Issue 4, 2012

 

 


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Vol. 1, No. 4, 2012

Editor’s note: This volume covers the topics of dry eye disease, cornea/ corneal disease, contact lenses/complications, conjunctivitis, IOP/ glaucoma, keratoconus and cataract. The hope is that this augments your education, clinical practice acumen and keeps you up-to-date on important topics concerning contact lenses and the anterior segment. We are striving to present, in a succinct and pithy format, important information that does not cut into your already busy schedule, delivering clinical nuggets for the benefit of all of your patients

 

 

 

 

 

dryDry Eye Disease

Khanal S and Millar T J. Barriers to clinical uptake of tear osmolarity measurements. Br J Ophthalmol 96:341–344, 2012.

Hyperosmolarity of the tear film has long been associated with dry eye and can lead to ocular surface damage. Until recently, measuring the osmolarity of the tear film in a clinical setting has been limited by the difficulty in obtaining collection samples, especially in dry eye patients.

In this study, the commercially available TearLab osmometer (TearLab Corp, San Diego CA) was investigated to determine the osometer’s usefulness and reliability in a purely clinical setting.

A large number of tests were conducted on only a few subjects in an effort to determine it’s variability within individuals. Re-searchers found that the TearLab instrument produces a fairly wide variation between readings (up to 35mOsm/l), and produces occa-sional random readings.

For these reasons, the researchers determined that an average of 3 readings is required to reliably predict a patient’s tear osmo-larity at a 95% confidence level. Of additional interest, they found no inter-observer or inter-instrument differences, and determined that results were not affected by ambient temperature or humidity.
Contrary to popular belief, this study did not find diurnal variation of tear film osmolarity, which correlates
with other studies (i.e., Begley, et al. and Gilbard,et al.).Although the simplicity of this device makes obtaining
tear samples very quick and easy in a clinical setting, it becomes quite costly if 3 readings have to be taken for
each eye, since all measures require a new single-use chip.

In this small study, a portable infrared video security camera, equipped with a simple +20D lens system, was used to capture images of the everted lower lid to deter-mine meibomian gland (MG) dropout rates.

Not surprisingly, increased MG loss significantly cor-related with reduced lipid layer thickness and tear break-up time, as well as an increased Ocular Surface Disease Index (OSDI) score. Interestingly, MG loss was much higher in females. This research suggests that an MG loss of 32% or more strongly predicts that a patient will be symptomatic for dry eye.

Meibomian gland (MG) atrophy may be higher in contact lens wearers. Of course, absence of these glands leads to reduced lipid layer thickness in the tears, in-creased tear evaporation, inflammation and symptoms of dry eye. Animal models suggest that the use of topical azithromycin ophthalmic solution, a broad-spectrum macrolide, may have anti-inflammatory effects and in-hibit tear cytokine production. This small, unmasked pilot study evaluated the safety and efficacy of AzaSite (Merck, Whitehouse Station NJ) in patients with contact lens-related dry eye (CLRDE).

Subjects who administered the medication twice per day for the first 2 days and then 1 drop per day for 27 more days experienced significantly increased comfort-able contact lens wear time compared to those who used rewetting drops every 4 hours. In addition, the medica-tion was well-tolerated, and treated subjects reported improved ocular dryness symptoms, especially in the evening.This pilot study provides evidence that topical azithromycin ophthalmic solution may be efficacious in treating CLRDE, however, larger, double-masked trials are certainly required to fully investigate this treatment option.

Chronic dry eye is a prevalent and persistent problem in most practices. Several studies have documented the effectiveness of 0.05% cyclosporine; however, patients typically report that it may take up to 3 months to feel significant improvement.

The study was designed with 2 groups of moderate to severe dry eye sufferers, 21 subjects per group. Group 1 used 1% methylprednisolone in the first month (4 times a day for the first week, then tapered off by the end of the month) along with 0.05% cyclosporine (2 times daily), which they continued for 2 more months. Group 2 only used 0.05% cyclosprine for the 3-month trial. Data collec-tion occurred at a baseline exam, 1 month, 2 months and 3 months (symptoms scores, TBUT, Schirmer, anterior segment staining) and pro-inflammatory factors in tear samples were analyzed at the 3-month visit.

