Saturday, September 22, 2012

Abstract: Evaporation rate through contact lenses

This is an interesting piece looking at contacts in terms of whether they accelerate or slow down tear evaporation. It's all theoretical at this stage i.e. in vitro tests trying to figure out what factors and additives (from our natural tears or elsewhere) affect the evaporation rates but definitely intriguing.

Accelerated evaporation of tears may contribute to dry eye symptoms. It is not clear whether contact lenses decrease or increase the rate of evaporation of tears. In this study, the rates of evaporation through contact lenses (ERTCL) were measured in vitro to gain insight to this question. Contact lenses were equilibrated with various solutions to determine if they influenced ERTCL in vitro. ERTCL was measured gravimetrically. ERTCL measured in vitro for used contact lenses was about 20% faster than for buffer alone suggesting that natural tear components bound to the lenses changed the ERTCL. One natural tear component that binds to contact lenses is waxes. Equilibration of contact lenses with wax increased the ERTCL by about 30% suggesting that waxes might potentially increase ERTCL in vivo. Squalene, found in sebum and possibly meibum was infused into the contact lenses as a step toward decreasing the ERTCL. Squalene decreased ERTCL by over 60% in vitro. Soaking a contact lens in DuraSite(®) with benzalkonium chloride (BAK) did not alter the ERTCL. ERTCL were about 40% higher than the evaporation rate of DuraSite(®) alone or without BAK. In addition to lowering the ERTCL, the squalene in contact lenses could be a source of terpenoids to replace the terpenoids deficient in patients with MGD. If the ERTCL could be minimized in vivo, contact lenses could potentially be used to relieve dry eye symptoms in patients with evaporative dry eye.
Cont Lens Anterior Eye. 2012 Aug 17. [Epub ahead of print]
Department of Ophthalmology and Visual Sciences, University of Louisville, 301 E. Muhammad Ali Blvd., Louisville, KY 40202, USA.

Abstract: Case report on scleral lenses in a severe exposure case

We report an interesting case of therapeutic scleral lens management of bilateral exposure and neurotrophic keratopathy resulting from bilateral cranial nerve (CN) palsies including V, VI and VII, which caused lagophthalmos and anaesthetic corneas. Subsequent development of severe exposure keratitis with vascularisation and keratinisation of the inferior cornea was previously treated with intensive ocular lubrication, botulinum toxin injections to the upper eyelid levator muscle, temporary tarsorrhophies, bilateral amniotic membrane grafts, punctal plugs, lid taping, gold eyelid weights and soft bandage contact lenses. Corneal integrity was re-established but visual acuity remained significantly compromised by corneal vascularisation, scarring and keratin deposits. Visions on presentation to the contact lens department were R 1.90logMAR, L 1.86logMAR. Therapeutic, high Dk, non-fenestrated, saline filled, scleral lenses were fitted. Daily wear of these lenses have protected and hydrated the cornea, enabling corneal surface recovery whilst retaining visual and social function. The visual acuities 6 months post-scleral fitting with lenses in situ are R 0.90logMAR and L logMAR0.70.

Cont Lens Anterior Eye. 2012 Aug 14. [Epub ahead of print]
Manchester Royal Eye Hospital, Manchester Academic Health Science Centre, Oxford Road, Manchester, United Kingdom.

Abstract: Tear osmolarity and ocular changes in pterygium

Here's a link on pterygium if you're not familiar with it.

To determine abnormalities in tear osmolarity (TO), tear function, and impression cytology in patients with pterygium and to assess the relationship between the variables.

Thirty eyes from 30 patients with primary nasal pterygium and 30 eyes from 30 volunteers without ocular pathologies or dry eye symptoms were enrolled in the present study. TO test, tear ferning test, fluorescein tear breakup time, Schirmer test, and impression cytology of the conjunctiva were performed. Analysis of variance was applied for intergroup comparisons, and Pearson correlation was used to calculate the strength of relationships between the variables. A statistical significance level of P <0 .05=".05" considered.="considered." p="p" was="was">

Pterygium patients had significantly higher TO, lower crystallization percentage, and lower goblet cell density (GCD) than control patients. A weak but significant negative correlation seems to exist between TO and crystallization percentage (r = -0.425, P < 0.01) and between TO and GCD (r = -0.295, P < 0.05).

