Excerpts From: The International Glaucoma Review, Volume
7-1, 2005:
World Glaucoma Congress
(Second in a Series From This Publication)
From the American Glaucoma Society Meeting (March, 2005)
- Physician treatment of disease is not uniform for all ethnic
groups and gender. In this study [OHTS], the authors demonstrate
that women are not treated as frequently as men for a given
level of disease. This information has ramifications for current
treatment paradigms and glaucoma suspects.
- Jeffrey Liebmann and James Brandt
M & T Commentary:
We are not sure what to make of this, except to point out that
since women generally outlive men, perhaps it is even more
important to detect and treat OHT and/or POAG in women than
men, since their optic nerves may have to be protected for
a longer period of time.
From Glaucoma at ARVO (May 2005)
- The measurement of progressive change in field is complex and
the ideal method has not yet been devised.
- Therapy for ocular hypertensives is complicated by inadequate
compliance, side-effects, and failure to take effect of quality
of life into account .
- A cost-benefit analysis suggested that treatment of ocular
hypertensives with IOP greater than 24mmHg is within the cost
range of therapies considered valuable in general medical treatment.
- The cost of saving one eye from blindness by treatment of
ocular hypertension was estimated at $800,000.
- About 1.3 million ocular hypertensives are being treated in
the United States at this time.
- Harry Quigley
- A population-based glaucoma survey in China found that POAG
was slightly more common than PACG.
- Tin Aung
M & T Commentary:
Such knowledge probably applies to Chinese-Americans as well,
so we need to be cognizant that narrow angles should be detected
and gonioscopically quantified, particularly in this special
subset of our population.
RE: 24-hours IOP
Comment by Tasos Kontas
The current day-to-day management of glaucoma often ignores
the biological rhythm inherent in the only parameter we can
currently treat, the intraocular pressure (IOP) and its clinical
implications. Since glaucoma is a 24-hour disease, it is logical
that we should aim to determine and control the IOP throughout
the 24-hour cycle. Sadly though, we generally assess the IOP
control by a single, daytime office measurement. Although the
detection and follow-up of glaucoma patients with single IOP
measurements is quick and convenient, this strategy may provide
inadequate, or even misleading information and may not reflect
the pattern of IOP characteristics before and during therapy.
It is now well established that peak IOP is often missed, and
of course IOP fluctuation cannot be determined with a single
IOP measurement. It is thus important to investigate the correlation
between office-hour IOP readings and 24-hour IOP parameters.
In an interesting and clinically relevant paper Mosaed et al.
employ a retrospective review of records from a sleep laboratory
to determine the correlation between office-hour IOP (four
readings between 9:30 and 15:30) and peak nocturnal IOP in
untreated healthy and glaucomatous eyes. Overall Mosaed et
al. find a strong correlation between supine IOP during office
hours and peak nocturnal IOP. There was no correlation between
office-hour IOP and peak nocturnal IOP in young healthy subjects,
highlighting the greater unpredictability of 24-hour IOP characteristics
in younger patients. On the other hand, the correlation between
mean office-hour sitting IOP and peak nocturnal IOP was strong
in older untreated glaucoma patients. In the same group, a
strong correlation existed between mean supine IOP readings
during office hours and peak nocturnal IOP. In these patients
there was only a small mean difference (0.4mmHg) between supine
IOP and peak nocturnal IOP. These data may help the clinician
in estimating the nocturnal IOP in their untreated glaucoma
patients. The study reiterates once again that the mean IOP
from several readings during office hours is far superior to
a single reading and suggests that employing an IOP reading
in the supine position may be helpful. Similar to other studies
in this field the question remains how relevant are these data
to the day-to-day clinical practice and how accurately the
sleep laboratory setting reflects real life glaucoma? Clearly,
it will be important to determine in the future whether these
correlations apply in other clinical settings and, as the authors
point out, we need to determine whether these relationships
are also applicable to glaucoma patients receiving medical
or other forms of therapy.
The duration and homogeneity of 24-hour IOP lowering effect
is a key characteristic of successful therapy. It may be important
to develop (just like our medical colleagues have done in the
management of arterial hypertension), suitable IOP indices
such as the trough to peak ratio, the morning to evening IOP
ratio and the smoothness index assessing the features of antiglaucoma
therapy. Nevertheless, much remains to be elucidated in this
important area.
