FDA Consumer magazine

May-June 2005 Issue

http://www.fda.gov/fdac/features/2005/305_eye.html

By Michelle Meadows

Tears serve as a protective coating for the eyes. They keep the eyes moist, provide essential nutrients, and wash away dust and other particles. When the eyes don't produce enough tears or the right quality of tears, the result is a condition that doctors call keratitis sicca, popularly known as "dry eye."

Just as the name suggests, this condition makes the eyes feel dry, scratchy, and gritty. Other symptoms include burning, stinging, itching, pain, sensitivity to light, redness, blurry vision, and the feeling that there is a speck of dirt in the eye. There may also be a stringy discharge from the eyes. And though it may seem strange, dry eye can cause the eyes to water. "This can happen because the eyes are irritated," says Carolyn Begley, O.D., a professor of optometry at Indiana University in Bloomington. "You may experience excessive tearing the same way you would if something got in your eye."

But these tears won't necessarily make the eyes feel better. Reflex tears--the watery type that are produced in response to injury, irritation, or emotion--don't have the lubricating qualities necessary to prevent dry eye. Tear film is made of water, oil, and mucus, all of which are important for maintaining good eye health. The cornea, which covers the front of the eye, needs these tears continuously to protect it against infection. Most people who have dry eye experience mild irritation with no long-term effects, Begley says. But if the condition is left untreated or becomes severe, eye damage and vision loss can occur. Severe problems with dry eye can cause eye inflammation, corneal infection, and scarring.

"When dry eye symptoms are severe, they can interfere with quality of life," Begley says. "Some people may have trouble keeping their eyes open or they may not be able to work or drive." Fortunately, identifying the cause of the problem and seeking treatment early can make a big difference in easing the discomfort.

Common Causes

Aging is one of the most common causes of dry eye because tear production decreases as we get older. Dry eye affects more women than men because hormonal changes, such as those that occur in pregnancy, menstruation, and menopause, can decrease tear production. Environmental conditions also can play a role. Wind, heat, dust, air conditioning, cigarette smoke, and even hair dryers can make the eyes dry. Some people benefit from avoiding dusty, smoky areas, wearing sunglasses, and using a humidifier to moisten the surrounding air.

Another common culprit is not blinking enough, which happens during activities such as watching TV and computer use. "Each time you blink, it coats the eye with tears," Begley says. "You normally blink about every 12 seconds. But we've done studies of people playing computer games, and found that some people blinked once or twice in three minutes."

Begley says that about half of all people who wear contact lenses complain of dry eye. That's because soft contact lenses, which float on the tear film that covers the cornea, absorb the tears in the eyes. Dry eye also occurs or gets worse after LASIK and other refractive surgeries, in which the corneal nerves are cut during creation of a corneal flap. The corneal nerves stimulate tear secretion. Begley says, "If you've had dry eyes from wearing contact lenses or for any other reason and you are thinking about refractive surgery, this is something to consider."

Dry eye also can be caused by certain medications, including antihistamines, some antidepressants, birth control pills, nasal decongestants, and the prescription acne drug Accutane. And some autoimmune diseases, such as lupus, rheumatoid arthritis, and Sjögren's syndrome, can attack the tear glands.

Other diseases can also cause dry eye. For example, certain types of thyroid disease can interfere with blinking. Blepharitis, an inflammation of the eyelids, can interfere with the oil glands in the eyes.

Diagnosis and Treatment

Even though many treatments for dry eye are available without a prescription, it's wise to see a health care professional to evaluate the cause of the condition and to help you pick the best treatment.

Eye doctors use a combination of routine clinical exams and other specific tests for dry eye. For example, the Schirmer test uses a tiny strip of paper placed on the edge of the lower eyelids. "This measures how much moisture is in the eye, and it's also useful for determining the severity of the problem," Begley says. Doctors may also use dye, such as fluorescein or rose bengal, which is placed on the eye to stain the surface. This is to see how much the surface of the eye has been affected by dryness. Another test, tear break-up time (TBUT), measures the time it takes for tears to break up in the eye.

The first line of treatment for dry eye is usually over-the-counter demulcent drops, also known as artificial tears. These lubricate the eye and ease symptoms. Commonly found ingredients in these products include hydroxypropyl methylcellulose, the ingredient in Bion Tears and GenTeal, and carboxymethylcellulose, contained in Refresh Plus and Thera Tears. Always read the directions, but these products can generally be used as often as needed throughout the day.

