Issue 3, 2012

 


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Vol. 1, No. 3, 2012

Editor’s note: This volume covers the topics of ocular surface inflammation
and infection, dry eye disease, contact lens, and refractive
surgery. The hope is that this augments your education and 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.

 

 

 

 

lklkOcular Surface Inflammation and Infection

Choi, JA and Chung S. Combined application of autologous serum
eye drops and silicone hydrogel lenses for the treatment of persistent
epithelial defects. Eye & Contact Lens 37(6):370–373, 2011.
Persistent epithelial defects (PEDs) can be caused by several
conditions, including dry eye, limbal stem cell deficiency and
neurotrophic keratitis. The patient may experience chronic pain and
even vision loss with PEDs. Separately, bandage contact lenses as
well as autologus serum use have had some success. This study investigated the effectiveness of combining SiHy contact lenses and autologous serum in patients with PEDs who were not responding to previous therapeutic efforts.
Eight eyes exhibiting PED for an average of 90 days (range: 30–240 days) were treated with Acuvue Oasys contact lenses and 50% v/v autologous serum solution (diluted using sodium hyaluronateeye drops). The PEDs of all 8 eyes healed after an average treatment period of 11.8 +/- 4.9 days, and complete resolution was noted in all subjects. The authors suggest that the combination of SiHy CL’s and autologous serum may serve as a useful treatment option for this sometimes recalcitrant condition, and the paper contains interesting before and after photographs. Kashiwabuchi RT, Carvalho FR, Khan YA, et. al. Assessing efficacy of combined riboflavin and UV-A light (365 nm)
treatment on Acanthamoeba trophozoites. Invest Ophthalmol Vis Sci 2011;52:9333–9338, 2011.Acanthoamoeba keratitis remains a serious sight-threatening infection that frequently results in a penetrating
keratoplasty, despite the use of anti-microbial compounds (particularly, propamidine isethionate [Brolene]).
In this paper, in vitro and in vivo studies (using Chinese hamsters) were conducted to explore whether treatment with riboflavin (vitamin B2) plus UV-A could improve clinical outcomes. The rationale for this study stemmed from the fact that pathogen inactivation using photochemical means has shown promise with other corneal microbes, including
certain bacteria, fungi, and blood-borne parasites. The technique is also currently utilized to pre-treat blood products. Riboflavin-UV-A application has shown promise in increasing Type I collagen diameter and overall corneal rigidity in collagen cross-linking studies for keratoconus, which the authors postulated might strengthen corneal resistance against acanthamoeba enzymatic degradation.However, when compared to treatment using Brolene in both in vitro and in vivo models, riboflavin-UV-A treatment did not enhance treatment outcomes. Garg P. Fungal, Mycobacterial, and Nocardia infections and the eye: an update. Eye 26:245–251, 2012. This manuscript describes a thorough ophthalmic update on rare but sight-threatening organisms, including fungi, atypical Mycobacteria and Nocardia. These infections tend to be slowly progressive, and the clinical picture is often muddled since they regularly mimic other organisms. Due to their infrequent involvement in ocular infection, they are not typically at the forefront of most eye care practitioner’s minds, which can create even further diagnostic delay and detrimental outcomes.
This paper outlines the most common ophthalmic structure invaded by each pathogen, characteristics of infection
and the diagnostic and therapeutic challenges each organism presents. Since successful outcomes for these infections often depend on a high degree of clinical suspicion by the examining doctor, it is important for eye care practitioners to continue to remain informed about the latest diagnostic and therapeutic information.Useful information within the manuscript is as follows: Fungus: The most common ophthalmic fungal infection
reported in this paper is keratitis, usually associated with trauma, prolonged use of topical medications, ocular
surgery, systemic disease and contact lenses. Confocal microscopy, although expensive, offers an in-vivo examination of the cornea to aid diagnosis; it is an alternative to corneal biopsy, which damages tissues and
has a high sampling error. In addition, the authors report that 38% of infective scleritis cases are caused by fungi,
also often following ocular trauma. Diagnostic delay is common because clinical signs often appear identical to
immune-mediated scleritis. Treatment options for ocular fungal infections are relatively limited and are hindered by poor tissue penetration.Some have successfully managed deep fungal keratitis with lamellar keratoplasty; however, it is reported that up to half of all cases fail by the end of the first year. Atypical Mycobateria (AM): The most common ophthalmic infection due to AM is also keratitis secondary to trauma, often by metallic corneal foreign body. Like
fungal keratitis, the disease presents with a variety of clinical features; however, all patients in this paper had a central or paracentral localized infiltrate that extended into the stroma. When involved in endophthalmitis, AM seems to be responsible for forming multiple white plaques between the crystalline lens and its posterior capsule. Specific
stains, such as the Ziehl-Neelsen acid fast stain and Lowenstein-Jensen media, should be ordered for all cultures
to aid diagnosis. Treatment recommendations include amikacin, clarithromycin and azithromycin, however,
many cases require surgical intervention.

