THE IATROGENIC DRY EYE AND ITS MANAGEMENT
Frank J. Holly, Ph.D.,
President of the Dry Eye Institute
Based on the Harold Stein Lecture given at the CLES
Meeting, in Orlando, FL on 01/23/03. Revised on 03/31/03
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-- TITLE SLIDE --
The goal of my talk here today
is to take a look at a dry eye problem that a disproportionately large number
of patients seems to acquire following refractive surgery, the
iatrogenic dry eye. Most importantly we shall take a look how it is
managed and how this treatment regimen could be improved.
Slide 2: Refractive Surgery and the dry eye
During the past decade or so, new surgical techniques
came into use by which the cornea is reshaped to correct refractive errors
such as myopia, hyperopia, and various degrees of astigmatism. The connective
tissue part of the cornea is selectively destroyed to produce a new and
hopefully correct curvature.
The main problem is, after reshaping the stroma, to cover
the altered surface with a smooth and intact layer of epithelium which is
normally highly enervated. And due to the nature of these highly specialized
corneal epithelial cells, this is where commonly the problems originate.
With the exception of radial keratotomy using radial cuts
into the cornea, the other methods are based on removing part of the stroma.
To access the stroma, the epithelial layer is either sliced partially off
with some connective tissue attached underneath to form a flap which is
replaced at completion (LASIK) , or the epithelial tissue is removed, and then
replaced, or the epithelial cells are permanently removed in the hope that
this tissue will re-grow over the altered surface.
Slide 3: Surgical complications related to the dry eye state
Sixteen out of eighty post-surgical
complaints for each of the procedures are closely related to dry eyes as can
be seen on this slide. The specific surgical techniques do not seem to
make much difference as far as the type of complications is concerned.
Here we will mostly deal with patients who
undergone LASIK surgery, since this is the most popular technique at present
so that one meets most such patients with complications.
Dry eye appears to be a major refractive surgical
complication. The dry eye state is a disease of complex etiology
where the biophysical and surface chemical factors play a major role. It is
not well understood, it is not easy to diagnose, and even harder to manage.
So it was an unpleasant surprise that a considerable number, now estimated as
high as 50 % of the patients undergone LASIK surgery complained of dry eyes of
various severity.
Fortunately, many of these improve in three to six
months, but a significant portion (about 20%) do not do so.
Slide 4: Poll results of members of the Surgical Eyes, Inc
To find out about the management of post surgical eyes a
survey was conducted among the 4,000 plus registered members of Surgical
Eyes Foundation, a web-based organization. The survey was conducted with
the permission and assistance of Ron Link, the Executive Director of the
Surgical Eyes Foundation. The survey invited patients who were diagnosed
with dry eye after refractive surgery to reply to questions concerning their
post-operative care and the treatment modalities employed in their management.
The questions were aimed at the major complication, the post-surgical dry eye.
163 patients replied to the survey. 98% of them had Lasik surgery.
__________________________________________________________________________________________
Slide 5:
Provision of post-surgical care
We found out that the majority of the patients of this
group were followed either by their surgeons or more frequently by the
optometrist associated with the surgeon, some times by both. In a
considerable number of cases a third doctor was also consulted usually in the
second year. In rare cases, up to ten eye care professionals had been
consulted by one patient to find a solution to stubborn complications.
Slide 6:
Medication/Device employed in post-surgical patients with complications
It was of interest to find out whether either steroidal
anti-inflammatory agents or antibiotics agent were topically applied following
surgery as a prophylactic measure. In 72% of the cases steroids were
prescribed and in 68% cases antibiotics were employed.
Not surprisingly all patients (100%) have been prescribed
artificial tears, since this subpopulation was specified as those who had been
diagnosed with dry eyes following surgery. Some of them had the
condition prior to surgery and, in practically all cases, their condition have
become more severe after surgery.
Punctal plugs (1-4) were prescribed in 56% of the cases
the majority of which obtained two plugs. Less than one third of these
patients were offered four plugs.
