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Topical Presbyopia Correction Takes a Step

Chemically-induced pupil contraction may soon emerge as an alternative treatment for patients with presbyopia, reports a new study in the September 2015 Eye & Contact Lens.

Researchers in Egypt investigated the use of a parasympathomimetic drug (carbachol) and an alpha agonist (brimonidine) in a double-masked, randomized placebo-controlled clinical trial involving 48 naturally emmetropic and presbyopic subjects. A treatment group (n=30 eyes) received a single dose of carbachol 2.25% plus brimonidine 0.2% eye drops, and a control group (n=18) received placebo drops.

Researchers found the protocol “permits acceptable reading vision for many presbyopes, even in older subjects.“Because of increased depth of focus from the smaller pupil, it does not blur distance vision or immediate vision as does typical monovision therapy, and the perception of normal brightness in the untreated eye eliminates symptoms of dimming from the smaller pupil of the treated eye.” More

Contact Lenses
Dilute Eye Drops

Silicone hydrogel contact lenses may limit absorption of certain anti-infective agents used to treat ocular surface diseases, reports a new study in the September 2015 Eye & Contact Lens.

Researchers from the University of Pittsburgh School of Medicine performed a biological assay to determine the activity of diffused moxifloxacin, polyhexamethylene biguanide (PHMB) and amphotericin B (AmB) against Staphylococcus epidermidis and Saccharomyces cerevisiae. Results indicated sufficient diffusion of moxifloxacin and PHMB at 30 minutes, but not AmB. Ultimately, however, only moxifloxacin demonstrated efficacy at the 60-minute mark, and at 10 times the amount of the most common commercial formulation. More

Focus on HOAs May Increase Surgery Success

Managing quality of vision after lamellar keratoplasty was the subject of a recent literature review published in the November 2015 Cornea. With respect to the studies evaluated, researchers found no significant difference in postoperative visual acuity between DALK and PKP; however, outcomes after DSAEK were significantly better than after PKP. More

Antibiotic Resistance Results Released

Bausch + Lomb has announced the five-year results from its Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) surveillance study.The study pinpointed significant methicillin resistance among staphylococcal isolates from ocular infections, with many strains demonstrating multi-drug resistance. More

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

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20 Pearls on Surgical Comanagement

The optometrist’s role in comanagement of cataract and refractive surgery has expanded beyond mere screening and referral to active engagement in pre- and post-op care. And the line between these two previously distinct surgeries continues to blur as the refractive component becomes more central to patient expectations following cataract surgery. To help optometrists meet surgical challenges both old and new, the November issue of Review of Cornea & Contact Lenses is devoted to exploring these responsibilities. Below are 20 pearls shared by experts in the field. For more detail, click through to read the original articles for each.

1. Ocular surface disease disproportionately affects cataract patients. One study found that 62.9% had a tear break-up time of less than five seconds, 76.8% showed positive corneal staining, 50% showed central corneal staining, 48.5% had a Shirmer score of 10 or less, and 58 eyes (21.3%) scored less than five. More

2. Most laser eye surgery patients experience some degree of dry eye in the first six months post-op, with symptoms persisting for longer than that in nearly 20% of patients. Take note of factors that may contribute to its development—e.g., systemic medicine use, contact lens wear and the presence of eyelid disorders—prior to the procedure to minimize onset. More
3. Prior to surgery, evaluate tear film composition and meibomian gland status. A tear concentration with greater than average mOsm/L and elevated matrix metalloproteinase inflammatory mediators can indicate an abnormal ocular surface environment, while use of a transilluminator can reveal the level of meibum quality and gland integrity. More

4. Surgeons reduce astigmatism of less than 1.0D during cataract surgery by positioning the cataract incision on the steep axis to induce wound flattening, which results in a decrease in cylinder. Complications include difficulty placing the incision at certain axes in patients with prominent brow or nasal ridges and unpredictable healing of the incision. More
5. Post-refractive surgery patients with residual refractive error may benefit from large diameter, reverse geometry GP lenses, which allow for complete vaulting of the central cornea, enhance patient comfort, and improve centration and visual acuity. More
6. Efficacy rates for the small-incision lenticule extraction (SMILE) procedure—which eliminates the excimer laser—have demonstrated that 95% of eyes achieve at least 20/30 uncorrected distance visual acuity at three months for even moderate to high myopia levels. Refractive stability is typically achieved at one week. More

