Tuesday, July 24, 2007

Study: Intralase flaps and dry eye (again)

Effect of hinge position on corneal sensation and dry eye after laser in situ keratomileusis using a femtosecond laser.
J Cataract Refract Surg. 2007 Jul;33(7):1190-4.
Mian SI, Shtein RM, Nelson A, Musch DC

Most of this is stuff that's been published before, basically demonstrating that flap position does not matter if you're using a femtosecond laser (as opposed to a microkeratome where it's been proven over and over that flap position does affect dry eye). But the part I was interested in is...

RESULTS: Corneal sensation was reduced with both superior-hinged and temporal-hinged LASIK flaps 1 week and 1, 3, 6, and 12 months after surgery (P<.0001).

YES BUT HOW MUCH at 12 months? and what was the dropout rate?

Oh for an unlimited budget... I let my JCRS subscription lapse this year.

Study: (Lab science) Thyroid and dry eye

Influence of Thyroid Hormone on Thyroid Hormone Receptor {beta}-1 Expression and Lacrimal Gland and Ocular Surface Morphology.
Invest Ophthalmol Vis Sci. 2007 Jul;48(7):3038-42.
Dias AC, Módulo CM, Jorge AG, Braz AM, Jordão AA, Filho RB, de Paula JS, Rocha EM.

CONCLUSIONS: Chronically reduced levels of TH lead to biochemical and structural changes and modulate the levels of Thrb in LG. These events confirm that LG is a target organ for TH and may facilitate understanding of the mechanism related to dry eye in hypothyroidism.

Looking forward to some follow-up studies on this one.

Study: Another strike against the LASIK suction ring...

...not that 1-month results necessarily tell us much, but at least they highlight the need for MORE study and that is key. There are simply far too many people out there with long-term very high pain/discomfort from LASIK dry eye whose 'obvious' clinical signs (Schirmer, staining, BUT) do not explain their degree of discomfort. We need more info.

Effect of suction ring application during LASIK on goblet cell density.

J Refract Surg. 2007 Jun;23(6):559-62.
Rodriguez-Prats JL, Hamdi IM, Rodriguez AE, Galal A, Alio JL

PURPOSE: To study the effect of LASIK surgery on conjunctival goblet cells as one of the proposed mechanisms for dry eye occurring after LASIK.... CONCLUSIONS: The application of the microkeratome suction ring induced changes in the perilimbic conjunctiva. These changes contribute to the pathology of dry eye. Goblet cell count remains affected at 1 month postoperatively.

Study: Probing those little lipids further...

Temperature-induced conformational changes in human tear lipids hydrocarbon chains.
Biopolymers. 2007 Jun 28; [Epub ahead of print]
Borchman D, Foulks GN, Yappert MC, Ho DV.

As a first step to characterize human meibum and tear lipids, infrared spectroscopy was applied to characterize the molecular structure/conformation and packing of hydrocarbon chains. Temperature-induced phase transitions were fit to a sigmoid equation and were experimentally reproducible and were similar for multiple samples collected from the same person. No hysteresis was observed. Hydration of polar tear lipids increased their phase transition cooperativity, enthalpy and entropy. Hydrophobic interactions in meibum lipid (ML) were stronger than in tear-fluid lipids (TL), as reflected by the higher entropy and enthalpy of the gel to liquid crystalline phase transition of ML.The results of this study provide further evidence of the differences in the composition and structure of ML and TL. The conformational changes observed in the hydrocarbon chains of ML with temperature suggest that the observed therapeutic increased delivery of ML with eye lid heating could be related to the increased disorder in the packing of the hydrocarbon tails. This work also highlights the power of infrared spectroscopy to characterize molecular structure/conformation, and packing of human tear lipids and provides a basis to be applied next to study tear film lipid composition-structure-function relationships and lipid-protein interactions in relation to age, sex and dry eye symptoms. (c) 2007 Wiley Periodicals, Inc. Biopolymers, 2007.

MOST interesting. I have been so pleased to see an escalation of interest in heat treatment for MGD at last. Sounds like we are on our way to learning more about the actual mechanics and what form(s) are most likely to be helpful to various types of conditions? Hurray. May we see much more investigational work along these lines.

