Excerpts From: The International Glaucoma Review, Volume 8-2,
2006
(Sixth in a Series)
Gonioscopy
- Gonioscopy is indispensable to the diagnosis and management
of all forms of glaucoma and is an integral part of the eye
examination.
- An essential component of gonioscopy is the determination
that iridotrabecular contact is either present or absent. If
present, the contact should be judged to be appositional or
synechial (permanent). The terms ‘iridotrabecular contact’
(and number of degrees) and ‘primary angle closure suspect’
should be substituted for ‘occludable’, as more accurate. The
determination of synechial contact may require indentation
of the cornea during gonioscopy, in which case a goniolens
with a diameter smaller than the corneal diameter is preferred.
- It is desirable to record gonioscopic findings in clear text.
Describing the anatomical structures seen, the angle width,
the iris contour and the amount of pigmentation in the angle
are all desirable.
M & T Commentary
While a utopic glaucoma workup includes attentive gonioscopy,
studies of clinical practice patterns reveal that less than
50% of doctors perform gonioscopy, thus impeaching the term,
“indispensable,” to characterize this procedure. As we have
stated before, in our combined 50 years of caring for patients
with glaucoma, gonioscopy has yielded the least valuable
diagnostic information relative to all the other tests and
procedures routinely performed in a glaucoma workup. That
being true, it is still wise to include gonioscopy in your
glaucoma workup, as there are those uncommon patients for
whom these findings can be key to managing their disease.
Mechanisms of Angle Closure Glaucoma
- Angle closure may be understood by regarding it as resulting
from blockage of the trabecular meshwork caused by forces acting
at four successive anatomic levels: the iris (pupillary block);
the ciliary body (plateau iris); the lens (phacomorphic glaucoma);
and vectors posterior to the lens (malignant glaucoma).
- Although the amount of pupillary block may vary among eyes
with angle closure, all eyes with angle closure require treatment
with iridotomy.
Management of Acute Angle Closure Crisis
- Laser peripheral iridotomy (LPI) should be performed as soon
as feasible in the affected eye(s), and should also be performed
as soon as possible in the contralateral eye.
- Medical management is the recommended first step in treating
acute angle closure.
- Laser iridoplasty can be effective at breaking acute attacks
and should be considered if an attack cannot be broken by other
means.
- Primary cataract extraction may be a treatment option.
Laser and Medical Treatment of Primary Angle Closure Glaucoma
- Medical treatment should not be used as a substitute for laser
peripheral iridotomy (LPI).
- Prostaglandin analogues appear to be the most effective medical
agent in lowering IOP following LPI, regardless of the extent
of synechial closure.
M & T Commentary
This latter point is true, but it is important to recognize
that beta-blockers and alpha adrenergic agonists, such as
brimonidine, are “rapid onset” drugs and therefore are key
pharmacotherapeutic players in the quick reduction of IOP.
Certainly, the prostaglandins have the potential to ultimately
achieve the greatest IOP reduction, but these drugs may take
a day or two (at least) to achieve uveoscleral tissue remodeling
via enhancement of matrix metalloproteinase activity. Moreover,
LPI trumps medical therapy in an acute setting, and so prostaglandin
use after LPI would be an excellent treatment choice (as
would a once-daily topical beta-blocker).
Detection of Primary Angle Closure Glaucoma
- Angle closure case detection or opportunistic screening should
be performed in all persons forty years of age and older undergoing
an eye examination.
- Given the low specificity of the flashlight test, it is not
recommended for use in population-based screening or in the
clinic.
- A shallow anterior chamber is strongly associated with angle
closure.
- An acute attack of angle-closure is not glaucoma; if the optic
nerve and visual field are normal, it is only an acute angle-closure.
M & T Commentary
We think any patient with Grade II or less Van Herrick angles
should have gonioscopy, particularly when that patient is
over 40 years of age. The last bullet is right on the money;
an angle-closure attack is just that – it is not glaucoma
unless measurable damage occurs to the optic nerve. For instance,
most patients with glaucomatocyclitic crisis do not develop
glaucoma.
