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Corneal Scars Are Forever—Or Are They?

  • A new treatment for corneal scarring using stem cells grown from the patient’s healthy stroma could one day reduce the need for grafts, according to research published in the December 2014 Science Translational Medicine.

    DMEK in Vitrectomized Eyes: Successes, Setbacks

  • Descemet’s membrane endothelial keratoplasty (DMEK) is successful in restoring visual acuity in vitrectomized eyes, says a new study published in the January 2015 Cornea. However, graft failure and the overall complication rate are both higher than in standard DMEK procedures.
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  • Hepatitis C virus (HCV) RNA, commonly found in the tear fluid of patients with chronic HCV, may also be prevalent in the tears of dry eye patients who exhibit no clinical evidence of HCV, according to a study published in the January 2015 Cornea. Researchers used real-time polymerase chain reaction testing to detect HCV RNA in tear fluid collected from 36 dry eye patients and 20 healthy controls. Twenty-one of the 36 (i.e., 58.3%) dry eye tear samples tested HCV RNA-positive, while none of the control samples tested positive. These findings, say the researchers, may indicate a possible etiological role of HCV in causing dry eye.
  •   The researchers also evaluated 15 serum samples collected from dry eye patients. Enzyme-linked immunosorbent assay for anti-HCV was negative in all 15—a result they say further confirms the presence of HCV RNA without active viral infection. Normal levels of alanine aminotransferase were also observed in all 15, but alkaline phosphatase was abnormal in 12 of the 15 samples. This indicates the patients likely do not have subclinical hepatitis, but it cannot be completely ruled out.

  • A new hydrophilic daily disposable soft multifocal lens for presbyopic correction, called NaturalVue, has received FDA 510(k) clearance. Similar to a spherical contact lens, the NaturalVue 1-day multifocal is designed to be easy to fit, with one base curve, one diameter and one “universal” add power, which accommodates up to 3.00D of equivalent near power, says manufacturer Visionering Technologies.

  • SynergEyes has released eight video tutorials designed to assist doctors with fitting the Duette Progressive lens for astigmatic presbyopes who no longer attain acceptable near vision from soft multifocal contact lenses. The step-by-step tutorials cover lens design, fitting and dispensing, as well as how to achieve good near vision, distance vision and patient compliance.
  • Read More Here

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    Scleral Lenses – 20 Pearls

    Once used only in special cases, scleral contact lenses have gone mainstream as an option for irregular corneas, ocular surface disease and refractive error alike. This growth in popularity means you need to be aware of the benefits and challenges these lenses offer more than ever. To help, the January issue of Review of Cornea and Contact Lenses is devoted to improving your understanding of sclerals. Below are 20 great pearls from the experts. For more detail, click through to read the full articles.

    1. The fitting goals for all scleral lenses share three characteristics. The lens should (1) land on the conjunctiva overlying the sclera without causing excessive tissue compression or vascular blanching, (2) completely and measurably vault the cornea and limbus, and (3) exhibit minimal vertical or lateral movement on the blink. More
    2. Improve patients’ opinions of your practice and increase your productivity by educating your staff on scleral lenses, which will allow them to better recommend scleral lens options and answer some questions before the patient even sits in your chair. More

    3. Fluorescein, used to define the fluid reservoir during the fitting process, can either be applied to the ocular surface directly or placed in the bowl of the lens prior to application. The former will reduce the risk of staining clothing or fingers during lens application, however. More

    4. When switching a patient from corneal GP lenses to sclerals, keep in mind that while you may have empirically ordered corneal lenses, sclerals will require a diagnostic lens fitting. Additionally, remember it’s possible that if you refit patients just out of their GPs, a power shift can occur over the first month during which their corneal curvature rebounds because they no longer had a lens that is supported by the cornea. More

    5. Providing new scleral lens wearers with adequate information on lens care and demonstrating a variety of insertion and removal methods can dramatically reduce patient dropout by bypassing common reasons for abandonment, such as difficulty with lens handling. More
    6. If you’re uncertain of which lens to select during the diagnostic fit, err on the side of greater sagittal depth. It is much easier to estimate the amount of additional sagittal depth required to clear the cornea in a lens that fits with considerable corneal touch. More

