Abstract: Pipeline drug development

My main comment on this review of what's going on in drug development is:

Why have I never heard of gefarnate, and is there really any current research going on with it? I see abstracts 10 years older and more, but nothing current. Since there are other references in this abstract to dead ducks (e.g. rebamipide, which probably wasn't officially dead till after this article was complete and waiting for press) I'll assume for the moment that this is an out of date reference... unless anyone would care to enlighten me otherwise.

Incidentally, here's a link to our dry eye drug pipeline page.

Therapeutic targets in dry eye syndrome.
Peral A, Dominguez-Godinez CO, Carracedo G, Pintor J.
Drug News Perspect. 2008 Apr;21(3):166-76.

Dry eye is a multifactorial disease of the tears and the ocular surface that manifests with a wide variety of signs and symptoms. It is prevalent in about 33% of the population worldwide. Due to the importance of the pathology, new tests, drugs and technologies have been developed to assist the diagnosis, management and follow-up of the disease. Current available therapies try to alleviate symptoms and to reduce signs in order to restore the ocular surface. Depending on the etiology of the pathology it is possible to use lubricants, secretagogues, biological tear substitutes or antiinflammatory drugs, either independently or combined. Nowadays, the therapies under clinical trial are devoted to stimulating tear components (e.g., diquafosol, a P2Y receptor agonist), or mucin secretion (e.g., rebamipide, an amino acid analogue of quinolinone). Others include gefarnate, a water-insoluble terpene fatty acid that contributes to restoring mucins on the ocular surface, or cevimeline, an oral cholinergic agonist that reduces the symptoms associated with dry eye. Other potential compounds described in patents are in a lower phase of drug development. These compounds come from different families of therapies, and among others, can be found in the form of steroidal and nonsteroidal antiinflammatory agents, vitamins A and D, neurotransmitters and neuropeptides.

Journal: Musings about why we don't "get" dry eye

While trying to chase bugs and a mini-abrasion off my brain this morning I was pondering once again some of the reasons why I think good dry eye care is such a scarce commodity.

Western medicine has this annoying way of looking at things in nice neat boxes for ease of use.

Are we looking at a person, or a pair of eyes? Ophthalmology seems to want to box up the eye and isolate it from the rest of the body. Yet most of dry eye is attributable to side effects of medications and surgeries; auto-immune disease; hormones; skin disease; eyelid mechanics; unfriendly home and office environments full of dried out air and allergens; and lousy diet.

Eye surfaces and a sophisticated lubricating system, or a tear film? Similarly, the cornea folks want to box up the tear film ("Three layers... not enough oil... add oil...") and/or the ocular surface ("Inflammation Is The Enemy...Must Fight Inflammation...")

What's missing?

Well, the rest of the body, for one. We pay lip service to it by pushing fish oil supplements, or going on allergy hunts, and under certain circumstances we test for Sjogrens, and we think we've done our duty and can return to the much more comfortable business of suppressing surface inflammation medically.

Then there's the complex interworkings of the tear system. This is increasingly evident in scientific findings - the ones that bother to look for the connections. (Mess with my MGs? Guess what - my mucus will suffer too. Mess with my nerve endings? You'll screw up my aqueous production. Mess with my aqueous? You'll screw up my MGs. And on and on.)

And then there's the question of what's happening on the infamous ocular surfaces themselves. You see what you look for, which raises many interesting questions of emphasis. For example, is the problem an inadequate or imbalanced tear film - or the surface state that occurs as a result, such as the "de-wetting" or whatever it is that's causing excessive pain? But again, that idea would take us out of the medical box into another area of science altogether. Sorry, no can do!

Ponder ponder ponder. Off to start the day now.

Journal: Foreign body sensation

I woke up in the middle of the night convinced a bug had walked onto my eye.

Talk about foreign body sensation.

I couldn't feel it - not with my fingers, I mean - and I was so sleepy nothing could have dragged me out of bed to look in a mirror. Nevertheless, this idea of a bug on my cornea was on my brain the instant I woke up and I couldn't shake it. And I'm not talking spider - probably never would have felt something like that - I mean something with a nice hard scaly body that can really scratch.

My cornea hurt like heck. My drops weren't in their usual place by my bed. So, I just rubbed my eye a bit and tried to go back to sleep.