There is evidence to suggest that pterygium appears to induce unfavorable conditions of increasing TO that could trigger alterations in tear crystallization and GCD. Being aware of TO changes seems essential to understand the complex relationship among pterygium, tear film functions, and ocular surface changes.

Cornea. 2012 Aug 15. [Epub ahead of print]
*Ocular Surface Research Group, Optics and Optometry Department, Universitat Politècnica de Catalunya, Terrassa, Spain †Department of Opthalmology, Terrassa Hospital, Terrassa Health Consortium, Terrassa, Spain.

Abstract: Mini scleral lenses in dry eye

Use of mini scleral contact lenses in moderate to severe dry eye.

To evaluate fitting feasibility and efficacy of mini scleral contact lenses in moderate to severe dry eye patients.

Prospective interventional case series, this study included those patients with grades III and IV dry eye disease, whose symptoms could not be controlled by conventional treatments. Demographic data, UCVA, BSCVA were evaluated before fitting. Mini scleral lens fit was assessed by single experienced practitioner and best corrected vision with mini scleral lens was assessed. After dispensing mini scleral lens, BCVA with mini scleral lens, and possible contact lens related problems were assessed in each visit. Ocular comforts, frequency of artificial tear use, contact lens handling problems were asked in each follow up visit. For those who did not choose to wear lenses, the reason was asked. All data were analyzed using descriptive statistical tests.

Twenty eyes of 13 patients were fitted. Mini scleral lens was dispensed for 19 eyes in them assessment of fit was either ideal (n=9) or acceptable (n=10). Seven patients got their lenses; four patients (seven eyes) of them were satisfied with their lenses based on decrease in discomfort and dry eye symptoms, decrease artificial tear need frequency and improvement in visual acuity during mean follow up period of 18.25 months (range: 15-20). None of them was affected with any contact lens related complication.

Mini scleral contact lenses can be considered helpful in management of moderate to severe dry eye.

Cont Lens Anterior Eye. 2012 Aug 16. [Epub ahead of print]
Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Iran.

Abstract: Passive smoking as a risk factor for dry eye in children

Not surprising, but also something we don't hear about a lot!

Adult active smoking is a risk factor for dry eye. We hypothesize that passive smoking in children can also produce the same effects.

We included 112 school children presenting with eye discomfort. Assessment of eye dryness and its severity levels depending on symptoms of dry eye, visual symptoms, tear breakup time (TBUT), Schirmer-1 test, and corneal fluorescein staining were done for all of them. Exposure to cigarette smoking was assessed by history-taking and urinary cotinine levels.

Dry eye was found in 80/112 children. Passive smoking was documented in 76/112 children. Number of cigarettes to which the child was exposed per day and the duration of exposure to passive smoking were significantly higher in children with dry eye compared to those without. Urinary cotinine, and cotinine/creatinine ratio (CCR) was significantly higher in children with dry eye compared to those without dry eye. Multiregression analysis showed that the most important determinants of dry eye were CCR and number of cigarettes/day.
Now a note about this bit:
Passive smoking represents a significant risk factor of dry eye in children comparable to that shown with active adult smoking. Male children are more prone to this effect.
I looked up the smoking rates by country on Wikipedia. Basically, a lot of men (28.7%) smoke, but very few women. Seems reasonable to suppose that the higher rate of male kids being affected is simply because the boys are spending more time with dad than mom.

J Ophthalmol. 2012;2012:130159. Epub 2012 Jul 31.
Department of Ophthalmology, Faculty of Medicine, Ain Shams University, Cairo, Egypt.