dryDry Eye Disease

Lira M, Olivera ME and Franco S. Comparison of the tear film clinical parameters at two different times of the day. Clin Exp Optom 94(6): 557-561, 2011.Central or paracentral localized infiltrate that extended
into the stroma. When involved in endophthalmitis, AM seems to be
responsible for forming multiple white plaques between the crystalline lens and its posterior capsule. Specific stains, such as the Ziehl-Neelsen acid fast stain and Lowenstein-Jensen media, should be ordered for all cultures to aid diagnosis. Treatment recommendations include amikacin, clarithromycin and azithromycin, however, many cases require surgical intervention. Patients often complain of eye discomfort and dryness
as the day progresses. Previous studies have shown that tear pH, osmotic pressure, and nocturnal inflammatory
mediators vary diurnally, which all may lead to end of day dryness. The goal of this study was to quantify and qualify
the tear film in a healthy, non-contact lens-wearing population.The study included 51 subjects (43 women, 8 men)
with an average age of 21.1 years. Measurements were conducted in the morning and afternoon of the same day, using a series of standard clinical tear film tests. Schirmer test and tear meniscus height measures did not demonstrate clinically significant diurnal differences, however, a statistical difference was noted in tear break-up time (TBUT). On average, afternoon TBUT and non-invasive TBUT showed a statistical decrease compared to the morning measurement of 2.2 and 1.2 seconds, respectively. Researchers also found that TBUT was significantly different than NITBUT for the afternoon measurements, but only in the group with poor tear film quality.The authors suggest that the addition of fluorescein to the tears when quality is declining (i.e., near the end of the
day) may induce greater differences, especially in those with poorer initial tear film quality. Previous studies indicated that optical quality is affected by superficial punctate keratopathy (SPK) positioned at the entrance pupil while changes in the post-blink tear film have negligible effects on higher-order aberrations.The researchers in the current study used wavefront aberrometry (Topcon Harman-Shack) and a functional VA instrument (Nidek) to investigate the major causes of visual deterioration in dry eye patients with Sjogren syndrome. Functional VA was measured as a function of time and compared to baseline vision, which was referred to as the visual maintenance ratio (VMR). The primary focus of the study was to ascertain whether SPK or tear film changes are the major cause of visual deterioration. Also, the correlation between serial aberration measurements and functional VA was reviewed.
The right eye of 22 dry eye patients with Sjogren syndrome (1 male, 21 females, mean age 57 +/-14 years,
range 34–87) and 10 healthy volunteers (5 males, 5females, mean age 47+/-7 years, range, 41–61) were
compared. Results show a statistical difference in patients with SPK versus controls for Schirmer values, fluorescein/Rose Bengal scores and BUT. Functional VA, VMI and the variation in visual acuity were statistically different between patients with SPK and those without, as well as in normal controls. Coma aberrations