M & T Commentary:
Interesting! It may be that one day, we will all be measuring
IOP in both supine and sitting positions as a component of
our glaucoma evaluations. Of course, this would require
all of us to have either Kowa or Perkins hand-held Goldmann
applanation tonometers in our offices.
Central corneal thickness and thickness
of the lamina cribrosa in human eyes: JB Jonas and Holbach
L. Investigative Ophthalmology
and Visual Science 2005; 46: 1275-1279
Conclusion: In nonglaucomatous human globes, central corneal
thickness may not correlate significantly with lamina cribrosa
thickness, peripapillary scleral thickness, and shortest distance
between intraocular space and cerebrospinal fluid space.
Histologic artifact and sectioning methods could partially
account for the lack of an association. The study results
may suggest clinically than an assumed relationship between
central corneal thickness and susceptibility to glaucoma cannot
explained by an anatomic correspondence between corneal thickness
and histomorphometry of the optic nerve head.
Comments by Peter Shah
Jonas and Holbach published an excellent and high recommended
histomorphometric study evaluating the relationship between
central corneal thickness and lamina cribrosa thickness in
enucleated nonglaucomatous human eyes. All eyes had been removed
because of malignant choroidal melanoma. Mean central corneal
thickness (CCT) of 616.6 ± 108.3 micrometers and mean central
lamina cribrosa thickness (LCT) 378.1 ± 117.8 micrometers were
statistically independent of each other. The study showed
that CCT did not correlate significantly with LCT, peripapillary
scleral thickness or shortest distance between the intraocular
space and cerebrospinal fluid space.
An observational retrospective cross-sectional study by Shimmyo
and Orloff aimed to determine whether there is an association
between central corneal thickness (CCT) and axial length (AL)
in a clinical setting. There was no statistically significant
relationship between central corneal thickness and axial length.
In particular the authors found that thinner corneas are not
associated with longer eyes.
This clinical observational cross-sectional study by Henderson
et al. examined the relationship between retinal nerve fiber
layer (RNFL) measurements obtained by scanning laser polarimetry
with variable corneal compensation (using the GDx VCC) and
corneal thickness (CCT) measurements in ocular hypertensive
(OHT) patients. This well-conducted study compared 44 OHT
patient with 48 healthy subjects.
Higher GDx VCC parameter nerve fiber indicator (NFI) scores,
indicative of thinner RNFL, were correlated significantly with
thinner CCT measurements in the OHT patient group. The NFI
values were not significantly different between OHT patients
with thicker corneas and healthy subjects. The authors comment
that these findings support the notion that RNFL defects as
assessed by the GDx VCC may represent early glaucomatous damage
in OHT eyes. It is important to remember that the study was
not designed to assess this possibility as a primary outcome
measure.
Comment by Anders Heijl
The paper [the Erlangen Glaucoma Register, Jost Jonas et al.]
addresses the relationship between corneal thickness and glaucoma
damage at the time of referral and with perimetric progression.
The authors find that low CCT was significantly associated
with larger damage at baseline. [This finding] is in agreement
with observations made by several other groups. I agree with
the authors that the most plausible explanation of the finding
is ‘a selection artifact’ by referring ophthalmologists. Glaucoma
patients with thinner corneas have lower pressure readings
on Goldmann tonometry, and we and many others have observed
how patients with very clear manifest normal tension glaucoma
are missed in ophthalmic practice - probably just because they
fail to raise a suspicion of glaucoma in the examining ophthalmologist
unless the discs are very abnormal. The normal tension glaucoma
patient has a good chance of (or a high risk of) being classified
as normal after a comprehensive eye examination - even if the
reason for the visit is a positive family history of glaucoma.
M & T Commentary:
As we consistently stress in our lectures, be obsessively compulsive
in your examination of optic nerve heads. If there is any
reasonable suspicion of even early glaucomatous optic neuropathy,
obtain a CCT measurement and recheck the IOP at a different
time of the day. Also, a baseline scan (GDx-VCC, OCT, or
HRT) could be helpful as well.