Risk Factors for Glaucoma
- Based on the five-year and ten-year incidence data of open-angle
glaucoma in a cohort from Blue Mountain Eye Study, the incidence
was found as 4.5% (95%Cl: 3.5~5.5) higher in females (5.6%)
than males (3.0%) increasing markedly with age. Higher IOP,
cup disc ratio > 0.5, disc hemorrhage, and reduced corneal
thickness were all associated with increasing risk of glaucoma.
Indications for Early, Aggressive Glaucoma Treatment
- Early aggressive treatment in glaucoma may be indicated when:
1. presenting IOP is high;
2. there is advanced glaucomatous damage at presentation;
3. there is an advanced rate of glaucomatous damage progression;
4. central vision loss is expected within the lifetime;
5. there are risk factors, such as advanced glaucoma in the
second eye.
- Consider ALT as a primary procedure in pigmentary glaucoma,
pseudoexfoliation, and in patients above 60 years of age.
Flashes from a Symposium on Truths and Myths in Glaucoma
- A lot of the current reasoning that certain diagnostic methods
can identify glaucoma earlier than others is more myth than
truth.
- The alleged proof for IOP fluctuations as an independent risk
for glaucoma progression is rather weak. (See the February,
2007 issue of Ophthalmology for more on this.)
- Laser trabeculoplasty is a valuable option as first choice
of therapy in open-angle glaucoma
- The interpretation of the results of clinical trials is always
a matter of opinion, and guidelines are therefore as much ‘opinion
based’ as ‘evidence based.’
M & T Commentary
Very interesting. As can be seen, a lot of what is generally
believed (or accepted) to be true is many times more opinion
than proven fact. This is just another reason to consistently
read the literature and look for enduring consensus of expert
opinion.
CCT (Central Corneal Thickness)
Since the 2002 report of the Ocular Hypertension Study (OHTS)
that central corneal thickness (CCT) was an independent and
powerful predictive factor for glaucoma, we have seen an
explosion of interest in CCT and its role in glaucoma. Investigators
have generally taken two paths. The first has been to develop
a ‘correction nomogram’ to allow the clinician to adjust
Goldmann applanation tonometry (GAT) according to CCT. The
second has been to link CCT to other parameters of the globe,
perhaps to the lamina cribrosa itself.
There is an approximate 1mmHg adjustment for each 25 micron
difference from 550 microns. It remains an open question whether
such a nomogram should be used to correct measurements in individual
patients. Several engineering models suggest that other characteristics
of the cornea (such as stiffness and viscoelastic properties)
have an impact on GAT accuracy that dwarfs CCT, that these
properties vary independently of CCT, and in fact vary with
the true IOP. Thus for two patients with central corneal thicknesses
of 635 microns, correcting IOP downwards by 3mmHg may make
sense for the individual with a thick, stiff cornea, but probably
corrects in the wrong direction for an individual with a thick,
but more flexible cornea. Applying a fixed algorithm to an
individual is fraught with problems.
In a study that measured corneal hysteresis (a measure of
the viscoelastic properties of the cornea) along with CCT and
axial length, CCT was found to be associated with the stage
of glaucoma, and lower cornel hysteresis was associated with
progressive visual field worsening.
The recent finding that CCT is among the most heritable aspect
of ocular structure, suggesting that CCT is genetically regulated,
lends credence to the idea that CCT is linked somehow to glaucoma
risk at a fundamental, biological level.
Conflicting findings and approaches as represented by these
studies are typical of early work in any new field, as we begin
to investigate potential biological links. The story of CCT
and glaucoma is just starting to get interesting!
M & T Commentary
Interesting, indeed! Recently, a woman in her 40s presented
in our office and requested a glaucoma evaluation because
her father, who lived in another state, had been told he
had glaucoma. Our examination found this lady to have CCTs
of 640, IOPs of 23, and C/D ratios of 0.2. We’d be willing
to bet her father also has thick corneas and actually does
not have glaucoma, but ocular hypertension. We hope to be
able to render a second opinion to this patient’s father
when he comes down for a visit. We believe many cases of
ocular hypertension are errantly called “glaucoma.” Remember,
it’s all about the optic nerve! Study the optic nerve. In
glaucoma, all findings revolve around the optic nerve! There’s
an intended message in our redundancy here.