and total higher order aberration were statistically increased in patients with SPK.As one might expect, when the SPK was more severe, a greater decrement in visual performance was noted. VMR was also correlated with coma and higher order aberration profiles, suggesting its applicability in ascertaining visual performance.The researchers concluded that epithelial damage in the form of SPK within the central optical zone of the cornea is a more important factor for impairing visual performance than a thinning tear film. They also considered functional VA measurements to be a suitable and equally effective method to measure visual performance compared to objective aberration measurements. Mataftsi A, Subbu RG, Jones S, et al. The use of punctal plugs in children. Br J Ophthalmol 96:90–92, 2012. Ocular surface disease secondary to dry eye is rare in children; however, when present, it tends to be associated with systemic disease. The data from a recent study conducted by the Children’s Hospital of Pittsburgh validated this statement, finding that 72% of their pediatric dry eye subjects had concurrent systemic disease.The three most common systemic diseases in this population were Achalsia, alacrima, hypoadrenalism syndrome (AAA), Stüve-Wiedemann syndrome and atopic disease. The most frequent ocular surface issues were
punctate epithelial erosions, corneal scarring and corneal neovascularization.This retrospective study looked at the use, long-term efficacy and tolerability of punctal occlusion with silicone plugs in this young population and found that, in general, this procedure is a safe and effective form of dry eye treatment for children.Patients ranged from 1.5 to 13.8 years of age, and nearly 70% of insertions were performed under general anesthesia; 32% of patients had to undergo a repeat procedure, and 19% experienced spontaneous plug extrusion within 6 months. All children experienced reduction in ocular surface disease, and visual acuity improved in 60%, which is of particular importance because of the ocular development that occurs in this age group. Pflugfelder S. Tear dysfunction and the cornea: LXCIII Edward Jackson Memorial Lecture. Am J Ophthalmol 152:900–909, 2011.Tear-associated disorders of the ocular surface can cause patient discomfort due to exposure of corneal nerve endings and visual disruption due to an irregular optical surface, which causes light scattering and optical aberration. In addition to discussing treatment therapies, this comprehensive paper reviews corneal epithelial disease as a direct consequence of tear dysfunction (TD). Dr.Pflugfelder reports that the eye is open 92% of the time, which makes the cornea the most exposed mucosal surface in the body, always at risk for dessication. Faced with the additional complex challenge of
opposing microbial invasion and healing without scars,the cornea must rely heavily on a resilient tear film for
numerous tasks. Healthy tear film composition depends on many factors, including proper lacrimal and
meibomian gland function, and adequate tear clearance rates.Reported risk factors for TD include age, contact
lens wear, high consumption of omega 6 essential fatty acids, diabetes mellitus, smoking, prolonged computer
use, low humidity and high osmolality environments.The paper reports that decreased tear break-up time
results in rapid corneal cooling, which in turn causes increased nerve firing and a sensation of pain or discomfort
in the patient. It also reviews common treatment methods, including the use of topical cyclosporine A, corticosteroids, autologous serum, oral tetracyclines, omega fatty acids and botulinum toxin A to decrease
epithelial disease. Lastly, the author discusses the use of PROSE (prosthetic replacement of the ocular surface ecosystem) for severe cases, which is basically a scleral-bearing contact lens, designed to provide a fluid-filled, body temperature,protective barrier over the damaged cornea for symptom relief and enhanced healing.