This study supports the concomitant use of 1% meth-ylprednisolone and cyclosporine in the first month of treatment. The combined use demonstrated an improve-ment in subjective symptom relief within the first month and also a decrease in dry eye signs (Schirmer and fluorescein staining); however, the results were the same after 3 months between groups. Both study groups showed a decrease in inflammatory factors (IL-6 and IL-8) at 3 months; however, no statistical differences were noted between the methylprednisolone and cyclosporine groups.

Ibrahim OM, Dogru M, Kojima T, et al. OCT assessment of tear meniscus after punctal occlusion in dry eye disease. Optom Vis Sci 89(5): 770–776, 2012.

This study presents an objective method to measure tear meniscus changes after dry eye treatment, using the Visante OCT. The primary measurement was tear menis-cus height before and after silicone punctal plug occlu-sion (SuperFlex, Eagle Vision) in 30 eyes that were non-responsive to non-preserved artificial tear treatment.

The subjects were age and sex matched with 30 control eyes treated only with non-preserved artificial tears. Baseline measurement was performed with the Visante OCT, along with slit lamp tear measurement height, strip meniscometry testing, TBUT, vital dye staining (fluorescein and Rose Bengal) and Schirmer 1 testing.

After 1 month, slit lamp TMH and OCT measure-ments improved for the punctal plug group ( p<0.01) and was unchanged for the controls. Both groups showed an increase in Schirmer 1 testing; however, the punctal plug group showed significant improvement in strip meniscometry scores, TBUT and vital dye staining (p<0.05). All patients exhibited symptoms prior to punctal occlusion; this diminished to 10% after the study.

This study validates the use of OCT as a non-invasive and efficient tool for monitoring dry eye patients who have undergone punctal occlusion.

Kim JH, Kim JH, Nam WH, et al. Oral alcohol administration disturbs tear film and ocular surface. Ophthalmology 119(5): 965–971, 2011.

The effects of alcohol are well documented, but to this point no official study of the effects of alcohol consump-tion on the tear film has been documented. Twenty healthy male volunteers between 20–25 years-old with no history of dry eye, liver disease, or ophthalmic surgery were recruited.

Two groups were created: an alcohol group and a control group. The alcohol group consumed 0.75g/kg body weight of ethanol between 8 and 10 PM. The tear film was evaluated in all groups at 6 PM (pre-drinking), at midnight, at 6 AM and 8 AM. Tear osmolarity, ethanol concentration in tears and serum, Schirmers, TBUT, cor-neal punctate erosion and corneal sensitivity were all measured.

The percentage of ethanol in the blood serum was 0.072, which is over the legal limit to drive in Korea, the country where the study took place. Overall, the ethanol group showed trace ethanol (0.031%) in the tear film at midnight and showed an increase in tear osmolarity and fluorescein staining, while exhibiting a shorter TBUT the next morning. Corneal punctate erosions and Schirmer’s test results were the same between groups.

This study highlights the effect of alcohol consump-tion on the ocular surface, which could exacerbate signs and symptoms in patients with ocular surface disease. It also demonstrates that the effect can last over the course of an evening.

lklkCornea/Corneal Disease

Miri A, Alomar T, Nubile, M, et al. In vivo confocal micro-scopic findings in patients with limbal stem cell deficiency. Br J Ophthalmol 96:523–529, 2012.

The diagnosis of limbal stem cell deficiency (LSCD) can often be made clinically via biomicroscopy; how-ever, it can be difficult to identify remaining normal limbus and determine the extent of affected cells. which is of extreme importance when considering treatment options.

This paper describes the micro-anatomical and mor-phological features of LSCD using non-invasive in-vivo confocal microscopy with the Heidelberg Retina Tomo-graph II Rostock Corneal Module.

In general, the central cornea in partial LSCD pa-tients was found to be normal, except for the presence of dendritic and inflammatory cells. In eyes with conjunct-ivalised corneal epithelium, intraepithelial cysts were common, which were usually surrounded by goblet cells.