For a surprisingly high number of patients (50%)
ointment was prescribed despite the strong possibility that ointments
interfere with both the wettability of the ocular surface and lid lubrication.
Slide 7: Other
treatments of dry eyes in post-surgical patients:
The last question referred to any other treatment the
post-surgical dry eye patients received in the past. Permanent
cauterization of the puncta and the use of bandage lenses, were the most
common to treatment employed. Diluted autologous serum instilled
topically has also been used especially in South America, and China. This
slide also lists the various types of artificial tears suggested by the
attending eye care professional which indicates some confusion as to the
mechanism of action of the various tears.
It is of interest to know that one patient participated
in our survey, who had undergone radial keratotomy fifteen years ago
and he still suffers from dry eye. And there are quite a number of
patients among this group, who, one to three years after their LASIK surgery,
are still waiting “for the surface of the eyes to heal”.
Slide 8: Properties of the Tear Film
The tear film consists of a lipid and an aqueous fluid
layer and forms the most important refractive surface in the eye.
Superficial Lipid Layer. The source of these lipids is the
meibomian glands along the lid edges. It consists only one percent of the
tear film in thickness. The superficial lipid layer retards
evaporation and protects the tear film from the invasion of the highly polar
skin lipids and contributes to stability by providing a low energy surface.
Aqueous Tear Layer. This
layer is still very thin approximately 10 micrometers. If we visualize
that an erythrocyte on its edge would form a “coral reef” in the tear film,
then we can realize how smooth the epithelial surface has
to be to allow the tear film to be continuous. It contains electrolytes,
enzymes and various other proteins and glycoproteins. The most surface
active component (lacrimal surfactant) is sialo-mucin which is mostly secreted
by the goblet cells of the conjunctiva. Some of the proteins (lysozyme,
lactoferrin, etc.) are secreted by the lacrimal glands, and some (albumin and
other serum proteins) originate from the blood serum, especially in an
inflamed eye when the blood vessels of the conjunctiva are dilated.
Ocular Surface.
Often referred to as the mucin layer. This layer is about as thick as
the superficial lipid layer and does two things;
-
makes the surface lacrophilic
-
maintains this lacrophilicity (by masking entrapped lipid molecules)
Slide 9: Stability
of the tear film: Closed eye
Closing eye lids compress the superficial lipid layer. Only the aqueous
tear layer remains under the lid which provides hydrodynamic lubrication as
long as it remains stable. When the eye lids are lax and floppy, or
where the globe (cornea) and lid congruity is compromised, or when ointment is
applied to the eye surface problems can arise. The tear layer continuity under
the eye lid is important for effective hydrodynamic lubrication. When
this is compromised, discomfort and further damage to the epithelium can occur
both on the global and on the tarsal side.
When the tear film
ruptures in the open eye then the so called dry spots form. This can
happen in people with healthy eyes and normal tear film. All it takes is
to refrain from blinking for more than 30 seconds or some time even a minute
or two. It depends also on the environment. Turbulent, relatively
dry air (air conditioning, air plane ambience) will accelerate the process.
Slide 10: Factors that increase tear film
stability
Now let us see what can go wrong
with this delicate system designed to ensure a highly refractive, optically
smooth surface for the cornea.
In the present view of the dry eye, the lipid is often
blamed for causing the dry eye (Meibomian gland dystrophy, MGD). The
full role of the lipids in tear film stability is often poorly understood.
Without going into technical details I can state that the following two
extremes can compromise the tear film, the stability of both the aqueous and
lipid layer. 1/ when the lipid polar fraction is excessive and the
polarity is high and 2/ when there is insufficient polar fraction to stabilize
a duplex lipid film over the aqueous tear layer.
The dry eye syndrome is also called ocular surface
disease usually implying an abnormal tear film, eye irritation, some
epitheliopathy and can be associated with sterile inflammation of the cornea,
conjunctiva, and the lids. Dry eye is something of a misnomer since the ocular
surface does not literally dry out: that is, the tear film does not completely
evaporate. Rather, 'dry eye' occurs because the ocular surface becomes
lacrophobic, compromising the tear film's stability. The tear film break-up
time shortens to a time interval less than that between consecutive blinks.
