk of complications postoperatively.

A preoperative assessment should include a dry eye questionnaire to determine if the patient is symptomatic, but even asymptomatic patients should be suspiciously evaluated for objective signs of dry eye disease. Current options for evaluating and diagnosing dry eye have changed dramatically over the last several years with point-of-care (POC) testing, which offers improved specificity and objectivity.

There’s not just one test that gives us an answer if the patient has DED; POC testing should be used in conjunction with other examinations. Tear osmolarity and MMP-9 assays can establish a diagnosis of DED and its severity or grade, but they cannot distinguish between aqueous deficiency and evaporative dry eye. Another valuable POC test is meibography, which allows visualization of the meibomian glands (MG) and evaluation of duct dilation, MG dropout and/or glandular atrophy. This powerful tool permits us to educate our patients on the importance of preventive care and performing a treatment that can halt progressive damage to the glands. Corneal topography can help us evaluate for irregularity or distortion secondary to dry eye disease. For a more comprehensive look at DED examinations, see the chart on this page.6

In a retrospective review following LASIK surgery, Levinson et al found that dry eye disease and blepharitis were the most common diagnoses resulting in patient dissatisfaction postoperatively despite relatively good postoperative visual acuities. The most common chief complaints among the 109 patients (157 eyes) were poor distance vision (63%), dry eyes (19%), and redness/pain (7%).7

Dry eye exam

Evaluate for:

  • Tear meniscus
  • Tear quality
  • Tear breakup time
  • Presence of lid disease (lagophthalmos, blepharitis or meibomianitis)6

For conjunctival staining, use:

  • Lissamine green
  • Rose Bengal6

Assess cornea for:

  • Punctate keratitis
  • Filaments
  • Anterior basement membrane abnormalities
  • Evidence of prior refractive surgery

METHODS OF MANAGEMENT

Management of ocular surface disease depends on the type of dry eye disease but may include:

  1. Artificial tears
  2. Nutritional supplementation
  3. Topical cyclosporine and/or lifitegrast
  4. Topical steroids
  5. Thermal pulsation
  6. Microblepharoexfoliation
  7. Amniotic membrane
  8. Punctal occlusion.

Topical cyclosporine 0.05% perioperatively may accelerate corneal stromal nerve regeneration and expedite visual recovery and refractive stability after LASIK and PRK.8-10 Treatment has also been shown to improve quality of vision after implantation of multifocal intraocular lens implants.11

Omega-3 nutritional supplementation has been shown to decrease tear osmolarity and inflammation,12 increase tear production with the potential for faster epithelial healing and visual recovery after PRK,13 and possibly accelerate the regeneration of the corneal nerves.14 After initiation of therapy (four to six weeks), I re-evaluate patients to ensure refractive and biometric stability and to see if their dry eye condition has responded sufficiently for accurate measurements. If a patient has persistent corneal staining and/or filaments, then I delay or avoid surgery altogether.

Those patients who develop more severe dry eye disease postoperatively are typically unhappy. They often complain of blurred vision, foreign body sensation and discomfort and are less likely to respond to conventional dry eye therapy. These patients may benefit from more advanced forms of therapy, including autologous serum tears, amniotic membrane/drops and scleral lens.

Another potential therapy for our dry eye patients is nasal neurostimulation, which is in the pipeline for dry eye disease. This device stimulates the nasal mucosa and the trigeminal nerve and is thought to increase the production of all three layers of the tear film. It also may address the neurogenic component of dry eye disease.15,16

ARE RECENT INNOVATIONS THE ANSWER?

Patients who have had femtosecond or thin-flap LASIK may experience less disruption of the tear film and less compromise in corneal sensation than those who have had traditional LASIK.17,18

Some degree of postoperative dry eye is expected and is typically transient after PRK and LASIK19 but may be chronic in up to 20% of patients.20

In summary, exacerbation of dry eye disease is a common risk factor and complication after refractive cataract surgery, and should be incorporated in the informed consent discussion. However, to maximize patient outcomes and satisfaction, it is imperative to evaluate for dry eye and optimize the ocular surface prior to performing any refractive cataract surgical procedures. OM