Hillenaar T, Cleynenbreugel H, and Remeijer L. How normal is the transparent cornea? Effects of aging on corneal morphology. Ophthalmology 119:241–248, 2012.

Three hundred eyes of 150 normal subjects were evaluated by in vivo confocal microscopy (IVCM) using the Confoscan 4 (NIDEK Technologies, Albignasego, Padova, Italy), to determine the effects of aging on corneal morphology. Subjects were classified into 5 age groups and were evenly distributed between male and female. Eight common features observed with IVCM were investigated for age-related changes.

Investigators found 4 common degenerative fea-tures in the aging cornea: anterior stromal microdots, posterior stromal folds, opacification of the anterior limiting lamina (Descemet’s membrane) and corneal guttae, all of which were statistically significant.

Three percent of all eyes showed characteristics of epithelial basement dystrophy, which were believed to be an age-related change since they were not observed in patients under 40 years, however, this could not be statistically confirmed.

Dendriform cells, part of the innate and adaptive immune system, were observed in 8 to 20% of eyes but were without age-related significance. The investigators also describe two cases of what they call a novel “salt and pepper endothelium.

hhhContact Lenses

Panaser A and Tighe B. Function of lipids—their fate in contact lens wear: An interpretive review. Contact Lens and Anterior Eye 35:100–111, 2012.

This article provides a comprehensive review of the structure and function of lipids, both in the tear film and other body sites, including synovial joints and pulmonary lining. The authors compare and contrast meibomian.

Hyatt AJ, Rajan MS, Burling K, et al. Release of vancomycin and gentamicin from a contact lens versus a fibrin coating applied to a contact lens. Invest Ophthalmol Vis Sci 53(4): 1946–1952, 2012.

The idea of using a contact lens for drug delivery to the eye dates back to the 1960s. Topical administration via eye drops often requires frequent application and can result in extreme variation of drug exposure due to quick drainage, overspill and user error.

Furthermore, in cases of severe microbial keratitis, drops often need to be instilled throughout the night, making it inconvenient for the patient and leading to non-compliance.

In order for a contact lens-based drug delivery system to be successful, it must allow for a consistent, slow delivery of medication to the eye while maintaining bactericidal concentration.

Previous studies have shown that a contact lens just soaked in an antibiotic solution can produce effective results for a few hours; however, unmodified lenses tend to release medication too quickly for long-term or over-night use.

This ex vivo study investigated 2 additional modes of drug delivery systems for vancomycin and gentami-cin, medications commonly used in the treatment of severe microbial keratitis. Antibiotics were loaded into a small amount of fibrin gel (to slow drug release), which was then applied either to the concave surface of a commercially-available bandage lens or sealed between 2 lenses.

Both systems (bandage and sealed) surpassed the minimum bactericidal concentration for a 3-day period for many of the micro-organisms that cause keratitis; however, the majority of the antibiotic release occurred during the first 8 hours for the single-lens modality.

Sandwiching the fibrin gel-antibiotic complex be-tween 2 lenses significantly slowed down the rate of release, but the examiners reported that the thickness of the double-lens system was impractical for actual use. This investigation shows promise for the use of antibi-otic/fibrin for delivering antibiotics to treat bacterial keratitis.

Garcia-Lazaro S, Ferrer-Blasco T, Radhakrishnan H, et al. Visual function through 4 contact lens-based pinhole systems for presbyopia. J Cataract Refract Surg 38: 858– 865, 2012.

For many patients, presbyopia can cause a significant decrease in their quality of life. Several solutions have been suggested, and one of the most recent involves the use of artificial pupil inlays to correct presbyopia.

The researchers were interested in assessing the ef-fects of differing artificial pupil design systems on visual performance. The study examined visual acuity, defocus, contrast sensitivity, and stereoacuity. The artificial pupils corneal inlays were mimicked using soft contact lenses (Balafilcon A). An 8.0mm diameter opaque zone with varying pupil sizes of 1.6, 2.5 and 3.5 mm were tested, as well as a 4.0 mm opaque zone with a 1.6 mm pupil.