Comment by the IGR Editor
The role of peripapillary atrophy (PPA) in the management of
glaucoma remains intriguing. The advantage of peripapillar
atrophy over disc hemorrhages is that peripapillar atrophy
is always present. Jonas presents a review on peripapillar
atrophy in which he states that it is “among several morphologic
variables to detect glaucomatous abnormalities. It is a variable
of the second order.” It is also useful for the differentiation
of various types of glaucoma or differentiation from AION.
M & T Commentary:
While ONH hemorrhages can be a marker for progressive optic
nerve disease, we have never found PPA to be particularly
helpful in our glaucoma evaluations or monitoring.
RE: Medical Treatment
Comment by Donald Minckler
A retrospective clinic-based case series by Osborne et al.
analyzes presumed allergies due to topical or systemic medications
among consecutive patients with primary open-angle glaucoma
who reported discontinuing a drug because of allergic symptoms
during the recruitment period May 1999 through September 2001.
The authors interpret the data as indicating that brimonidine
(0.2%) among all currently utilized agents, is most likely
to cause allergic symptoms (itching follicular conjunctivitis,
chemosis, periocular dermatitis) and most importantly that
this drug predisposes and accelerates subsequent allergic reactions
to other topical agents including some timolol preparations
and dorzolamide.
Nevertheless, the conclusions highlight an important issue
in suggesting that a widely utilized glaucoma drug, long-recognized
as relatively allergenic, may accentuate or predispose to allergy
among subsequently employed agents, which by themselves are
less likely to induce allergic symptoms. The conclusions imply
that brimonidine is an immune stimulant and the clinical implication
would be to place this agent last in the trial spectrum.
Evaluation of retinal nerve fiber, optic nerve head, and macular
thickness measurements for glaucoma detection using optical
coherence tomography: Medeiros FA; Zangwill LM; Bowd C; Vessani
RM; Susanna R Jr.; Weinreb RN.
American Journal of Ophthalmology 2005; 139: 44-55
Conclusions: RNFL and ONH measurements had the best discriminating
performance among the several Stratus OCT parameters. A combination
of ONH and RNFL parameters improved the diagnostic accuracy
for glaucoma detection using this instrument.
Optical coherence tomography longitudinal evaluation of retinal
nerve fiber layer in glaucoma: Wollstein G; Schuman JS; Price
LL; Aydin A; Stark PC; Hertzmark E; Lai E; Ishikawa H; Mattox
C; Fujimoto JG, et al.
Archives of Ophthalmology 2005: 123: 464-470
Conclusions: A greater likelihood of glaucomatous progression
was identified by OCT vs automated perimetry. This might reflect
OCT hypersensitivity or the true damage identified by OCT before
detection by conventional methods.
M & T Commentary:
Once again, it is demonstrated that structural changes commonly
precede functional compromise. While scanning instrumentation
is not an absolute essential in glaucoma care, the information
obtained with these devices can help refine and quantify
diagnostic and therapeutic care. Plan to purchase one of
these as soon as practical.
Optic nerve damage in highly myopic eyes with chronic open-angle
glaucoma: Jonas JB; Budde WM.
European Journal of Ophthalmology 2005; 15: 41-47
Conclusions: At a given intraocular pressure in chronic
open-angle glaucoma, optic nerve damage may be more pronounced
in highly myopic eyes with large optic discs than in non-highly
myopic eyes. This may suggest a higher susceptibility for
glaucomatous optic nerve fiber loss in highly myopic eyes than
in non-highly myopic eyes.
Enhance postoperative filtering bleb-induced vision difficulties
with well-fitted GP contact (oxygen-permeable) lenses: Pederson
K.
Optometry 2005; 76: 115-122
Conclusion: GP contact lenses can be successfully worn in
eyes with filtering blebs. However, to reduce the risk of complication
and infection, proper fitting guidelines should be followed
and patients should return for evaluations at intervals of
6 months or less.
Subacute Angle Closure Glaucoma
Headaches as the main presenting symptom of subacute angle
closure glaucoma: Nesher R; Epstein E; Stern Y; Assia E;
Nesher G:
Headache 2005; 45: 172-176
The diagnosis of subacute angle closure glaucoma is suspected
in patients with narrow angles of the anterior chamber of the
eye, presenting with periodic ocular, or periocular pain.
