COMFORT LEVEL DEPENDS ON SOLUTION/LENS COMBINATION
Silicone hydrogel lenses have become more popular for daily wear and there are now six materials widely used in the United States, each with a different chemical composition and material property. The 10-point quantitative area scale used in these clinical studies determined both severity and extent of corneal staining of various solution/lens combinations. Results showed that several biguanide solution/lens combinations continued to exhibit excess staining 2 to 4 hours after lens insertion. Those solutions that were preservative free showed minimal staining and a higher level of comfort.
All patients should thus have a thorough slit lamp examination within the first week of being prescribed a new solution/lens combination. To maximize the visibility of any staining that might be present, sodium fluorescein, a cobalt filter, and a yellow filter should be used. Patients should also be educated about their prescribed solution and the potential consequences of switching solutions. Also make sure they are still using the prescribed solution.
Andrasko G and Ryen K. Corneal staining and comfort observed with traditional and silicone hydrogel lenses and multipurpose solution combinations. Optometry 79: 444-454, 2008.
CORNEAL LACERATION CAN CAUSE RARE EPITHELIAL INGROWTH
A 45-year-old woman complained of decreased vision and haloes in the left eye for two months. Before this, her left eye had been injured by an iron wire and she had been treated for a traumatic corneal lamellar laceration. Further examination revealed an epithelial ingrowth (grade 2, extending more than 2 mm from the flap edge) within the flap-stroma, which required surgical debridement of the epithelial sheet followed by careful realignment of the flap. Her vision improved and there was no recurrence of epithelial ingrowth at the one-year follow-up examination.
Bansal R, Jain A, and Sukhija J. Epithelial ingrowth within the interface following traumatic corneal lamellar laceration. Ophthalmic Surg Lasers Imaging 39: 217-220, 2008.
NATURAL READING IS A SERIAL PROCESS
An eye-tracking experiment was designed to determine whether the type of lexical processing that occurs during natural reading is more consistent with a serial-attention or attention-gradient model. Four tasks were involved: participants had to detect an embedded asterisk; the letter q; whether a word rhymed with blue; or whether a word referred to an animal in a display of 1-4 simultaneously displayed words. Response times and eye movements were only modestly affected by the number of words in the asterisk-detection task but increased markedly with the number of words in the other three tasks. For the latter, participants were more likely to shift their initial gaze towards the left and then scan from left to right, indicating these three tasks were completed one word at a time. These results suggest that attention may not be serial for tasks that do not require significant lexical processing, but is approximately serial for tasks that do.
Reichle E. Vanyukov P, Laurent P and Warren T. Serial or parallel? Using depth-of-processing to examine attention allocation during reading. Vision Research, 48: 1831-1836, 2008.
RULE OUT THE WORSE FIRST
The worse should be considered first when a contact lens patient has a red eye. Infection should be ruled out by taking the patient’s history (when symptoms began, how long they’ve been persisting, and if there is any change in the level of pain). If pain has increased, it could be a bacterial infection. If there is constant pain, it could be a small lesion. Inflammation could also be caused by lens-induced gram-negative bacteria.
Shovlin J. Infectious until proven sterile. Review of Optometry Online. http://www.revoptom.com/index.asp?page=2_13922.htm.
RULE OUT THE WORSE FIRST
WHAT IS THE BEST TREATMENT FOR WET AMD?
The answer to the question is it depends on the individual patient. Some patients may need more treatments and others fewer. Laser treatments, such as laser photocoagulation and photodynamic therapy, only decrease disease progression. Antiangiogenic medications (anti-VEGF drugs) are more promising and may restore vision loss. Macugen, pegaptanib sodium, is an FDA-approved treatment for wet AMD that has demonstrated stabilization of vision. A better drug that has improved vision that is also FDA approved is Lucentis, which is derived from bevacizumab. More recently, Avastin has shown potential as an effective treatment and is undergoing trials to compare it to Lucentis.
Shechtman D and Karpecki P. 21st Century AMD Treatments. Review of Optometry Online. http://www.revoptom.com/index.asp?page=2_13926.htm.
PREPRESCRIBING COMBIGAN DEPENDS ON PATIENT
Combigan is a fixed combination of brimonidine (an alpha-2 adrenergic agonist) and Timolol (a beta blocker) that is used twice daily to reduce intraocular pressure. In the case of a 58-year-old white female patient with glaucoma, the replacement of timolol with Combigan helped meet her target IOP and was well tolerated. Such fixed combinations offer the benefits of convenience, cost and safety; however, they can limit individualization of dosing and can result in inappropriate usage together with their components.
Sowka J and Kabat A. The pros and cons of combigan. Review of Optometry Online http://www.revoptom.com/index.asp?page=2_13925.htm.
BE HONEST WITH CATARACT PATIENTS ABOUT IOLs
Custom cataract correction with premium intraocular lenses (IOLs) can help patients be less dependent on glasses after cataract surgery. However, patients who choose such a lens may not know what to expect and must be informed that no synthetic lens will be as precise as the natural one. They must understand that they will still need glasses for some activities after surgery. Also, be sure to carefully discuss the strengths and weaknesses of the specific lens that will be employed. After surgery, careful management will help keep patients satisfied. After all, a satisfied patient means more referrals for your practice.
Foster G. Premium IOLs: how to manage patient expectations. Review of Optometry Online. http://www.revoptom.com/index.asp?page=2_13920.htm.
TEN STEPS FOR CORRECTLY DIAGNOSING DRY EYE
If a disease is incorrectly diagnosed, it can lead to further damage, higher costs for the patient, and a bad reputation. A good protocol for proper diagnosis of dry eye involves 10 steps: listen carefully to the patient’s medical history; think systemic by asking about the patients’ overall health; slow down and don’t rush to examine the details; perform your diagnosis the same way every time; use a two-step staining process with lissamine green followed by sodium fluorescein; test for tear film stability; assess tear volume with Schirmer’s test score: check aqueous outflow; observe the meibum for viscosity and clarity; and last put it all together, looking for patterns so you can prescribe the best treatment. Ask the patient more questions if necessary.
Morris S. Dry eye management: your 10 step approach to making the correct diagnosis. Optometric Management Online. http://www.optometricmanagement.com/article.aspx?article=101914.
MASS SPECTROMETRY METHOD CAN DETECT CYCLOSPORIN A.
The levels of cyclosporine A in tears and the anterior segment of the eye, following long-term oral intake for autoimmune diseases, were analyzed using turbulent flow chromatography coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) 12 hours after the last oral intake. This method can measure low concentrations in very small samples. The current immunoassay method requires a 10 ng/ml detection limit and larger sample volumes.
Cyclosporin A was found in all tear samples at a mean concentration of 22.4 ng/ml, which was ~1/3 of the blood concentration. The drug was not found in any of the aqueous humour or anterior capsule of the lens samples, which was attributed to the intraocular barrier preventing CsA diffusion. The concentration of the drug also was positively correlated with the blood level.
Mora P, Ceglarek U, Manzotti F, Zavota L, Carta A, Aldigeri R and Orsoni J. Cyclosporin A in the ocular fluids of uveitis patients following long-term systemic administration. Graefes Arch Clin Exp Ophthalmol 246: 1047-1052, 2008.
