Current Issue

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Vol. 1, No. 6, 2013

Editor’s note: This volume covers the topics of ocular surface disease,
conjunctival disease, refractive/cataract surgery, corneal disease and
contact lenses. 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.

 

 

 

 

 

dryOcular Surface Disease

Sze-Yee L, Petznick A and Tong L. Associations of systemic
diseases, smoking and contact lens wear with severity of dry eye.
Ophthalmic Physiol Opt 32:518–528, 2012 Singapore investigators sought to determine if certain factors with known associations to dry eye disease, such as contact lens wear, smoking, ocular surgery and systemic disease, are also linked to dry eye severity. Interestingly, only rheumatoid arthritis was found to be associated with more severe signs of dry eye. The authors found increased ocular surface damage (SPK) of the superior cornea in these patients, which they hypothesized was due to constant contact of the superior cornea to inflammatory cytokines expressed by the palpebral conjunctival vasculature. Additionally, they found that although older individuals tend to have more severe clinical signs, they did not experience greater symptoms, which corroborates the observation that one cannot
predict disease severity by symptomology alone. Amniotic membrane grafts are known to promote natural wound repair while reducing scarring and inflammation. In ophthalmology, these grafts are often sutured into place; however, this usually requires general anesthetic,which can be contraindicated in certain cases. ProKera (Bio-Tissue, Inc., Miami, FL) is a sutureless amniotic membrane device that can be placed on the cornea to facilitate healing while it dissolves over a few weeks. This case report describes the successful use of ProKera, placed using only topical anesthetic, in a 19-year-old woman with acute Stevens-Johnson Syndrome. Both eyes were free of clinically-significant scarring and symblepharon after more than one year, and the patient was still enjoying pain-free and stable vision.Meibography is a useful clinical test to assess meibomian gland morphology, glandular changes an eventual diagnosing of meibomian gland dysfunctions. In this study of 24 subjects (female 14: mean age 46,
range 19–69) meibomian gland loss was examined by 3 experienced clinicians assessed subjective and semi -objective grading systems. Testing was done with a non-contact infrared meibographer, with resultant images evaluated by the same 3 clinicians using a 4-scale grading system, a 5-scale system and lastly a digital analysis (DA). Results of the study indicated that the 4-scale system demonstrated a slight to moderate reliability while the 5-
grade scale system was fair to substantial in reliability. Overall, the 5-grade scale systems proved superior in
intra- and inter-observer agreement; however, one clinician did not demonstrate an intra-observer difference
between the 2 scales. Intra- and inter-observer results were best when the semi-objective grading via the DA evaluation was applied. However, as noted by the authors, this may be too cumbersome in a busy clinical setting.Symptoms of burning, itching, foreign body sensation with signs of debris and swollen, hyperemic eyelids are
commonly seen with blepharitis. Standard treatments involve lid hygiene, which may be supplemented with
topical antibiotics, steroids, antibiotic/steroids and antiseptics. Bibrocathol (Posiformin 2%) is a topical antiseptic
ointment used in the treatment of blepharitis; however, it is not available in the United States. The study was designed as a multi-center, randomized, double-masked, placebo-controlled parallel-group trial of 197 patients, evaluating the effects of bibrocathol 2% eye ointment on acute blepharitis. Patients were randomly assigned in a 1:1 ratio to receive either bibrocathol 2% or the vehicle (placebo). Overall, patients showed significantly better improvement on bibrocathol compared to the placebo. Ironically, a larger proportion of subjects in the placebo group
experienced adverse events in the form of a hypersensitivity reaction. The researchers suggest that this may be the
result of the blepharitis itself and not necessarily an outcome of the placebo ointment. Specific symptoms demonstrating a reduction with bibrocathol include edema, erythema, debris and meibum.In this study, bibrocathol ointment proved to be an effective and tolerable treatment for blepharitis. The stated prevalence of dry eye disease is estimated to be between 11 and 22%. Ocular lubricants are often used as a treatment for symptoms; however, their effect oftentimes is short-lived. Agents with higher viscosities have the potential to last longer on the eye, but must retain this ocular surface viscosity to be effective. The authors sought to use the discipline of rheology to
study the effects of pH, temperature and dilution on various components of tear supplements. Ocular lubricants
studied included sodium hyaluronate, carboxymethylcellulose sodium/glycerin, hypromellose, and carmellose sodium. In summary, this study showed that kinematic viscosities of ocular lubricants are independent of pH but are
strongly dependent on changes in temperature and dilution.Kinematic viscosity decreased between 25 and 38%
with each ocular lubricant when the temperature was increased from 22 to 35° C. pH did not affect the viscosity
of hypromellose or carmellose sodium. Dilution dramatically decreased the viscosity of each of the ocular lubricants,
especially sodium hyaluronate.Further development of lubricants with viscosities more tolerant of temperature and dilution effects will help increase lubrication duration (retention time) and maximize long-lasting comfort.