hhhContact Lens & Contact Lens Care Systems

Wright EA, Payne KAP, Jowitt TA, et al. Preservation of human tear protein structure and function by a novel contact lens multipurpose solution containing proteinstabilizing agents. Eye & Contact Lens 38(1): 36–42, 2012.The tear film contains proteins with antimicrobial
functions such as secretory IgA, lipocalin, lysozyme, and lactoferrin. Contact lens wear and contact lens solutions can denature these proteins. A new solution formulation (Biotrue, B+L) has been reported to maintain a natural tear film structure. Biotrue contains protein-stabilizing agents, which include hyaluronic acid, poloxamine, and sulfobetaine 10. Sulfobetaine 10 has been used previously as a laboratory agent in the
renaturation of proteins.Researchers studied an investigational solution comprised
of Biotrue without its disinfection components to measure its solitary effect on proteins. Proteins were exposed
to sodium dodecyl sulfate (SDS), a protein-denaturing reagent, with and without the investigational Biotrue
test solution. Antimicrobial activity of the investigational solution was also assessed in the presence of the tear film
proteins lysozyme and lactoferrin.Results showed that native tear film proteins, lactoferrin and lysozyme, showed decreased antibacterial and bacteriolytic activity after SDS treatment. The investigational Biotrue solution prevented SDS-initiated protein denaturation and the loss of antimicrobial activity.This study concludes that an investigational contact lens solution of Biotrue may have the ability to protect the integrity and stability of tear proteins. This protection may augment the solution’s antimicrobial properties. Additionally,allowing the protein to remain in its native state may reduce inflammatory responses known to occur as a result of denatured protein. Researchers studied an investigational solution comprised of Biotrue without its disinfection components to measure its solitary effect on proteins. Proteins were exposed to sodium dodecyl sulfate (SDS), a protein-denaturing reagent, with and without the investigational Biotrue test solution. Antimicrobial activity of the investigational solution was also assessed in the presence of the tear film proteins lysozyme and lactoferrin.Results showed that native tear film proteins, lactoferrin and lysozyme, showed decreased antibacterial and bacteriolytic activity after SDS treatment. The investigational Biotrue solution prevented SDS-initiated protein denaturation and the loss of antimicrobial activity. This study concludes that an investigational contact lens solution of Biotrue may have the ability to protect the integrity and stability of tear proteins. This protection may augment the solution’s antimicrobial properties. Additionally,allowing the protein to remain in its native state may reduce inflammatory responses known to occur as a result of denatured protein.Cho, P, Cheung SW and Charm J. Visual outcome of Soflens Daily Disposable and Soflens Daily Disposable for Astigmatism in subjects with low astigmatism. Clin Exp Optom 95(1): 43–47, 2012.
In this double-masked, non-dispensing cross-over study, 41 subjects were tested wearing spherical and astigmatic daily wear disposable lenses. Subjects were between 19 and 41 years of age and had a myopicspherical prescription between 0.50 D and 6.00 D and astigmatism of not more than -1.25 D in at least one eye.Objectively, high contrast (100%) and low contrast (10%) charts were used to assess vision. The subjects answered a questionnaire regarding vision, comfort, and lens handling. Lens fitting, over-refraction and visual acuity were assessed after 10 minutes of lens wear by an unmasked examiner in a scotopic environment.On average, high and low contrast visual acuity gains were 4 and 5.5 letters, respectively, for toric lenses. Overall,visual acuity was better with toric lenses compared to spherical. Of the 41 subjects, 24 (59%) subjectively reported better vision with toric lenses, 9 (22%) reported no difference and 8 (20%) subjects reported better vision with spherical lenses. There were no significant differences in comfort or insertion between the two lens types. Potter RT. Creating policies for the contact lens practice. Contact Lens Spectrum, 26(11):28–32, 2011.People become frustrated when they are asked to pay more for a product than what they were initially told it would cost, and rightfully so. This situation can easily
occur in a practice if there are no written guidelines for the patients, doctors and staff.This article, authored by a private practitioner, gives suggestions on how to decide what office policies should be in place, including contact lens fitting and re-fit, patient non-compliance, expired prescriptions and lens returns.Sample templates are included, as well as suggestions about how to present this information to patients. Rebound tonometers rely on processing the recoil movement of a rod probe’s interaction with the cornea.They are portable and do not require topical anesthetic or fluorescein to measure intraocular pressure (IOP). This study sought to determine the accuracy of the ICare tonometer over disposable hydrogel (Acuvue 2) and silicone hydrogel (Acuvue Oasys) contact lenses.Results indicated that IOP, which was measured over a variety of lens powers (-2.00, +2.00 and -6.00) was not significantly different for the silicone hydrogel test group;however, readings were statistically lower for the +2.00 hydrogel lens. This was an unanticipated result, and is opposite to trends observed with “air puff ” tonometers.The decreased IOP was consistent for all powers measured with hydrogel lenses.Prior studies have demonstrated that rebound
tonometery measurements are affected very little by changes in corneal thickness and curvature compared to changes in biomechanical corneal properties. This led the authors to speculate that the placement of a hydrogel lens on the cornea might result in a reduction of Young’s modulus compared to the cornea itself, or to that of the new surface created by a cornea-silicone hydrogel lens combination.

