Early Detection Saves SightAn initiative of Guide Dogs NSW/ACT and The University of New South Wales

DIABETIC RETINOPATHY

Evidence indicates that early detection of Diabetic Retinopathy (DR) by regular examination, is key to reducing vision loss and blindness from diabetes.

Risk factors

• Age• Type of diabetes

(over the same duration, Type 1 may develop more severe DR compared with Type 2)

• Elevated HbA1c• Duration of diabetes• Systemic hypertension• Hyperlipidaemia • Renal disease• Pregnancy (in women who had

Type 1 or Type 2 diabetes prior to pregnancy)

• Family history of DR

Examination frequency1

• All patients with diabetes should have a dilated fundus examination and visual acuity assessment at least every two years.

• High risk patients without DR should be examined at least annually. This includes those with a longer duration of diabetes, poor glycaemic control, systemic hypertension, renal disease or hyperlipidaemia.

• Patients with non-proliferative diabetic retinopathy (NPDR) should be examined annually, or at 3 - 6 monthly intervals, depending on the DR level.

• All cases of mild or moderate NPDR should be followed closely to detect signs of sight-threatening retinopathy.*

• Pregnant women with diabetes should have a comprehensive eye examinationinthefirsttrimester. If DR is found, they need close follow-up throughout pregnancy. This does not apply to women who develop gestational diabetes.

• Women with gestational diabetes do not need ophthalmic surveillance after delivery, unless the diabetes persists.

• Children with pre-pubescent diabetes onset should be screened at puberty, unless other considerations indicate the need for an earlier examination.

Examination protocolsVisual acuity

Measure this prior to pupil dilation. It should be noted that visual acuity may be unaffected, even in the presence of sight-threatening DR.

Slit lamp examination

To assess for iris neovascularisation.

Pupil dilation^

This is a standard of care when examining patients with diabetes.

Slit lamp fundoscopy and binocular indirect ophthalmoscopy (BIO)#

The accepted routine practice is to perform this test after pupil dilation, using an appropriate lens (eg 90D or 78D for funduscopy; Panretinal or 20D lens for BIO).

Fundus photography

This can be used to supplement the findingsofdilatedfundusevaluationby further documenting the retinal appearance.

Fundus photography can assist with future monitoring and to communicate with other health care practioners such as general practitioners, or ophthalmologists.

Limitations of non-mydriatic and digital photography are outlined on pages 63, 64 and 67 of the 2008 NHMRC Guidelines1.

Imaging technology

The 2008 NHMRC Guidelines1 do notspecificallyrecommendtheuse of imaging technologies, but do acknowledge their contribution in early diagnosis and monitoring.

The Centre for Eye Health offers the following imaging modalities:

Optomap widefield imaging

Captures a single fundus image, encompassing up to 200 degrees of the retina. This can be obtained with undilated pupils, although pupil dilation usually improves the image quality.

Optical Coherence Tomography (OCT)

Provides optical-sections through the macula, retina or optic nerve head. OCT can provide information regarding macular thickness and localised areas of macular oedema, as well as haemorrhages, hard exudates, cotton wool spots and neovascularisation.

Simultaneous stereo-photography

Digital 3D images of the macula area can be obtained with the Kowa WX 3D cameras to assist in the detection ofclinicallysignificantmaculaoedema(CSME) and to provide baseline documentation of macular appearance to aid in future monitoring.

Grading TheModifiedAirlieHouse(Wisconsin)classificationsystem(Table1)hasbecome the basis for detailed grading of DR.

TheETDRSstudyquantifiedtheriskof retinopathy progression, associated with individual retinal presentations, usingtheWisconsinclassificationsystem2.

The International Clinic Diabetic and Diabetic Macula Edema Disease SeverityScale(Table2)hasamodifiedclassificationsystemwhichemphasisesthe timeframe for referral, and elaboratesondefinitionsfor macula oedema.