REFERENCES

  1. Sambursky R, O’Brien TP. MMP-9 and the perioperative management of LASIK surgery. Curr Opin Ophthalmol. 2011;22:294-303.
  2. Yu EY, Leung A, Rao S, Lam DS. Effect of laser in situ keratomileusis on tear stability. Ophthalmology. 2000;107:2131-2135.
  3. Shtein RM. Post-LASIK dry eye. Expert Rev Ophthalmol. 2011;6(5):575-582.
  4. Trattler WB, Reilly CD, Goldberg DF, et al. Cataract and dry eye: Prospective Health Assessment of Cataract Patients’ Ocular Surface (PHACO). Poster presented at: ASCRS; March 2011; San Diego, CA.
  5. Epitropoulos AT, Matossian C, Berdy GJ, Malhotra RP, Potvin R. Effect of tear osmolarity on repeatability of keratometry for cataract surgery planning. J Cataract Refract Surg. 2015;41(8):1672-1677.
  6. AAO Cornea/External Disease PPP Panel, Hoskins Center for Quality Eye Care. Dry Eye Syndrome PPD 2013. https://www.aao.org/preferred-practice-pattern/dry-eye-syndrome-ppp--2013 .
  7. Levinson BA, Rapuano CJ, Cohen EJ, Hammersmith KM, Ayres BD, Laibson PR. Referrals to the Wills Eye Institute Cornea Service after laser in situ keratomileusis: reasons for patient dissatisfaction. J Cataract Refract Surg. 2008;34(1):32-39.
  8. Peyman GA, Sanders DR, Batlle JF, Féliz R, Cabrera G. Cyclosporine 0.05% ophthalmic preparation to aid recovery from loss of corneal sensitivity after LASIK. J Refract Surg. 2008;24(4):337-343.
  9. Salib GM, McDonald MB, Smolek M. Safety and efficacy of cyclosporine 0.05% drops versus unpreserved artificial tears in dry-eye patients having laser in situ keratomileusis. J Cataract Refract Surg. 2006;32(5):772-778.
  10. Ursea R, Purcell TL, Tan BU, et al. The effect of cyclosporine A (Restasis) on recovery of visual acuity following LASIK. J Refract Surg. 2008;24(5):473-476.
  11. Donnenfeld ED, Solomon R, Roberts CW, Wittpenn JR, McDonald MB, Perry HD. Cyclosporine 0.05% to improve visual outcomes after multifocal intraocular lens implantation. Cataract Refract Surg. 2010;36(7):1095-1100.
  12. Epitropoulos AT, Donnenfeld ED, Shah ZA, et al. Effect of oral re-esterified Omega-3 nutritional supplementation on dry eyes. Cornea. 2016;35(9):1185-1191.
  13. Ong NH, Purcell TL, Roch-Levecq AC, et al. Epithelial healing and visual outcomes of patients using omega-3 oral nutritional supplements before and after photorefractive keratectomy: a pilot study. Cornea. 2013;32(6):761-765.
  14. He J, Bazan HE. Omega-3 fatty acids in dry eye and corneal nerve regeneration after refractive surgery. Prostaglandins Leukot Essent Fatty Acids. 2010;82(4-6):319-325.
  15. Friedman NJ, Butron K, Robledo N, Loudin J, Baba SN, Chayet A. A nonrandomized, open-label study to evaluate the effect of nasal stimulation on tear production in subjects with dry eye disease. Clin Ophthalmol. 2016;10:795-804.
  16. Gumus K, Schuetzle K, Loudin JD, et al. Randomized, controlled crossover trial comparing the impact of sham or intranasal neurostimulation on conjunctival goblet cell degranulation. Poster presented at: ARVO; May 1-5, 2016; Seattle, WA.
  17. Nettune G, Pflugfelder S. Post-LASIK tear dysfunction and dysesthesia. Ocul Surf. 2010;8(3):135-145.
  18. Salomao MQ, Ambrosio R, Wilson SE. Dry eye associated with laser in-situ keratomileusis: mechanical microkeratome versus femtosecond laser. J Cataract Refract Surg. 2009;35(10):1756-1760.
  19. Perez-Santonja JJ, Sakla HF, Cardona C, Chipont E, Alio JL. Corneal sensitivity after photorefractive keratectomy and laser in situ keratomileusis for low myopia. Am J Ophthalmol. 1999;127(5);497-504.
  20. Shoja MR, Besharati MR, Dry eye after LASIK for myopia: Incidence and risk factors. Eur J Ophthalmol. 2007;17(1):1-6.

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