It's my left eye, normally the good one of the two. True, I wasn't wearing my usual moisture goggle or even a sleep mask. In fact I was so worn out I don't think I even put drops in last night. But I don't recall ever having any very memorable spontaneous abrasion in that eye, at least not in recent years. When I get into any serious trouble at night it's always my right eye that gets the worst of it.

When I finally got up, sure enough, the eye was a nice shade of pink and had lots of mucous strands as though it had been trying to push something out. I hunted around and couldn't find any sign of something in my eye, so if there ever was something there, I guess it got away. It's been awhile since I had that strong an FBS right in the middle of my cornea. I've been back to the mirror several times to see if I could find anything, you know, like a tiny little leg or something. Nope, nothing. I've been pouring in the Dwelle, and the pain's starting to go down at least. And the way I noticed that is about the time I started becoming aware of how much my right eye hurts. Nothing like one kind of pain out-shouting another.

Teacher, I need a blackboard to go write on...

I will take care of my eyes before bed.
I will take care of my eyes before bed.
I will take care of my eyes before bed.
........................................

Abstract: Dry eye and refractive surgery

Predictably:

1) I could live without the Restasis/plug/Intralase cheerleading, but never mind

2) I am pleased to see the first three sentences of the Conclusions stated so nicely and I just wish these could be lifted verbatim and placed in every Informed Consent form for laser surgery, with a required verbal explanation by the physician.

3) I am just as disgusted with the last sentence of the Conclusions as I always am at this kind of a conclusion. Why laser these people with pre-existing dry eye at all?

Postrefractive surgery dry eye.
Curr Opin Ophthalmol. 2008 Jul;19(4):335-41.
Quinto GG, Camacho W, Behrens A.
The Wilmer Ophthalmological Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-0005, USA.

PURPOSE OF REVIEW: To report the recently published literature on ocular surface changes after refractive surgery, as well as the outcomes of treatment modalities on postrefractive surgery dry eye.

RECENT FINDINGS: Cyclosporine, the first US Food and Drug Administration approved agent to treat the underlying pathological mechanism of chronic dry eye, has demonstrated promising results in dry eye patients. Further, there may be an additive effect of topical cyclosporine and punctal occlusion. Femtosecond lasers for corneal flaps in laser in-situ keratomileusis seem to induce fewer signs and symptoms of dry eye and may be attributed to the creation of thinner flaps.

SUMMARY: Dry eye is one of the most common complications after photorefractive keratectomy and laser in-situ keratomileusis. Keratorefractive surgery is known to cause damage to the corneal sensory nerves. Several studies have demonstrated a decrease in corneal sensation, tear secretion, and tear film stability several months after keratorefractive surgery. For patients with preoperative dry eye, the ocular surface must be treated accordingly prior to surgery.

Abstract: Review of recent published research

Dry eyes: etiology and management.
Curr Opin Ophthalmol. 2008 Jul;19(4):287-91.
Latkany R.

PURPOSE OF REVIEW: Until recently, the cause of dry eye syndrome was uncertain and the treatment was palliative. Since discovering that dry eyes are caused by inflammation, there has been an abundance of research focusing on anti-inflammatory therapies, other contributing causes, and better diagnostic testing. This review summarizes some of the interesting published research on ocular surface disease over the past year.

RECENT FINDINGS: The definition of dry eye now highlights the omnipresent symptom of blurry vision. The re-evaluation of ocular surface staining, tear meniscus height, and visual change will allow for a better diagnosis and understanding of dry eyes. Punctal plugs, and oral and topical anti-inflammatory use will strengthen our arsenal against ocular surface disease.

SUMMARY: Major progress has occurred in the past few years in gaining a better understanding of the etiology of dry eye syndrome, which will inevitably lead to more effective therapeutic options.

Abstract: Tear glands, tit for tat, and... is this interesting or is this interesting!

Well, kewl - someone's finally speaking my language (so to speak)!

OK so it's only rabbits but I found this extremely suggestive. Has it been all said and done long ago and I just never noticed? Seriously, maybe it's just leaky brain syndrome but I honestly don't remember coming across something like this before, simple as it is.

They cauterized shut the meibomian glands of one eye and observed the effects on the tear film. Aqueous tears (i.e. from the lacrimal glands) increased and goblet cell density (i.e. mucous-makers) DECREASED.

Just playing guessing games here as I'm only looking at an abstract not data but:

Let's agree to ignore the lacrimal gland increase on the basis that screwing with the rest of the tear system has left such a bad surface that the bunnies are getting lots of reflex tearing.

