Week 9 - SIGN Glaucoma

Question 1

The SIGN guideline

Answer 1

• March 2015 Scottish Intercollegiate Guidelines Network (SIGN)
• Evidence Based clinical practice guideline developed for NHS Scotland
• First SIGN guideline which relates directly to optometric practice is for Glaucoma
• Important shift in responsibility towards community optometry.
• Referral for glaucoma now more involved and we must ensure our referrals are accurate…
• The new guideline helps us achieve this

Question 2

Components of a glaucoma referral

Answer 2

• History
• IOP
• Central Corneal Thickness
• Anterior chamber assessment
• Visual Fields
• Disc assessment
• Imaging

Question 3

History:

Answer 3

• Age and Ethnic Orgin
• Previous history of OHT or glaucoma
• Previous ocular history
- uveitis, psuedoexfoliation, pigment dispersion, myopia
• General Health
- Diabetes?, High Blood Pressure?, Peripheral Vascular disease, Migraine, Raynauds phenomenon, Sleep Apnoea
• Previous medications
- steroid use
• Family history of glaucoma
- Who?

Question 4

Risk factors of POAG

Answer 4

• Age
• Black ethnicity (2.9:1)
• Family history in a first-degree relative (3.3:1)
• Diabetes (1.8:1)
• Hypertension (1.8:1)
• Peripheral vascular disease (2.1:1)

Question 5

Risk Factors for ACG:

Answer 5

• Age
• Female sex (3.25:1)
• Eastern asian ethnicity

Question 6

IOP:

Answer 6

• Measured using applanation tonometry
• Protocol in place to ensure regular calibration
• Establish a baseline
• Minimum of two readings on a single occasion
• Record time, reading and instrument
• Should consider for referral if
- IOP >25 mmHg irrespective of CCT
- IOP 21-25 AND CCT <555m AND Aged ≤ 65
• Monitor in the community if IOP <26 and CCT > 555um and no signs of glaucoma

Question 7

ССТ:

Answer 7

• Important independent risk factor for glaucoma
• At increased risk of glaucoma if CCT < 555nm
• Measured using pachymeter
• Record CCT mean, SD and the pachymeter you used

Question 8

When to refer based on IOP and CCT:

Answer 8

• Irrespective of other signs of glaucoma SIGN guidelines recommend referral when:
•”IOP is >25mmHg - irrespective of CCT”
•”IOP 21-26, central corneal thickness is <555 and patient is aged under 65”

Question 9

Anterior chamber assessment:

Answer 9

• Van Herrick’s or Gonioscopy acceptable when referring
- Refer irrespective of other signs refer if:
- Van Herricks technique shows a peripheral anterior chamber angle which is less than a quarter of the corneal width

Question 10

Van Hericks scale:

Answer 10

• Grade 4: > Cornea
• Grade 3: 1/4 to 1/2
• Grade 2: 1/4
• Grade 1: <1:4
• Dangerously Narrow Slit

Question 11

Anterior chamber assessment:

Answer 11

• Refer irrespective of other signs:
- Gonioscopy shows 270 deg or more where posterior pigmented trabecular is not visible

• Referral for narrow angles should not be based on OCT
- Low specificity for identifying low angles
- No standard AC protocol for OCT
- Variability between examiners when identifying scleral spur
• OCT can be used for an adjunct to examine angle configuration (Plateau iris, angle recession, Pupil block)

Question 12

What is looked for during slit lamp AC assessment?

