Consensus 5

edited by Robert N. Weinreb, Paul R. Healey and Fotis Topouzis
2008. xiv and 11 tables and 57 figures, , of with 1 in full colour. Hardbound.
ISBN-10: 90 62992 188.
ISBN-13: 978-90-6299-218-8
Published by Kugler Publications.
Click here for more information on all publications in the Consensus series.

See meeting photos

Summary Consensus Points

• Is OAG an important health problem?
• Is there an accepted and effective treatment for patients with the disease
  that is more effective at preventing morbidity when initiated in the early,
  asymptomatic stage than when begun in the later, symptomatic stages?
• Are facilities for diagnosis and treatment available?
• Is there an appropriate, acceptable, and reasonably accurate screening test?
• Is the natural history of the condition, including development from latent
  to manifest disease, adequately understood?
• Is the cost of case finding (including diagnosis and treatment of patients
  diagnosed) economically balanced in relation to possible expenditure on medical
  care as a whole?
• Are angle closure (AC) and angle-closure glaucoma (ACG) important health
  problems?
• Is there an accepted and effective treatment for patients with angle-closure
  glaucoma (ACG) that is more effective at preventing morbidity when initiated
  in the early, asymptomatic stage than when begun in the later, symptomatic stages?
• Are facilities for diagnosis and treatment available?
• Is there an appropriate, acceptable, and reasonably accurate screening test?
• Is the natural history of the condition, including development from latent
  to manifest disease, adequately understood?
• Is the cost of case finding (including diagnosis and treatment of patients
  diagnosed) economically balanced in relation to possible expenditure on medical
  care as a whole?

Is OAG an important health problem?

• Glaucoma is the leading cause of preventable irreversible blindness.
• The goal of glaucoma screening is to prevent visual impairment, preserve
  quality of life and visual functioning.
• Each society should determine its own criteria, including the stage
  of disease, for the allocation of an affordable proportion of its resources
  for glaucoma care and screening.
• The prevalence of open-angle glaucoma has been determined for some populations
  of European, African and Asian ancestry
  Comment: Prevalence, incidence and
  severity data are needed still for many regions of the world.
• Long-term data show a substantial frequency of glaucoma blindness in
  some populations.
  Comment: Additional population based data are needed on
  the rates and risks of vision loss

Is there an accepted and effective treatment for patients with the disease
that is more effective at preventing morbidity when initiated in the early,
asymptomatic stage than when begun in the later, symptomatic stages?

• High-quality randomized trials (treatment vs. no treatment) and meta-analyses
  have shown that topical ocular hypotensive medication is effective in delaying
  onset and progression of open-angle glaucoma (OAG).
• Treatments are effective, easy to use, and well tolerated.
• It is not known whether postponing ocular hypotensive therapy affects
  the rate of subsequent conversion from ocular hypertension to OAG or the
  rate of progression of visual field loss once OAG has developed.
• It is not known whether the reduction in progression rate from intraocular
  pressure (IOP) lowering therapy varies according to disease stage.
  Comment: Asymptomatic disease may include early, moderate, or at times severe stages
  of OAG.
• Current evidence suggests that glaucoma therapy itself is not associated
  with a measurable reduction of quality of life.
• Patients’ perceived vision-related quality of life (VRQOL) and visual
  f unction is correlated with visual field loss, especially binocular visual
  field loss, in OAG.

  Comment: the greater the visual field loss, or the later
  the stage of the disease, the more symptomatic the disease.

Are facilities for diagnosis and treatment available?

• The resources for diagnosis and treatment of glaucoma vary worldwide.

  Comment: Many countries have insufficient facilities to provide care at
  Summary consensus points 147 present practice standards relative to developed
  countries. There is a need to identify areas without facilities to help
  plan resource allocation.

• Fewer resources are required to diagnose glaucoma at moderate to advanced
  asymptomatic stages compared to very early stages.
• Treatment of glaucoma requires facilities for regular long-term monitoring.
  There is a need to study barriers to access for glaucoma care so that available
  facilities can be used optimally

Is there an appropriate, acceptable, and reasonably accurate screening test?