Your health care professional can guide you in choosing the right one for you. "Some people use drops for red eyes, but that can make the eyes even more dry," Begley says. Red eyes could be caused by numerous factors, from allergies to an eye infection, which is why a proper diagnosis is important. If you wear contact lenses, use rewetting drops specifically for contact lenses. Other types of drops may contain ingredients that damage the lens.

Restasis (cyclosporine ophthalmic emulsion) is the only prescription product for chronic dry eyes. Approved by the Food and Drug Administration in 2002, the drug increases tear production, which may be reduced because of inflammation on the eye surface. In a clinical trial involving 1,200 people, Restasis increased tear production in 15 percent of patients, compared with 5 percent of patients in the placebo group, says Wiley Chambers, M.D., deputy director of the FDA's Division of Anti-Inflammatory, Analgesic and Ophthalmologic Drug Products.

Restasis is usually given twice a day, 12 hours apart. It should not be used by people with eye infections or hypersensitivity to the ingredients. It has not been tested in people with herpes viral infections of the eye. The most common side effect is a burning sensation. Other side effects may be eye redness, discharge, watery eyes, eye pain, foreign body sensation, itching, stinging, and blurred vision.

For people who have not found dry eye relief with drugs, punctal plugs may help. "These are reserved for people with moderate or severe dry eye when other medical treatment hasn't been adequate," says Eva Rorer, M.D., a medical officer in the FDA's Division of Ophthalmic and Ear, Nose, and Throat Devices.

In each eye, there are four puncta, little openings that drain tears into the tear ducts. Punctal plugs are inserted into the puncta to block tear drainage. Some doctors try out temporary ones made of collagen first to make sure that permanent ones will not cause excessive tearing. Permanent plugs are usually made of silicone. In recent years, Rorer says, some plugs have been approved that are made of thermally reactive material. "Some of these are inserted into the punctum as a liquid and then they harden and conform to the individual's drainage system." Others start out rigid and become soft and flexible, adapting to the individual's punctal size after they are inserted. Artificial tears are usually still required after punctal plug insertion."

The risks of punctal plugs are fairly minimal," Rorer says. "There is a risk of eye irritation, excessive tearing, and, in rare cases, infection."

Am J Ophthalmol. 2006 Apr;141(4):758-60.   

McCulley JP, Aronowicz JD, Uchiyama E, Shine WE, Butovich IA.  Department of Ophthalmology, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas.  

PURPOSE: To establish scientific relationship between relative humidity (RH) and aqueous tear evaporation to elucidate possible significance of this relationship in normals and aqueous tear deficiency patients.  

DESIGN: Prospective experimental laboratory study.  

METHODS: Ocular surface evaporation was determined using evaporometry and calculated for two ranges of RH, 25% to 35%, and 35% to 45% in a randomized clinical patient population.  

RESULTS: Average evaporative rate in the higher humidity range was between 0.029 +/- 0.009 through 0.043 +/- 0.016 mul/cm(2)/min. At lower humidity, range was between 0.044 +/- 0.013 through 0.058 +/- 0.018 mul/cm(2)/min. Differences in the corresponding evaporative rates were statistically significant (between P < .003 through P < .043) for each analysis.  

CONCLUSIONS: A decrease of 10% RH resulted in an average difference of between 28.33% to 59.42% increase in evaporation. The increase in evaporation at lower humidity has significant clinical implications for patients with aqueous deficient dry eyes, and possibly those undergoing laser-assisted in situ keratomileusis (LASIK).

Am J Ophthalmol. 2006 Mar;141(3):438-45.

De Paiva CS, Chen Z, Koch DD, Hamill MB, Manuel FK, Hassan SS, Wilhelmus KR, Pflugfelder SC.

Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas.

PURPOSE: To determine the incidence of dry eye and its risk factors after myopic laser-assisted in situ keratomileusis (LASIK).

DESIGN: Single-center, prospective randomized clinical trial of 35 adult patients, aged 24 to 54 years, with myopia undergoing LASIK.

METHODS: setting and study population: Participants were randomized to undergo LASIK with a superior or a nasal hinge flap. They were evaluated at 1 week and 1, 3, and 6 months after surgery. intervention: Bilateral LASIK with either a superior-hinge Hansatome microkeratome (n = 17) or a nasal-hinge Amadeus microkeratome (n = 18). main outcome measures: The criterion for dry eye was a total corneal fluorescein staining score >/=3. Visual acuity, ocular surface parameters, and corneal sensitivity were also analyzed. Cox proportional-hazard regression was used to assess rate ratios (RRs) with 95% confidence intervals.