Optic Nerve Health
The glaucomatous process is best recognized by the damage it
causes to the optic nerve in so-called ‘characteristic’ ways.
Valid determination of the health of the optic nerve is, then,
one of the most important and direct methods of evaluating
and managing patients with glaucoma.
Because physicians rely so heavily on the presence of ‘cupping,’
as a sign of a disc damaged by the glaucomatous process, critical
consideration of the validity of this sign is appropriate and
important. There are fatal flaws in the cup-to-disc ratio system,
however, and indeed all systems that use the width of the cup
as a measure of the presence of glaucoma damage. One of those
fatal flaws, not recognized until recently, is that the size
of the cup is strongly affected by the size of the optic disc.
Not evaluated by this study, but of equal importance, is the
recognition that small discs tend to have small cups, and that
systems that do not take this into account will also yield
misleading results when considering small discs, indicating
that discs are normal, when in fact they are acutely pathologic.
M & T Commentary
Arguably, the world’s foremost expert in the optic nerve is
Jost Jonas, of Germany. He stresses that optic disc size
need not be exactly measured, but rather a, “crude assessment,”
as to whether the disc is small, normal-sized, or large is
all that is necessary. This is an excellent point that pushes
us to become even more attentive to the optic nerve.
Non-responders to Latanoprost
How much will latanoprost lower the IOP of your prostaglandin-virgin
POAG/OHT patient and what are the chances it will do so?
Most ophthalmologists will readily (and rightly) answer ‘30%
on average’ to the first question, but you are likely to
collect a diverse set of answers to the second one. Published
studies based on differing patient groups, criteria for non-response,
and treatment durations quote non-responder (or ‘low-responder’)
rates from as low as 2% to as high as 50%.
Rossetti et al. have designed a prospective multicentric study,
enrolling 340 patients across 10 Italian teaching hospitals,
to evaluate the prevalence of non-responders to 30-day latanoprost
monotherapy among patients never exposed previously to prostaglandins;
the non-responders were subsequently enrolled in a three-arm
cross-over trial to investigate their response to timolol,
brimonidine, and pilocarpine. The proportion of non-responders,
defined as patients with an IOP reduction lower than 15% was
very low: 14 patients out of 340 (4.1%), while the proportion
of ‘high responders,’ defined as patients with an IOP reduction
higher than 40% reached 41.2% (140 patients out of 340). The
short follow-up with only one time-point beyond baseline (at
one month) did not permit evaluation of the proportion of long-term
non-responders. Still, and although it is unlikely to affect
individual clinical practice, the study sheds some new light
on the question of non-response to prostaglandins, principally
of interest to pharmacoeconomists, health authorities and the
pharmaceutical industry.
Compliance With Treatment
It is well known and unfortunate that compliance, adherence
and persistence are far from ideal in the real world. When
to treat is the topic of an ongoing discussion. The question
is often whether to treat ocular hypertension or to wait for
the earliest conversion.
Quality of Life and Visual Field Loss
Value-based medicine is the practice of medicine based upon
the patient value (improvement in length-of-life and/or quality
of life) conferred by interventions. Kobelt et al.’s recent
study found that ocular utilities diminish as vision in the
better-seeing eye decreases, a finding very similar to that
noted by other researchers. Of great interest is the fact
that Kobelt and colleagues noted visual field loss did not
correlate with utility change until the loss was far advanced.
Thus, similar to the findings of the group at the Center
for Value-Based Medicine and others, preservation of field
in glaucoma patients has not been demonstrated to improve
quality-of-life, at least not until glaucoma is far advanced.
Does this mean that treatment of glaucoma confers no or minimal
value in most cases? While this may seem so at face value,
nothing could be further from the truth. The diminution in
quality-of-life which occurs in end-stage glaucoma is so severe
that treatment confers considerable value. Even when costs
and outcomes (value gain) are discounted over the years, the
treatment remains highly valued because the end-result without
treatment is so grim.
M & T Commentary
Probably the best guide for titrating therapeutic intensity
is the RATE of visual field progression. We think many doctors
are pathologically quick to start or intensify medical and/or
laser therapy; some are diagnostically “asleep at the wheel.”
