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  • Scleral Lenses May Affect Corneal Nerve Structure

  • Extended wear of fluid-filled scleral contact lenses may change cornea nerve function in patients with certain diseases, according to research in the April 2015 Cornea.

    Researchers found basal tear production significantly decreased and corneal sensation increased in patients with distorted corneas following long-term wear of an ocular prosthetic device. In contrast, tear production and corneal sensation did not change in prosthetic-wearing patients with OSD. This difference, the researchers say, may be because patients with DC have a healthier ocular surface; thus, the intact lacrimal functional unit “responds to the constant saline exposure by reducing the basal tear production and increasing corneal sensation, which are possible signs of improvement in corneal disease.” More

  • No Link Between Age and Astigmatic Visual Acuity

  • Age has no significant difference on visual acuity in the presence of defocus and astigmatic blur, reports a study in the March 2015 Optometry and Vision Science.

    Researchers dilated the right eyes of 22 participants using 1.0% cyclopentolate, then provided them each with artificial pupils mounted on the back of a trial lens. To evaluate visual acuity, researchers simulated thirteen blur conditions using five spherical lens conditions and two cross-spherical lenses at four negative cylinder axes. Participants were asked to read lines of decreasing size of high-contrast letters based on the Bailey-Lovie chart through the center of the artificial pupil. Ultimately, researchers found no significant differences in visual acuity between the two age groups, disproving their hypothesis regarding the older group having less decrease in visual acuity with blur. More

  • CXL May Accelerate Epithelialization

  • Corneal crosslinking may reduce length and severity of treatment in patients with moderate bacterial keratitis, according to research in the April 2015 Cornea.

    Researchers separated 32 bacterial keratitis patients into two groups: one treated using standard medical therapy (i.e., lubrication, fortified cefazolin (50 mg/mL) every hour, and systemic doxycycline every 12 hours following loading doses of fortified cefazolin and gentamicin) and one treated with CXL and standard medical therapy. No statistically significant difference was noted between the two groups one day following treatment, but epithelial defects and the area of infiltrates were both smaller in the CXL group by day seven of treatment. More

  • Antibiotics Reduce Corneal Infections

  • Use of certain antibiotics should strongly be considered to help prevent secondary corneal infections in patients wearing therapeutic soft contact lenses, says research in the March 2015 Eye & Contact Lens.

    Researchers cultured 40 therapeutic soft contact lenses of patients being treated for recurrent corneal erosion syndrome with topical tobramycin 3% and topical sodium hyaluronate 0.1%. Nine of the 40 lenses yielded positive cultures, with Staphylococcus epidermidis identified as the predominant microorganism. No clinical signs of infectious keratitis were found, however, suggesting tobramycin or ciprofloxacin are effective in preventing secondary corneal infections during therapeutic lens wear. More

  • Trehalose-Based Eyedrops Thicken Tear Film

  • A single dose of certain artificial tears may have a beneficial effect on the tear film thickness (TFT) of dry eye patients, reports a study in the April 2015 Cornea.

    In a randomized, double-masked controlled parallel group study, patients received a single dose of either unpreserved trehalose 30 mg/mL and sodium hyaluronate 1.5 mg/mL (TH-SH); unpreserved sodium hyaluronate, 0.15% (HA); or sodium chloride, 0.9% (NaCl) eye drops. Ten minutes after instillation, researchers observed an increase in TFT of the TH-SH group and the HA group, whereas no significant change was observed in the NaCl group. Interestingly, the increase in TFT remained statistically significant up to 240 minutes following instillation in the TH-SH group, but only 10, 20 and 40 minutes following instillation in the HA group, suggesting longer corneal residence of the TH-containing eye drops.

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

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    20 Pearls on Contact Lens Complications

    With over 30 million contact lens wearers in the US alone, some issues—either from noncompliance to wear and care guidelines, or simply bad luck—are inevitable. But, they present far too often in many practices. To help, the April Review of Cornea & Contact Lenses is devoted to improving your understanding of contact lens complications. Below are 20 great pearls shared by experts in the field. For more detail, click through to read the original articles for each.