Thursday, September 20, 2012

New website for Dalsey Adaptives

For those of you who use the Dalsey Adaptives lighted plunger system for your PROSE or other lenses, they've got a new product name and a new website:

See Green (TM) Lens Inserter Kit

Please visit their website for the kit, replacement parts, plungers, stands, etc.

Tuesday, September 18, 2012

Abstract: Locating corneal pain in the brain

The cornea has been a focus of animal electrophysiological research for decades, but little is known regarding its cortical representation in the human brain. This study attempts to localize the somatotopic representation of the cornea to painful stimuli in human primary somatosensory cortex using functional magnetic resonance imaging (fMRI). In this case study, a subject was imaged at 3T while bright light was presented in a block-design, which either produced pain and blinking (during photophobia) or blinking alone (after recovery from photophobia). Pain and blinking produced precisely localized activations in primary somatosensory cortex and primary motor cortex. These results indicate that noxious stimulation of the cornea can produce somatotopic activation in primary somatosensory cortex. This finding opens future avenues of research to evaluate the relationship between corneal pain and central brain mechanisms relating to the development of chronic pain conditions, such as dry eye-like symptoms.

PLoS One. 2012;7(9):e44643. Epub 2012 Sep 4.
P.A.I.N. Group, Center for Pain and the Brain, Children's Hospital Boston, Massachusetts General Hospital, McLean Hospital, Harvard Medical School, Boston, Massachusetts, United States of America.

Abstract: Autologous platelet-rich plasma on PEDs

Platelet-rich plasma (PRP) harbors high concentrations of growth factors related to the promotion of wound healing. We evaluated the efficacy of PRP eyedrops in the treatment of persistent epithelial defects (PEDs).
Autologous PRP and autologous serum (AS) were prepared from whole blood. The concentrations of transforming growth factor (TGF)-β1, TGF-β2, epidermal growth factor (EGF), vitamin A and fibronectin in the PRP and AS were analyzed and compared. The corneal epithelial healing efficacy of PRP was compared with that of AS in patients with PED induced by post-infectious inflammation.
The concentrations of TGF-β1, TGF-β2, EGF, vitamin A and fibronectin in the PRP and AS were not statistically different. However, the concentrations of EGF in the PRP were significantly greater than in the AS. AS was used in 17 and PRP in 11 eyes of 28 patients. The healing rates of the corneal epithelia of the PRP-treated eyes were significantly higher than those treated with AS.
The PRP was effective in the treatment of PEDs. This may be attributable to its high concentration of platelet-contained growth factors, most notably EGF. PRP could be an effective, novel treatment option for chronic ocular surface disease.

Jpn J Ophthalmol. 2012 Sep 13. [Epub ahead of print]
Nune Eye Hospital, Daegu, South Korea.

September bonus coupon

Use this coupon for 15% off any order!

Valid through end of the day Friday (9/21).

Abstract: Use the Comments button to vote for the best title for this one

Read this study, and select the option which best summarizes it.

a) Higher education doesn't pay.
b) Men cope with dry eye pain twice as well as women.
c) Half as many men get dry eye as women.
d) Obviously the economy is doing well, since we're all able to spend so much more on dry eye drugs than we used to be able to.
e) Don't you wish you'd invested in Allergan prior to 2002 when Restasis was approved?
f) ________

