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Glaucoma FAQ section
Juvenile open-angle glaucoma PDF Print E-mail
Written by Administrator   
Wednesday, 13 January 2010 18:48

Juvenile open-angle glaucoma (JOAG) is a rare, often inherited condition affecting 1 in 10,000 babies. It develops after the 3rd year of life and is therefore seen in older children and adolescents. It is characterized by underdevelopment of the outflow channel of the eye (anterior chamber angle). The fluid (aqueous humour) produced behind the iris, is unable to drain through the sieve-like structure (trabecular meshwork) back into the bloodstream, which in turn causes a raise in intraocular pressure. It is also associated with nearsightedness (myopia) where light rays come into focus in front of instead of on the retina.

There is evidence that juvenile glaucoma is caused by a genetic defect, referred to as autosomal dominant inheritance. This means that both males and females are equally affected because the gene is found in one of the autosomes (any chromosome other than X or Y); means a child of a parent found to have the gene will have a 50% chance of inheriting juvenile glaucoma. It appears to be more common in males than females, and it affects both eyes in two-thirds of children. However, the older the child is, the more likely it is that the glaucoma will affect only one eye.

Unlike congenital glaucoma, signs and symptoms of juvenile glaucoma may go undetected until problems with vision occur.  Where there is a family history of glaucoma, regular eye checks are important from a young age.

TREATMENT
Checking and treating intraocular pressure in young children is very difficult and the most effective course of treatment is surgery.

Goniotomy - A very fine needle knife is used to make a small cut in the sieve-like system (trabecular meshwork) to open up the underdeveloped channel and to allow the fluid to drain. A special lens called a gonioscope is used so the surgeon can see inside the eye. A second goniotomy may be required if the pressures does not lower sufficiently.

Trabeculectomy - It may be necessary for the surgeon to to perform this procedure to create a new drainage channel for the fluid to pass through. A flap is made over a small hole in the tough outer wall of the eye (sclera) to form a new drainage route for the fluid to leave the eye under the thinner skin covering the sclera (conjunctiva).

Tube shunt - A device called a shunt is used to create an artificial passage to direct intraocular fluid out of the eye. A common form of implant is called the Ahmed valve, which has a valve mechanism to reduce the chance of the eye pressure going too low.

Cyclodiode laser - The laser is used to reduce the production of aqueous humour by destroying part of the ciliary body where the fluid is produuced.  The laser beam travels through the white part of the eye through the surface behind the iris. Some of the ciliary body remains and less fluid will be produced to effectively lower pressure within the eye.

The surgeon may prescribe medication in the form of eye drops to help reduce intraocular pressure. Some complications can occur, such as developing a lazy eye (amblyopia); nearsightedness (myopia; detached retina, irregular cornea (astigmatism) and lens dislocation. Regular check ups are advisable, as even after effective treatment, eye pressure can creep up in later life. Of course this can still be treated, but the earlier this is identified, the more effective the treatment. If the condition is caught early, the outlook is good in round 80-90% of children affected.

nerve fibre layer scan

Scan of optic nerve -GDx scan.

Last Updated on Thursday, 21 January 2010 23:30
 
Craig Burnett Curriculum Vitae PDF Print E-mail
Written by Administrator   
Wednesday, 13 January 2010 11:29

CURRICULUM VITAE for Mr. Craig A.M. Burnett

B.Sc. (1st Hons), M.B.B.S. (London), FRCOphth

Having finished my Higher Surgical Training in Cambridge, I obtained my Certificate of Completion of Specialist Training in Ophthalmology and gained entry in the Specialist Register of the General Medical Council. I have subsequently completed a sub-specialist Fellowship in Glaucoma. I am now a Consultant Ophthalmic Surgeon & a Glaucoma Specialist.