An attentive, thoughtful, non-reflexive approach to glaucoma
decision-making should be a common goal. These findings demonstrate
how little visual field loss affects quality of life.
Ocular Drug Delivery for Glaucoma
Human sclera is more permeable than the cornea to many hydrophilic
and hydrophobic drugs. Further more, the rate of diffusion
is determined by molecular mass and size. While drug diffusion
through the cornea is not very efficient, the rate of drug
diffusion through the sclera is significantly higher, roughly
equal to the cornea denuded of epithelium. Further, the surface
area of the sclera (approximately 17cm2) is a lot bigger
than the cornea (approximately 1cm2). Thus, an effective
case was made that perhaps the most compelling location from
which to deliver sustained drugs to the eye (either anterior
or posterior) may be the scleral surface.
The future for glaucoma therapies is very bright indeed. Opportunities
are being developed that aim to deliver drugs in a sustained
manner for prolonged periods of time that rely less on individual
patient administration.
Reports from Recent Studies
A study in Singapore found that optical pachymetry and ultrasound
measurement of anterior chamber depth (ACD) performed less
well than limbal chamber depth (LCD) measurement in detecting
occludable angles. LCD also gave the best performance in
detecting primary angle closure. Conclusion: LCD estimation
outperforms other methods of measuring ACD as a screening
tool for the detection of occludable drainage angles in the
Chinese population in Singapore.
The purpose of a study in London, UK, was to establish whether
the effect of improved glaucoma detection in the community
suggested by an intervention study is maintained when intervention
is extended to include all optometrists in the area. Methods:
Optometrists in the Ealing, Hammersmith, and Hounslow areas
were invited to ongoing training sessions following completion
of an intervention study. The number of optometrist initiated
referrals to Ealing Hospital Eye Clinic (EHEC) for suspect
glaucoma was assessed over a 12-month period. Results: A total
of 376 new referrals for suspected glaucoma were assessed at
EHEC during the 12-month period of data collection. Conclusion:
The rising number of new referrals for glaucoma together with
maintenance of the positive predictive value suggests an impact
on the number of new cases of glaucoma detected in the community.
We believe the next step is to perform the study in an alternative
location to see if the effect is repeatable elsewhere. If proven
to be the case, there is a coherent argument for widespread
adoption of this strategy to improve glaucoma case finding.
M & T Commentary
What in this world were these optometrists doing before “ongoing
training sessions” in glaucoma detection? Are not ALL optometrists
around the world trained to at least detect glaucoma? We
are not quite sure what to make of this. Sounds fishy to
us!
In this study, Bromen et al. sought to measure the impact
of central corneal thickness (CCT), a possible risk factor
for glaucoma damage, and corneal hysteresis, a proposed measure
of corneal resistance to deformation, on various indicators
or glaucoma damage. Glaucoma Service underwent measurement
of hysteresis on the Reichert Ocular Response Analyzer and
measurement of CCT by ultrasonic pachymetry. In multivariate
generalized estimating equation models, lower corneal hysteresis
value , but not CCT, was associated with visual field progression.
When axial length was included in the model, hysteresis was
not a significant risk factor. Conclusions: Thinner CCT was
associated with the state of glaucoma damage as indicated by
CDR (cup-to-disc ratio). Axial length and corneal hysteresis
were associated with progressive field worsening.
Kaushik et al. conducted an optical coherence tomography study
to determine the correlation between retinal nerve fiber layer
thickness and central corneal thickness in patients with ocular
hypertension. Conclusion: Ocular hypertensives with CCT x 555
microns may represent patients who have either very early undetected
glaucoma or an inherent structural predisposition to glaucomatous
damage. This may in part explain the higher risk of these patients
for progression to glaucoma.
A study conducted by Oliveira et al. indicates that central
corneal thickness is not related to anterior scleral thickness
or axial length. Conclusion: this study does not support the
hypothesis that a thin CCT is a surrogate marker for abnormal
sclera or laminar thickness as an independent cause of increased
glaucoma risk.