In summary, these inlays increased the depth of field of the eye by decreasing aperture size of the pupil. However, uncorrected and corrected visual acuity at distance was lower in the artificial pupil group when compared to controls. The artificial pupils did improve intermediate vision. The inlays, however, did not give satisfactory near vision.

ccConjunctivitis

Karpecki P. Contact lens wear and ocular allergy: Proper diagnosis and management of ocular allergies will help symptomatic patients continue with contact lens wear. Contact Lens Spectrum 27:26–32, 2012.

This is a superb comprehensive review regarding the diagnosis and treatment of ocular allergy in contact lens wearers. Ocular allergies may affect up to 12 million contact lens wearers. The author presents the incidence and prevalence of chronic allergy in the United States, as well as interesting information regarding quality of life studies in these patients.

Tips for differentiating several ocular allergy condi-tions, including atopic and vernal keratoconjunctivities, giant papillary conjunctivitis and seasonal and perennial allergic conjunctivitis are given, as well as up-to-date recommendations for specific disease management.

Rathi VM, Mandathara P, Vaddavallli P, et al. Fluid-filled scleral lenses in vernal keratoconjunctivitis. Eye & Contact Lens 38(3): 203–206, 2012.

As scleral contact lenses continue to increase in popu-larity as a vision correction device, many clinicians are also exploring therapeutic uses for them. The authors examined the charts of 4 patients who suffer from vernal keratoconjunctivitis (VKC) in conjunction with the asso-ciated conditions of keratoconus and limbal stem-cell deficiency (LSCD).

All of the subjects were fitted with the PROSE lens, a large diameter (18 mm) fluid-filled scleral. Mean age was 17.5 years, 3 patients (5 eyes) were diagnosed with keratoconus, and 1 patient (2 eyes) was diagnosed with LSCD.

The average wearing time for the lens was 8.3 hours. Mean log Mar VA was 0.4 before PROSE and 0.18 with PROSE. Visual acuity improved 2 lines in 6/7 eyes. The patient with LSCD also benefited from an improved ocular environment, likely the result of a reduction in shearing action of lids on the cornea, in addition to the prevention of corneal desiccation.

aaKeratoconus

Gordon-Shaag A, Millodot M, Ifrah R and Shneor E.
Aberrations and topography in normal, keratoconus-
suspect, and keratoconic eyes. Optom Vis Sci 89(4): 411–
418, 2012.

This study compared inferior-superior (IS) topogra-
phy with higher order aberrations of the cornea and eye to
determine if one method was superior to the other. The
investigators used an L80 wave+, a dynamic tool with the
ability to measure corneal topography and aberrations
simultaneously through seventh-order Zernike values.
Ninety-two eyes were used: 21 with suspected keratoco-
nus, 23 with manifest keratoconus and 48 eyes without
keratoconus. Alone, IS corneal topography values showed an asym-metry 9.4 times higher in suspected keratoconus versus the normal subject population, and 37.3 times higher in keratoconic eyes when compared to normals. Corneal aberrations, however, were much higher in keratoconic eyes with corneal and ocular vertical coma, 38.6 and 78.5 times higher respectively than normal eyes. Suspected keratoconus was much lower, with corneal values 5.3 times higher and ocular values 4.0 times higher than normal eyes.The study shows that both methods have merit in identifying likely keratoconus.

Jinabhai A, Charman WN, O’Donnell C and Radhakrishnan H. Optical quality for keratoconic eyes with conventional RGP lens and simulated, customized contact lens corrections: A comparison. Ophthalmic Physiol Opt 32: 200–212, 2012.

Keratoconus will induce corneal distortions that ulti-mately increase the optical aberration profile of the eye. In this article, the researchers attempt to explore, theoreti-cally, the impact of translation and rotation of an ideal customized soft lens in mild, moderate and severe kerato-conus to reduce lower and higher order aberration com-pared to standard RGP lenses.

