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Corneal Staining: Dry Eye or Something More?

BY DEBBIE S. MURNAN, OD, BS

A 31-year-old Native American female presented to the Northeastern State University Oklahoma College of Optometry for an annual contact lens examination. Her chief complaint was slightly blurry vision OD and OS over the previous two weeks while wearing her contact lenses. She did not own a pair of glasses. She also reported chronic dry eye, which had been especially bothersome over the past two months.

The patient's systemic history was positive for lupus, rheumatoid arthritis, and a clotting disorder known as antiphospholipid antibody syndrome, all of which were diagnosed more than five years prior to the exam. Her medications included prednisone, Plaquenil (Sanofi-Aventis), Coumadin (Bristol-Myers Squibb), and Fosamax (Merck & Co., Inc.). She had no known drug allergies.

The patient's ocular history over the past three years was remarkable for bilateral dry eye and mild superficial punctate keratitis located centrally and inferiorly on both corneas. During that time, she had been wearing Proclear (CooperVision) spherical contact lenses with a base curve of 8.2mm and powers of –5.50D OD and –6.00D OS. Clear Care (CIBA Vision ) lens care solution was prescribed.

The patient had a history of noncompliant contact lens wear and care, including occasionally sleeping in her lenses.

Diagnostic Data

The patient reported that her current contact lenses were her last pair and were about one week old. She was using a Wal-Mart store brand multipurpose solution. She also reported that she had been wearing her contact lenses for only two hours prior to the exam and that she usually wears her lenses for 12 or more hours each day. She maintained visual acuities of 20/20-2 OD and 20/20 OS with her current contact lenses. An over-refraction of +0.50 –0.75 × 180 OD and +0.50 –0.75 × 170 OS improved her visual acuity to 20/20+2. Pupils were equal, round, and reactive to light with no afferent pupillary defect present. Confrontation visual fields were full on arcuate testing OD and OS, and extraocular muscle testing demonstrated no restrictions.

Slit lamp exam revealed clear, well-centered contact lenses with appropriate movement in each eye. The slit lamp exam also revealed clear lids and adnexa, +1 conjunctival injection, and mild inferior palpebral conjunctival papillae in each eye.

After removing the lenses, the corneas were examined and remarkable for 0.5mm of neovascularization (360 degrees) and two small peripheral white infiltrates OD, located at about 7 o'clock and 10 o'clock. Upon fluorescein evaluation, both corneas exhibited significant, diffuse superficial punctate keratitis (SPK) staining, especially inferiorly and centrally (Figures 1 and 2). Tear breakup time was about six seconds in each eye.

Figure 1. OD corneal staining with fluorescein.

Figure 2. OS corneal staining with fluorescein.

Treatment and Follow Up

With signs of corneal hypoxia including corneal vascularization and infiltrates, we refitted the patient into a silicone hydrogel contact lens, Acuvue Oasys (galyfilcon A, Vistakon), with a base curve of 8.4mm and powers of –5.50D OD and –6.00D OS. Visual acuities with the new lenses were 20/20 OD and OS. They demonstrated appropriate centration, movement, and comfort.

In addition to the higher-Dk lens, the treatment plan included Systane (Alcon) artificial tears before and after lens removal and a switch from her store brand multipurpose solution to Opti-Free Replenish (Alcon).

We educated the patient about the multiple factors likely contributing to her chronic dry eye, including systemic conditions, systemic medications, overwear of contact lenses and contact lens/care solution incompatibility. We also educated her about the importance of compliance with lens wear and care and the need for a spare pair of glasses.

At the one-week follow-up visit, the patient was very happy with the vision and comfort provided by her new lenses, and she did not report any symptoms of ocular dryness. She reported wearing her lenses for just one hour prior to her exam. Visual acuities were maintained at 20/20 OD and OS, and the slit lamp exam revealed trace corneal staining in each eye. The plan was to continue with her current contact lenses, artificial tears, and lens care regimen until her next progress exam.

Systemic Associations

The etiology of dry eye, which is usually multifactorial, can be classified as either aqueous deficient or evaporative. Common associations include connective tissue disease (e.g. Sjögren's syndrome, rheumatoid arthritis, and systemic lupus erythematosus); conjunctival scarring; medications such as antihistamines, oral contraceptives, phenothiazines, and beta blockers; vitamin A deficiency; and post-LASIK surgery. As mentioned previously, the patient had a positive medical history for two connective tissue diseases: rheumatoid arthritis and lupus. Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by polyarthritis, synovitis of joint and tendon sheaths, cartilage loss, and, in most patients, the presence of the IgM rheumatoid factor in the blood. One of the most common ocular manifestations of RA is keratoconjunctivitis sicca (KCS) or dry eye due to autoimmune lymphocytic infiltration and destructive fibrosis of the lacrimal glands. KCS is evident in 15 percent to 25 percent of patients who have RA.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that typically occurs in young patients and is characterized by skin eruptions, joint pain, and vasculitis. SPK is the most common corneal manifestation, occurring in approximately 20 percent of SLE patients. Scleritis is another ocular manifestation of lupus, and although it is present in only 1 percent of patients, its presence indicates the severity of the systemic vasculitis.