OVERVIEW

Consultant in Ophthalmology with Special Interest in Glaucoma (November 2006 -present)

Hull & York Medical School Clinical Tutor (2007 - present)

International Glaucoma Association Research Award (Dec 2005)

Clinical Fellow in Glaucoma & Glaucoma Research Fellow (April 2005 – November 2006)

CCST / GMC Specialist Register (April/May 2005)

‘Neuroprotection in Glaucoma’ MD thesis (registered)

‘Recognised Teacher’ for MBBS degree programme (2006)

Scholarship for intercalated BSc degree course (1991)

Physiology BSc degree (with First Class Honours) (1992)

Degrees

1992 Physiology BSc (First Class Honours) including:

Neurophysiology at University College Hospital

& 1st Class Hons in research project (published)

June 1995 MBBS (London)

April 2005 – present MD (‘Neuroprotection in Glaucoma’ thesis registered)

Professional Exams

April 1997 MRCOphth (part 1)

May 1999 MRCOphth (part 2)

Feb 2000 MRCOphth (part 3) all parts on first attempt

March 2005 FRCOphth (Exit Assessment January 2005)

April 2005 Certificate of Completion of Specialist Training (CCST)

May 2005 GMC Specialist Register

AWARDS

1985-1986 US National Honor Society (scored in the 99th centile)

1991 Qualified for a Medical Research Council Award

(on basis of pre-clinical exam results)

and received a Charing Cross Scholarship for intercalated BSc

(fees waived for degree course)

2002 The Cambridge University Hospitals John Cairns Memorial

Specialist Registrar Prize

2005/2006 International Glaucoma Association Research Award

2006 Best Presentation Award at British Ophthalmic Anaesthesia Society

8th Annual Scientific Meeting, Birmingham


ELECTIVES

Feb 1994 University of North Carolina (Orthopaedics)

July/Aug 1994 Republic of China (Oroplastic Surgery with Prof Noordhoff)

June/July 1997 East Africa (Ophthalmology in Nyeri, Kenya, with

the Fred Hollows Foundation)


PUBLICATIONS

PD Clarke, DL Clift, M Dooldeniya, CAM Burnett, and NA Curtin (1995),

Effects of a-cyano-4-hydroxycinnamic acid on fatigue of isolated mouse

muscle. Journal of Muscle Research and Cell Motility 16, 611-617.

Burnett CAM, Potts MJ, Fouladi MK. Uniocular fields of fixation in thyroid eye disease

following treatment with a graded immunosuppressive regime. IOVS 1999; 40:

S25.

Fouladi MK, Burnett CAM, Potts MJ. Medical treatment of compressive optic

neuropathy in thyroid eye disease. IOVS 1999; 40: S25.

Mayer E, Herdman G, Burnett CAM, Kabala J, Goddard P, Potts MJ. Serial STIR

magnetic resonance imaging correlates with clinical score of activity in thyroid

eye disease. Eye 2001; 15: 313-318.

Burnett, C.A.M. One of the most devastating eye conditions: two case presentations of

fungal endophthalmitis. West Suffolk Hospital ejournal / issue 4; January 2002.

Burnett, C.A.M. Metastatic choroidal tumour secondary to breast carcinoma. West

Suffolk Hospital ejournal / issue 5; June 2002.

Murphy CC, Burnett CAM, Spry PGD, Broadway DC, Diamond JP.

A two-centre study of the dose-response relationship for trans-scleral diode

laser cyclophotocoagulation in refractory glaucoma. British Journal of

Ophthalmology (October) 2003; 87:1252-1257.

Niyadurupola N, Burnett CAM, Allen LE. Reversible Posterior Leukoencephalopathy

(RPLS) a cause of temporary cortical blindness. British Journal of

Ophthalmology 2005; 89 (7): 924-925.

Burnett C.A.M., Newman D. Choroidal metastases from malignant testicular lymphoma:

twenty years after orchidectomy. Submitted to Am J of Ophthal.