• The best single test or group of tests for open-angle glaucoma screening
  is yet to be determined.
• Optimal screening test criteria are not yet known.

  Comment: Screening
  test criteria depend upon health care system, location, and prevalence of
  open-angle glaucoma (OAG).

  Comment: The sensitivity and specificity of tests
  for population-based screening are unknown, as most have been tested only
  on selected groups, not populations.

• Diagnostic test accuracy may vary according to the severity of the disease.
• The tests available and effective for case-finding are not necessarily
  the same as those for population- based glaucoma screening which requires
  a very high specificity to be cost-effective.
  Comment: Screening requires
  a test with a high specificity. Diagnosis requires a test with a high sensitivity.

  Comment: Individuals at high risk require highly accurate tests.

Is the natural history of the condition, including development from latent
to manifest disease, adequately understood?

• Open-angle glaucoma (OAG) incidence rates are known for untreated and
  treated patients with ocular hypertension.
• OAG progression rates vary greatly among patients.
  Comment: More research
  is required to determine the extent and basis of progression rate variation.
• Progression event rates for patients (in clinical trials, under clinical
  care or observation) in terms of percent of patients/eyes progressing per
  year are available both for OAG and ocular hypertension.
• Progression data expressed as rate of disease progression (i.e., expressed
  in dB/year or in % of full field/year) are very sparse.

Is the cost of case finding (including diagnosis and treatment of patients
diagnosed) economically balanced in relation to possible expenditure on medical
care as a whole?

• The best evidence to date, based on two modeling studies, suggests:
  1. Screening of high-risk subgroups may be more cost-effective than screening
     the entire population. 148 Summary consensus points
  2. Screening may be
     more cost-effective as glaucoma prevalence increases
  3. The optimal screening
     interval is not yet known
  4. Screening may be more cost-effective when initial
     assessment is a simple strategy that could be supervised by non-medical
     technicians.

  Comment: More research is needed for the implementation of
  the best screening program for glaucoma.
  Comment: Expert consensus is required on how cost data should be collected and reported in glaucoma care. This
  includes reporting visually relevant outcomes on a per-patient basis.
  Comment: Additional data are required to develop a glaucoma disease staging system
  based on disability.

• Population-based screening studies are required to determine optimal
  screening strategies and their cost-effectiveness.
• Multi-eye disease screening needs to be evaluated as to whether it would
  be more cost-effective than glaucoma-only screening.

Are angle closure (AC) and angle-closure glaucoma (ACG) important health
problems?

• Primary angle-closure glaucoma (PACG) accounts for approximately 25%
  of all glaucomatous optic neuropathy worldwide, but 50% of bilateral glaucoma
  blindness.
• Visual impairment from primary angle closure (PAC) and PACG can result
  from ocular damage other than glaucomatous optic nerve damage (e.g., corneal
  decompensation, cataract, ischemic optic neuropathy).
• Some Asian populations have a high prevalence of advanced angle-closure
  glaucoma.
• PACG is predominantly asymptomatic.
• PACG is a problem of sufficient magnitude that public health intervention
  should be evaluated.

Is there an accepted and effective treatment for patients with angle-closure
glaucoma (ACG) that is more effective at preventing morbidity when initiated
in the early, asymptomatic stage than when begun in the later, symptomatic stages?

• Angle closure is a progressive condition that can lead to glaucoma.
• Iridotomy or iridectomy is the preferred initial treatment for cases
  of PAC and PACG.
  Comment: Iridotomy or iridectomy eliminates pupillary block.
• There is no evidence to support medical treatment alone for PACG in
  the absence of iridotomy or iridectomy.
• Medical treatment may be indicated for lowering IOP after iridotomy
  or iridectomy, following risk assessment.
  Comment: Research is needed to
  determine whether a residual increase in IOP following iridotomy or iridectomy
  requires treatment
• Iridotomy or iridectomy will not always alleviate irido-trabecular apposition
  since mechanisms other than pupillary block may be present, such as plateau
  iris or phacomorphic angle closure.
  Comment: Peripheral iridoplasty may
  be effective in further opening the angle and preventing further closure.
  Unlike iridotomy or iridectomy, peripheral iridoplasty sometimes needs to
  be repeated.
• There is good evidence that preventive iridotomy or iridectomy will
  eliminate the risk of acute angle closure when performed on the fellow eye
  of patients who have experienced acute angle closure.
• There is insufficient evidence for deciding which PACG patients should
  undergo lens extraction alone (without trabeculectomy).
  Comment: Lens extraction
  alone may be considered in eyes with mild degree of angle closure (less
  than 180º of PAS), mild optic nerve damage/ visual field damage or those
  that are not on maximum tolerated medical treatment.

