RCCL E-NEWS, October 2, 2015
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CDC Report Notes Widespread Lens Care Noncompliance

One in six US adults wears contact lenses, and virtually all engage in some form of risky behavior concerning lens care. Those are a few highlights of a new report from the US Centers for Disease Control (CDC) on contact lens wearer demographics and behavioral influences on risk of contact lens-related eye infection, part of the organization’s Morbidity and Mortality Weekly Report.

The population-based study identified 40.9 million contact lens wearers (i.e., one sixth of the adult population) in the country, with 93% wearing soft contact lenses. A subset of the contact lens-wearing population (n=1,000) also completed the CDC’s Contact Lens Risk Survey. More


Study Links CL Wear with Increased MGD Risk

Contact lens wearers, especially those who have worn lenses long-term, may be at increased risk for meibomian gland dysfunction (MGD), reports a study in the September 2015 Cornea. Researchers evaluated the meibomian gland health of 41 daily soft lens wearers vs. 31 age-matched non-lens wearers, using measurements of meibum expressivity and lid margin abnormality. More


Lens Performance Issues Linked to Cosmetics

Certain cosmetic products may have a significant adverse effect on contact lens shape, wettability and optical performance, report studies published in the July 2015 Eye & Contact Lens. Researchers in Canada coated seven silicone hydrogel lens materials with nine marketed brands of cosmetics: three hand creams, three eye makeup removers and three mascaras.

Makeup removers were found to have the greatest impact on lens diameter, sagittal depth and base curve, while mascaras were most detrimental to optical performance and wettability. The researchers note that in some cases the effects were irreversible despite lens cleaning. More


 Keratoprosthesis Suitable for Unilateral VA Patients

Patients with good unilateral visual acuity may be better candidates for a Boston keratoprosthesis (BKPro) implant than previously believed, reports a study in the September 2015 Cornea. Previously, implantation was only considered for patients with severe bilateral visual impairment, due to long-term risk and low expectations.

In a retrospective analysis of 37 BKPro patients (28 for failed PK, nine primary BKPro implants) with pre-op BCVA of 20/40 or better and mean follow-up of 31.7 months, the most common complications were elevated IOP and retroprosthetic membrane formation. Ultimately, the researchers reported, half of patients achieved the minimum VA required for binocular functioning, with one-third achieving BCVA similar to the contralateral healthy eye. More

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



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20 Pearls on Custom Contact Lenses

The contact lens industry has nearly perfected mass production of stock lenses—and lately, custom specialty lenses like sclerals, multifocals and orthokeratology lenses are beginning to flourish. With so many options, it’s hard to know what to choose and how to use it. To help, the September issue of Review of Cornea & Contact Lenses is devoted to improving your understanding of the different custom contact lenses available today. Below are 20 pearls shared by experts in the field. For more detail, click through to read the original articles for each.
1. As the simplest way to fit GP lenses, empirical fitting saves chair time; however, success using the first lens is only about 40% when employing K readings and refractive measurements. Use topographical software, Sim K information and corneal e-values or asphericity to help make the lens design more accurate. More
2. As a general rule, spherical GPs can be used when refractive astigmatism equals corneal astigmatism of less than 2.5D. Any residual astigmatism can be applied to the front surface; however, in cases of higher corneal astigmatism, back-surface or bi-toric GPs should be used. More

3. OCT or Scheimpflug imaging can improve scleral lens fit by objectively measuring the contour depth of the cornea and sclera out to nearly 15mm, to provide a known starting point for diagnostic fitting. OCT can also measure the tear reservoir and edge contour to the sclera at follow-up. More
4. Try fitting presbyopic patients looking for crisp, uninterrupted vision at both distance and near with translating GP multifocals to avoid inherent limitations of simultaneous vision designs. Pay attention to lower lid anatomy to ensure the lens rests appropriately on the lid and translates upwards as needed. More
5. After using a diagnostic lens set, rub and rinse each lens with a cleaner, then disinfect it, blot it and store it dry. When it’s time to use the set again, the lenses should be recleaned, rinsed and applied with a wetting or conditioning solution. More
6. You can use OCT to evaluate scleral edge profile during fitting: a lens that is too flat will demonstrate edge lift on OCT, which can lead to debris buildup and subsequent fogging of vision, while a lens that is too tight can “dig in” to the conjunctival-scleral complex and lead to discomfort and redness. More

7. When selecting a scleral lens, ensure adequate but not excessive vault. This should measure 150μm to 250μm centrally once lens settling has occurred, and should taper back to eventually land on the sclera just past the limbus. Inadequate vault can lead to cornea/lens touch. More
8. GP multifocals are a good option for high astigmats with presbyopia; these lenses can be fit empirically and typically provide the greatest range of clear vision. Note: some lens movement is typical, but significant movement can impede visual function. More
9. When fitting soft toric multifocals for high astigmats with presbyopia, fit the toric aspect first and adjust for rotation and instability before fitting the multifocal aspect. More
10. Many GP lens patients experience excessive lacrimation and foreign body sensation as a result of initial lens placement. Use proparacaine during the initial diagnostic lens fitting to numb the eye. More
11. Measuring pupil size in both photopic and scotopic conditions can help determine initial zone sizes when fitting either GP or custom soft multifocals. Keep in mind that add power may vary depending on the patient’s most desired working distance. More
12. Candidates for soft custom lenses include those who are experiencing refraction, rotation or fit issues in their current lenses due to corneal irregularity—particularly high astigmatism—and GP lens candidates who are concerned about discomfort. Astigmatic presbyopes are also well suited to wear custom soft lenses. More
13. When fitting presbyopes with custom lenses, consider the patient’s desired working distance when making the choice between two lenses. If higher add powers are required, many GP multifocals have adds greater than 3.0D. Some custom labs can also manufacture lenses with an add power up to 4.0D. More
14. The introduction of front surface aspheric multifocal or aspheric-concentric combination designs, capable of providing high add powers, has made GP multifocals the “go-to” lenses for presbyopes interested in clearer vision. More
15. Sagittal depth of the cornea (influenced by corneal diameter) may play a significant role in the lens/cornea fitting relationship. It’s measured by horizontal visible iris diameter (HVID). Lens base curves and diameter should be manipulated for patients with an irregular HVID measurement to prevent lens decentration. More
16. Assess the upper eyelid position when selecting an initial lens diameter for a GP lens. Generally, if the lid is positioned at or near the upper limbus, a lid-attached fit can be achieved with a diameter of 9.4mm or greater. An interpalpebral fit may require a smaller, steeper lens with a diameter of 9.2mm or less. More

17. Try using a scleral lens designs like corneal-scleral, semi-scleral, mini-scleral and conventional to fit keratoconic, post-trauma and post-surgical patients—these lenses mask corneal irregularities and are better tolerated than traditional corneal GPs. More
18. Consider using a specialized diagnostic fitting set for patients with keratoconus, pellucid marginal degeneration and patients who wear bifocal lenses due to variations in pupil size and GP lens designs. More
19. Employ HVID to determine appropriate lens diameter for GP lens stabilization and centration—an inadequate amount can lead to excessive lens movement and discomfort and subsequent patient dropout. More
20. Problems with first- and second-generation hybrid designs include limited oxygen transmission, tearing of the junction between the center GP and soft skirt, and a tight fitting relationship. More recent designs have since addressed these issues. More
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