Study: Claritin vs. Elestat in the drying contest

An open-label, investigator-masked, crossover study of the ocular drying effects of two antihistamines, topical epinastine and systemic loratadine, in adult volunteers with seasonal allergic conjunctivitis.
Clin Ther. 2007 Apr;29(4):611-6.
Ousler GW, Workman DA, Torkildsen GL.

CONCLUSIONS: These healthy adult volunteers with a history of seasonal allergic conjunctivitis had no clinical signs of ocular drying after 4 days of twice-daily treatment with topical epinastine. After 4 days of once-daily dosing, systemic loratadine was associated with clinical signs of ocular dryness, including decreased tear volume and tear flow. Use of loratadine was also associated with an increase in global fluorescein staining, indicating an increase in ocular surface damage.

Elestat eyedrops twice a day did not cause visible drying, but Claritin (taken internally) once a day did.


Study: What people are really doing with Restasis

Real-world utilization patterns of cyclosporine ophthalmic emulsion 0.05% within managed care
Can J Clin Pharmacol. 2007 Summer;14(2):e240-5. Epub 2007 Jul 10
Chiang TH, Walt JG, McMahon JP, Mansfield JE, Simonyi S.
Conducted at Allergan's facility in Irvine CA.

CONCLUSIONS: Most patients used about 1 vial per day, less than the labeled 2 per day. The cost to managed care for cyclosporine 0.05% ophthalmic emulsion may be less than anticipated. Key words: Cyclosporine 0.05% ophthalmic emulsion, longitudinal patient database, cost, utilization.

Gosh. Maybe it has something to do with the burning. Or maybe patients are getting confused when given a veritable cocktail of steroids, tears and Restasis as so many do these days.

ABC News / Dry eye spotlight

For those that didn't see it, ABC did a dry eye piece last week featuring Dr. Latkany.

Here's a link

Study: Airplanes are bad for dry eye (really???)

Increased evaporative rates in laboratory testing conditions simulating airplane cabin relative humidity: an important factor for dry eye syndrome

Eye Contact Lens. 2007 Jul;33(4):174-6
Uchiyama E, Aronowicz JD, Butovich IA, McCulley JP.

PURPOSE: To quantitatively explore the relationship between low relative humidity conditions, as experienced in airplane cabins during flight, and increases in aqueous tear evaporation as a potential explanation for increased dry eye symptoms noted by people when in low humidity environmental conditions.... CONCLUSIONS.: These studies quantitatively show the negative impact of environmental low relative humidity conditions, including those associated with commercial airplane travel, on aqueous tear evaporation dynamics. The increased evaporative rate is similar in healthy subjects and patients with dry eye. These findings provide useful data for the development and evaluation of treatment paradigms for any person who notes dry eye symptoms in low relative humidity environments.

No surprises in the results, but this study underscores the need for protective measures for people already suffering from dry eye, such as foam-lined eyewear, a sleep mask, or a Tranquileyes goggle.

Study: Relationship between staining, aqueous tear deficiency and MG dropout

Pattern of vital staining and its correlation with aqueous tear deficiency and meibomian gland dropout

Eye Contact Lens. 2007 Jul;33(4):177-9
Uchiyama E, Aronowicz JD, Butovich IA, McCulley JP

Basically just confirming some correlation of staining with Schirmer and gland dropout. Any correlation to be found in dry eye is A Good Thing, but I wish I knew more about this one e.g. Schirmer method employed and MG dropout evaluation specifics.

PURPOSE.: To assess the relationship between the degree and anatomic location of ocular surface vital staining and the degree of aqueous tear deficiency in patients with dry eye, as measured by the Schirmer test, and the presence of meibomian gland dropout....CONCLUSIONS.: The presence of corneal vital staining correlates with a more severe dry eye as shown by the Schirmer test. Patients with dry eye have an increased meibomian gland dropout. The degree and pattern of vital staining correlate with the severity of dry eye.