To correct high astigmatism, cataract surgeons may combine limbal relaxing incisions (LRIs) with toric IOL use. LRIs produce a coupling effect, in which the amount of flattening that occurs in the incised meridian is nearly equal to the amount of steepening that occurs 90 degrees away, with little resulting change in spheroequivalent. This obviates the need to make any change in implant power. More
8. Patients with compromised corneas can be especially sensitive to debris build-up under a contact lens, and dryness and discomfort with increased wearing time, particularly when blinking is reduced while performing prolonged near tasks. Thus, always be proactive about ocular allergies in post-surgical patients, as they have an especially difficult time tolerating allergic compromise. More
9. Blepharitis is a common pre-surgical concern. Treat inflammatory blepharitis using topical antibiotics like topical azithromycin and/or topical antibiotic/steroid combinations, or both, in addition to lid hygiene regimens. Treat infectious Staphylococcus with an antibiotic ophthalmic ointment or drop to prevent continued issues. Use steroids to help decrease inflammation. More
10. Begin your pre-op exam with the external ocular adnexa. Look for any redness of the face or periorbital area, rhinophyma or other classic signs of rosacea. Perform a gross examination of the periorbital area to identify any lid dermatochalasis that might cause functional limitations on vision. More
11. When evaluating patients postoperatively, evaluate refractive success in quarter-diopter steps rather than single-diopter steps to ensure good visual acuity. More
12. Take type of procedure into account when evaluating a patient for postoperative dry eye—for example, in the case of the Kamra corneal inlay, dryness on the central aspect of the cornea is most detrimental to the patient’s refractive success and should be aggressively managed. More

When treating a postoperative refractive surgery infection, fortified antibiotics like vancomycin, tobramycin and/or a fourth-generation fluoroquinolone can be used, but keep in mind that a more atypical organism may be the cause in patients who are nonresponsive to conventional treatment. If so, tailor treatment based on culture results. More
14. When planning astigmatism correction during a cataract procedure, surgeons will consider the magnitude and axis of the astigmatism, corneal pachymetry, incision location, degree of irregular or asymmetric astigmatism, desired entry site, corneal pathology, patient age and status of the fellow eye. More
15. A rotated toric IOL will require realignment as soon as possible due to the possibility of adhesions forming between the capsular bag and IOL. More
16. The all-femto SMILE refractive surgery is less invasive than excimer procedures and removes the possibility of flap dislocation. The cornea inherently maintains a greater biomechanical structure and fewer corneal nerves are incised; as a result, a lower frequency of dry eye complaints and a shorter healing cycle are expected. More
17. Research has shown fish oil containing eicosapentaenoic and docosapentaenoic polyunsaturated fatty acids and omega-3 fatty acids may reduce inflammation and increase tear production. Consider advising patients with dry eye to take high-dose capsules containing omega-3 and omega-6 fatty acids on a daily basis beginning one month before surgery to help maintain the tear film. More

18. Complications that can arise following cataract surgery include: (1) acute increased IOP from retained viscoelastic, causing corneal edema or microcystic corneal bullae, and (2) wound leak, causing hypotony. More

19. Because SMILE is completed intrastromally, it eliminates environmental influences found in LASIK and PRK—i.e., air purity, humidity, barometric pressure and temperature of the operating room—that can affect the photoablation ability of the excimer beam and the amount of dry cornea removed with each pulse. This explains why a -10D treatment is just as predictable as a -1D treatment with SMILE. More
20. In determining the power and meridian of a toric IOL, the surgeon will take into account the vector sum of the preexisting corneal astigmatism and surgically induced astigmatism. Other factors that affect post-op uncorrected acuity are effective lens position and the spheroequivalent power of the IOL on the effective toricity of the IOL at the corneal plane. More

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