Shaw AD, Burnett CAM, Eke T. “A simple technique for indirect gonioscopy for patients

who cannot be examined at the slit-lamp. Br J of Ophthal 2006 Sep; 90(9): 1209.



PRESENTATIONS

Burnett CAM. Uniocular fields of fixation in thyroid eye disease. Oral presentation.

VIth International Symposium on Graves’ Ophthalmopathy ; Amsterdam: 1998.

Addison PKF, Ramsay AS, Dart JKG, Osborne SF, Burnett CAM, Jordan K.

Floaters increase after uncomplicated phacoemulsification. Paper pres.

(UKISCRS) Chester, Sept 2002 & poster (ESCRS) Rome, Feb 2003.

Burnett CAM. “A Super Model in a Blue Movie” glaucoma models & real-time neuronal

cell imaging. Speaker at Key Issues in Glaucoma Meeting; Newmarket: March 2006.

Burnett CAM, Broadway DC. The great debate - combined phacotrab vs. sequential

surgery. Bedford Study Day; Bedford: June 2006.

Tsatsos M, Burnett CAM, Broadway DC, Eke T. Local anaesthesia for cyclodiode:

sub-Tenon's vs. peribulbar anaesthesia. Oral presentation, British Ophthalmic

Anaesthesia Society; Birmingham 2006.

POSTERS

Burnett CAM, Fouladi MK, & Potts MJ. Short Tau Inversion Recovery (STIR) sequence magnetic

resonance imaging in the assessment of disease activity in thyroid eye disease.

Oxford Congress ; July 1999.

Herdman G, Burnett CAM, Mayer E, Kabala J, Goddard P, Potts MJ. STIR MRI &

thyroid eye disease. Imaging Oncology in Science ; Birmingham 2000.

Mayer E, Herdman G, Burnett CAM, Kabala J, Goddard P, & Potts MJ. Serial STIR

magnetic resonance imaging correlates with clinical score of activity in thyroid

eye disease. The Royal College of Ophthalmologists Annual Congress; 2001.

Burnett CAM, Sanderson J, Tovell V, Broadway DC. Stimulation of P2X7 receptors in human

retinal neurons causes lethal Ca2+ influx. The UK and Eire Glaucoma Society 26th Annual

Meeting, Dec 2005.

Burnett CAM, Sanderson J, Tovell V, Broadway DC. Stimulation of P2X7 receptors in a

pulsatile manner causes lethal Ca2+ overload in human retinal neurons. The

Association for Research in Vision and Ophthalmology (ARVO). May 2006.

Burnett CAM, Sanderson J, Tovell V, Broadway DC. Purinergic signalling in the retina.

The Royal College of Ophthalmologists Annual Congress; Manchester 2006.

Burnett CAM, Rai C, Broadway DC, Eke T. Sub-conjunctival local anaesthesia for

trabeculectomy surgery gives good surgical outcomes.The Royal College of

Ophthalmologists Annual Congress; Manchester 2006.

Burnett CAM, Rai C, Broadway DC, Eke T. Audit of standardised subconjunctival

intracameral local anaesthetic technique for trabeculectomy surgery. British

Ophthalmic Anaesthesia Society Meeting; Birmingham 2006.

Julie Sanderson, Craig A.M. Burnett, Victoria Tovell, & David C. Broadway.

“Stimulation of P2X7 purinoceptors causes calcium overload and cell death in human

retinal neurons.” 1st International Conference of the International Society for Ocular

Cell Biology, Homerton College, Cambridge. 6th – 10th September 2006.

Mr C Burnett

Mr C Burnett.

Last Updated on Thursday, 21 January 2010 23:35
 
Normal pressure glaucoma PDF Print E-mail
Written by Administrator   
Wednesday, 13 January 2010 11:28

Normal pressure glaucoma (or normal tension glaucoma) is an optic neuropathy associated with low intraocular pressure (ie less than 22 mmHg).