CLINICAL GUIDELINESEdition 4 :: May 2012

“High-risk patients without DR should

be examined at least annually”

contact us at 1300 421 960 or cfeh.com.au

Table 1 : Classification of diabetic retinopathy into retinopathy stages (Wisconsin level) and predictive value of retinal lesions (adapted from Focal Points)

Retinopathy Stage Definition Rate of progression (%)

to PDR to high-risk stage

1 year 3 years 1 year 5 years

Minimal NPDR (level 20) Ma only not documented

Mild NPDR (level 35) Ma and one or more of: retinal haem, HEx, CWS, but not meeting Moder-ateNPDRdefinition

5 14 1 15

Moderate NPDR (levels 43,47)

H/Ma≥stdphoto2A(Figure1)inatleastonequadrantandoneormoreof:CWS,VB,IRMA,butnotmeetingSevereNPDRdefinition

12-26 30-48 8-18 25-39

Severe NPDR preprolifera-tive (level 50+)

Any of: H/Ma>std photo 2A in all four quadrants, IRMA >std photo 8A (Figure 2) in one or more quadrants, VB in two or more quadrants

52 71 15 56

PDR (level 60+) Any of: NVE or NVD <std photo 10A (Figure 3)w, vitreous/preretinal haem and NVE<1/2 disc area (DA) without NVD

46 75

High-risk PDR (level 70+) Any of: NVD>1/4 to 1/3 disc area, or with vitreous/preretinal haem, or NVE>1/2 DA with vitreous/preretinal haem

Severevisualloss(VA≤6/240)developsin 25-40% within two years

Advanced PDR High-risk PDR with tractional detachment involving macula or vitreous haem obscuring ability to grade NVD and NVE

Macular Oedema Retinal thickening wtihin two disc diameters of macula centre Can occur at any stage of DR

ClinicallysignificantMacu-lar Oedema (CSME)

Retinal thickening within 500µ of macular centre with adjacent thickening Can occur at any stage of DR

FIGURE 1: STANDARD PHOTO 2A FROM THE WISCONSIN GRADING SYSTEM2,4

FIGURE 2: STANDARD PHOTO 8A FROM THE WISCONSIN GRADING SYSTEM2,4

FIGURE 3: STANDARD PHOTO 10A FROM THE WISCONSIN GRADING SYSTEM2,4

Glossary • CSME:Clinicallysignificantmacular

oedema (oedema abbreviated as ‘E’ as in US literature.)

• CWS : Cotton wool spot

• DA: Disc area

• ETDRS : Early Treatment Diabetic Retinopathy Study

Referral criteriaPatients should be referred to an ophthalmologist urgently (within four weeks) if there is any unexplained fall in visual acuity.

This is also the case if there is any suspicion of diabetic macular oedema (DME) or proliferative diabetic retinopathy (PDR).

The international grading scale (Table 2) also contains recommended referral criteria.

• H/Ma : Haemorrhages/microaneurysms

• HbAIC : Haemoglobin AIC (glycosylated haemoglobin)

• Hex : Hard exudates

• IRMA : IntraRetinal microvascular abnormalities

• NPDR : Non-proliferative diabetic retinopathy

• NVD : New vessels on the (optic) disc

• NVE : New vessels elsewhere

• PDR : Proliferative diabetic retinopathy

• VB : Venous beading

Table 2 : International Clinical Diabetic Retinopathy and Diabetic Macular Oedema Disease Severity Scales and Recommended Referral Patterns

Retinopathy Stage Findings on ophthalmoscopy ETDRS Level

Rate (%) of progression to PDR Management

Early High Risk

1 year 3 years 1 year 3 years

No apparent retinopathy No abnormalities 10

Minimal NPDR Microaneurysms only 20

Mild to moderate NPDR More than just microaneurysms but less than severe NPDR

35, 43, 47 5-26 14-48 1-8 7-24 Ophthalmology referral

Severe NPDR Any of the following:• More than 20 intraretinal

haemorrhages in each of four quadrants

• Definitevenousbeadingintwo or more quadrants

• Prominent intraretinal microvascular abnormalities in one or more quadrant AND no signs of proliferative retinopathy