 

ccConjunctival Disease

Patients (1,061, aged 1–94 years-old) were enrolled in
a hospital-based study to determine if there is a relationship
between conjunctivochalasis (the presence of redundant
folds in the conjunctiva) and pinguecula. Both conditions
were associated with aging, and pinguecula severity
correlated positively with the degree of
conjunctivochalasis, at least concerning the nasal and
temporal sides. An increase in conjunctivochalasis in downward gaze also correlated with severity of pinguecula, as well as the presence of inferior SPK. The authors believe that dry eye symptoms associated with reading in downward gaze may actually be indicators of conjunctivochalasis and not solely dry eye.

 

 

kjjRefractive/Cataract Surgery

Autologous serum eyedrops, which are drops made
from a patient’s own blood serum, contain growth factors,
proteins, vitamins and neurotrophic factors that can facilitate
ocular surface healing in recalcitrant cases.
Similar drops can also be made from umbilical cord
blood, with a few advantages. Not only does umbilical
cord blood have higher concentrations of healing factors compared to peripheral blood serum, a large volume of drops can be prepared in advance and without an invasive
blood draw. Unmasked investigators in Korea found that 20% umbilical cord serum eyedrops, instilled 4–6 times per
day in combination with conventional post-operative LASEK treatment (0.5% topical moxifloxacin, 0.1% topical
fluorometholone and preservative-free tears), led to a reduction in early post-operative haze, a known potential
complication of the procedure. Additionally, the investigators observed improved tear film and ocular surface health compared to that in patients only using conventional therapy, at least for the first 3 months post-op. Due to an aging population, cataract surgery is becoming increasingly more prevalent. Although several advancements in cataract procedures have occurred, patients still experience post-surgical corneal swelling and refractive changes.
The researchers conducted a prospective, non-randomized, case series study that included 6 visits by patients undergoing cataract surgery. Refraction and corneal thickness measurements were made at the baseline
visit before cataract surgery, the first day after surgery, and weekly for 4 weeks after surgery. Refractive error and
corneal thickness measurements were performed with a portable ARK-30 autorefractor and Orbscan II topographer,
respectively. The study was composed of 124 eyes of 79 patients with a mean age of 66.5 (range, 23–90 years-old). Review of these patients showed that the spherical refractive error with the autorefractor became stable 1 week after an uneventful cataract surgery. The same holds for the cylinder component; however, although not statistically significant, a slight increase is still observed at week 2, 3 and 4. A significant increase in corneal swelling
occurred at 1 day, 1 week and 2 weeks post-operatively.

 

ccCorneal Disease

Pazopanib (GlaxoSmithKline, King of Prussia, PA)
was originally approved for the treatment of renal cell
carcinoma, but has also been found to have potential
ocular indications, including the inhibition of laser-induced
choroidal neovascularization and diabetic retinal vascular leukostasis.
In this study, investigators from the Massachusetts Eye and Ear Infirmary and the Brigham and Women’s Hospital in Boston found that 3 weeks of topical use reduced the corneal neovascular area, invasion area and
vessel length. The 0.5% formulation was very well tolerated, with no significant ocular or systemic side effects. Results remained stable for at least 12 weeks, and even continued to improve in some cases after treatment was ended.Lastly, patients with new or less severe cornealneovascularization tended to show the greatest response.