Now look at the goblet cells: We've just simulated severe MGD or MG atrophy, goblet cell density is down so presumably mucous production is down. I've always felt that the 'unexplained' element with some of the patients who have severe burning or other 'surface symptoms' (including the infamous 'menthol sensation), despite decent aqueous production and a relatively quiet LOOKING ocular surface, might have as a common factor poor mucus resulting in poor 'wetting' (in a feeble attempt to speak Dr. Holly's language). If so, this might explain why some of these patients can max out on antibiotics, heat treatment, bleph treatment etc and still be in symptomatic hell. Furthermore, it might also help explain why simply applying something that 'wets' better (like Dwelle) can seriously improve symptoms even if the MGs remain completely unproductive, something I was puzzling over in an earlier post using our DEZ member 'Rozjen''s remarkable experience as an example... So now what I really want to know is whether it just compensates for the absence of the substance that is normally responsible for tear adherence or, as suggested in earlier studies, also actually improves goblet cell density. In due course hopefully we'll actually nail this down. Oh for research dollars. It wouldn't really take all THAT much.

[Changes in lacrimal secretion in rabbits according to meibomian glands activity][Article in Romanian]
Oftalmologia. 2007;51(4):121-5.
Stan C, Visan O, Samoila O, Mogosan C, Craciun C, Mera M.

PURPOSE: The purpose of this issue is to create an experimental animal model of dry eye and study the alteration of lachrymal secretion in time.
MATERIALS AND METHODS: We used a group of 8 rabbits in which the Meibomian gland orifices of the right eye were individually closed by cauterization, the results being related to the sound left eye.
RESULTS: We studied: the quantitative alteration of the lachrymal secretion using Schirmer 1 test; the alteration of lachrymal film using rose-bengal and fluorescein staining; the variation in tear protein concentration and histopathological changes in conjunctiva.
CONCLUSIONS: We found histopatological changes in conjunctiva and in the lachrymal secretion consisting in conjunctival goblet-ceil density decrease and watery secretion increase, probably due to lachrymal viscousity decrease mechanism.

Abstract: Dry eye after cataract surgery

This is nothing more than a blurb... But there is so little out there on dry eye after cataract in mainstream peer reviewed journals that I'll take anything I can get. I would love to see the raw data to get any idea of the correlations between incision size, topical meds and severity/persistence of dry eye after surgery. (Any MD, or co-managing ODs out there that happen to have collected data to share?)

[Clinical correlations between dry eye and cataract surgery][Article in Romanian]
Nistor MC, Nistor C.
Oftalmologia. 2007;51(4):79-82.

Cataract procedure is sometimes followed by dry eye symptoms. The dimensions of the incisions, topical medication and other manoeuvres are responsible for these phenomena. I tried to objective them by break-up-time (BUT) and Schirmer test. The favourable outcomes of artificial tears confirm this theory.

BOTOX / Blepharospasm alert

As some of you know, BOTOX injections can be used to treat blepharospasm. Typically patients get injections every 3 months.

I have heard from two different patients quite recently who experienced sudden complications from an injection. In one case, the lid froze open, causing severe pain and great risk to the cornea. In another, there are less severe but still serious problems with lid closure.

I am very concerned about this. If I've personally heard of two in a row, make no doubt there's more of it happening out there somewhere. Furthermore, LID PARALYSIS AND INCOMPLETE LID CLOSURE ARE NOT LISTED AS RISKS anywhere that I can find. Allergan's site lists ptosis, dry eye and corneal inflammation as side effects. The FDA site lists 'droopy eyelid' lasting a few weeks. This is more serious than any of those, however.

DOCTORS, please be on the alert for this and by all means file a Medwatch report or make sure your rep does. If any of your patients experience this please make sure they learn about ALL available remedies including things like Tranquileyes moisture goggles which will help hold their lids closed at night. If that's not suitable for your patient for some reason we can help you find alternatives such as eyelid-friendly tapes or sleep masks.

PATIENTS, if any of you reading this have experienced this complication, please urge your doctor to report it to the FDA. Whether or not your doctor undertakes to do so, please also file a Medwatch report on your own.

Here is the link to the FDA site for adverse event reporting.

As we witnessed so recently with LASIK, failure to report adverse events associated with drugs and medical devices has serious repercussions:

(1) it cripples the FDA's ability to pursue post-market safety issues, and

(2) it prevents future patients from receiving accurate information about the risks they may be undertaking.