In extreme cases, usually associated with keratinization of the corneal
epithelium, the ocular surface becomes so non-wetting that no tears can wet it
completely, the tear film break-up time becomes zero. Then one has a
truly dry eye (xerophthalmia).
Slide 11: Rupture of
the tear film/Dry spot formation
So the cause of tear film
break-up (premature in dry eyes), the rupture of the tear film, often at
several locations, is due to local nonwetting. If the tear film ruptures
before the next blink, and this happens repeatedly, the demise of the surface
epithelium commences. Epithelial cells of the cornea do not take well to
be exposed to the atmosphere. Soon eye irritation and epithelial surface
damage occurs. The cellular damage can be made visible with vital dyes.
When the epithelial damage spreads deeper than the
surface layer, the epithelial tissue (4-5 cells thick) can become loosened,
water-logged, and leaky to both water and electrolytes. In refractive surgery
especially, the adhesion of the epithelium to the corneal stroma is weakened
resulting in recurrent epithelial defects and corneal erosions.
Injured epithelial cells may also secrete collagenase, an
enzyme that can dissolve the collagen fibers in the corneal stroma, the
scaffolding of the cornea, and result in corneal ulceration.
Diagnosis of Dry Eye Syndrome:
In the past, for decades, dry eye states of different levels of severity
were often misdiagnosed. The medical term, keratoconjunctivitis
sicca, means the inflammation of the cornea and conjunctiva due to
desiccation. Inflammation in people=s
mind is often associated with infection. However, sterile inflammation
caused by tear film instability is more common than one would believe.
The above mentioned keratoconjunctivitis is often of that type.
A healthy tear film complete
with continuous tear meniscus of normal width (> 0.20 mm) protects the eye and
lid edges from infection. A fragile tear film surrounded by a scanty
tear meniscus offers no such protection and often is accompanied by some
inflammation of lid margin the lids (blepharitis) in addition to
keratoconjunctivitis. Infection can also be present.
Infection is treated with
antibiotic ointment or drops, inflammation is treated with steroids or NSAIDs.
These medications have side effects and often aggravate the cause; the
instability of the tear film.
The following methods were found
to be useful for the differential diagnosis of the dry eye state:
Slide 12: Tear film
break-up time
It is an important parameter in deciding the relative
stability/instability of the tear film and the wettability of the corneal
epithelium. It has been proven that continuous aqueous film can form over
hydrophobic surfaces only if they are not thinner than a critical thickness
ranging from a few tenth of a millimeter to several millimeters. The
tear film being about 0.01 millimeter thick can only exist over a hydrophilic
(or at least lacrophilic surface) and must rupture over hydrophobic areas.
[Aqueous layers thicker than 0.1 mm would be affected by gravity and would be
unable to firm a film of even thickness on a vertical surface , the eye of a
standing or sitting person].
Slide 13: Vital staining
Fluorescein sodium salt is often used in contact lens
fitting and to detect epithelial abnormalities when used with a cobalt blue
filter. It stains water soluble or penetrable structures.
Rose Bengal and Lissamine green stains lipid-like structures for
example mucus strands heavily contaminated by lipids, dead or dying epithelial
cells, etc.
These two latter dyes stain similarly but the advantage
of Lissamine green over Rose Bengal is that it does not cause discomfort.
Slide 14: Characteristic 3 o’clock- 9 o’clock staining by Rose bengal of
a dry eye
This staining pattern is characteristic of a typical dry
eye of the sicca type. In areas between the lid edges (in the palpebral
fissure) the damaged epithelium stains.
Slide 15: Blinking and the tear film. Does the tear film re-form?
When the lids close (upper lid moves downward), only the
superficial lipid layer is compressed. The aqueous tear layer under the
lid remains intact and serves as a lubricating layer resulting in hydrodynamic
lubrication.