Our patient also had a medical history of antiphospholipid syndrome, a condition characterized by recurrent venous and arterial thrombi, thrombocytopenia and associated antiphospholipid antibodies, anticardiolipins, and lupus anticoagulant. When antiphospholipid disease is associated with SLE and/or other collagen vascular diseases, it is called secondary antiphospholipid syndrome. Ocular manifestations may include mild anterior uveitis and episcleritis.

Differential Diagnoses

When considering differential diagnoses for a patient presenting with dry eye signs and symptoms, it is important to consider SPK secondary to another etiology. SPK manifests as pinpoint corneal epithelial defects that may be confluent if severe. The symptoms of SPK are very similar to those of dry eye, such as foreign body sensation, red eye, photophobia, mild blurring of vision, and watery discharge. Contact lens wear and dry eye syndrome itself can cause SPK, as can blepharitis, trauma, topical drug toxicity, chemical or radiation burn, exposure keratopathy, conjunctivitis, trichiasis, floppy eyelid syndrome, entropion, ectropion, Thygeson's SPK, and contact lens-related problems.

In the case of our patient, she had a long-term history of contact lens wear, as well as chronic SPK and ocular dryness. It is important to not assume that her autoimmune conditions were the only etiology for her dry eye, as this condition can often have a multifactorial etiology. Many contact lens-related issues such as solution toxicity, incompatible lens/solution combinations, tightlens syndrome, contact lens overwear, and giant papillary conjunctivitis can cause significant SPK. We know from our patient's history that she is consistently non-compliant with wear and care of her lenses.

SPK is a significant ocular finding, especially in contact lens wearers, because it indicates a compromised corneal surface that can increase the risk of microbial invasion and ulcerative keratitis. Stern et al (1982) found that bacteria, specifically Pseudomonas aeruginosa, adhere more readily to the edges of damaged corneal epithelium than to bare stromal tissue.

Although corneal staining has been seen to some extent in many hydrogel contact lens patients, moderate-to-severe staining may be more clinically significant. Nichols et al (2002) found that patients who were noncompliant with their lens care system were more likely to have some degree of corneal staining, while factors such as age, gender, medication use, wearing time at the exam, lens water content, and type of lens care system (e.g. chemical, hydrogen peroxide) were not significantly associated with corneal staining.

Care Solution Complications

Ocular response to different lens care systems is important to consider, as solution toxicities and lens/solution incompatibilities can result in ocular surface compromise. When a solution compromises the corneal surface, it is often a cell-mediated response to a component of the solution such as a preservative.

Common preservatives used in multipurpose solutions are Dymed (polyhexanide), a PHMB-based preservative used in Bausch & Lomb's ReNu products, and Polyquad (polyquaternium-1), which is used in Opti-Free products. Manufacturers must determine the appropriate preservative concentration to use that will adequately disinfect the contact lens without causing adverse effects to the ocular surface. An additional concern is that some preservatives can be absorbed into the lens matrix, increasing the risk for corneal toxicity.

Carnt et al (2007) found that corneal infiltrates were three times more likely to occur in eyes exhibiting solution toxicity with punctate epithelial staining compared to eyes unaffected by solution toxicity. Hydrogen peroxidebased solutions consistently resulted in the lowest rates of toxicity staining and corneal inflammation. Begley et al (1994) found the greatest amount of corneal disruption in rabbit eyes following the application of contact lenses soaked in a PHMB-based solution compared to Opti-Free and hydrogen peroxide solutions. Other studies have also found PHMB-based solutions to be associated with higher degrees of corneal staining, especially with Group 2 lenses. Only minimal staining and corneal disruption were observed in subjects using Opti-Free multipurpose solution.

The Andrasko Corneal Staining Grid is a compiled reference tool for eyecare professionals that summarizes biocompatibility of different contact lens/solution combinations. The grid displays percentages of average corneal staining area at two hours post-application with different lens/solution combinations. As mentioned earlier, our patient had been wearing Proclear lenses for more than three years and she frequently used a store brand multipurpose solution, which is currently PHMB-based. According to the Andrasko Corneal Staining Grid, this lens/solution combination demonstrated an average corneal staining area of 61 percent.

Based on the grid, by switching our patient to Acuvue Oasys lenses and Opti-Free Replenish, the expected average corneal staining area should be reduced to about 5 percent. As previously stated, the patient presented with significantly less corneal staining after only one week of switching to the new lens/solution combination and using artificial tears.

Conclusion

Because dry eye syndrome's etiology is often multifactorial in nature, it is vital to evaluate all aspects of a symptomatic patient's medical and ocular history, especially when significant corneal staining is present. When contact lenses are involved, it is important to be aware of potential lens wear and care complications that can contribute to ocular dryness and corneal disruption. Taking a thorough history and recommending biocompatible lens/solution combinations will provide patients a greater opportunity for success and satisfaction with their contact lenses. CLS

The author would like to thank Dr. Bill Edmondson, professor at the Northeastern State University Oklahoma College of Optometry, for his assistance in managing this patient and reviewing this case report.

To obtain references for this article, please visit http://www.clspectrum.com/references.asp and click on document #163.

Dr. Murnan is a recent graduate from the Northeastern State University Oklahoma College of Optometry, Tahlequah, Oklahoma.