Study: Plug retention and complications

Long-term Retention Rates and Complications of Silicone Punctal Plugs in Dry Eye

Am J Ophthalmol. 2007 Jul 11; [Epub ahead of print]
Horwath-Winter J, Thaci A, Gruber A, Boldin I.

This was a study of 95 silicone punctal plugs by FCI Ophthalmics.

RESULTS: The retention rate of the plugs was 84.2% after three months, 69.5% after one year, and 55.8% after a median of two years (range, 17 to 93 months). No infection was observed, but granulomatous formation occurred in three eyes (one with extrusion, two with intrusion). Three plugs had to be removed for local discomfort or epiphora, and one piece of a broken plug intruded. Canalicular stenosis after spontaneous loss occurred in 14.3% after three months, in 26.9% after one year, and in 34.2% after a median of two years.

Patients reading this, please bear in mind we're talking about punctal plugs, i.e. the ones that sit on the surface, not the ones shoved all the way in the cannaliculi.

Nothing surprising about the results. But given the high chances of losing plugs, we advise anyone considering getting plugs to first confirm with their doctor's office what the charge is (if any) for replacing lost plugs within the first year.

Study: Warm compresses & blurred vision

Taken at face value this study's conclusions fall distinctly under the "duh" category for me. I've used a rice baggy for years. Between the slight pressure from the weight of the rice, and the increased oil in the tear film, I expect temporary vision blurring and that's why I do it at night.

On the other hand, I hear from people now and then who get quite worried when their vision is blurry so it's nice to have a study saying "not to worry - it's just temporary".

My only question about this study is... what form of moist, warm compress lasts 30 minutes??? Not a washcloth, for sure.

Warm Compress Induced Visual Degradation and Fischer-Schweitzer Polygonal Reflex

Optom Vis Sci. 2007 Jul;84(7):580-587.
Solomon JD, Case CL, Greiner JV, Blackie CA, Herman JP, Korb DR.

CONCLUSIONS.: Warm compress application induces transient visual degradation. Although there was no correlation between visual degradation and AR, CT, CCC, LLT, or the presence of striae or corneal edema, visual degradation correlated positively with the polygonal reflex, which was observed following warm compress application.

Study: Tear film osmolality in postmenopausal women

It is good to see that there is more and more research underway on this specific population. Note that Argentis also has a drug under development specifically for menopausal women, developed at SCO.

Tear film osmolarity and ferning patterns in postmenopausal women
(click for abstract)
Optom Vis Sci. 2007 Jul;84(7):588-92.

Srinivasan S, Joyce E, Jones LW.

Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.

CONCLUSIONS.: Osmolality in mild and moderately DE PMW is higher than in NDE PMW and tear ferning is a rapid, simple, noninvasive laboratory procedure that indicates altered tear quality in PMW with symptoms of dry eye.

p.s. I'm about 8 months behind (jeepers!) on medical literature. Hoping to catch up gradually over the next few weeks, so expect a lot of abstracts to be bubbling on these pages.

Monday, July 23, 2007

New patent application: Good news for MGD sufferers?

I was pleased to see this patent application which someone dug up and posted on Dry Eye Talk:

Melting meibomian gland obstructions

Consistent with certain embodiments, an apparatus provides regulated heat to at least one of a patient's eyelids, using a heater unit having a heating element that produces heat that is transferred to the patient's eyelid when an electrical signal is applied thereto. A temperature regulator applies an electrical signal to the heating elements in order to achieve heating of the heating elements to a specified temperature range. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.

I had heard that there are some heat treatments for MGD in the works, this presumably one of them. Developments like this are heartening news for chronic dry eye patients and their doctors, and certainly for me. When I first came across the EyeFeel device sold in Dr. Tseng's practice in Miami, I tried to get the manufacturer to let me import it for commercial sale. I believed then, as now, that if there were an FDA approved medical device like that specifically sold for treatment of MGD, it would be a huge step forward in terms of raising interest and awareness among doctors, not to mention improving compliance amongst patients. Alas, nothing came of it. So life goes on and I continue peddling my humble Rice Baggy, and teaching people to make homemade versions.

After being chronically overlooked and undertreated for so long, is diagnosis and treatment of meibomian gland dysfunction at last going to get some attention?