    1. Because CLARE can result from contact lens wear while the eye is closed for any period of time—either a short afternoon nap or a full night or extended wear—ask all patients how many times per week they sleep or nap in their lenses as part of your routine history-taking procedure. More
    2. Because spectacle blur can result from poor GP lens fit, among other reasons, be sure to evaluate and educate the patient on signs and symptoms. In more extreme cases, deep stromal striae or opacification of the cornea can be seen, which is indicative of further potential issues. More
    3. When treating 3 and 9 o’clock staining in a GP lens wearer, which is a result of mechanical trauma to the peripheral cornea, check the edge of the contact lens and evaluate lens centration and wettability. Altering the diameter of the lens can also resolve staining. More

    4. During scleral lens application, have the patient keep their head parallel to the ground, open both eyelids wide, place the solution-filled lens on the conjunctiva and then close the eyelids. This prevents air bubbles from forming underneath the lens, which can compromise comfort, vision and corneal health. More
    5. You can manage peripheral infiltrates associated with lid margin disease using inexpensive early fluoroquinolones; central or more aggressive infiltrates, however, require a fourth-generation FQ. In severe situations (e.g., perforation risk, monotherapy failure, central aggressive ulcers with potential vision loss), consider a combination fortified-antibiotic. More
    6. Visuals can improve patient education and may help enforce adherence. For instance, an asymptomatic extended wear patient may have significant corneal neovascularization that can be imaged using a slit lamp and shown to them. Or a patient who overwears their lenses may benefit from seeing their lens deposits up close. More
    7. Since there’s no exact match in ICD-9 for CLARE exists, report it using a symptom code for the chief compliant, such as eye pain, redness or epiphora. If there is an accompanying corneal infiltrate, include additional codes for central and peripheral corneal opacity. More

    8. Provide all scleral lens patients with a preprinted, signed medical prescription for unit-dose sodium chloride 0.9% inhalation/irrigation solution. Some pharmacies still require a prescription for this solution despite it being a non-prescription item. More
    9. Lens edge design plays a major role in enabling or hindering foreign body entrapment, so polish the secondary curves and roll the edge and check for any chips to reduce potential. More

    10. Scleral lenses can be cleaned using any solution approved for corneal GP lenses; however, because there is less tear flow under the edge of a scleral lens, direct patients to also use a separate daily cleaner to ensure the lens surface is both clean and free of pathogens. More
    11. Following a CLARE episode, consider changing lens fit, material, modality and/or replacement schedule before resuming lens wear to reduce potential for reoccurrence. More
    12. Culture a case of bacterial keratitis if: (1) there’s a large central corneal infiltrate that extends to the mid- to deep stroma, particularly with significant corneal thinning or scleral extension; (2) it’s chronic in nature or unresponsive to broad-spectrum antibiotics; (3) atypical clinical features suggest fungal, amoebic or mycobacterial keratitis; or (4) the history is unusual. More
    13. Wondering if a corneal infiltrate is sterile or infectious? Divide the cornea into two distinct regions and consider whether the infiltrate presents in the periphery (non-infectious) or central 6mm (infectious) of the cornea. More
    14. Direct scleral patients with dry eye and those whose lenses exhibit areas of touch or minimal clearance to fill their lenses with clear unit-dose artificial tears for extra lubrication and corneal protection. Avoid milky or viscous tears, which will compromise visual clarity. More

    15. When diagnosing CLARE, look for diffuse conjunctival and limbal hyperemia, as well as multiple corneal epithelial and subepithelial infiltrates. The infiltrates are generally peripheral or mid-peripheral and don’t typically exhibit overlying punctate staining, indicating minimal epithelial involvement. More
    16. When culturing a case of microbial keratitis, scrape from the advancing borders of the infected area, as the microbial population will be abundant there. First instill a topical anesthetic, then use a heat-sterilized platinum spatula, blade, jeweler’s forceps or similar sterile instrument to obtain a sample. A thiol or thioglycollate broth-moistened dacron/calcium alginate or sterile cotton swab can also be used. More
    17. If a daily wear scleral lens patient exhibits lens adhesion, try altering centration and curvature of the lens to achieve a more centered fit. When the lens decenters, the secondary and peripheral curve junctions contact the flatter areas of the cornea, which, when combined with pressure from the eyelids, can lead to lens adherence. More

    18. Evaluate all patients presenting with a red eye for microbial keratitis by looking for a discrete area of fluorescein staining, typically greater than 1mm in diameter and often located in the central cornea. More

    19. Although CLARE is most often associated with tight fit or poor movement of extended-wear, low Dk, high water hydrogel lenses, more recently it has been associated with SiHy lenses, GPs, high oxygen permeability silicone elastomer lenses and overwear of daily disposables. More
    20. Even the most seasoned contact lens wearers may not know how to appropriately care for their lenses. Devise a consistent conversation to have with all contact lens patients and modify it according to individual needs. Emphasize the importance of adherence and correct patient-specific errors to help prevent complications. More

    Review of Optometry® is published by the Professional Publications Division of Jobson Medical Information LLC (JMI), 11 Campus Boulevard, Newtown Square, PA 19073.

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