(Note that after it was widely reported that only 140 "consumer complaints" had been received by the FDA about LASIK in 8 years, more than 200 more complaints were filed in less than a month - uncomfortable testimony to the FDA's failure to make their reporting system known and to physicians' and/or manufacturers failures to report poor patient outcomes.)

As conscientious consumers and professionals let's do our part to make things safer for future patients!

Thanks everybody.

Abstract: BAK BAAAD

Hopefully you all know this. But, it doesn't hurt to have the world expert in BAK say so. If your doctor has you on a BAK-containing medication used multiple times daily and has NOT discussed the risks with you, bring him a copy of this and talk about it.

On the other hand, sigh, in light of the problems preservative free vials pose for the elderly (see recent post) solutions are not always obvious or readily at hand.

Detrimental effect of preservatives in eyedrops: implications for the treatment of glaucoma.
Baudouin C.
Acta Ophthalmol. 2008 Jun 3. [Epub ahead of print]

Antiglaucoma medications are often associated with ocular adverse reactions such as dry eye, and burning or stinging sensations. These undesirable effects may lead to treatment discontinuation and reduced quality of life in patients with glaucoma. Antiglaucoma medications usually contain benzalkonium chloride (BAK) as a preservative. Animal studies, in vitro studies and in vivo experiments have demonstrated various adverse effects of BAK. Clinical studies have also shown an increased incidence of adverse events with BAK and have demonstrated that the withdrawal of preservatives reduces these effects. Collectively, these data suggest that preservative-free antiglaucoma treatments have clinically relevant benefits for patients.

Abstract: Dry eye at high altitudes....

Jimminy crickets. These people are DRY. More than half of 40+year olds in Tibet are symptomatic and 25% have a Schirmer at or under 5.

Altitude, altitude, altitude. This is why when I get a phone call from an area code in Colorado or New Mexico, I know what I'm going to hear before the conversation starts.

Dry eye syndrome in elderly Tibetans at high altitude: a population-based study in China.
Lu P, Chen X, Liu X, Yu L, Kang Y, Xie Q, Ke L, Wei X.
Cornea. 2008 Jun;27(5):545-51.

PURPOSE: To determine the prevalence of dry eye syndrome, analyze the relationship between dry eye symptoms and signs, and identify associated risk factors for dry eye syndrome in an elderly Tibetan population at high altitude.

METHODS: A population-based survey was conducted from October 2006 to December 2006. A stratified, clustered, random sampling procedure was used to select 2632 native Tibetan people > or = 40 years of age. Symptoms of dry eye were assessed by using a 6-item validated questionnaire. Dry eye syndrome was diagnosed in those subjects having 1 or more symptoms often or all the time. Positive signs included a tear film breakup time of < or = 10 seconds in 1 or both eyes, a Schirmer test score of < or = 5 mm, or a fluorescein score of > or = 1. Correlations between symptoms and signs were analyzed.

RESULTS: Of a total of 2632 eligible subjects, 2229 (84.69%) were examined. The data of 1840 participants were analyzed. Of 1840 participants, 52.4% (95% confidence interval: 50.2-54.7) were symptomatic. The tear film breakup time of < or = 10 seconds was seen in 35.3% (95% confidence interval: 33.1-37.5), a Schirmer test score of < or = 5 mm was seen in 24.7% (95% confidence interval: 22.8-26.7), and a fluorescein score of > or = 1 was seen in 5.8% (95% confidence interval: 4.7-6.9). The correlations between dry eye symptoms and signs were statistically significant. Independent risk factors for dry eye syndrome were positive dry eye signs, increased age, low education level and socioeconomic status, and higher altitude.

CONCLUSIONS: This study shows a high prevalence rate of dry eye syndrome in elderly Tibetans, representing an important health problem.

Abstract: Do your eyes dry out between blinks?

To be honest I'm slightly puzzled as to why we need an "Index" to define this particular baby.

Seems like a sub 1.0 result is the equivalent of a cardiologist saying "Yes, indeed you have heart trouble" which, considering you went to his office complaining of chest pains, you probably already knew.

But hey, if having another number on the chart is helping in some way, fine.