W.C. Stewart et al. conducted a study of mean intraocular
pressure and progression based on corneal thickness in primary
open-angle glaucoma. Conclusions: This study suggests that
the reduction of intraocular pressure helps to prevent progression
in patients with primary open-angle glaucoma. However, for
patients with thinner corneas, pressure reduction may potentially
be of even greater importance to help avoid glaucomatous progression.
Harweth and Quigley’s study on visual field defects and retinal
ganglion cell losses in patients with glaucoma concluded visual
field defects based on standard clinical perimetry are proportional
to neural losses caused by glaucoma. Clinical
Relevance: The
evidence for quantitative structure-function relationships
provides a scientific basis for interpreting glaucomatous neuropathy
from visual thresholds and supports the application of standard
perimetry to establish the stage of the disease.
A study by Y. Barkana et al. looked at the clinical utility
of intraocular pressure monitoring outside of normal office
hours in patients with glaucoma. Conclusions: In glaucoma patients
with advanced disease or progression that are disproportionate
to known IOP measurements, 24-hour monitoring of IOP may reveal
a greater role for pressure-related risk for glaucoma progression
than previously suspected and may alter treatment strategies.
From their study comparing the ICare tonometer with Goldmann
the applanation tonometer in glaucoma patients, Brusini et
al. concluded: The ICare tonometer can be useful in a routine
clinical setting. The IOP readings are quite in accordance
with those obtained by GAT. The measurements seemed to be influenced
by CCT variations, and thus pachymetry should always be taken
into consideration.
L. N. Davis et al. conducted a study to evaluate the ICare
clinical rebound tonometer. Conclusion: Measurement of IOP
in normal, healthy subjects using the ICare rebound tonometer
produced a small, statistically insignificant, positive bias
when compared with the Goldmann tonometer. Intersessional repeatability
of IOP taken with the ICare is poorer than that of IOP taken
with the Goldmann tonometer, but is comparable with that of
other non-Goldmann-type tonometers currently available. For
more information on the ICare tonometer, consult their website:
www.sussexvision.co.uk/icare_tonometer.html
Shioto et al. set out to examine the distribution and determinations
of intraocular pressure in a normal pediatric population. Children
in this study had a mean age of 6.68 years, and a mean IOP
of 12.02mmHg. Conclusion: The IOP in children is much lower
than that in adults.
Fiorelli et al. wanted to see if automated perimetry (AP)
performance could be affected by exposure to Mozart. The study
group (30 subjects) underwent AP after listening to Mozart’s
Sonata for Two Pianos in D Major, and the control group (30
subjects) underwent AP without previous exposure to the music.
All subjects in both groups were naïve to AP. Results: The
study group had significantly less fixation loss, false positive,
and false negative rated compared to the controls (p < 0.05).
Conclusion: Listening to Mozart seems to improve AP performance
in normal subjects naïve to AP.
A study was conducted by Brusini et al. to assess the Humphrey
Matrix 30-2 test in detecting functional glaucomatous damage.
Conclusions: Frequency doubling perimetry (FDP) appeared more
sensitive than standard automated perimetry (SAP) in detecting
early glaucomatous visual field loss. The FDT-N-30 test showed
a slightly higher ability to detect early glaucomatous damage
in patients at risk for the development of glaucoma, whereas
the Matrix-30-2 test provided a more detailed characterization
of the glaucomatous visual field loss pattern, although it
required 30% more time.
Iacono et al. conducted a study to evaluate whether scanning
laser polarimetry with variable corneal compensation can measure
the effect of ageing on retinal nerve fiber layer (RNFL) thickness.
Conclusions: Analysis by GDx-VCC confirmed previous reports
about significant age-related RNFL thinning. However, a lower
rate per year was found, probably because GDx-VCC measurements
are much more reliable than those obtained with the previous
generation of polarimeters.
In their study, D. M. Stein et al. set out to determine the
effect of corneal drying on optical coherence tomography (OCT)
outcome. Conclusion: Corneal dryness affects OCT scan quality
and measured nerve fiber layer thickness after a short exposure
time. It is recommended to instruct those who are scanned to
blink frequently or to instill artificial tears.
S. H. Kim’s and K. H. Park’s study looked at the relationship
between recurrent optic disc hemorrhage and glaucoma progression.