The following are known associations of normal pressure glaucoma:
• steroid use (eg nasal sprays, inhaled or oral steroids, or steroid creams) - in this case steroids may infact elevate IOP but this may not be detected and be falsely diagnosed as normal pressure glaucoma
• vasospasm – migraine / Raynauds
• coagulopathies – previous blood loss or shock like epsiode
• systemic nocturnal hypotension
• autoimmune disease
• thyroid disease (increased risk)
• sleep apnoea (especially in overweight men)
• Alzheimer's disease

Other problems to be considered
• intermittent IOP elevation - can be excluded with diurnal IOP measurements
• burnt out glaucoma
• congenital anomaly
• myopia with peri-papillary atrophy
• optic nerve coloboma
• vascular etiology
• carotid occlusion
• previous blood loss
• hereditary optic neuropathy
• Lebers optic neuropathy
• tonometric error (thin cornea)

Investigations
• FBC – rule out anaemia
• CRP / ESR – rule out a condition called "anterior ischaemic optic neuropathy"
• VDRL/FTA – syphilis is a very rare association
• ANA – autoimmune diseases, also Ro, La, Sm
• paraproteinaemia – rule out lymphoproliferative disease
• Lebers – mitochondrial testing where indicated

Imaging
• HRT / OCT / GDx
• MRI if asymmetry, unusual VF, progressive fields, dyschromatopsia, APD with mild cupping
• carotid dopplers
• CXR to rule out sarcoidosis

Other tests
• 24 hour ambulatory blood pressure monitoring

Treatment
• ALT not recommended
• Trabeculectomy with Mitomycin C, if IOP in single digits is required
• In some cases, your physician might recommend Ginkgo Biloba (40mg three times a day). There is some evidence that points to a benefit here, but this medication is not suitable for everyone and it's use is advised on a case-by-case basis, after discussion with your glaucoma specialist.
• Future medication, for selected subgroups of patients with glaucoma, may include memantine, a tablet medication that may have beneficial protective effects on the optic nerve (randomised controlled trials are awaited).

alternative treatment for NPG

Ginkgo Biloba - not recommended for most patients with glaucoma - little evidence for benefit.

Last Updated on Sunday, 21 October 2012 18:53
 
Glaucoma glossary PDF Print E-mail
Written by Administrator   
Wednesday, 13 January 2010 11:27

angle closure glaucoma

A type of glaucoma caused by a sudden and severe rise in eye pressure. Occurs when the pupil enlarges too much or too quickly, and the outer edge of the iris blocks the eye’s drainage canals. Can be either acute or chronic.

aqueous humour
The fluid produced in the front part of the eye.

bleb
An slightly raised area under the eyelid, on the surface of the eye itself, that lies over the new drainage opening created during surgery.

central vision
What is seen when you look straight ahead or when you read.

ciliary body
Tissues located around the lens of the eye that supply fluid to nourish the eye.

congenital glaucoma
A rare form of glaucoma that occurs in babies and young children. This condition can be inherited. It is usually the result of incorrect or incomplete development of the eye’s drainage canals during the prenatal period.

conjunctiva
A thin, clear membrane that lines the inner surface of the eyelids and the outer surface of the eyeball, except for the cornea.

cornea
The clear part of the eye located in front of the iris.

drainage canals
Small openings around the outer edge of the iris. These canals provide the final pathway for fluid to leave the inside of the eye. Also referred to as the trabecular meshwork or Schlemm’s canal.

glaucoma suspect
A person may be considered a glaucoma suspect on the basis of high intraocular pressure, an unusual appearance of the optic disc or visual field, a family history of glaucoma, or narrow angles between the iris and cornea.

gonioscopy
In this test, a contact lens that contains a mirror is gently placed on the eye. The mirror lets the doctor look sideways into the eye to check whether the angle where the iris meets the cornea is open or closed. This helps the doctor decide whether open angle or angle closure glaucoma is present.

