Glaucoma for professionals David Kinshuck

• cyclodiode technique
• 5FU technique
• OCT etc
• brittle angles
• after refractive surgery
• how to find schwalbe's line
• NA-AION
• toxic optic neuropathy or glaucoma
• glaucoma and the night
• glaucoma and steroids
• glaucoma and cupped discs
• glaucoma and arcuate scotoma
• disc drusen
• disc notches symptoms
  
• asymmetric glaucoma
• see arcuate scotoma...due to glaucoma?
• see cupped disc...differential diagnosis
• more about pressure
• symptoms
• examining fields
• measure discs
• notes about fields
• Glaucoma genes
  
  
• hypotony
  

Some notes

• 270o avoid long ciliary nerve over horizontal recti, and leave space for tube or trabeculectomy
• (6-10 shots for very advanced glaucoma in seeing eye non-rubeotic)
• 1500ms x 1500 mj x 40 shots first go, fewer/same shots subsequent sessions (this high dose is for rubeotic glaucoma)
• transilluminate ciliary body (in the dark) to find it (shine the light form the opposite side of the eye)
• heel 1.5mm away from limbus in standard eye
• avoid pops and carbon on the probe
• lots of risks
• see treatment protocol for rubeotic glaucoma

Some notes

• post mitomycin trabeculectomy
• post-op...a bleb is failing when cork-screw vascular changes develop
• the bleb may be flat, thickened, with  a high IOP
• inject 8-10mm away from the limbus

• progression...more than 20micons loss of nerve fibre layer thickness
• review article (full article subscription only in 'Eye'); Prof Khaw's library
• See the Early Manifest Glaucoma Trial see and see. Treatment for advanced glaucoma does not always work, see.
• Occasionally the eye pressure may be slightly inaccurate.
• The measurement accuracy depends whether the cornea is of normal thickness, or thicker or thinner. See here.
• Some patients do not respond to drops, e.g. xalatan 10-25%.
• Pigmentary glaucoma, which accounts for 50% of glaucoma in Greece, may cause field defects quickly...pressure control is critical.
• The College of Ophthalmologists (and common sense) suggests it is very important to take images (photos, stereo photos, HRT or GDX) at the onset, that is at the time of diagnosis. Images then taken during treatment years later can be compared. It is not known what the image interval should be, but this will vary from patient to patient.
• HRT and GDX machines are useful tests (MOS 2006).
  • But the database of 'normals' is small, so it is difficult to interpret the result.
  • The machines are new. It is impossible to have a long follow up for a particular patient.
  • And, if there is a deterioration, it is difficult to know what is due to glaucoma and could have been prevented, and what is natural deterioration that could not have been prevented.
  • The machines are new, and there will be new models every year. The pictures taken using today's models will be completely different from the models used in 2011, and it may be very difficult to compare the results with such a long gap. As glaucoma is a disease that can may take 5 years to change, this is a real problem.
  • No machine is good at judging highly myopic discs for instance, and these patients' eyes are the hardest to judge whether glaucoma, if is its present, is getting worse.
  • Patients may be impressed with these machines, but they are not as helpful as the companies say. For instance, (MOS 2006) it was reported that if there is a deterioration between HRT images between visits...you should really wait for three separate visits to confirm this...there is a natural fluctuation in disc size parameters (this seems over-cautious to me).
  • HRT is not useful for advanced cupping as it cannot determine the rim volume accurately enough.
  • As far as diagnosing glaucoma is concerned, an abnormal HRT makes glaucoma 84% likely if IOP raised or if there are other risk factors. But if there are no risk factors, and the HRT is abnormal, there is a 24% risk of glaucoma. (College meeting, 2006)
  • disc photos..15^o
  • Photos detect disc haemorrhages more accurately than ophthalmologists.
  • Certainly, clinical impression, including IOP, field, disc appearance, and disc image must all be taken into account.
  • There are other imaging methods such as OCT, but these essentially have similar problems.
  • The machines are expensive. It may be more cost effective to employ an extra nurse to advise patients regarding a healthy lifestyle and using the drops regularly.

• eg, patient age 36, squash ball injury 5 ago, IOP normal
• 1 year ago, IOP 25
• today IOP 48 & 0.9 cup disc
• gonio...recessed angle ++

typical case, intermittent IOP rises initially, then constant....

eg congenital glaucoma, ectropian uvea, axenfeld/reigers, high iris insertion, JOAG, trauma, previous angle closure, plateau iris, uveitis, PXF, HZO, HSVU, high myope, steroid, very old patient

• PRK: pressure drops <3mm: 1mmHg ~ 30micron ablation ~ 0.4 dioptre
• lasix: 1mmHg ~ 18micron ablation; 0.12mmHg ~1 dioptre
• Goldman underestimates IOP as cornea is thinner

• non-arteritic anterior ischaemic optic neuropathy
• ~60y age, always >40y
• painless loss of vision, like a smudge or smear
• one or several steps of visual loss
• some recover vision
• swollen disc at diagnosis...small optic nerve...'crowded disc'
• colour vision ~ visual acuity
• risk factors...diabetes, blood pressure, cholesterol, smoking, high homocysteine level
• ?nocturnal hypotension
• if gets worse...check for tumour etc
• 15%..second eye affected  (if risk factors are treated)
• posterior ischaemic optic neuropathy (non-arteritic) is related to bleeding, major surgery, hypotension. Usually some risk factors.
• smaller discs are affected....much less common with large optic disc diameters.