Conclusion: No differences were found between the recurrent
and single disc hemorrhage (DH) groups in terms of clinical
characteristics. Recurrent DH in cases of glaucoma may reflect
more rapid optic nerve head damage progression than single
DH.
In a study by Plange et al., 51 patients with normal-tension
glaucoma (NTG) and 28 age-matched controls underwent 24-hour
blood pressure monitoring to assess their night-time blood
pressure variability. Results of the study showed that patients
with NTG had increased variability of night-time blood pressure
measurements compared to controls. Increased fluctuation of
blood pressure may lead to ocular perfusion pressure fluctuation
and may cause ischemic episodes at the optic nerve head.
Bleckman and Keuch’s study examined cataract extraction with
posterior chamber lens implantation in the treatment of acute
glaucoma. Conclusion: Primary cataract extraction including
posterior chamber lens implantation into eyes with angle-closure
glaucoma reduced intraocular pressure to normal levels, increased
visual acuity, and decreased the number of antiglaucomatous
drugs. Eyes with angle-closure glaucoma do not respond differently
to phacoemulsification and lens implantation compared to eyes
with narrow angle without pressure elevation during and after
phacoemulsification.
Rhee, Ramos-Esteban, and Nipper’s study assessed rapid resolution
of topiramate-induced angle-closure with methylprednisolone
and mannitol. Purpose: Topiramate-induced angle-closure glaucoma
(TiACG) is believed to be related to its sulfonamide moiety.
Although the exact mechanism is unknown, the time course and
constellation of symptoms are consistent with a possible inflammatory
pathophysiologic condition. Results: The combination of the
two systemic medications resulted in the resolution of the
attack with a much more rapid time course than is seen typically
for extreme cases of TiACG. Mannitol treatment alone did not
lower the intraocular pressure after 90 minutes, although improvement
was noted four hours after methylprednisolone. Conclusion:
For severe cases of TiACG that are associated with very high
intraocular pressures, the combination of mannitol and methylprednisolone
can induce a rapid improvement. Inflammation may be a component
of TiACG.
M & T Commentary
Topamax (topiramate) is a widely used systemic medicine in
the US. It is generally used for seizure disorders, migraine
HA, weight loss, and bipolar disorder. There have been hundreds
of patients who have developed bilateral, simultaneous, angle-closure
events, presumable from iatrogenic swelling/effusion of the
ciliary body. These events are treated just like routine
anatomic angle-closure events, except that a cycloplegic
agent is substituted for pilocarpine! We think the need to
use mannitol and/or IV methylprednisolone is rare, but it’s
good to be aware of such options in the event they are needed.
The Beaver Dam Eye Study sought to examine the association
between optic disc cupping and retinal vein occlusion (RVO).
Results: 58 patients in the study sustained RVO at 5 or 10
years after the baseline examination. Those sustaining RVO
were older, had higher IOP, and were more likely to have definite
or probable glaucoma at the baseline examination. The odds
of having an incident RVO increased with increasing cup-to-disc
ratio at baseline. Conclusion: Cup-to-disc ratio is a significant
predictor of risk of incident RVO.
Sijssens et al. conducted a study to identify the risk factors
for ocular hypertension and secondary glaucoma in children
with uveitis. Results: Elevated intraocular pressure developed
in 35% of children with pediatric uveitis regardless of the
form or type of uveitis during a follow-up of 5 years. Secondary
glaucoma, however, developed more frequently in juvenile idiopathic
arthritis-associated uveitis (38%) compared with other forms
of uveitis (11%) and more frequently in children with uveitis
who were ANA positive (42%) than in those who were ANA negative
(6%). Elevated intraocular pressure occurred in two-thirds
of all children within the first 2 years after the diagnosis
of uveitis. Conclusion: In children with uveitis in this series,
juvenile idiopathic arthritis-associated uveitis and ANA-positive
uveitis without evidence of arthritis are the most important
risk factors for developing secondary glaucoma.
A study by Girkin, McGwin, Jr., and McNeal was conducted to
determine if sleep apnea is associated with an increased risk
of developing glaucoma. Conclusion: This nested case-control
study does not support a large impact of sleep apnea on the
eventual development of glaucoma relative to other putative
risk factors.