intraocular pressure (IOP)
The inner pressure of the eye. Normal intraocular pressure usually ranges from 12-22 mm Hg, although people with relatively low pressures can still have glaucoma (see normal tension glaucoma).

iris
The colored part of the eye that can expand or contract to allow the right amount of light to enter the eye.

laser surgery
A type of surgery in which a tiny, powerful beam of energy is used to solve problems in the eye. There are three common forms of laser surgery for glaucoma:

laser peripheral iridotomy: creates a new drainage hole in the iris, allowing the iris to fall away from the outflow channel so fluid can drain out of the eye.

laser trabeculoplasty: in this procedure, the laser is aimed toward the normal drainage channels of the eye, in an attempt to open those channels so fluid can leave the eye more efficiently.

laser cyclophotocoagulation: this laser procedure is usually used in people who have severe glaucoma and are not responding to standard glaucoma surgery. The laser is used to partially destroy the tissues that make the fluid in the eye.

lens
Located behind the iris, the lens directs light onto the retina.

microsurgery
Surgery performed with a microscope in which a tool is used to make a tiny, new opening in the sclera so that intraocular fluid can drain out of the inside of the eye.

mm Hg
An abbreviation for millimetres of mercury, a scale for recording intraocular pressure.

normal tension glaucoma
Also called low tension glaucoma. A rare form of glaucoma in which intraocular pressure stays within the normal range (12-22 mm Hg), but damage still occurs to the optic nerve and visual fields.

ophthalmoscopy
A test used in glaucoma management to view the optic nerve. A device with a small light on the end is held up to the inside of the eye in a darkened room. This device lights up and magnifies the eye, so that the shape and colour of the optic nerve can be seen.

optic nerve
The nerve in the back of the eye that carries visual images to the brain.

perimetry
Also known as the visual field test. A test that produces a map of the complete field of vision, to check whether there is damage to any area of vision.

peripheral vision
The surrounding areas of vision. These are usually the first areas of vision affected by glaucoma. Also referred to as "side vision".

primary open angle glaucoma
The most common form of glaucoma in the UK. This form of glaucoma usually develops very slowly as the eye’s drainage canals gradually become clogged. There are no early warning signs for primary open angle glaucoma, which is why it is often called the “sneak thief of sight.” Also known as open angle glaucoma.

pupil
The opening that monitors how much light enters the inner part of the eye.

retina
The part of the eye that transmits light and images to the brain through the optic nerve.


sclera

The tough, white, outer protective covering of the eye.

secondary open angle glaucoma
A form of glaucoma that occurs as the result of an eye injury, inflammation, or tumour. Includes pigmentary glaucoma and steroid-induced glaucoma.

selective laser trabeculoplasty (SLT)
A type of laser surgery that uses a combination of frequencies allowing the laser to work at very low levels. It treats specific cells “selectively” and leaves untreated portions of the trabecular meshwork (the mesh-like drainage canals surrounding the iris) intact.

tonometry
The use of a device to measure the pressure in the eye. There are two types of tonometry:

Air Puff: This is the only type of tonometry that does not touch the surface of the eye. The patient sits facing the instrument, and a warm puff of air is directed at the eye.

Applanation: The patient’s eye is first treated with numbing
drops and a stain called fluorescein. The tonometer is then placed
gently on the cornea, and a very small amount of pressure is applied to the cornea. The patient may sit in front of the tonometer or a hand-held tonometer may be used.


trabecular meshwork

The mesh-like drainage canals in the drainage angle.

5-FU
A medication designed to stop the healing process. Sometimes used around the bleb to stop it from healing or scarring over.

OCT image of angle

OCT showing open angle.

