Home' Trinidad and Tobago Guardian : March 13th 2015 Contents Friday, March 13, 2015 www.guardian.co.tt Guardian
G A celebration of World Glaucoma Week 2015.
Ms SALalchan MBBS, FRCOphth(Lond), CCT (Lond)
International Ophthalmologist Education Award (American Academy of Ophthalmology)
Your EYES are ORGANS just like your HEART.
Think of living life without them,
Get them checked by a Consultant Ophthalmic Surgeon.
Glaucoma is the world's leading cause of irreversible blindness with an
estimated 70 million people affected, 10% of who are blind. It is a
neurodegenerative disease which, to date, the only modifiable risk
factor remains the intra-ocular pressure. gly, ninety (90%) of patients in
the developing countries are undiagnosed.
Glaucoma-related blindness in the Caribbean is an eye opener.
Patients in the Caribbean have one of the highest reported rates
of glaucoma. Barbados Eye Study clearly demonstrated higher risk in
Afro-Caribbean ethnicity compared to Caucasians. Persons over the age
of 50 yrs, 1 in 11 had glaucoma and over the age of 70yrs this
increased exponentially to 1 in 6. Glaucoma occurs 10 years earlier; it
is more aggressive; demonstrates greater progression; and is less
responsive to treatment in populations such as ours.
Diagnosing Glaucoma by an Ophthalmic Surgeon/Ophthalmologist
The NICE (National Institute for Clinical Excellence- UK) Guidelines
advocates the role of the Consultant Ophthalmologist in definitive
diagnosis and formulation of treatment strategy. Notably, many patients
also incorrectly believe that diagnosing glaucoma is simply 'a pressure
check' ie the intraocular pressure. This results in delayed diagnosis as
demonstrated by a local cohort with 8.9% of patients having advanced
glaucoma at presentation. This emphasises the role of a qualified
The 'glaucoma composites' is a collection of investigations that are
used to diagnose both the type and severity of glaucoma by your
ophthalmic surgeon. This term was coined by Dr Lalchan to help
patients appreciate the subtleties of early diagnosis and aid education
Glaucoma composite 1
Goldmann's Tonometry- measurement of the intraocular pressure.
Previously, it was believed that an IOP <21mmg was normal. There is
overwhelming evidence that this is no longer true. In fact, there is
evidence that 30% of POAG occurs at 'normal' intraocular pressures ie
glaucoma can and certainly does occur at IOP <21mmHg. This is
referred to as normal tension glaucoma.
This recognition has caused glaucoma specialists to realise that
individual optic nerve display varying degrees of pressure sensitivity
and clearly, IOP alone is misleading.
Glaucoma composite 2
Pachymetry- Central corneal thickness (CCT)
The Ocular hypertension Treatment Study (OHTS) demonstrated that
patients with a CCT of <555um independently had an increased risk (3
fold) of developing glaucoma.
Glaucoma composite 3
Gonioscopy- viewing of the drainage angle.
Gonioscopy allows for diagnosing the various glaucoma subtypes such
as open angle vs primary angle closure vs angle recession (traumatic
damage) etc as both the prognosis and treatment strategies are
Glaucoma composite 4
Stereoscopic view of the optic nerve
A dilated stereoscopic view and photographic documentation of the
optic nerve are important for both evaluation and objective
assessment. This has prompted the search for more objective imaging
Glaucoma composite 5
Automated visual field testing/perimetry
Up to 50% of the nerve fibre layer has to be damaged before changes
are detected. In the context of early detection and prevention of
blindness this is no longer acceptable. There is again a shift towards
diagnosing pre-perimetric glaucoma ie before 50% nerve fibre layer has
been irreversible lost.
Glaucoma composite 6
Laser-assisted imaging of the optic nerve
Optic nerve imaging modalities have been introduced that provide an
objective, quantitative analysis and serial monitoring of the optic nerve
head parameters and nerve fibre layer. These laser scanning modalities
include OCT (Optical Coherence Tomography), CSLO (Confocal
Scanning Laser Ophthalmoscopy) and HRT (Heidelberg Retinal
Tomography- scanning laser polarimery). These modern diagnostics can
increase the sensitivity and specificity to 97% in glaucoma detection.
It is important that patients appreciate the paradigm shift. It is no longer
simply 'a pressure check' by any stretch of the imagination.
GiFT urges you to take the glaucoma composite challenge,
it might be an eye opener and save your sight.
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