Read Refractive Surgery Outlook
Treating Dry Eye Before Surgery
By Linda Roach
To achieve the best possible visual outcomes, refractive surgeons continuously update the equipment and techniques they use in surgery. Likewise, surgeons should be taking steps to assure that their preoperative testing routines are rigorous enough to detect the sometimes subtle signs of dry eye, according to a chorus of experts around the world.
Ruling out dry eye and associated disorders is essential “if you don´t want to have a dissatisfied patient after a perfect uncomplicated surgery,” said Jose M. Benitez del Castillo, MD, PhD, a well-known expert in dry eye disease. Dr. Benitez is professor and chairman of ophthalmology at Complutense University and director of the ocular surface and inflammation unit of Hospital Clinico San Carlos, both in Madrid, Spain.
Dry eye is not a small problem for patients, he said. “Patients with LASIK-related dry eye complain not only about discomfort,” Dr. Benitez said. “They also complain about visual problems when reading, driving and using computers.
“Asking the patient about dry eye symptoms and contact lens intolerance, and performing simple tests to evaluate the healthiness of the ocular surface should be routine,” Dr. Benitez said. “Also, it is key to diagnose and treat meibomian gland dysfunction before surgery, as this is the most frequent cause of dry eye.”
Normalizing the Surface Before Surgery
If there are indications of even mild surface inflammation, tear film abnormalities or meibomian gland dysfunction (MGD), Dr. Benitez treats the disease to normalize the ocular surface before surgery.
A. John Kanellopoulos, MD, medical director of Laservision Eye Institute in Athens, Greece, and a clinical professor of ophthalmology at New York University School of Medicine agrees about the importance of dry eye testing before refractive surgery.
“It is well known that corneal refractive surgery – LASIK more than surface ablation – will interfere with lubrication of the ocular surface. And if the surface is already compromised, surgery may turn a borderline dry eye into a problematic situation for the patient, who will be suffering from dry eye over the long term,” he said.
“Severe dry eye and blepharitis can interfere with the correct refractive error measurements. They also can interfere significantly with healing in the early postoperative period and with the long-term refractive effects of the surgery,” he added.
Screening Cataract Patients
Although support in peer-reviewed literature is sparse, Dr. Benitez believes that ophthalmic surgeons also should look for undiagnosed dry eye in their cataract patients – especially those who are paying extra for a premium IOL.
“In my opinion, ophthalmologists are aware of the relationship between refractive surgery and post-surgery ocular surface disease, and most of them do evaluate the ocular surface before refractive surgery,” Dr. Benitez said. “Nevertheless, the same surgeons do not study and treat the ocular surface before performing cataract surgery and implanting premium IOLs.”
An unstable tear film can introduce errors into the process of determining IOL power, he said, because refractive power and topography fluctuate as the tear layer does. A compromised tear film also changes corneal reflectivity.
This combination produces inaccurate preoperative K readings, mistaken IOL power selection and unhappy patients, Dr. Benitez said. Dissatisfaction will be highest in premium IOL recipients, he said.
He also worries that the surgery itself might cause undetected cases of mild and borderline dry eye to become severely symptomatic.
Unless treated successfully before the surgery, blepharitis and MGD can put cataract patients at higher risk for infection and surface inflammation.
Screening: Start With the Basics
Although incongruent signs and symptoms can occur with mild dry eye, the first step toward identifying at-risk patients is to ask them questions, according to diagnostic algorithms published by an international collaboration of experts on dry eye and MGD.
This means taking a good patient history and administering a validated symptom questionnaire to determine whether diagnostic tests are necessary, according to reports from the International Dry Eye WorkShop (DEWS) and the International Workshop on Meibomian Gland Dysfunction.1,2
The seven validated questionnaires listed by DEWS each consist of as few as three questions and as many as 57.
Because MGD can be asymptomatic and is not always obvious, the meibomian panel also recommended that eye care practitioners screen for MGD by adding gland expression (i.e., moderate digital pressure to the central lower lid) to the routine patient workup.
Diagnosis and Monitoring: Be Selective
Screening may indicate the need for objective testing in some patients. The DEWS and MGD reports provide a short list of preferred tests for general clinical use and a longer list of technology-intensive tests recommended for corneal specialists and researchers.
The DEWS group evaluated approximately 100 available tests, categorizing them into functional groupings. Templates that detail the methodologies for each test and data on their accuracy are posted on the web site of the Tear Film & Ocular Surface Society (www.tearfilm.org),3 along with videos demonstrating testing methods.4 The MGD diagnosis subcommittee critiqued the tests in a narrative format, which are attached to the report as appendices.5
The MGD panel’s testing protocol for general use – revised and updated from the DEWS version – recommended the following sequence:
- Symptom questionnaire.
- Blink rate. Use the rate to calculate the blink interval (BI).
- Lower tear meniscus. Measure its height.