The continuity and therefore the stability of this tear
layer between the lid and the globe is imperative for effective lubrication
that protects the epithelial surface both of the eye and on the inner surface
of the lid (tarsal conjunctiva).
Epitheliopathy is often an accompanying sign of moderate
to severe dry eyes. Various problems with epithelial integrity, poor
adhesiveness, lack of intactness, epithelial erosion of various kinds
exacerbated by poor lid lubrication were found even more frequently in
patients with post-surgical dry eye.
Initially the discomfort may not be great due to nerve
damage, but eventually with regenerating enervation, these epithelial problems
can be quite painful. Discontinuity in the lubricating tear layer may
cause contact adhesion between the lid and globe – especially at night - which
can often lead to damage (erosion) to both global and tarsal conjunctiva.
Contact adhesion is often a sign of the absence of hydrodynamic lubrication of
the lids.
Slide 16: Blinking (continued)
Normal blinking frequency is 5-8 times a minute depending on external
conditions. Most of the blinking is complete, i.e. the two lid edges
meet. In
incomplete blinking, the upper eye lid goes down barely past the pupil.
If such blinks dominate the blinking pattern they can cause inferior punctuate
staining by fluorescein.
Infrequent blinking, where the blinking time interval exceeds the tear
film break up time, especially when combined with incomplete blinks may cause
epithelial damage and dry eye symptoms. Staring is a state
where the blinking frequency drastically decreases, e.g. during work with a
computer.
A decrease in corneal sensitivity such as that may result
from Lasik surgery may frequently suppress the blinking reflex and thereby
diminish its frequency.
Slide 17: Treatment Modalities
The goals of dry eye treatment
are two-fold: to alleviate the symptoms that cause discomfort to the patients
and to prevent or reverse complications that might deteriorate vision.
With proper treatment in most patients good vision can be restored and
preserved and long lasting relief from discomfort can be achieved.
Classically the following approaches have been used to
manage the dry eye:
Slide 18: Tear Supplementation
The supplementation of aqueous
teas by a tear substitute is by far the most important treatment in
all form of the disease. All the patients participating in the survey
have been employing them. Often the use of preservative-free
preparations is suggested regardless of the composition of the tear
substitute. Harmful preservatives should certainly be excluded.
However, the fact is that often a well formulated artificial tear containing a
benign preservative, proves to be superior to a preservative-free drop if its
only advantage of the latter is the lack of preservative.
In general, many types of
artificial tears have been tried by the dry eye patients without noticing much
beneficial effects. Frequent and heavy doses (flushing) were
occasionally suggested with often harmful results, (punctate staining, burning
sensation) resulting from the leaching of the mucin layer coating the ocular
surface.
Slide 19: Tear Supplementation, cont.
The ideal tear substitute should provide treatment to the
underlying problems. It should definitely enhance the wettability of the
ocular surface. At present, none of the commercial artificial tears
address this issue.
The other misconception that still lurks in the mind of
eye care professionals and artificial tear manufacturers is that high
viscosity results in long retention time and therefore it is advantageous.
Indeed, preparations that are 300 times more viscous than aqueous tear are
still used in post-lasik eyes. Needless to say such a formulation is
unable to form a lubricating layer between the lid and globe and if it did, it
would contribute considerably to the epithelial surface damage.
Slide 20: Oncotic Pressure
Hypertonic salt solutions can do more harm than good when
the epithelium looses its semi-permeability towards electrolytes. Hyper-osmolality
is needed but has to be achieved with large molecules unable to penetrate the
injured epithelium. So that the formulations should have a sufficiently
high oncotic pressure instead of hypertonicity.
Are preservative-free artificial tears are really
better for dry eyes?
Hypoallergenic preservatives, which are also
nontoxic, may be used without harm. Those with hydrophilic properties as
an adsorbed layer can even be beneficial. In any case, solely the lack
of preservatives per se does not make the formulation to be
efficacious. - Unfortunately, the “preservative-free label” is
often just a marketing tool.