53 A-E 52 71 17 44 Ophthalmology referral

Proliferative DR One of the following:• Neovascularisation• Vitreous / preretinal haemor-

rhage

61,65,71 75,81,85

46 67 Ophthalmology referral; laser treatment

Macula Oedema

Absent No retinal thickening or hard exudates in posterior pole

Present Mild - some retinal thickening or hard exudates in posterior pole but distant from the macula

Moderate - retinal thickening or hard exudates approaching the centre of the macula but not involving the centre

Severe - retinal thickening or hard exudates involving the centre of the macula

Ophthalmology referral; consider laser

Consider laser

Laser treatment

Early Detection Saves Sight

Footnotes* The 1997 NHMRC guidelines suggested that patients should be referred to ophthalmologists if DR greater than the presence of occasional microaneurysms was found.

The latest guidelines suggest that whilst there doesn’t appear to be any recent data to suggest that this timing needs changing, the NHMRC committee felt that because there is no clear evidence to support routine referral at a particular level of non-proliferative DR, the 1997 referral recommendation should no longer be used as a guideline.

^ 0.5 to 1.0% Tropicamide is safe and markedly increases the sensitivity of DR screening. The incidence of acute angle closure glaucoma from the use of mydriatic drops is rare, from 1 to 6 per 20,000 people.

# Sensitivity of direct and indirect ophthalmoscopy is variable depending on the skill level of the examiner.

Direct ophthalmoscopy is limited by weaknesses inherent in the instrument itself.

contact us at 1300 421 960 or cfeh.com.au

FIGURE 4: MINIMAL NPDR (RED FREE) FIGURE 5: MILD NPDR FIGURE 6: MODERATE NPDR

FIGURE 7: SEVERE NPDR WITH CSME

FIGURE 8: SEVERE NPDR WITH IRMA

FIGURE 9: PROLIFERATIVE DIABETIC RETINOPATHY

References1. NHMRC Guidelines for the Management of Diabetic Retinopathy. http://www.nhmrc.gov.

au/_files_nhmrc/publications/attachments/di15.pdf

2. Fundus Photograph Reading Centre. Department of Ophthalmology & Vision Sciences University of Wisconsin – Madison. http://eyephoto.ophth.wisc.edu/ResearchAreas.html

3. Ginsburg,LH,AielloLM.Diabeticreinopathy:classification,progressionandmanagement.Focal Points (AAO). 1993;XI:1-14.

4. Davis, MD, Hubbard, LD, Trautman, J, Klein, R, Kroc. Collaborative Study Group. Studies ofretinopathy:methodologyforassessmentandclassificationwithfundusphotographs.Diabetes. 1985; 34:42-49.

How can CFEH assist? Centre for Eye Health (CFEH) can provide a range of ocular imaging services, at no cost to the referring optometrist or to the patient, to aid in assessing for diabetic retinopathy.

The referrer maintains patient management at all times, and is encouraged to consider the CFEH imaging service as an extension of their own optometric practice.

SCOPE professional development sessions are held regularly at the Centre, providing practical training in interpreting the instrument results, and offering CPD points.

This edition prepared by Paula Katalinic, Principal Staff Optometrist.

Disclaimer: Although every care is taken by CFEH to ensure that this document is free from any error or inaccuracy, CFEH does not make any representation or warranty regard-ing the currency, accuracy or completeness of these Guidelines. Printed May 2012.

*You may wish to view these images in a larger size by downloading the PDF version at www.cfeh.com.au/clinical-guidelines

for more informationRetina Australia provides information and support to people affected by all retinal dystrophies.

www.retinaaustralia.com.au