The Ocular Protection Index.
Ousler GW 3rd, Hagberg KW, Schindelar M, Welch D, Abelson MB
Cornea. 2008 Jun;27(5):509-13

The interaction of the time between blinks, or the interblink interval (IBI), and tear film breakup time (TFBUT) helps to regulate the integrity of the ocular surface. A protected surface exists when the TFBUT matches or exceeds the IBI. In contrast, an unprotected surface exists when TFBUT is less than the IBI. This is clinically relevant because repeated intermittent exposure of a tear film-deficient cornea can lead to ocular discomfort and the development of clinical signs, such as keratitis and redness. The relationship between TFBUT and IBI has been quantified by the Ocular Protection Index (OPI), which is calculated by dividing TFBUT by IBI. If the OPI is <1.0, the patient has an exposed ocular surface, putting them at risk for the development of the signs and symptoms of dry eye, whereas if the OPI is >or=1.0, the patient's ocular surface is tear film protected. The OPI has proven to be useful in assessing the factors that may cause or exacerbate dry eye. This review discusses the development and use of the OPI model, its relationship to dry eye, and factors that are known to alter blink rate and tear film integrity.

Newsblurb: Dry eye in the UK

Well gosh. With a title like this...

‘Dry Eye’ syndrome wreaks havoc on Brits

...I thought surely there must be starting to be a major turnaround in public awareness of dry eye in the UK!

Alas, today was not the day - it turned out to be an infomercial for B&L's sodium hyaluronate drop Hycosan. Nevertheless, there has certainly been an increase in the past six months or so in little newspaper blurbs and healthcare Q&A sections covering dry eye... all good signs.

Drug news: Diquafosol in Japan

Per a recent press release by Inspire, partner Santen is expecting to file for approval in Japan later this month.

DURHAM, N.C.--(BUSINESS WIRE)--May 16, 2008--Inspire Pharmaceuticals, Inc. (NASDAQ: ISPH) announced today the receipt of a $1.25 million milestone payment from its Asian dry eye partner, Santen Pharmaceutical Co., Ltd., related to the completion of Santen's Phase 3 testing of diquafosol tetrasodium, referred to as DE-089, for the treatment of dry eye. Santen has announced that it expects to file an application by the end of June 2008 for marketing approval in Japan.

Inspire and Santen have a collaborative agreement for the license, development and supply for diquafosol for the therapeutic treatment of ocular surface diseases, including dry eye, in Japan, China, South Korea, the Philippines, Thailand, Vietnam, Taiwan, Singapore, Malaysia and Indonesia. If the product is approved by regulatory authorities, Santen will be responsible for commercialization of the product in the designated countries and Inspire will receive royalties on net sales of the product, based on undisclosed rates specified in the agreement.

Christy L. Shaffer, Ph.D., President and CEO of Inspire, stated, "Santen has been successful in developing and commercializing ophthalmic products in Japan. We are pleased that Santen is moving rapidly toward a Japanese marketing application, which could lead to a meaningful royalty stream for Inspire, if the product is approved."

4/25/08 FDA LASIK hearing: AAO response

The May 2008 message from AAO president David W. Parke II, MD gives some distinct insight to how the AAO feels about what's going on in LASIK-land and to what extent they are interested in initiating any positive changes.

....We need to work harder at screening prospective patients, informing them of their risks and, frankly, managing expectations.

It is indeed gratifying to know that somebody "gets" what complications patients have been telling them for so many years. Though I think they might have dispensed with "managing expectations" as being redundant. If you screen patients carefully, and give them thorough and accurate information about their risks, there are unlikely to be any inappropriate expectations to manage. There might be fewer customers as well, however.

By the by, I am curious to know whether the AAO feels that working harder at "screening" prospective patients includes such things as looking out for contact lens intolerant patients who are probably at higher risk for LASIK dry eye. - Particularly considering Dr. McDonnell, who was representing AAO at the hearing, went out of his way to mention that such patients often seek LASIK, but - so far from cautioning that this may be a warning sign - he also seemed to suggest that LASIK is safer than contacts overall.

Then too, it seems the AAO desire to help LASIK patients retain vital information they may need down the road for cataract surgery:

The Academy is also developing a new “K-card” to be given to patients by their LASIK surgeons, which captures a patient’s preoperative keratometry readings and refraction. It is often difficult to track down this critical data years later, when the patient is in need of cataract surgery or additional eye care. We are exploring ways to store this information digitally for easy retrieval.

I am struggling to suppress some excessively uncharitable thoughts enough to keep my comments within the bounds of civility. But screw it. Some spades just need to be called spades.