Slide 21: Preservation of Aqueous Tears
To preserve existing tears either the drainage of the
tears should be diminished or the evaporation lessened.
Slide 22: Punctal
Plugs to improve the tear meniscus
A normal tear meniscus surrounding the tear film along
the lid edges contains tears several-fold more than needed for the tear film.
Scanty, uneven tear meniscus can be observed in dry eye patients. By
decreasing tear drainage using punctual plugs, the tear meniscus can be
restored. If the tear secretion rate is significant, however, this
procedure results in epiphora.
Punctal plugs placed into either the upper or lower
puncta, or often into both, have gained considerable popularity. Their
use results in the increase of tear volume and that can be helpful.
Rationally, when their employment had resulted in epiphora, their use was
discontinued. Not so with iatrogenic eyes. Even if the plugs are
painfully irritating and tears stream down the cheek, the patient is told that
these are the wrong type of tears and one just should ignore them. If
the plugs do not stay in or are highly irritating, permanent closure of the
puncta could follow.
It is a mistake to view the plugs as a panacea for dry
eye discomfort. Usually in many dry eye patients the tear volume is
sufficient if only the tear film can be made more stable. Plugging all
four of the puncta is especially disadvantageous because it blocks all tear
drainage except through evaporation. The palpebral fissure becomes
filled with a shallow stagnant pool of tears where the decomposing epithelial
cell debris slowly accumulates.
Slide 23: What about lipid ointments?
In addition to the punctal plugs the use of
ointments in the eye also belongs to this category. We have already
mentioned their use to prevent nocturnal lid adherence due to lack of
lubrication. Due to the importance, we repeat our warning here.
Ointments consist of apolar lipids which are intensely hydrophobic.
Smearing ointment over the ocular surface could not possibly improve tear film
instability and the mucin layer cannot possibly mask such a large amount of
lipid. Blurry vision often results. The only reason, the use of ointment
at night does not result in a complete fiasco is its complete lack of
polarity. It cannot spread over hydrophilic surfaces and therefore it is
not a tenacious contaminant. Still, it is wise not to rely on ointments
in managing dry eye symptoms as it presents another obstacle to the tear film
system attempting to form a continuous tear film over the ocular surface.
While various oils often serve as lubricants in
machinery, in the human body, almost exclusively aqueous macromolecular
solutions serve such a purpose, such as synovial fluids in joints. The
lubricant for the relative movement of the lid and the globe is also an
aqueous (tear) layer. Attempting to prevent contact adhesion with heavy
doses of mineral oil and other nonpolar lipids) ointments interfere with
lubrication as well as with visual acuity.
Slide 24: Stimulation of Tear Secretion:
Secretagogues have been used
in Europe for several decades but their use has not spread to the American
market. With some stretch of the imagination, cyclosporine-containing
drops (Restasis from Allergan) could be placed in this category. The
most interesting such drug in Europe was eledoisin which at first was prepared
from the salivary gland of the Mediterranean octopus and actually one patient
in the survey from Italy has been treated with eledoisin as well as sodium
hyaluronate solution.
Hydrochloric salt of
pilocarpine (an anti-glaucoma medication) also induce tearing when taken
orally. It is quite toxic so this drug is rarely used for such a
purpose.
Slide 25: Efficacious Artificial Tears:
The important properties
expected for efficacious artificial tears or ophthalmic demulcents are shown
on this slide. We regret to state that none of these properties
can be found in the commercially available OTC collyria. Hydrogen
carbonate buffer (highly unstable), low electrolyte content, lack of
preservative, or peroxide preservatives, gel form, and high viscosity are the
components or the properties touted.
Slide 26: Aqueous Pharma Eye Drops
The properties judged important
for efficacy, however, can be found in the eye drops of Aqueous Pharma; Dwelle®,
Dakrina®, FRESHKOTE™ and REDKOTE™. The most important parameter, the
wetting synergistic polymer combination is found in all four artificial tears.
