RCCL E-NEWS, JUNE 11, 2015
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Even Good Compliance May Not Eradicate Fungi

Fungal contamination of contact lens cases can occur despite patient compliance with proper lens handling, cleaning and replacement instructions, reports a study in the March 2015 Eye & Contact Lens.

Researchers cultured contact lens solution from two-cup storage cases (TCSC) filled with non-hydrogen peroxide-containing solutions, TCSCs with a hydrogen peroxide solution and single-cup storage cases (SCSC) containing hydrogen peroxide solutions, identifying the presence of seven molds, seven yeasts and one a mold in combination with a yeast. Interestingly, the peroxide group had a higher rate of fungal isolation compared with the multipurpose solution group.

Another study suggests topical amphotericin B (AMB) and natamycin may be particularly effective against certain fungi—specifically, the Candida species. More

Osmolarity Levels in Eye Drops Documented

Variations in the osmolarity of topical eye drops may influence clinical performance, and this trait warrants greater attention, reports a study published in the May 2015 Cornea.

Researchers in Germany evaluated the impact of hypo¬osmotic and hyperosmotic conditions on ex vivo corneal thickness and integrity (specifically, glucose and lactate levels) in a rabbit model of induced corneal edema by filling the anterior chamber with a hypoosmolar solution.

After 48 hours, two hyperosmolar solutions—Omnisorb (preserved with BAK) and Ocusaline (preservative-free)—were topically applied every 15 minutes over the course of one hour. Omnisorb reduced corneal thickness by 279μm vs. 258μm for Ocusaline. The authors say that this suggests eye drops containing preservatives may be more beneficial than preservative-free solutions in some cases, at least initially. More

Multifocal Halo Reduction Possible?

A new lens surface modification that smoothes out surface discontinuities could reduce the halo effect commonly experienced by patients with multifocal intraocular or contact lenses, reports a study in the December 2014 Optics Communications. Coauthor Zeev Zalevsky, PhD, of Israel’s Bar-Ilan University says “the proposed surfacing technique can be very important in significantly improving [vision], especially the night vision performance of any IOL for presbyopia correction,” noting that it could in theory be added to any multifocal lens. More

Structural Changes in FES May Indicate Glaucoma Risk

Patients with floppy lid syndrome (FES) may have structural changes that could signal risk for glaucoma development, says a study in the May 2015 Cornea. Researchers in Spain performed a corneal biomechanical evaluation on 208 eyes—72 with FES and 136 without FES—of 107 patients, measuring corneal hysteresis (CH), corneal resistance factor (CRF), central corneal thickness (CCT), Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc). Noncontact IOP and all corneal biomechanical properties were measured using the Ocular Response Analyzer (Reichert).

Mean CH was significantly lower in patients with FES compared with those without FES (i.e., 9.51 ± 1.56 vs. 11.66 ± 9.11), which may “constitute a risk factor for glaucoma due to an association with the response of the corneoscleral shell and the ocular vasculature to IOP-induced stress,” say the researchers. More

Scleral Vault May Impact Corneal Health

Hybrid contact lenses with tear vaults of more than 100μm may be detrimental to corneal health because of inadequate surface oxygen supply, reports a study in the March 2015 Eye & Contact Lens. Slit lamp and OCT evaluations found that fitting hybrids with the manufacturers’ recommended tear vault of 100μm or less resulted in acceptable corneal surface oxygen values, around 100mm Hg, while vaults greater than 100μm created less ideal corneal surface pO2—as low as 0mm Hg.

The researchers had hoped to find an acceptable way to calculate corneal surface pO2 under a hybrid lens, but inconsistent results between the slit lamp and OCT limited reliability. Despite the study’s limitations, it highlights the need for a better clinical method for measuring corneal surface pO2. More

Check out more articles from the May issue of RCCL here!

 

 




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20 Pearls on Ocular Inflammation

Inflammation is the body’s response to a stimulus it perceives as offensive. While an effective defense mechanism, the inflammatory process can cause scarring and damage to healthy tissues if not mediated properly. The May issue of Review of Cornea & Contact Lenses is devoted to exploring methods of mediating this delicate process. Below are 20 great pearls shared by experts in the field. For more detail, click through to read the original articles for each.