hhhContact Lens &Tear Film Interaction

Szcaesna DH. Assessing tear film on soft contact lenses
with lateralshearing interferometry. Eye & Contact Lens
37:342–347, 2011.Lateral shearing interferometry was used in this study to assess tear film surface quality in contact lens wearers.
It is known that the mere placement of a lens on the eye changes the dynamics of the tear film that can potentially lead to tear evaporation, deposit formation and ultimately to symptoms of dryness and lens discomfort. According to the author, this novel technique demonstrated
superior performance in terms of its ability to characterize subtle changes in tear film kinetics and in its ability to predict dry eye compared to other non-invasive methods, namely high-speed videokeratoscopy and dynamic wavefront sensing.The method demonstrated using interferograms to
assess the difference in contact lens wetting from morning to afternoon. It also supported previous studies,which showed better tear film stability over high water content hydrogel lenses compared to those of low water content.
Omali, NB, Proschogo N, Zhu H, et al. Effect of phospholipid deposits on adhesion of bacteria to contact lenses. Optom Vis Sci 89(1):52–61, 2012. Studies have shown that silicone hydrogel contact lenses tend to accumulate more lipid than hydrogel contact lenses, most notably phosphatidylcholine (PC), sphingomyelin (SM), oleic acid, oleic acid methyl ester and cholesterol. All may cause bacterial adhesion to contact lenses, thus increasing the risk of microbial infection.The purpose of this study was to quantify and qualify the phospholipids present on worn contact lenses, using mass spectrometry. A secondary outcome measure was provided by analyzing lipid deposition in unworn contact lenses and comparing bacterial levels. Samples were analyzed for lipid from 22 subjects
wearing either a senofilcon A (n=11) or balafilcon A (n=11) contact lens. Subjects used either Aquify or Renu
MultiPlus disinfection systems. In addition, an in vitro analysis of lipid deposition was conducted after lenses
had been soaked in either an SM or PC solution bath. A determination of bacterial adhesion and growth in unworn
lenses with and without lipid deposition was also made.Study results on worn contact lenses demonstrated a significantly greater number of lipid species on balafilcon lenses (n=18) when compared to senofilcon (n=11). The
major phospholipid species present on both lens materials worn were SM and PC. Balafilcon demonstrated greater levels of SM and PC adherence when using ReNu MultiPlus versus Aquify. Increased levels of lipid were also found in Balafilcon with ReNu MultiPlus when compared to Senofilcon with ReNu MultiPlus. The in vitro analysis showed equal deposition of SM and PC between the two lens types studied. As the authors point out, this was the first study to identify the adhesion of bacteria to adsorbed phospholipid species. Their results suggest that the two adhered
phospholipid species studied (0.1 and 0.5 mg/mL) did not alter the adhesion of any strain of P. aeruginosa or S.
aureus (p < 0.05); phospholipid deposition also showed no effect on the growth of P. aeruginosa or S. aureus. Kojima T, Ibrahim OM, Wakamatsu T, et al. The impact of contact lens wear and visual display terminal work on
ocular surface and tear functions in office workers. Am JOphthalmol 152:933–944, 2011. Previous studies have shown a connection between dry eye symptoms and contact lens wear or VDT use. The researchers in this study investigated tear film attributes of contact lens-wearing office workers using a VDT, since little information is available on the ocular surface characteristics in this group. Sixty-nine contact lens (CL) wearing subjects
between 28 and 73 years-old were compared to 102 age and sex-matched non-CL wearing control subjects. Measurements consisted of vital staining, Schirmer strip (tearquantity), BUT (tear stability) and tear meniscus height.
Questionnaires assessing ocular surface symptoms and VDT use with contact lenses were used. Groups were also
divided based on the amount of time spent using a VDT (long term, >4hrs and short term, <4hrs).A statistical difference between the CL wearing group and controls was found in tear meniscus height, mean dry eye symptom score, mean visual symptom score, mean environment score, total dry eye severity score and mean dry eye symptom scores when aggravated by air conditioners. The mean tear meniscus height was lower in long-term users with and without CLs when compared to short-term non-CL wearers. The mean symptom score was significantly lower in short-term non-CL wearers compared to the other three subgroups. All of this suggests an exacerbation of symptoms when VDT is combined with CL wear. The researchers, however, did not find a significant difference between tear film measurements or mean dry eye severity and CL replacement schedules.

kjjRefractive Surgery

This study examined the effect of a monovision correction on 25 post-LASIK patients with a mean age of 49.3 years. Visual acuity, contrast sensitivity function, ocular aberrations, stereoacuity, light scattering index,and visual-discrimination capacity were analyzed preoperatively and three months postoperatively. Light scattering was assessed using visual discrimination as measured using halo software. Visual discrimination gives a measure of the effect of LASIK monovision on night vision, typically described by patients as haloe around light sources.The same surgeon performed all the LASIK procedures between December 2008 and October 2009, using an Allegretto Wave Eye-Q 400 Hz laser (Wavelight AG). The dominant eye was corrected fully for distance vision while the nondominant eye was corrected for near, with an effective near addition 1.25 Diopters. Nearly three-fourths of the subjects were myopic when entering the study. Results demonstrated a significant difference in postsurgical spherical aberrations between the dominant and nondominant eyes. Monovision correction after LASIK improved functional near vision in presbyopic patients.Postoperative visual acuity was considered good for distance vision; however, contrast sensitivity and stereoacuity diminished significantly when compared to preoperative values. Postoperative contrast sensitivity decreases were observed in both monocular and binocular test conditions. The visual discrimination capacity was significantly decreased in the non-dominant eye, as well as under binocular conditions.