They all also have low viscosity to enhance lid lubrication and decrease shear
forces at the vulnerable ocular and tarsal surfaces. The first three of
the drops contain high (>50 mmHg) oncotic pressure for healing damaged
epithelial tissues. Dakrina® contains vitamin A to improve mucin
deficiency, and FRESHKOTE contains lipids for eyes that have lipid
abnormality. REDKOTE™ contains vitamin B12 to promote healing of the
ocular surface.
Slide 27: The Iatrogenic Dry Eye
From the aforesaid it should be clear that the physiology
of the lacrimal system and the pathophysiology of the dry eye are poorly
understood by the profession and management of dry eyes more relies on
tradition and fads than sound science. It took considerable courage
(ignorance may be a bliss) to do penetrating intervention in the delicate and
complex cornea to change its refractive properties without considering the
complications that directly result from refractive surgery. It turned
out that one of the major (albeit often temporary) complications for all the
various surgical procedures was the dry eye.
When up to 50% of post-lasik patients ended of with dry
eyes for considerable time periods, the unexpected complication found the
surgeons and their assistants unprepared. Often optometrists had
to be engaged to take over the postoperative care of this numerous and serious
complication. Due to the complex nature of the disease and the lack of
information on iatrogenic dry eyes, even today there is no agreement as to the
diagnostic methods applied and the treatment modalities employed. Often
inadequate methods were for the treatment of this complication due to the
unfamiliarity of this admittedly complex disorder.
Early this year of 2002, with the support of Surgical
Eyes Foundation, a patient advocate group, an informally organized project
started where the patients were encouraged to manage their dry eyes
complication along the sound physiological principles discussed above.
Their attending eye care professionals were encouraged to co-operate wherever
it was feasible. Physiologically sound modern eye drops were made
available to patients from a compounding pharmacy through arrangements made by
the owner of the drops, Aqueous Pharma, Ltd. to manage their
laser-damaged eyes.
Slide 28: Surgical Eyes Foundation, Dry Eye Institute, & Aqueous Pharma
Many of these ideas resulted form an unusual clinical
study through cyberspace, via the participation of many devoted and motivated
leaders and members of Surgical Eyes Foundation, a web-based organization
with the co-operation of the Dry Eye Institute, many of the eye care
professionals in charge of the recuperating patients, and Aqueous Pharma which
made the drops available through a compounding pharmacy.
Slide 29: Rational Approach to Post-lasik Dry Eye Management
This approach excluded haphazard and harmful treatment
modalities that they are in vogue in the treatment of post-lasik patients,
such as use of ointments, use of antibiotics for sterile inflammation, use of
steroids when the inflammation was from the direct result of poor tear film
stability, and the too frequent use (flooding the ocular surface) of otherwise
benign eye drops, and the discontinuation of highly viscous drops and gels.
Depending on the diagnosis of the patients and her symptoms, the proper
Aqueous Pharma drop or a combination of such drops were recommended.
Feedback from the patients was very helpful in deciding the type of drops used
and their schedule.
Slide 30: Results obtained with Surgical Eyes Foundation Members
After six months of this open
study where more than 200 patients participated, a polling of these patients
took place. The participants were asked whether the following statement
was “TRUE”, “FALSE or they were “UNCERTAIN” whether
it was true or false: The statement was:
“At least some of
these (Aqueous Pharma) drops helped my conditions more than other regimen(s) I
have tried.”
Slide 31: Efficacy of Aqueous Pharma Drops
in Post-Lasik Patients (N=48)
Almost 80% answered “TRUE”, out
of 50 patients who participated in this poll. The records kept for over
two hundred patients showed that at least that many responded with enthusiasm
and renewed hope to these drops. There were exceptions, but by following
up with most patients who first did not seem to respond well, the cause often
could be found and corrected. We can probably safely assume that by avoiding
the present trial-and error approach to managing of post-Lasik dry eyes, and
with further education of the doctors in the diagnosis and treatment of the
iatrogenic dry eyes (cf. the next two slides) even better results could be
achieved in the future.