 

hhhContact Lenses

Twenty subjects undergoing overnight myopia
orthokeratology (19–33 years of age) were studied for
changes in thickness of different corneal layers. Corneal
topography and ultra-high resolution optical coherence
tomography (UHG-OCT) demonstrated that visual acuity
change with orthokeratology might be attributed to thickness
changes in the corneal epithelium, and not Bowman’s
layer. All areas of the central corneal epithelium, as well as
in the superior mid-peripheral epithelium, became thinner,
while the epithelial thickness in the nasal and temporal
aspects became thicker. Eyelid forces on the upper cornea or possibly even superior lens decentration during
sleep may explain why the superior corneal epithelium was thinner than inferiorly. The thickness of Bowman’s
layer did not change in any area measured. Contact lens wear is consistently cited as a risk factor for the development of microbial keratitis, a pathological event that may affect vision.Efforts have been made to protect the contact lens wearer through contact lens care solutions or contact lens materials. Some strategies have involved using antimicrobial cationic peptides (AMPs), such as melimine to prevent microbial colonization on the contact lens surface.In this study, melimine was covalently bonded to etafilcon A lenses and compared to a control lens without
the addition of melimine. Measurements of cytotoxicity and material parameters showed no ill effect with the addition of melimine. Fluorescence microscopy confirmed a reduction (P>0.001) of acanthamoeba, and multidrug-resistant S. Aureus and P. aeruginosa. A significant reduction in fungal species as well as Serratia marcescens was also demonstrated. Results also demonstrated an increase in wettability in lenses coated with melimine as observed using the captive bubble technique (Test lens 22.7 versus Control 69.3, Advancing angle). Early results are promising and further studies need to be done to determine commercial availability. Piggyback lens systems for the management of keratoconus date back to the early 1970s, and are typically used to increase contact lens comfort for the patient. Conflicting ideas exist in the literature as to which soft contact lens power provides optimal fitting characteristics for the overlying gas permeable (GP) lens.The authors investigated 30 keratoconic eyes with all
stages of severity and found that negative-powered soft lenses may be preferable for piggyback fitting because
they provide a flatter central mean keratometry reading, reduced corneal eccentricity and a thinner central thickness
for improved corneal oxygenation, compared to plus lenses.Additionally, investigators found that coma aberration
is lower with negative soft lenses, which happens to be the proposed major aberration affecting visual quality
in keratoconic eyes. One major limitation of this study was that GP lenses were not actually fit over the soft lenses
evaluated. Little is known about the effect of simultaneous vision multifocal lenses on the retinal nerve fiber layer and macular thickness measurements using an OCT. This study was conducted at the University of Valencia
on 30 presbyopic patients (21 women) with a mean age of 50.42 ± 7.82 years. The mean spherical refraction for the
subjects was -0.88 (± 1.18) D with a mean near add of +1.74 (± 0.86) D. All subjects were free of any ocular
pathology and had a visual acuity of 0.0 logMAR or better. Using the Retinal Nerve Fiber Layer (RNFL) Thickness
Analysis mode of the Cirrus HD (Carl Zeiss, Meditec, Dublin, CA, USA) OCT, the average, superior, nasal,
inferior, temporal and 12 o’clock-hour RNFL thicknesses were obtained. In the Macular Thickness Analysis mode
of Cirrus HD OCT, the average cube thickness, macular cube volume, central subfield thickness, inner and outer
macular thickness (superior, inferior, nasal and temporal area) were obtained. Measurements were performed with
and without contact lenses. A lack of statistical significance was found in RNFL thickness between the lens and non-lens wearing measurements. Similarly, the mean macular volume was not different in the 2 populations. Signal strength was also shown to be unaffected by multifocal contact lens wear. A crossover study was conducted comparing the visual quality of multifocal lens wearers at the University of Valencia. A sample of 20 presbyopic subjects, 15 women and 5 men (42–48 years-old) were studied. Inclusion criteria were spherical equivalent error between +3.00 and -3.00 D, astigmatism ≤ 0.50 D, monocular corrected distance visual acuity of 0.0 logMAR (Snellen 6/6 or 20/20) or better, a pupil size greater than 3 mm, and normal binocularity. The PureVision low add lens is an anterior near-center aspheric design with a range of up to +1.50 D. The other lens, Acuvue Oasys for Presbyopia, is also a near-center design and uses zones that alternate between near and distance powers. The medium power was used, which provides an add power between +1.50 and +1.75 D. The results of this study suggest that both simultaneous vision multifocal CLs studied provide an optimal distance visual quality under photopic and mesopic conditions, but a better visual acuity under mesopic conditionswas noted for the PureVision lens. Both lenses provided comparable visual performance at an intermediate distance; however, the near add seems to be insufficient for those with early presbyopia who require more-demanding near visual quality.