The AAO has known about this problem for YEARS. One of its own members, Craig Berger MD (a corneal specialist in Tampa, Florida) has repeatedly tried to persuade them to actually do something about it, going so far as to develop his own internet-based software system (see Safeguard Your Sight) to help patients safeguard the information they will assuredly need eventually - and will almost as assuredly not be able to find when that day comes.

Has the AAO ever showed a particle of interest? Nothing doing. And even now, when the FDA hearing - which resulted in an agreement to add explicit warnings about this problem on the FDA website - has finally goaded them into some semblance of action, will they consider consulting with Dr. Berger after all the time he's invested? Nothing doing. Their idea of helping patients is giving them a card with their vitals.

By golly, that sounds like a wonderful solution which surely all future LASIK patients will appreciate. Lookie! I'm a card-carrying member of the LASIK club! No more glasses. Intead I get to carry a piece of paper in my wallet for the next 30 years which, if I am lucky enough to understand anything about on the day I get it, I will almost certainly forget altogether within the next year.

Funny, this almost reminds me of the card I got from my surgeon in the mail a week after surgery (at which point I couldn't read a stopsign to save my life) stating that I'm legal to drive without corrective lenses. Apparently for a fleeting moment during one of my early post-op exams - probably overcorrected and squinting - I squeezed out a 20/40 OU UCVA in a manifest refraction.

Bottom line: If I was holding out any hopes that the AAO would be just a teensy, weensy bit different from ASCRS in terms of its inclination to promote higher standards than the last 10 years status quo, I am no longer deluding myself.

Abstract: Comparing artificial tears

This is an in vitro comparison of several artificial tears and how long they protect epithelial cells from dessication. As acknowledged in the abstract, whether it happens this way 'in vivo' is up for grabs. Personally I don't find any of it all that interesting because I don't think we should be satisfied with such brief protection in any case.

Americans will not be familiar with these brands... Artelac and Acuolens are hypromellose drops, Vidisic is a carbomer gel, Hyal Drops are sodium hyaluronate, and Viscofresh is carmellose.

Lubricating agents differ in their protection of cultured human epithelial cells against desiccation.
Paulsen K, Maile S, Giebel J, Tost FH
Med Sci Monit. 2008 Jun;14(6):PI12-16

Background: In dry eye, as a disease of the ocular surface, the instillation of artificial tears should compensate for the deficit in wetting and protect the mucosa against drying.

Material/Methods: The desiccation protection of different pharmacological substances was tested using the conjunctival epithelial cell line Chang 1-5c-4 (series 1) and the corneal cell line 2.040 pRSV-T (series 2). On confluent cell growth the cultures were wetted for 20 min with various preservative-free preparations of artificial tears The cell cultures were exposed to a constant air flow for 0, 15, 30 and 45 minutes. Cells were incubated with the vital dye Alamar Blue and subsequently absorption of the oxidised form of the dye was measured using an ELISA-Reader.

Results: Cell survival rates in series 1 after 0, 15, 30, 45 min were (1.02;0.81;0.35;0.32) for Artelac(R) EDO, (0.82;0.69; 0.63;0.54) for Vidisic(R) EDO, (0.77;0.80;0.67;0.70) for Vidisic(R) Fluid EDO, (0.76;0.70;0.36; 0.34) for Acuolens(R), (0.97;0.46;0.35;0.33) for Viscofresh, (0.88;0.85;0.37; 0.33) for Hyal Drops SDU, (0.71;0.44;0.34;0.33) for PBS and in series 2 (1.03;0.84;-0.21;-0.20) for Artelac(R) EDO, (0.89;0.92;0.93;0.86) for Vidisic(R) EDO, (0.96;0.88;0.85;0.85) for Vidisic(R) Fluid EDO, (1.01;0.75;-0.02;-0.03) for Acuolens(R), (0.98;0.17;-0.22;-0.20) for Viscofresh, (0.97;0.83;0.03;-0.21) for Hyal Drops SDU and (0.96;0.26;-0.24;-0.21) for PBS. Vidisic(R) Fluid EDO and Vidisic(R) EDO showed a significantly better protective effect after a drying period of 30 and 45 min.

Conclusions: The protection capability of pharmacological substances against desiccation can be studied in a standardised cell culture system of human epithelial cell lines. Whether these in vitro results are conferrable to the efficacy of artificial tear drops in vivo has to be evaluated in clinical trials.