To study dry eye medication use and expenditures from 2001 to 2006 using a nationally representative sample of US adults.
This study retrospectively analyzed dry eye medication use and expenditures of participants of the 2001 to 2006 Medical Expenditure Panel Survey, a nationally representative subsample of the National Health Interview Survey. After adjusting for survey design and for inflation using the 2009 inflation index, data from 147 unique participants aged 18 years or older using the prescription medications Restasis and Blephamide were analyzed. The main outcome measures were dry eye medication use and expenditures from 2001 to 2006.
Dry eye medication use and expenditures increased between the years 2001 and 2006, with the mean expenditure per patient per year being $55 in 2001 to 2002 (n = 29), $137 in 2003 to 2004 (n = 32), and $299 in 2005 to 2006 (n = 86). This finding was strongly driven by the introduction of topical cyclosporine emulsion 0.05% (Restasis; Allergan, Irvine, CA). In analysis pooled over all survey years, demographic factors associated with dry eye medication expenditures included gender (female: $244 vs. male: $122, P < 0.0001), ethnicity (non-Hispanic: $228 vs. Hispanic: $106, P < 0.0001), and education (greater than high school: $250 vs. less than high school: $100, P < 0.0001).
We found a pattern of increasing dry eye medication use and expenditures from 2001 to 2006. Predictors of higher dry eye medication expenditures included female gender, non-Hispanic ethnicity, and greater than a high school education.
Cornea. 2012 Jan 6. [Epub ahead of print]
Galor A, Zheng DD, Arheart KL, Lam BL, Perez VL, McCollister KE, Ocasio M, McClure LA, Lee DJ.
*Division of Ophthalmology, Miami Veterans Affairs Medical Center, Miami, FL †Department of Ophthalmology, Bascom Palmer Eye Institute, Miami, FL ‡Department of Epidemiology & Public Health, University of Miami School of Medicine, Miami, FL.

Monday, September 17, 2012

Abstract: LASIK, PRK and dry eye

This is the kind of study that makes me grind my teeth.

The technical term for it is GIGO (garbage in, garbage out).

First clue is "self-reported dry eye". Second clue is "a questionnaire" - as opposed to specifying the name of a scientifically validated questionnaire. Now if they really did use a decent questionnaire I'll have a new case of foot in mouth disease but in my experience if they're going to use a validated questionnaire, they say so in the abstract.

The result? Naturally, nobody has dry eye after LASIK or PRK in this study after 12 months. - Interesting in the context of the gobs of other studies in which anywhere from 2% to 36% had dry eye at 6 to 12 months postop.

Why on earth would anybody bother to document this, other than for marketing purposes?

I mean I'm sorry but if you're going to talk about dry eye at all, do what people do in real dry eye studies: pick 4 to 6 items off the well known standard clinical measures and symptom questionnaires, making sure you have both signs and symptoms covered.

I expect things like this from back in the dark ages (i.e. 1990s) of LASIK... but in this day & age, we should be measuring things that are meaningful and putting them in context.

Prospective, Randomized Comparison of Self-reported Postoperative Dry Eye and Visual Fluctuation in LASIK and Photorefractive Keratectomy.

We sought to prospectively compare postoperative symptoms of dry eye, visual fluctuations, and foreign body sensation in patients undergoing LASIK and photorefractive keratectomy (PRK).
Randomized clinical trial.
Sixty-eight eyes of 34 patients were treated with wavefront-guided LASIK and PRK.
One eye was treated with LASIK and the fellow eye was treated with PRK. Eyes were randomized by ocular dominance. Patients completed a questionnaire preoperatively and at each postoperative visit evaluating symptoms of dry eye, dry eye severity, vision fluctuations, and foreign body sensation.
Change in self-reported dry eye with secondary outcome measure of visual fluctuations and foreign body sensation scores after LASIK and PRK.
Both groups of eyes experienced significant increases in symptoms of dry eye, vision fluctuation, and foreign body sensation after LASIK and PRK at postoperative months 1, 3, and 6. However, by the 12-month postoperative visit, there was no increase in dry eye symptoms over the preoperative baseline levels in either group. Patients undergoing PRK experienced significantly higher levels of vision fluctuation at postoperative month 1 than those undergoing LASIK.
Both LASIK and PRK caused an increase in dry eye symptoms and severity, vision fluctuations, and foreign body sensation over baseline in the early postoperative period. At postoperative month 1, PRK caused greater vision fluctuations than LASIK. By 1 year postoperatively, all symptoms of dry eye, vision fluctuations, and foreign body sensation returned to their baseline, preoperative levels.
The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Stanford, California.
Ophthalmology. 2012 Aug 11. [Epub ahead of print]