The basics of tear film physiology were explained to the
highly motivated patients some of whom felt abandoned by their surgeon or the
designed optometrist. One requirement developed during the study:
In order to get the best results they should, on their own, wean themselves
away from treatment modalities that may adversely affect their eyes and
interfere with the efficacy of the Aqueous Pharma eye drops
Thus the use of ointments was
discouraged. In severe justified cases other methods were suggested.
The Dry Eye Institute handled the task of making the formulations available
and providing information for the effective use of the eye drops and other
aids. Volunteer doctor members were always available to provide a
sympathetic ear and general counsel.
The patient members kept
diaries on their daily progress and periodically were followed by their own
doctors. This unusual - to say the least - open study with motivated but
highly skeptical patients and volunteer doctors have been going on for almost
a year. Nearly 300 patients were involved during this time period.
At the end there was an anonymous poll where over 50 patients expressed their
opinion.
Many Surgical Eyes members have
tried all three types of eye drops unless their condition was severe enough so
that they started on Dwelle7
and continued later on Dakrina7.
Again a high percentage of the members did well, especially when they managed
to wean themselves away from ointments and other drops. Some did well on
REDKOTE7 only.
More made good progress on the Dakrina7/REDCOTE7
combination. When stuck eye lids were a problem, REDKOTE7
at night and Dakrina7
day time provided a better solution.
Some members tried Dwelle7
and Dakrina7 (one in
one eye and the other in the contra-lateral eye) and found no difference.
Several others did find a difference. Those participants of the latter
group probably had some goblet cell deficiency after surgery.
Occasionally some patients
reported stinging and lack of progress. Most of these cases the cause
was found to be chemical keratitis due to over-frequent use (dosing) of
artificial tears. In such cases better results were later obtained when
other drops and ointments were discontinued and the Aqueous Pharma drops were
used at least for two weeks. Some members had to be warned about not
using eye drops too frequently as that can lead to ocular surface leaching.
Sometimes infrequent blinking or incomplete blinking was also a problem which
was resolved once the patient started to consciously blink correctly and used
eye cover for the night.
Some laser clinics also did their own informal studies.
They were one TLC Clinic in Michigan and another TLC clinic in Toronto,
Canada. The Dry Eye Institute also undertook the supplying of these
drops to patients who requested them and followed their progress.
The TLC Clinic (in Toronto) found that 85% of their
postoperative problem patients benefited more from these drops than the
previously used regimen, even though this clinic was not in favor of using
ointments. They found that the most universally efficacious eye drop has
been Dakrina7.
They have not included FRESHKOTE in the study as this drop at that time was
not yet available.
There have been some indications that the Dwelle7
and Dakrina7
work better in certain eyes if not all four puncta are plugged. Under
such conditions the tear volume exchange is prevented but the evaporation is
not. The tear film and its surrounding tear menisci become stagnant like
a shallow pond with no outlets and that is not the best condition for the
underlying ocular surface attempting to recover.
In the following two slides I
attempt to summarize the diagnostic methods that can be helpful in diagnosing
dry eye states and also to summarize the treatment modalities that have been
found helpful in iatrogenic dry eye patients.
Slide 32: Management of Iatrogenic Dry Eyes:
diagnostic methods
.
Nine different tests suggested
starting with a thorough slit-lamp examination. It takes
practice, but even this basic method leads clues to the existence and the type
of the dry eye state in patients. Fluorescein staining
combined with blue cobalt filter make the tear film visible, shows
up local thinning and rupture, and also recurrent erosion as well as frank
epithelial defects, especially if the stroma is exposed.