However, some patients may present with headaches in the absence
of significant ocular discomfort, which often leads to misdiagnosis
and delay in specific therapy. Subacute angle closure glaucoma
should always be considered in the differential diagnosis of
adult-onset headaches.
M & T Commentary:
While excellent advice, always be sure to order a “sed rate”
in older patients with new onset HA once you have ruled out
angle closure events via tonometry and gonioscopy.
The investigation of retinal nerve fiber layer thickness in
eyes with optic nerve head drusen: Ocakoglu O.
Neuro Ophthalmology 2004; 28: 205-214
Purpose: To investigate the effect of optic nerve head drusen
(ONHD) on the retinal nerve fiber layer (RNFL) thickness.
Conclusion: We found a significant decrease in the RNFL thickness
of ONHD patients compared to that of the control subjects.
The measurement of VF indices did not show a significant difference
between various degrees of ONHD. In contrast, RNFL thickness
was significantly correlated with the amount of ONHD. This
suggests that OCT may allow the detection of early changes
in RNFL thickness in ONHD patients before observable changes
in the visual field are seen.
M & T Commentary:
Since the majority of patients with visible ONHD have visual
field defects, it is always wise to do a 30-2 visual field
on all such patients.
Nonarteritic ischemic neuropathy developing
soon after use of sildenafil (Viagra): a report of seven
new cases: Pomeranz HD; Bhavar AR.
J Neuroophthalmology 2005; 25: 9-13
Seven patients, aged between 50 and 69 years, had typical
features of nonarteritic anterior ischemic optic neuropathy
(NAION) within 36 hours after ingestion of sildenafil citrate
(Viagra) for erectile dysfunction. Six patients had vision
loss within 24 hours after use of the agent. Final visual
acuity in the affected eye ranged from 20/20 to light perception.
Both eyes were affected in one individual. All affected individuals
had pre-existing hypertension, diabetes, elevated cholesterol,
or hyperlipidemia. Seven similar cases have been previous
reported. Sildenafil may provoke NAION in individuals with
an arteriosclerotic risk profile.
M & T Commentary:
The preponderance of contemporary literature has not shown
a direct cause-and-effect relationship. The key here is that
patients with significant systemic cardiovascular disease
who have a small optic nerve head and/or a small C/D ratio
are certainly at risk for NAION, with or without the use
of any ED drug.
Compliance and persistency in glaucoma follow-up treatment:
Schwartz, GF
Current Opinions in Ophthalmology 2005; 16: 114-121
Purpose of Review: To summarize research published between
1980 and October 2004 regarding compliance (the extent to which
patients’ behaviors correspond with providers’ recommendations)
and persistency (total time on therapy) in patients diagnosed
with open-angle glaucoma or ocular hypertension; to suggest
approaches ophthalmologists [M & T: and optometrists] might
consider to improve compliance and persistency; and to identify
areas warranting future research. Recent Findings: Medication
compliance, the focus of most compliance-related research,
has been measured using a variety of methods including self-reports,
the medication possession ratio, and electronic monitoring.
Noncompliance rates of at least 25% commonly have been reported.
The primary obstacles to medication compliance appear to be
situational/environmental (e.g., being away from home or a
change in routine) or related to the medication regimen (e.g.,
side effects or complexity). Persistency with ocular hypotensive
therapies has been found to be poor. Retrospective cohort
studies using survival analyses have reported that fewer than
25% of patients are persistent over 12 months. Summary: Accurately
assessing patient compliance and persistency is important to
optimizing patient care. Physicians may mistake either medication
noncompliance or lack of persistency with poor efficacy. Such
errors would likely increase health care costs if they result
in unnecessary changes to a patient’s therapeutic regimen or
in surgery.
M & T Commentary:
The main reason we see established glaucoma patients every
three to four months is to urge them to comply and persist
with their therapy. (We also check their IOP and examine
their ONH.) Unrelenting encouragement plays a powerful role
in glaucoma patient care. Also, frequent “no-show” patients,
in our experience, are commonly “non-compliant.” Be sure
to have a system in place in your offices to monitor glaucoma
patient “no-shows.” This enhances care and defends against
malpractice.
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