anterior

Anterior Segment in Review

The research, diagnostic protocol and treatment protocol of the most pervasive front-of-the-eye conditions.

JIM OWEN, O.D., M.B.A., F.A.A.O., ENCINITAS, CALIF.

Everyone experiences a red, irritated eye at some point in his/her life. For some, it spurs their first eye doctor visit. For others, however, it is the start of a chronic condition.

In this article, I review the most prevalent anterior segment conditions and the current research, diagnostic and treatment protocols.

Allergy

“Episodes of watery, itchy eyes” affect 40% of the U.S. adult population, says a recent National Health and Nutrition Examination Survey. Dry eye disease and allergic conjunctivitis are not necessarily two separate diseases, says evidence from longitudinal studies.¹ The underlying etiologies of each condition are different. Nevertheless, both lead to ocular surface inflammation, which causes variable and fluctuating vision and scratchy, irritated eyes.

► Diagnostic protocol. Because of the connection between dry eye disease and allergic conjunctivitis, I perform a complete evaluation of the allergy patient’s tear function, including tear break-up time, corneal and conjunctival staining and tear osmolarity testing. Addressing any ocular surface problems compliments the treatment of the allergic condition.

►Treatment protocol. For patients I suspect of having ocular allergy, I instill an antiallergen drop. If this patient has allergies, he/she obtains relief within three minutes.

The following companies provide prescription allergy medication: Alcon, Allergan, Bausch + Lomb, Meda Pharmaceuticals, Santen and Vistakon.

Dry eye disease (DED)

The market of these patients is huge, with approximately $3.8 billion dollars spent on direct healthcare costs, says a 2013 report by Companies & Markets. The biggest challenge in treating these patients: Their signs do not always match their symptoms.

► Diagnostic protocol. Several new devices aid in the diagnosis of DED. TearScience LipiView (TearScience, Morrisville, N.C.) uses interferometry to measure the lipid layer’s thickness between blinks and gives a quantitative assessment in interferometric color units. There is a connection between lipid layer thickness and a patient’s dry eye symptoms.²

Another device: The TearLab Osmolarity System (TearLab, San Diego, Calif.) requires 50 nanoliters of tears to accurately measure a patient’s tear osmolarity. Readings above 312 mOsm have shown a 73% sensitivity and 92% specificity for diagnosing DED.³ Also, inter-eye differences in osmolarity have been shown as diagnostic for DED. Further, tear osmolarity may be valuable in determining contact lens wear schedule, material and/or solutions.

Finally, the RPS InflammaDry Detector (Rapid Pathogen Screening, Sarasota, Fla.) measures MMP-9 levels in the tear layer. It appears effective in both the diagnosis of DED and meibomian gland dysfunction and in revealing DED treatment success.³

► Treatment protocol. If a patient presents with DED, has mild symptoms and/or mild clinical findings and has not been using an artificial tear, I start him/her on an artificial tear a minimum of b.i.d.

Those patients who do not achieve significant relief from artificial tears are started on cyclosporine ophthalmic emulsion 0.05% (Restasis, Allergan), and I have these patients return in six weeks. If the patient has limited improvement in signs and/or symptoms at six weeks, I consider adding punctual plugs to the lower puncta.

If the patient presents with meibomian gland dysfunction, I start him/her on lid hygiene therapy (e.g. soaks, scrubs, massage, demodex wipes, if applicable), along with artificial tears. Also, the LipiFlow device (TearScience), which applies localized heat and pressure to the patient’s eyelids, has showed improvement in the production and quality of the liquid from the meibomian glands as well as improved DED symptoms following use.⁴ If the adult patient has significant anterior blepharitis, I prescribe a topical antibiotic ointment.

The following treatments are available for DED: artificial tears, corticosteroid gel, Restasis, Omega-3 essential fatty acids, topical antibiotics and punctal plugs.

Keratoconus

This condition affects one in every 2,000 patients. In the United States, close to 8,000 penetrating keratoplasty surgeries are performed each year due to keratoconus, says the Eye Bank Association of America.

► Diagnostic protocol. An increasing irregularity in the corneal curvature upon viewing corneal topography and a progressive thinning of the cornea defines keratoconus. There is a skewing of the axis of astigmatism greater than 10° and a steepening of the inferior cornea of more than 1.5D.

► Treatment Protocol. In addition to an array of soft and GP contact lens designs, corneal crosslinking (CXL) has been performed around the world for the treatment of keratoconus, and the FDA is currently investigating it for U.S. use.

Specifically, riboflavin drops and UV light are used to increase the covalent bonds between and within the corneal stroma’s collagen structure via epithelial defect.

While the treatment does not result in dramatic changes in corneal curvature or bestcorrected vision, it does appear to arrest disease progression.⁵

Therefore, if patients are treated before the cornea becomes too irregular, they can maintain a high quality of vision and are unlikely to need a corneal transplant.

A current study is evaluating the results of CXL when the corneal epithelium is “softened” with topical drops, while another study reveals an increase in penetration of riboflavin when ultrasound is administered to the cornea during riboflavin drops instillation.⁶ If treatment can be successful without epithelium removal, it will be more comfortable for the patient and decrease the risk of post-treatment infection.

Finally, both sequential and concurrent treatments of intracorneal ring segments with CXL resulted in improvement in best-corrected and uncorrected vision.^7,8

On the frontlines

Staying up to date on these prevailing anterior segment conditions leads to success with these patients, and therefore, growth for your practice. OM

1. Schaumberg DA, Sullivan DA, Buring JE, Dana MR. Prevalence of dry eye syndrome among U.S. women. Am J Ophthalmol 2003 Aug;136(2):318-26.

2. Blackie CA, Solomon JD, Scaffidi RC, et al. The relationship between dry eye symptoms and lipid layer thickness. Cornea 2009 Aug;28(7):789-94.

3. Tomlinson A., Khanal S., Ramaesh K, et al: Tear film osmolarity: Determination of a referent for dry eye diagnosis; Invest Ophthalmol Vis Sci. 2006 Oct;47(10):4309-15.

4. Lane SS, DuBiner HB, Epstein RJ, et al. A new system, the Lipiflow, for the treatment of meibomian gland dysfunction. Cornea. 2012 Apr;31(4):396-404.

5. Caporossi A., Mazzotta C. Baiocchi S, Caporossi T. Long-term results of riboflavin ultra violet a corneal collagen cross-linking for keratoconus in Italy: The Siena eye cross study. Am J Ophthalmol. 2010 Apr;49(4):585-93.

6. Hovakimyan M., Guthoff R., Stachs O., Collagen cross-linking current status and future directions; J Ophthalmol. 2012;2012:406850.

7. Ertan A, Karacal H, Kamburoglu G. Refractive and topographic results of transepithelial cross-linking treatment in eyes with intacs. Cornea. 2009 Aug;28(7):719-23.

8. El-Raggal TM. Sequential versus concurrent KERARINGS insertion and corneal collagen cross-linking for keratoconus. Br J Ophthalmol. 2011 Jan;95(1):37-41.

Dr. Owen is in private practice in Encinitas, Calif., and serves on the American Optometric Association’s Refractive Surgery Committee. E-mail him at encinitasod@gmail.com, or send comments to optometricmanagement@gmail.com.