Last Updated on Thursday, 21 January 2010 23:34
 
Pseudoexfoliation glaucoma PDF Print E-mail
Written by Administrator   
Wednesday, 13 January 2010 10:58

Pseudoexfoliation glaucoma: symptoms diagnosis and treatment of the condition


Exfoliative Glaucoma (pseudoexfoliation syndrome) is the most common identifiable form of secondary open-angle glaucoma within in the white population.  It is more common in females and is rarely seen below the age of 50.  The exact cause is unknown. It is characterized by flakes of granular, greyish-white material similar in appearance to dandruff, which is deposited on the lens, iris and ciliary epithelium (the surface layer of cells) and carried to the trabecular meshwork by the natural flow of aqueous fluid. It is thought these flakes are composed of abnormal basement material produced by all of the epithelial cells within the anterior segment of the eye.

These deposits create a blockage within the trabecular meshwork, creating an obstruction of the Schlemm canal, narrowing of the canal and ultimately the collapse of its walls. The result is raised intraocular pressure with associated glaucoma. Exfoliation refers to the scaling off of tissues in layers, particularly dead cells from the epidermis.  True exfoliation of the lens capsule is due to exposure of extreme intense heat through infrared radiation, which causes a thin membrane to peel off the anterior lens capsule.  Glaucoma in this case is uncommon.  Pseudoexfoliation material is found throughout the body. In the eye, it is characterized by deposits of pseudoexfoliative amyloides - a wax-like protein complex that has some starch-like qualities - believed to be produced by pigment epithelium in the iris, ciliary epithelium and the outer anterior lens epithelium.

SYMPTOMS

There are usually no symptoms until advanced glaucoma develops.

DIAGNOSIS

To determine diagnosis, the ophthalmologist may carry out the following examinations check for anterior (front) lens capsular changes using a slit-lamp check for narrowing of the anterior-chamber angle with a gonioscope measure intraocular pressure perform optical coherence tomography to measure the thickness of the macula - the tissue make-up of the nerve fibre layer - or to analyze individual layers of the retina with a non-invasive technique using light rays instead of ultrasound conduct a visual field test to assess peripheral vision Diagnosis will be confirmed by the presence of pseudoexfoliative material on the pupillary border of the iris, which will eventually come together to form a single mass shaped into a characteristic "bulls-eye" pattern.

TREATMENT

Pseudoexfoliative glaucoma will be treated in the same way as primary open-angle glaucoma, although intraocular pressure level in pseudoexfoliative glaucoma is usually higher and more difficult to lower. For this reason, laser surgery is often indicated earlier than with primary open-angle glaucoma. Selective laser trabeculoplasty may be particularly effective in pseudoexfoliation syndrome, however lower energy settings are required due to the increased pigmentation found in eyes with pseudoexfoliation.

Medication to effect constriction of the pupil - miotics - can theoretically help by reducing the rubbing of the posterior iris against the pseudoexfoliative material and reducing the amount of pigment and material released into the drainage route (however pilocarpine is used very infrequently nowadays). Topical (eye drop) medication similar to those taken for primary open-angle glaucoma may be prescribed. Argon laser trabeculoplasty may be used to effect increase in drainage of aqueous fluid out of the eye.  A laser beam is directed into the trabecular meshwork to form a new drainage route for fluid to leave the eye through a flap made over a small hole in sclera - the white tough outer wall of the eye.

FOLLOW-UP

Pseudoexfoliation syndrome can occur without raised intraocular pressure and will require only periodic monitoring to check any developing glaucoma and conduct a visual field test.  However, around 50% of people with raised intraocular pressure may develop glaucoma.

OUTLOOK

The incidence of visual field loss and optic nerve damage is higher than with primary open-angle glaucoma and follow-up every 1 to 6 months may be recommended depending on the severity of the glaucoma. Pseudoexfoliation syndrome usually affects one eye, but typically the good eye will develop signs of pseudoexfoliation in 40% of cases within seven years.

field loss in glaucoma
Advanced field loss - example of visual field test result

Last Updated on Thursday, 21 January 2010 23:26
 
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