Optical quality, as defined in this study, included wavefront aberrations and the point spread function. Three patients with differing degrees of keratoconus (mild, moderate, severe) first had naked eye wavefront measurements taken. Measurements were also taken after RGP’s and customized soft lenses had been placed on the eye. The customized aberration-correcting lenses were then used to theoretically construct the effects of rotation and translation.

Results indicated that lens rotations between 10° and 15° induced a large amount of positive coma. The accept-able range of tolerance to outperform an RGP lens is around 2° for rotation and 0.10 mm for translation. Thus, the customized soft lens only provides optical improve-ments when movement is contained within a very tight range, which current technology is unable to attain.

Jinabhai A, Charman WN, O’Donnell C and Radhakrishnan H. Optical quality for keratoconic eyes with conventional RGP lens and simulated, customized contact lens corrections: A comparison. Ophthalmic Physiol Opt 32: 200–212, 2012.

Keratoconus will induce corneal distortions that ulti-mately increase the optical aberration profile of the eye. In this article, the researchers attempt to explore, theoreti-cally, the impact of translation and rotation of an ideal customized soft lens in mild, moderate and severe kerato-conus to reduce lower and higher order aberration com-pared to standard RGP lenses.

Optical quality, as defined in this study, included wavefront aberrations and the point spread function. Three patients with differing degrees of keratoconus (mild, moderate, severe) first had naked eye wavefront measurements taken. Measurements were also taken after RGP’s and customized soft lenses had been placed on the eye. The customized aberration-correcting lenses were then used to theoretically construct the effects of rotation and translation.

hhhContact Lense Complications

Smith AF and Orsborn G. Estimating the annual economic
burden of illness caused by contact lens-associated corneal
infiltrative events in the United States. Eye & Contact Lens
38(3):164–170, 2012.
Approximately 35 million people in the U.S. wear soft
contact lenses. This study sought to estimate the annual
cost of contact lens related illness using published rates in Images
the literature of    corneal infiltrative events (CL-CIEs) in
soft contact lens wearers. A “bottom up” costing design was used to review this
literature on the    annual incidence of CIEs and on cost    Comstock/Comstock
estimates. Cost estimates would include eyecare practitioner office visits, emergency room visits, cost of therapeutic management, work-related productivity loss and laboratory costs. This review for 2010 showed 32,031 non-severe and 17,248 severe incidences of CIE. The estimated cost for treatment of non-severe CIE was $1,002.90 and for severe CIE it was $1,496.00, yielding an annual cost of $58 million in the U.S. alone for 2010. Moving forward, this study highlights the importance of proper management and treatment of soft contact lens wearers.

kjjCataract

Ang M, Chaurasia S, Angunawela R, et al. Femtosecond lenticule extraction (FLEx): Clinical results, interface evaluation, and intraocular pressure variation. Invest Ophthalmol Vis Sci 53(3): 1414–1421, 2012.

Images    This was    a prospective clinical study to assess the
results of the femtosecond lenticule extraction (FLEx) procedure on myopes and myopic astigmats. The study also evaluated the ultrastructural effects on the flap and stromal bed interface in human cadaveric corneas. Since exposure to suction in FLEx is twice that experienced in FS-LASIK the IOP was monitored in real time using a rabbit model. Sixty-six eyes were tested as part of the study and the preoperative spherical refraction was – 5.77 +/- 2.04 D with astigmatism of -1.03 +/- 0.72D. A minimal hyperopic shift occurred (mean SE +0.12 +/- 0.53D), and 94% of the subjects achieved an unaided VA of 20/25 or better 3 months postoperatively, with refractive stability at the 1-month mark. Predictability was good at 3 months with 82% of eyes falling within +/- 0.50 D of the attempted correction. A significant increase in higher order aberrations was observed 3 months after FLEx. The comparison of in vivo real time IOP changes in rabbits demonstrated no signifi-cant differences between the FLEx and FS-LASIK proce-dure. Scanning electron microscopy of human cadaver corneas yielded similar results between FLEx and FS-LASIK. This study offers data supporting good visual out-comes in patients undergoing a FLEx procedure.