  Comment: There is limited evidence for recommending lens extraction alone in eyes with mild PACG.
  Similarly there is limited evidence for recommending lens extraction alone
  in eyes with more advanced PACG.
  Comment: Published studies to date have
  been non-randomized, with small sample sizes and short follow-up.

• Although commonly performed, there is limited evidence about the effectiveness
  of combined cataract extraction and trabeculectomy in eyes with PACG.
  Comment: There is a need for studies comparing this form of surgery with separately
  staged cataract extraction and trabeculectomy.

Are facilities for diagnosis and treatment available?

• There is a need for a systematic assessment of the clinical capacity
  to identify and treat angle closure (AC).
•  Gonioscopy is essential for diagnosis and treatment. Comment:
  Inadequate clinical training and limited use of gonioscopy are major obstacles
  to successful case finding.

Is there an appropriate, acceptable, and reasonably accurate screening test?

• There is evidence that limbal anterior chamber depth (LCD) may be an
  appropriate screening test for angle closure.
  Comment: Using a LCD of 25%
  corneal thickness as a cut-off all those cases falling below this level
  would require gonioscopy. Approximately 4% of occludable angles may be missed
  by this method.
  Comment: More research is required concerning alternative
  screening tests.
  Comment: A screening test should not be used as a substitute
  for definitive diagnosis. 150 Summary consensus points
• Clinic-based case-detection should target established primary angle
  closure (PAC) and primary angle closure glaucoma (PACG) as blindness can
  still be prevented when interventions are implemented at these stages.
• Comment: The evidence supporting early detection and prophylactic treatment
  of primary angle closure suspects (PACS) is limited at present and cannot
  be justified where prevalence of PACS is high.
• Gonioscopy is the current gold standard of angle examination and is
  the appropriate test for diagnosing angle closure.
  Comment: Gonioscopy alone may not be suitable as a screening test.
  Comment: Gonioscopy combined with optic disc examination and intraocular pressure measurement may enable optimum
  detection of PAC, PACG and open angle glaucoma (POAG) in a clinic setting.
• For accuracy of clinic-based case detection of PAC/G improve, there
  needs to be a significant increase in the level and use of gonioscopy and
  disc examination training for ophthalmologists.

Is the natural history of the condition, including development from latent
to manifest disease, adequately understood?

• An episode of symptomatic acute angle closure (AAC) places the unaffected
  fellow eye at high risk of a similar fate.
• The current best estimate for progression from primary angle closure
  suspect (PACS) to primary angle closure (PAC) or PAC to primary angle closure
  glaucoma (PACG) is approximately 20-30% over 5 years.
  Comment: The data
  on the natural history of PACS/PAC/PACG are sparse and would benefit from
  confirmation in further studies.
• Asymptomatic angle closure is associated with later presentation and
  more advanced loss of vision than symptomatic angle closure where facilities
  for treatment are readily available.

Is the cost of case finding (including diagnosis and treatment of patients
diagnosed) economically balanced in relation to possible expenditure on medical
care as a whole?

• In assessing the cost-effectiveness of a screening program for angle
  closure and angle closure glaucoma, we must consider fully the costs and
  benefits of the program.
• Evaluation must consider the perspective of the decision maker, the
  incremental cost of the proposed program versus current programs and how
  we measure effectiveness.
• A thorough cost effectiveness analysis is not possible at present.
  Comment: In order to determine the cost-effectiveness of screening for primary angle
  closure (PAC)/primary angle closure glaucoma (PACG) we will need to be able
  to define clearly key elements of the screening process and the potential
  benefits of screening.