    7. When fitting a dry eye patient, start with sclerals designed for the regular/normal cornea, since it’s unlikely you will need the size or geometry that sclerals offer for fitting irregular corneas. But make sure to completely vault the cornea to avoid bearing on a surface that can be mildly compromised secondary to dryness. More

    8. Offering a scleral lens consult to your post-refractive surgery patients at routine exams can help grow your scleral patient base. Many are unaware there are contact lens options for them—this is especially true of early adopters who underwent refractive surgery using outdated techniques like radial keratotomy. More

    9. A diagnostic scleral lens fitting set, a trial lens set, a slit lamp and a phoropter—along with careful observation and evaluation—can provide all of the information necessary to successfully fit sclerals. Diagnostic lenses will allow you to assess the fit and over-refraction with either handheld trial lenses or a phoropter will provide the refractive information you need to order the lens. More

    10. Consider sclerals for patients with moderate to severe corneal irregularity who have struggled with corneal GP lenses. These lenses’ small relative size forces them to distribute their weight directly onto the uneven corneal surfaces, leading to destabilization of the fit. Scleral lenses, on the other hand, vault the cornea and rest on the sclera, meaning centration and stability remains unaffected. More

    11. It isn’t necessary to become familiar with all scleral designs, but have on hand at least two fitting sets—one for one larger (17.0mm to 18.0mm) and one for smaller (15.0mm to 16.00mm) designs. This will cover most indications. More

    12. Evaluate the lens fit immediately following application to determine if there’s too much or too little clearance. Because scleral lenses tend to settle with time, bracket the fit in large intervals until you find a lens that demonstrates approximately 100µm to 150µm more clearance than would be considered ideal, then allow the lens to settle for 20 to 30 minutes before the final evaluation. More

    13. If a GP patient suffers regularly from irritation due to environmental foreign bodies, consider switching to a scleral lens. Scleral lenses semi-seal to the eye and, when fit correctly, will not reposition with eye movement or blinking. This improves both comfort and stability, and prevents foreign bodies entrapment. More

    14.Distract the patient during the initial lens application,—to ease apprehension—by having them hold their lower lid while you apply the lens, or encouraging them to look at something, such as a bottle cap or other object in their lap. More

    15. Increase awareness of your practice by making local optometrists and ophthalmologists aware of your expertise in scleral lens fitting. Many doctors do not offer specialty contact lens services, so forming a relationship with them can be mutually beneficial: they will circulate your name to patients, and if you’re so inclined, you can do the same. More

    16. If the patient’s lids cannot be opened widely enough for direct application of the lens, try placing one edge of the lens beneath the upper or lower lid and “folding” or “tipping” it into place. If you need to manipulate the angle of the lens during application, a relatively viscous non-preserved product can help prevent excessive fluid loss and entrapment of air bubbles. More

    17. As scleral lenses are still relatively new additions to the market, do not assume complications associated with scleral lens wear are identical to those we see with other lens modalities, and do not assume risk factors for those complications are exactly the same as those that have been identified for other lenses. More

    18. Be sure to perform spherocylindrical over-refraction during the fitting and follow up. If it yields astigmatism, check over-topography to make sure the lens isn’t flexing, which can induce astigmatism. Increase center thickness to eliminate flexure. If the lens isn’t flexing, correct the residual astigmatism by adding front surface toricity. Over-refraction at follow-up can allow you to fine tune the power for any induced cylinder secondary to rotation. It’s more accurate than trying to apply LARS (left add, right subtract.) More

    19. Because the increased lens and fluid reservoir thickness of a scleral lens can potentially alter effective lens power, careful refraction over a diagnostic scleral lens is recommended to avoid power calculation errors. Using handheld trial lenses can help minimize the need to calculate power adjusted for vertex distance. More

    20. Because scleral lenses fit the sclera, not the cornea, their fit is stable regardless of astigmatic orientation. So, consider sclerals for against-the-rule astigmatism, which can be notoriously hard to fit with corneal GPs. Front surface toricity can also be added to sclerals for lenticular astigmatism; unlike corneal GP lenses, ballasted scleral lenses are stable due to their large diameter and semi-sealed fit. 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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