Tear film break-up time is an important parameter especially if it is done
by noninvasive methods. This is a direct measure of tear film
stability/instability and is believed to be one of the major causes of dry
eyes rather than insufficient lacrimation ability. Uneven or scanty
tear meniscus usually warrants the placement of temporary plugs in the
puncta starting with two. Corneal sensitivity is easy to measure
and should be followed in each such patient. Lacrimation ability
by Schirmer test can be useful if one understands the intricacy and actual
meaning of the measurement. The pattern of vitals staining of
cellular damage is a classical way of determining the degree of cellular
damage and the progress of the disease or its reversal during treatment.
Lack of goblet cells would indicate mucin deficiency. The lid
functioning, its frequency and completeness as well as lipid-globe
continuity are all important. Sleeping with inadequately closed lids
invariably lead to complications including contact adhesion and recurrent
erosion.
Slide 33: Management of Iatrogenic Dry Eyes:
treatment modalities
.
This slide summarizes the four major approach to the
management of dry eyes. These have been discussed in the body of the
presentation. Supplementation of tears by tear substitutes is the most
common way of handling such problems but the type and formulation of such eye
drops are important. They not only have to be able to form a thin
continuous film for visual activity’s sake, but also have to be able to
provide for hydrodynamic lubrications.
The other two types of approaches; the Preservation and
Stimulation of Tears are also briefly discussed. The use of ointment in
desperate cases may be justified but then one sacrifices gentle lubrication as
well as visual acuity.
Conclusions
Xerophthalmia, keratoconjunctivitis sicca, and other
manifestations of ocular surface disease have plagued humanity since
antiquity. Initially, and still in underdeveloped countries, poor
diet and lack of hygiene greatly contributed to the prevalence of this
disease. In modern times and industrial nations, the number of dry eye
patients is again increasing. Occupations and recreation requiring
prolonged continuous staring at near-by objects, especially monitor screens,
put additional strain on the eyes which are often in a polluted environment.
During the last decade another type of dry eye surfaced,
the iatrogenic dry eye, which is caused by or aggravated by refractive
surgery. While the causes are not exactly known and cannot always be
prevented, a consideration of the complexity and delicacy of the lacrimal tear
system will certainly result in the finding of some likely causes.
While the more serious post-
surgical complications possibly occur in only 3-5% of the cases, dry eyes
plague possibly up to one-half of surgical patients after refractive surgery!
We have only addressed here this most frequent complaint.
Dry eyes are hard to diagnose and it usually takes many
continued education hours and years of experience. Many refractive
surgeons, spending most of their time doing the surgical procedures, have
neither the time nor the expertise to do effective follow-up of their surgical
patients. Co-management with an optometrist well-versed in the
intricacies of the lacrimal system which directly affects contact lens
tolerance could have its advantages.
Our study strongly suggests that the present treatment
modalities in vogue are not the best for improving the dry eye states in post
surgical patients and healing their damaged epithelial surface. This is
especially true, since some of the present approaches violate the basic tenets
of tear film physiology. The use of ointment that interferes with the
wettability of the ocular surface, high viscosity drops that can damage the
already weakened epithelium, and hypertonic drops in an eye that has a damaged
(and therefore osmotically leaky) epithelium are but a few examples that
should be avoided when managing post-lasik dry eyes.
Slide 34:
Remind your patients: Please remember to blink
frequently and completely!
Acknowledgements
As the President of the Dry Eye Institute, I am honored
that our Institute could play a positive role in helping to diminish suffering
in patients with iatrogenic dry eyes, at least in some of the cases, and
improve vision in others. I am grateful to Ron Link, the Executive
Director of Surgical Eyes Foundation, for his relentless support, and also to
Joe Echols, the CEO of Aqueous Pharma, who made arrangements through a
compounding pharmacy to formulate these drops and making them available for
the patients.
Some of the patients provided
persistent moral and logistic support to others, myself included. These
are well represented by Cindy Brunett and several others. Sandy Keller
provided the list of post-surgical complications to the various types of
refractive surgery. There are also eye care professionals, Dr. Mason and
others who have shown tremendous support throughout the study, by conducting
their own clinical trials and encouraging patients when the going got tough.
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