Answer 12

• Pseudoexfoliation
• Pigment Dispersion
• Iridotomy
All require lifelong monitoring as they are at increased risk of developing Glaucoma - monitoring should include disc assessment, IOP and visual fields
AT FINDSORG

Question 13

When to refer for risk of angle closure:

Answer 13

• Irrespective of other signs of glaucoma SIGN guidelines recommend referral when:
• Using Van Herricks technique, a peripheral angle with of less than a quarter of the corneal thickness
• Using Gonioscopy, when posterior trabecular meshwork is not visible for ≥
270 degrees”

Question 14

SIGN recommendation for referral with visual fields:

Answer 14

• “A minimum of two visual field tests with consistent findings is recommended before referral to secondary-eye-care services. One test may suffice if the result is unequivocal.”
• Ideally should be same visual field instrument in primary and secondary care
• Frequency doubling perimetry may also be used as an alternative to standard automated perimetry

Question 15

Important things to consider regarding visual fields:

Answer 15

• If there is a defect? Is it changings?
- Progression could be glaucoma
- Stable could be defect due to a tilted disc or another longstanding defect
- Has the mean defect changed by more than 2dB?

•Does the visual field defect match the appearance of the disc?
- If a superior visual field defect is present in the right eye is there also loss of inferior neuroretinal rim in the right eye?

• Patient reliability
- If poor reliability on repeated occasions then visual fields are less helpful for diagnosis and disc assessment and glaucoma become more important tools
- Make use of visual field indices:
- 20% false positives
- 20% false negatives

Question 16

What are the 8 type of visual field scotoma’s?

Answer 16

• Nasal step
• Tempora wedge
• Established superior arcuate defect
• Early superior paracentral defect at 10°
• Superior, fixation-threatening paracentral defect
• Superior arcuate with peripheral breakthrough and early inferior defect
• Tunnel vision defect with temporal crescent sparring
• End stage complete visual loss

Question 17

Sign recommendation regarding disc assessment:

Answer 17

• “Irrespective of intraocular pressure, patients with one or more of the following findings should be referred to secondary eye care services”
- Patients with an optic disc haemorrohage should be referred irrespective of other signs of glaucoma
- Patients with cup to disc asymmetry - (difference in C:D of 0.2 or greater consider referral?)

Question 18

How can the disc be imaged?

Answer 18

• Fundus Photos
• OCT Scan (More info in Graeme’s OCT lecture)
• GDx

Question 19

What groups are at risk of glaucoma?

Answer 19

• PDS
• Pseudoexfoliation
• Myopic Discs
• Tilted Discs
• Optic Disc Drusen
• Patients with a history of primary angle closure who have had an iridotomy
• FHG
- At least every 2 years if no other risk factors
- At least annually if other risk factors are present
• OHT
- Record baseline disc appearance, visual field and IOP
- Review every two years

Question 20

When to refer - Summary

Answer 20

“Irrespective of intraocular pressure, patients with one or more of the following findings should be referred to secondary eye care services”
• Optic disc signs consistent with glaucoma in either eye
• A reproducible visual field defect consistent with glaucoma
• Risk of angle closure
- Using Van Herricks technique, a peripheral angle with of less than a quarter of the corneal thickness
- Using Gonioscopy, when posterior trabecular meshwork is not visible for 2
270 degrees”
• “IOP is >26mmHg - irrespective of CCT”
• “OP 21-26, central corneal thickness is <555 umand patient is aged under 65”

Question 21

Discharged patients: Who might return to community practice in future?

Answer 21

• Patients with untreated ocular hypertension where IOP is <26mmHg and ocular examination is otherwise normal
• Patients with untreated ocular hypertension where IOP is >25mmHg, ocular examination is otherwise normal and a low lifetime risk of glaucomatous visual disability
• Treated ocular hypertension where the re-referral criteria are documented
• Patients who have had an iridotomy and have an open angle, are not on topical medication and have no evidence of glaucoma
• Patients may be reviewed by a named accredited optometrist at the discretion of a consultant ophthalmologist

Question 22

Common mistakes in glaucoma referral:

Answer 22

• Poor description of reason for referral
• No list of the patients risk factors
• Poor description of the disc
• No/poor description of the angle
• Not repeating pressures
• Not stating which instrument was used…
visual fields
… for pachymetry, for IOP and for
• VF not enclosed
• VF not repeated
• In advanced disease delaying referral to repeat procedures