1. While synthetic corticosteroids vary in their relative balance of mineralocorticoid and glucocorticoid effects, all of them produce some degree of water and salt retention and hyperglycemia; thus, take caution when using them in cardiovascular and diabetic patients. More
2. Topical steroids can be used for two weeks with minimal effect on IOP. After two weeks, however, IOP can unpredictably rise with no discernable correlation regarding amount or time frame; pressure generally returns to baseline two to four weeks after the drug is discontinued. More


3. Choose your topical steroid based on the amount of information you’re treating (i.e., mild, moderate or severe). Mild surface inflammation is easily treated with less penetrating drugs such as Alrex or FML that help avoid the steroid response. Use Lotemax or Vexol for moderate inflammation and Pred Forte or Durezol for severe inflammation. More

4. Conjunctivochalasis may respond to topical cyclosporine: the drug inhibits the effect of proinflammatory cytokines IL-1β, TNF-α, IL-1 and IL-6. These cytokines are responsible for the degeneration of the elastic fibers, which contributes to the drooping conjunctival tissue that is characteristic of the condition. More

5. New formulations available on the market mean that steroids can now be used to alleviate symptoms of dry eye or lid inflammation on a short-term basis, or in cases where symptoms are exacerbated. Steroids are also now indicated for the treatment of corneal ulcers. More
6. A topical steroid should be chosen based on which one has the lowest effective dosage, longest dosing interval and shortest duration of therapy to prevent adverse effects and allow for discontinuation without withdrawal symptoms or flare-up of the disease. More

7. Note, posterior subcapsular cataracts (PSC) resulting from topical use are similar in presentation to those caused by systemic drugs. Most reports of PSC are secondary to topical ocular corticosteroids that have been administered for more than six months. More
8. Both topical and systemic NSAIDs are good for managing mild to moderate pain and can be combined with opiates like codeine, hydrocodone and oxycodone to enhance their effect. However, keep in mind all NSAIDs have some degree of potential to inhibit the beneficial antiplatelet activity of aspirin. More
9.Topical steroids can be used to treat superficial or anterior segment inflammation, but systemic treatment is necessary to treat diseases of the orbit or posterior segment; thus, optometrists must understand both the physiology of endogenous corticosteroids and the pharmacology of their synthetic analogs in order to fully use these agents in a successful anti-inflammatory regimen.More
10. Patients on long-term steroid therapy—even just one drop per day—should have their IOP checked every three months until the drug is discontinued, as with chronic steroid use, the IOP response can occur months to even years later rather than after just two weeks. More
11. Cyclosporine could be used to reduce levels of proinflammatory cytokines and matrix metalloproteinases (MMPs) in patients with keratoconus. A study separating keratoconus patients into a control group and study group treated with cyclosporine 0.05% twice a day found that MMP-9 levels in the study group, which had been significantly elevated at baseline, were reduced to levels comparable to the negative controls after six months. More
12. Corticosteroids work to inhibit both humoral (i.e., antibody production) ad cell-mediated (i.e., late-phase cellular response) immune responses, as well as the production of phospholipase A, which leads to a reduction in the body’s major inflammatory cytokines, prostaglandins and leukotrienes. More
13. If IOP increases from steroid use to the point that treatment is required, glaucoma drugs can be used to address the problem. Note, healthy discs can tolerate IOP in the high twenties to low thirties for a few weeks without significant compromise. More
14. Extended exposure to high-dose systemic corticosteroids produces a number of adverse effects, including weight gain, baldness, truncal obesity, impotence, humpback, amenorrhea, moon face, psychosis, hypercalcemia, anxiety, acne, depression, hirsutism, brittle hair, hyperhidrosis and skin discoloration. More
15. Prednisolone acetate 1% is the most active ocular corticosteroid and should be the drug of choice when maximal anti-inflammatory effect is required: a dosage of one drop every minute for five minutes each hour has been shown to decrease ocular inflammation by 72%, as compared to a decrease of 51% with hourly dosing and 11% with doses every four hours. More
16. The likelihood of steroid-linked cataract formation and glaucoma is significantly decreased due to high receptor affinity and rapid inactivation; however, the use of corticosteroids has been linked to cataract formation in patients with rheumatoid arthritis. More
17. NSAIDs are effective in low doses in reducing elevated temperature (i.e., fever), which is the body’s response to compromise by malignancy, infection or the introduction of certain chemicals, by inhibiting all forms of the enzyme cyclooxygenase (COX). COX is responsible for the formation of prostanoids, including prostaglandins that are responsible for increasing the body’s temperature to combat pathogens. More
18. Both endogenous systemic cortisol and exogenously administered synthetic glucocorticoids will produce adrenal glucocorticoid suppression; thus, use of corticosteroids for more than a few weeks can lead to adrenal suppression and adrenal atrophy. Long-term use of systemic corticosteroids can also lead to Cushing’s syndrome. Topical ophthalmic steroids, however, do not produce these adverse effects. More
19. Oxygen primarily diffuses through the material of a contact lens or dissolves in the tears and passes around the edges to the post-lens space. As such, hypoxic corneal swelling in contact lens wearers is mainly triggered by lack of adequate oxygen transmission (Dk/t). More

20. As topical steroids suppress the ocular immune system, they may also raise the risk of infection; however, they can be easily combined with topical antibiotics (i.e., fourth-generation fluoroquinolones) if potential infection is a concern. More
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