- Tear osmolarity (if available). Hyperosmolarity of tears is directly connected to the mechanism of dry eye and is thought to be the signature feature and possibly the best indicator of dry eye disease. But office-based testing was impractical until the TearLab Osmolarity System (TearLab Corp., San Diego) was approved for European use in 2008. U.S. approval came this year. The handheld device analyzes a 50 nanoliter tear sample in less than 30 seconds. [TearLab sells for about $10,000, or it can be acquired at no initial cost if the practice commits for three years to buy 1,500 or more bilateral test cards annually. The cards cost about $10 to $15 (€8 to €12) each, depending on annual usage, with bilateral reimbursement rates of $46.80 by U.S. Medicare and €23.20 in Germany.]
- Tear film break-up time (TFBUT). Instillation of fluorescein, followed by measurement of corneal and conjunctival staining with a blue exciter filter and a yellow barrier filter.
- Surface staining. Assessed immediately after TFBUT. (If yellow filter was not used, lissamine green is used for the conjunctiva.)
- Schirmer test (or phenol red thread test).
Dr. Benitez, who was a member of the MGD workshop’s definition and classification subcommittee, said his basic diagnostic routine includes: (1) tests of surface staining with fluorescein and lissamine green; (2) TFBUT, with a value for normal eyes of > 10 seconds; and (3) Schirmer I test of tear production (with anesthetic), with a score > 10 mm for normals.
Dr. Kanellopoulos said his practice assesses the tear film and ocular surface with standard tests. In addition, he looks for surface variance and decentration on topography and tests for tear osmolarity. “We’re very happy with the data that we’re receiving from the TearLab osmolarity device. It is very helpful,” he said.
The Surgery Decision
The American Academy of Ophthalmology’s Preferred Practice Pattern for dry eye, developed by the Academy’s Cornea/External Disease Panel and revised in 2011, does not address the issue of a possible connection between dry eye and cataract surgery. But it says this about refractive procedures:
Patients with pre-existing dry eye should be cautioned that refractive surgery, particularly laser-assisted in situ keratomileusis (LASIK), may worsen their dry eye condition (Nettune & Pflugfelder, 2010). [A:III]
Patients who have dry eye and are considering refractive surgery should have the dry eye treated before surgery (American Academy of Ophthalmology Basic and Clinical Science Course Subcommittee, 2011).6
Dr. Benitez agrees. “If any of the tests are abnormal, I treat the patient for at least six months before scheduling surgery,” he said.
He tells patients to stop wearing contact lenses for six months, and he prescribes anti-inflammatory medication, nonpreserved tear substitutes; daily supplements of omega-3 fatty acids and Meibomian gland dysfunction therapy (hot compresses and lid massage).
His therapeutic goal is high: “a perfect ocular surface.”
“If I cannot get it, I do not perform surgery – because refractive surgery is usually an elective surgery,” he said.
Dr. Kanellopoulos also postpones refractive surgery and prescribes therapy. But he leaves the ultimate decision about undergoing refractive surgery to the patient, despite a history of dry eye.
“I think most ophthalmologists have the knowledge that corneal refractive surgery is very commonly associated with dry eye and that some patients may pose greater risk of that. The question is whether physicians evaluate that and whether all these issues are discussed with the patients preoperatively,” Dr. Kanellopoulos said. “In my opinion, these decisions are decisions that the patient has to make, if the physician has explained all the risks.”
Dr. Benitez is a member of the scientific advisory board of TearLab Corp.
Dr. Kanellopoulos is a consultant for Alcon.
1. 2007 Report of the International Dry Eye WorkShop (DEWS). Ocul Surf. 2007;5(2):65-204. Review.
2. The International Workshop on Meibomian Gland Dysfunction. Invest Ophthalmol Vis Sci. 2011;52(4):1917-2085.
3. Templates under, “Additional DEWS Materials Available Electronically.” Tear Film & Ocular Surface Society Web site. Available at: www.tearfilm.org/dewsreport/.
4. Videos about dry eye tests. Tear Film & Ocular Surface Society Web site. Available at: http://www.tearfilm.org/tearfilm_videos.php.
5. Tomlinson A, Bron AJ, Korb DR, et al. The international workshop on meibomian gland dysfunction: report of the diagnosis subcommittee. Invest Ophthalmol Vis Sci. 2011;52(4):2006-2049. Print 2011 Mar. Review.
6. American Academy of Ophthalmology Cornea/External Disease Panel. Dry eye syndrome. Limited revision. San Francisco, Calif.: American Academy of Ophthalmology; 2011. 28 p. [119 references].
1. Read the DEWS report:
Web-only version (with online extras)
Download (PDF in English)
Translations (French, Italian, Persian, Chinese, German, Japanese and Spanish)
2. Read the MGD report:
The International Workshop on Meibomian Gland Dysfunction: Report of the Definition and Classification Subcommittee
Translations (Chinese, German, Greek, Japanese, Polish, Portuguese, Spanish)
Download a 2-page summary for clinical reference