The Blue Mountains Eye Study assessed the ten-year incidence
of retinal vein occlusion (RVO) in an older population. Results:
The cumulative ten-year incidence of RVO was 1.6%. Age was
significantly associated with the incidence of RVO. Conclusion:
Older age (x 70 years), increasing mean arterial blood pressure,
and atherosclerotic retinal vessel signs were significant predictors
of incident RVO.
A study by Banes et al. reported in the British Journal of
Ophthalmology 2006 shows agreement between optometrists and
ophthalmologists on clinical management decisions for patients
with glaucoma. Background/Aims: Although optometrists have
become an accepted part of the team in many hospital glaucoma
clinics, their decision making ability has not been assessed
formally. This study aims to document the accuracy and safety
of clinical work undertaken by optometrists in the hospital
setting by investigating their management decisions on follow
up of patients with glaucoma. Conclusion: Agreement between
optometrists and consultants, in glaucoma clinical decision
making, was at least as good as that between medical clinicians
and consultants. Within an appropriate environment, optometrists
can safely work as part of the hospital glaucoma team in outpatient
clinics.
M & T Commentary
This observation flies in the face of optometric performance
discussed earlier in this sixth review of glaucoma literature.
We are certainly not surprised that optometrists and ophthalmologists
perform similarly. We’re talking glaucoma here, not rocket
science. Really. Just how hard is it to diagnosis and treatment
glaucoma?! Next, we would like to see an objective assessment
of the “decision making ability” of the ophthalmologists.
Just in case anyone gets arrogant, let’s remember that in
the US, optometrists AND ophthalmologists fail to diagnosis
glaucoma about half the time. We truly have no explanation
for this except inexcusable inattentiveness!
The purpose of a study by S. C. Carroll et al. was to summarize
the current practice styles and patterns associated with glaucoma
management in ophthalmologists of Australia and New Zealand
as derived from a survey. In 69%, the first-line drug class
of choice was a prostaglandin analogue. New Zealand ophthalmologists
favored beta-blockers as their first-line agent because of
cost, government restrictions, and familiarity. Most respondents
stated, ‘hypotensive efficacy’ as the most important factor
in class choice. -2-agonists, carbonic anhydrase inhibitors,
and miotics were considered second-line agents because of side
effects and lack of hypotensive potency. Conclusions: The choice
of first-line agents for the treatment of glaucoma differed
between Australian and New Zealand ophthalmologists in part
as the result of government restriction of prostaglandin-class
drugs. Practice patterns seen in Australia parallel the current
evidence-based reported in peer-reviewed literature.
This same study found that New Zealand ophthalmologists proceeded
to surgical management of glaucoma earlier than did their Australian
colleagues. SITA-Standard 24-2 was the most commonly used modality
of perimetry, and was favored by glaucoma specialists. Conclusions:
Although substantial consensus was found in most areas of treatment,
a few areas showed diversity. The information gathered will
enable ophthalmologists to compare their own practices with
those of their colleagues. In addition, this survey provides
a baseline allowing future trends in management to be determined.
M & T Commentary
The New Zealand government needs to get a grip! A lot of these
expensive trabeculectomies could likely be prevented (or
postponed) if prostaglandin drugs were appropriately employed.
The Japanese Journal of Clinical Ophthalmology 2006 reports
on a study conducted by Kobayashi et al. on the current status
of topical medication by glaucoma patients. Conclusion: Eyedrops
are more correctly used by glaucoma patients with more advanced
visual field defect. Improved awareness of glaucoma may result
in better compliance.
M & T Commentary
We suppose that perhaps there is a direct relationship between
the threat of blindness and attentiveness to compliance.
Another study reported in the Japanese Journal of Clinical
Ophthalmology 2006 was devised by Inoue et al. to evaluate
ocular hypotensive effect and comfort before and after switching
0.5% timolol gel-forming solution to levobunolol once daily.
Conclusion: There was no difference in IOP before and after
switching timolol to levobunolol up to three months. Ocular
comfort was better while using levobunolol than timolol gel-forming
solution.
M & T Commentary
It was established many years ago that traditional solutions
of timolol and levobunolol perform as well as the “gel-forming”
brands of the same medications. The solutions are much less
expensive. We sincerely wonder why anyone prescribes these
expensive gel-forming brands.