RESULTS: The incidence of dry eye in the nasal- and superior-hinge group was eight (47.06%) of 17 and nine (52.94%) of 17 at 1 week, seven (38.89%) of 18 and seven (41.18%) of 17 at 1 month, four (25%) of 16 and three (17.65%) of 17 at 3 months, and two (12.50%) of 16 and six (35.29%) of 17 at 6 months, respectively. Dry eye was associated with level of preoperative myopia (RR 0.88/each diopter, P = .04), laser-calculated ablation depth (RR 1.01/mum, P = 0.01), and combined ablation depth and flap thickness (RR 1.01/mum, P = 0.01).

CONCLUSIONS: Dry eye occurs commonly after LASIK surgery in patients with no history of dry eye. The risk of developing dry eye is correlated with the degree of preoperative myopia and the depth of laser treatment.

Clin Exp Optom. 2005 Mar;88(2):89-96.

comparison of outcomes for Asian and Caucasian eyes.

Albietz JM, Lenton LM, McLennan SG.

Queensland University of Technology, Brisbane, Australia.

BACKGROUND: Dry eye is a common complication of LASIK surgery. Our clinical impression was that post-LASIK dry eye was more problematic for our Asian patients. The aim of this study was to determine if dry eye after LASIK is more prevalent, more sustained and more severe in Asian eyes compared with Caucasian eyes.

METHODS: This study was based on a retrospective analysis of a clinical database. Data (n = 932 eyes, 932 patients) was collected before and after (week 2 and months 1, 3 and 6) LASIK surgery. Patients were defined as Asian if both parents were of East Asian ethic origin. Assessments included dry eye symptoms, ocular surface staining, tear volume, tear secretion, tear film stability and corneal sensation.

RESULTS: Asian eyes had greater ocular surface staining, poorer tear film stability and lower tear volume before LASIK and at all times after LASIK. Dry eye symptoms occurring 'often or constantly' were more prevalent at all time points after LASIK in Asian eyes. Chronic dry eye persisting six months or more after LASIK was diagnosed in 28 per cent of Asian eyes and 5 per cent of Caucasian eyes (p < 0.001). Asian patients with chronic dry eye were predominantly female, reported dry eye symptoms, had greater ocular surface staining and lower tear secretion, stability and volume before surgery. After LASIK, Asian eyes had a slower return to pre-operative values for ocular surface staining, tear volume and corneal sensation.

DISCUSSION: The risk of chronic dry eye after LASIK was significantly higher in Asian eyes. Contributing factors could include racial differences in eyelid and orbital anatomy, tear film parameters and blinking dynamics and higher attempted refractive corrections in Asian eyes.Chronic dry eye and regression after laser in situ keratomileusis for myopia.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15050267&query_hl=1

J Cataract Refract Surg. 2004 Mar;30(3):675-84.

Albietz JM, Lenton LM, McLennan SG.

Centre for Eye Research, Queensland University of Technology, Kelvin Grove, Australia.

PURPOSE: To examine the relationship between chronic dry eye and refractive regression after laser in situ keratomileusis (LASIK) for myopia.

SETTING: Excimer Laser Vision Centre and Centre for Eye Research, Queensland University of Technology, Brisbane, Australia.

METHODS: This study was based on a retrospective analysis of a clinical database and a case study series. Data (N = 565 eyes) were collected before and after (2 weeks and 1, 3, 6, and 12 months) LASIK. Three case studies, which highlight appropriate management strategies for LASIK candidates with dry eye, are presented.

RESULTS: Regression after LASIK was related to chronic dry eye. It occurred in 12 (27%) of 45 patients with chronic dry eye and in 34 (7%) of 520 patients without (P<.0001). Patients with chronic dry eye had significantly worse myopic outcomes than those without (1 month, P =.02; 3 months, P =.01; 6 months, P =.004; 12 months, P =.008). The risk for chronic dry eye was significantly associated with female sex, higher attempted refractive correction, greater ablation depth, and the following pre-LASIK variables: increased ocular surface staining; lower tear volume, tear stability, and corneal sensation; and dry-eye symptoms before LASIK. The risk for regression was significantly associated with higher attempted refractive correction, greater ablation depth, and dry-eye symptoms after LASIK. Case studies demonstrated that intensive dry-eye treatment may improve the refractive outcome and alleviate the need for enhancement surgery.

CONCLUSION: The risk for refractive regression after LASIK was increased in patients with chronic dry eye.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16447938&query_hl=1&itool=pubmed_docsum

J Refract Surg. 2006 Jan-Feb;22(1):61-6.

Noda-Tsuruya T, Asano-Kato N, Toda I, Tsubota K.