• occupational/drug/food history
• eg red snapper fish 5x week for years has lots of mercury
• family history
• FBC AND B12 and folate and syphilis test
• lebers...test mitochondria DNA
• loss of visual acuity ..very rare in (non-advanced) glaucoma
• field..vertical defects...must exclude CNS lesion
• rapid...must exclude CNS lesion.
• if the disc defect is not proportional to field defect... ...must exclude CNS lesion
• often need MRI to exclude CNS lesion
• pale rim...must exclude CNS lesion
• ethanol, methanol, amiodarone, lead, Hg, etc
• viagra (disputed)
• endemic Cuba (?cassava), Hungary (?Hg)
• nutritional B12, thiamine, folate...treat (and treat alcohol/smoking/poor diet amblyopia) with replacement
• glaucoma does not cause loss in colour vision ...acuity loss always occurs first
• APD...if present, glaucoma less likely

• IOP varies at night
• lying supine/face down increases the eye pressure ~7mmHg
• normal blood pressure dips at night...it is not know whether this influences glaucoma
• Prof Shah feels that patients with Low/Normal tension glaucoma, who also use betablockers, may notice extra dips at night, and these may contribute to reducing optic disc perfusion and increasing visual field loss. Betablockers should be stopped if field is deteriorating (maximum glaucoma therapy), or certainly changed to alternative drugs, if at all possible.
• dips at night may contribute to AION/RVOs/MIs/RAO etc

• steroids..tablets, drops, nasal sprays, facial creams cause an increase in IOP
• this is reversible initially
• later irreversible
• eyes with glaucoma/older patients/diabetics/connective tissue disease/ notice bigger increases
• dose is cumulative
• dexamethasone is the most potent...2.2x prednisolone 1%
• IVT..the second injection has a much higher IOP effect
• IVT causes more increase in younger patients

• a cupped disc can also be due to AION/GCA/optic nerve compression/atherosclerosis/congenital/dominant optic atrophy
• pale rim...glaucoma less likely...usually non-glaucomatous

• these may be caused by optic disc drusen, which may be buried
• there may be a papilloedema appearance
• occasionally there is another cause...infiltration of optic nerve/demyelination/aneurysm etc see

• may be buried, seen with B scan
• can differentiate from papilloedema with B scan
• familial...dominant
• associated with small optic discs..these disrupt axonal transport...and this causes the drusen
• associated with short axial length
• associated with RP/Astreak/PXE/Alagille/Alstrom
• irregular margins
• unusual branching of vessels, such as trifurcation, cilioretinal vessel
• see photos
• enlarged scotomas
• superficial drusen..may cause a visual field defect
• they autofluosce...take photo using he FFA settings without the fluorescein injection
• papilloedema....hyperaemic/no venous pulsation
• linked to NAION (NAION may start with transient loss of VA)

• notch must be related to the field defect, otherwise suspect another cause
• see

• need <18 at 100% visits
• target 14mmHg or less
• each 1mm = 10% progression (Early Manifest Glaucoma Trial)
• big swings...surgery..suspect poor compliance
• optic nerve perfusion is related to pressure
• try and predict progression rate and tell patient
• Ocular hypertension study...treatment worthwhile if moderate or high risk of POAG

• field defects ...unable to read for pleasure
• reduced hand-eye coordination
• 33% of glaucoma patients have scotomas

• F  fidelity
• I   ?? ..type of defect
• E  extent
• L  location
• D  deviation

• fidelity....another word for reliabiliaty...how many false positives/negatives
• type of defect..bitemporal...?pituitary
• extent ...how large the defect is
• location...where is the defect
• deviation...is there a pattern deviation that excludes a cataract

• with an HRT!
• 90d lens...magification 1.4, so a measured 1mm disc is really 1.4
• 66d lens...measures size  = actual size

• 10.2 humphrey often best for advanced glaucoma
• 24.2 probably best for general use, occasionally need both
• 30.2 has too many peripheral artifacts
• ignore fixation losses unless high
• mention pupil size
• 5.2 for central field ...eg macular for hydroxycholoraquine toxicity
• IOHT...measure fields ~1-2 yearly
• stable glaucoma 1yearly
• mention disc size when discussing cupping

• myocilin Gly367Arg mutation....Swiss family, open angle