The Latanoprost-Induced Iris Pigmentation Study Group sought
to determine the incidence of latanoprost-induced increase
in iris pigmentation in Japanese brown iris eyes by identifying
changes in a series of iris color photographs. Conclusion:
Latanoprost instillation for at least 1 year induced increased
iris pigmentation in approximately 50% of the treated Japanese
eyes, which is a considerably higher percentage than that reported
in Caucasians.
The American Journal of Ophthalmology 2006 includes a report
on a study by A. J. Sit et al. to assess the sustained effect
of travoprost on diurnal and nocturnal intraocular pressure.
Conclusions: IOP lowering effect after omission of one to two
doses of travoprost is attenuated in the diurnal period but
sustained in the nocturnal period, the time corresponding to
the highest baseline habitual IOP.
M & T Commentary
While something that not all patients may need to know, the
prostaglandins tend to control IOP for two or three days,
and perhaps longer. Therefore, missing a drop periodically
will likely have no significant consequences to patients.
B. V. Kharod et al. reported in the Journal of Glaucoma 2006,
on their study of the effect of written instructions on accuracy
of self-reporting medication regimen in glaucoma patients.
At the end of their visits, patients were given a written chart
describing their ophthalmic medications, frequency, and dosage.
Conclusion: the education level of the patient and the number
of medications showed direct correlation with the patient’s
ability to report medications accurately. Patients showed improvement
in accuracy of reporting medications when given written instructions
about their regimen, regardless of their level of education
or number of medications.
Also reported in the Journal of Glaucoma 2006, is a study
conducted by I. McIlraith et al. on selective laser trabeculoplasty
as initial and adjunctive treatment for open-angle glaucoma.
Conclusion: Selective laser trabeculoplasty was found to be
equally efficacious as latanoprost in reducing intraocular
pressure in newly diagnosed open-angle glaucoma and ocular
hypertension over 12 months, independent of angle pigmentation.
Nonsteroidal anti-inflammatory therapy had similar efficacy
to steroids after laser therapy. These findings support the
consideration of selective laser trabeculoplasty as a first-line
treatment for newly diagnosed open-angle glaucoma or ocular
hypertension.
M & T Commentary
Both Argon laser trabeculoplasty and SLT provide a very similar
IOP-lowering effect. There is a lot of hype surrounding SLT,
and it is a good technology, but Argon laser trabeculoplasty
provides a very similar therapeutic effect.
The British Journal of Ophthalmology 2006 reports from A.
M. Morley’s and I. Murdoch’s study on the future of glaucoma
clinics. The number of patients seen with glaucoma-related
pathologies is predicted to increase significantly over the
next few years as a result on an ageing population, increased
optometric screening, and raised public awareness, In addition,
the recent glaucoma literature proposes more aggressive management
of ocular hypertension, open-angle glaucoma, and narrow angle
pathologies. This will overburden many glaucoma services and
demands a reappraisal of current management strategies. They
also suggest a range of strategies aimed at streamlining glaucoma
clinics. Examples include shared care schemes, multidisciplinary
teams, clinic guidelines/protocols, and alteration of clinic
review times. The predicted effect of such schemes on clinic
workloads is discussed, together with any existing validation.
M & T Commentary
“Increased optometric screening” may contribute to the “overburdening”
of glaucoma physicians. We have a ready solution to this
dilemma: optometrists not only screen and diagnose, but also
medically manage glaucoma! If the O.D. community steps up
to the plate, as we can and should, the public will be well-served
– and the poor glaucoma subspecialists will be spared this
terrible “burden.”
A comparison of the effects of acute and regular exercise
on intraocular pressure in Turkish athletes and sedentarians
was conducted in a study by R. Ozmerdivenli et al. In this
study, exercise was found to lead to a fall in the IOP in both
sportsmen and those leading sedentary lives with the fall less
apparent under anaerobic conditions than under aerobic conditions.
In conclusion, therefore, it can be said that in those with
an increased intraocular pressure, regular, moderately intense
aerobic exercise rather than short-lived intense exercise could
be more useful.
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