Minamiaoyama Eye Clinic, Tokyo, Japan.

PURPOSE: To evaluate the efficacy of autologous serum eye drops for dry eye after LASIK in a prospective, randomized study.

METHODS: Fifty-four eyes of 27 male patients who underwent LASIK were divided into two groups; patients who used autologous serum eye drops and those who used artificial tears postoperatively. Schirmer test with anesthesia, tear break-up time (BUT), and rose bengal and fluorescein staining for the ocular surface were prospectively compared between the groups. All values were also compared before and after surgery (at 1 week [except for Schirmer test], 1 month, 3 months, and 6 months) in each group.

RESULTS: Tear BUT was greater in the autologous serum eye drops group than in the artificial tears group at 6 months postoperatively. Rose bengal score was lower in patients using autologous serum eye drops than in patients using artificial tears at 1 month and 3 months postoperatively. No significant difference was noted between patients using autologous serum eye drops and patients using artificial tears in the value of Schirmer test with anesthesia and fluorescein scores. In the autologous serum eye drops group, tear BUT was increased at 3 months after LASIK, rose bengal score was lower at 1 month and 3 months, and fluorescein score was lower at 1 month after LASIK compared to preoperative values, respectively. In the artificial tears group, all values (Schirmer test, tear BUT, rose bengal score, and fluorescein score) showed no differences between before and after LASIK. No differences were noted in the subjective scores for dryness between the autologous serum eye drops and artificial tears groups.

CONCLUSIONS: The autologous serum eye drops group showed prolongation of the tear BUT and a reduction in rose bengal staining score.

http://www.ncbi.nlm.nih.gov/entrez/..1627&query_hl=6

J Cataract Refract Surg. 2001 Apr;27(4):577-84.
 
Hovanesian JA, Shah SS, Maloney RK.

Jules Stein Eye Institute and the Department of Ophthalmology, UCLA
School of Medicine, Los Angeles, California, USA.

PURPOSE: To determine the incidence and severity of patient complaints typical of dry eye and recurrent erosion syndrome after excimer laser refractive surgery and to compare the incidence of these symptoms after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).

SETTING: Outpatient university practice.

METHODS: A questionnaire was mailed to 1731 patients who had had primary myopic PRK or LASIK at least 6 months previously. Questions were designed to determine the incidence and character of ocular dryness and recurrent erosion symptoms and their impact on patient satisfaction and willingness to have surgery again. Responses from PRK and LASIK patients were compared.

RESULTS: Responses from 231 PRK patients and 550 LASIK patients revealed an incidence of dryness symptoms in 43% and 48%, respectively (P >.05). Soreness of the eye to touch was reported by 26.8% and 6.7%, respectively (P <.0001). Sharp pains occurred in 20.4% of PRK patients and 8.0% of LASIK patients (P =.0001). Complaints of the eyelid sticking to the eyeball occurred in 14.7% and 5.6%, respectively (P =.0001). All symptoms occurred predominantly on waking. Frequency of eyelid sticking (P <.0005) and sharp pain (P <.005) symptoms, as well as severity of sharp pain symptoms (P <.0001), were significantly greater in PRK patients than in LASIK patients. On a scale of 0 to 10 (10 high), median overall patient satisfaction with surgery was 9 in both groups. Soreness of the eyelid to touch occurred significantly more frequently among patients with symptoms of sharp pains on waking (P <.001) and the sensation of the eyelid sticking to the eyeball (P <.001). Patients with 1 or more symptoms were twice as likely as asymptomatic patients to have a satisfaction score of less than 8 (P <.001).

CONCLUSIONS: Ocular dryness symptoms occurred commonly after PRK and LASIK. Symptoms suggestive of mild recurrent erosions included sharp pains, the sensation of the eyelid sticking to the eyeball, and soreness of the eyelid to touch, a previously unrecognized symptom of this condition. These symptoms occurred commonly after excimer laser procedures but were significantly more common, more severe, and more prolonged after PRK. The presence of these symptoms had a significant effect on patient satisfaction.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11311627&query_hl=6

Abstract

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed

Ophthalmology. 2001 Jul;108(7):1230-5 
Effects of laser in situ keratomileusis on tear production, clearance, and the ocular surface.

Battat L, Macri A, Dursun D, Pflugfelder SC.
Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Florida, USA.Excerpts from the full text:

 - Corneal sensation remained reduced 16 months after LASIK 

 - Conjunctival sensation remained reduced 16 months after LASIK 

 - Tear clearance remained reduced 16 months after LASIK.