SCREENING FOR RETINOPATHY

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SCREENING FOR RETINOPATHY NEPHROPATHY

Prof.V.Mohan.,M.D.,Ph.D.,D.Sc.
DIRECTOR M.V.DIABETES SPECIALITIES
CENTRE,
VISITING PROFESSOR OF DIABETOLOGY
SRI RAMCHANDRA MEDICAL COLLEGE, PORUR
PRESIDENT MADRAS DIABETES RESEARCH FOUNDATION,
CHENNAI
PROFESSOR OF INTERNATIONAL HEALTH
UNIVERSITY OF MINNESOTA, USA
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CARDINAL PRINCIPLES FOR SCREENING
(WHO)
1. Important health problem with a presymptomatic
state 2. Acceptable screening procedures (both
by public and health care professional) 3.
Safe, effective and universally agreed
treatment 4. Economic cost of screening and
treatment should be less than that for diagnosis
and treatment
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THE SCREENING PATHWAY
Healthy
Disease or precursor detectable
Screening possible
Symptoms develop
Intervention to avert disease development or its
consequence
Advanced disease
Life prolonged
Death
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CLASSIFICATION
NON - PROLIFERATIVE DIABETIC RETINOPATHY
PROLIFERATIVE DIABETIC RETINOPATHY
WITHOUT MACULOPATHY
WITH MACULOPATHY
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VISUAL IMPAIRMENT AND RETINOPATHY
BJO, 2001
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IS SCREENING FOR RETINOPATHY JUSTIFIED?
Yes, because retinopathy.
is an important health problem has a known
natural history has effective treatment
screening is simple to perform acceptable to
patients cost effective comprehensive
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DIABETIC RETINOPATHY - SCREENING

• A simple diagnostic procedure, to identify
  those patients in whom prompt treatment is
  needed to prevent loss of vision
• It is not a complete clinical examination in
  itself

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EYE EXAMINATION - ROUTINE

• History
• Visual acuity
• Clinical examination of retina
• Direct ophthalmoscopy
• Indirect ophthalmoscopy
• Retinal color photography
• Fluorescein angiography

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OCULAR FUNCTION EXAMINATION

• Visual acuity (corrected), distance, reading
• Colour vision
• Visual field test - to test confrontation eye
  movements
• After dilation
• Lens
• Vitreous
• Fundus including disc and macula

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RETINAL EXAMINATION
Ophthalmoscopy Retinal photography
Polaroid photographs 35mm colour slides
Digital images - Scanner
- Video -
Digital camera
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OPHTHALMOSCOPY
Direct ophthalmoscopy and indirect ophthalmoscopy
through dilated pupil inexpensive, rapid,
efficient
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OPHTHALMOSCOPY

• Direct ophthalmoscopy enables adequate
  examination of only the posterior pole
• Indirect ophthalmoscopy provides insufficient
  magnification

• Slit lamp examination using either indirect
  ophthalmoscopy with convex aspheric lens or
  diagnostic contact lens yields more information
  on retinal thickening and proliferative
  retinopathy

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RETINAL PHOTOGRAPHY

• Seven 30 degree fields
• Two 45 degree fields
• Three photographs spread across the posterior
  pole

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OPHTHALMOSCOPY vs PHOTOGRAPHY
OPHTHALMOSCOPY PHOTOGRAPHY
No documentation Can be documented
is possible
Errors cannot be Photographs
can be detected
regraded
Observer bias Mutiple
grading is possible
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RETINAL PHOTOGRAPHS
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RETINAL PHOTOGRAPHY
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GOLD STANDARD FOR RETINAL SCREENING
Retinal photography is the gold standard for
screening diabetic retinopathy
Seven 30 - degree field of stereoscopic
photographs taken by a trained technician
Photographs can be taken by a mobile
unit with a camera and later assessed by a
trained reader Suited to serve even rural
communities
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SPECIFICITY AND SENSITIVITY OF OPHTHALMOSCOPY
AND PHOTOGRAPHY
Ophthalmoscopy
Photography
() ()
Sensitivity 65.7 87.3
Specificity 93.8
84.8
Owens et al, Diabetic Medicine, 1998
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WHO CAN DO SCREENING ?

• General practitioner
• Optometrists
• Clinicians in a hospital - based diabetes
  centre
• Ophthalmologists
• Diabetologists
• Retinal photography services
• Combination of all these

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ERROR RATES FOR DIAGNOSING DIABETIC
EYE DISEASE - OPHTHALMOSCOPY

Overall Serious errors ()
errors ()
Internist 74 70 Senior medical
resident 69 52 Diabetologist 66
50 Ophthalmologist 48
11 Retinal specialist 13 0
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NATURAL HISTORY OF NEPHROPATHY IN TYPE 1 DIABETES
Stage of hyper- filtration
Micro albumi- nuria
Macro albumi- nuria
Azotemia (Renal failure)
End stage Renal disease
Normo albumi- nuria
15 - 20 yrs
1 yrs
4 - 5 yrs
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PREVALENCE OF DIABETIC NEPHROPATHY
Diabetic Nephropathy

• Develops in 35 - 45 of Type 1 diabetic
  patients
• 20 - 30 of Type 2 diabetic patients
• Leading cause of ESRD in United States

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PREVALENCE OF DIABETIC NEPHROPATHY IN DIFFERENT
ETHNIC GROUPS
19 million Indians with diabetes 5 - 60 of type
2 diabetes depending on ethnic origin Caucasians
- 5 - 10 African Americans - 10 - 20 Pima
Indians - 60 Asian Indians - 10 Even with
10, 1.7 million Indian diabetics will
have Nephropathy
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SCREENING FOR MICROALBUMINURIA
Routine urinalysis for protein
Overt nephropathy Quantitative protein begin
treatment
For protein
- For protein
Condition that may invalidate urine albumin
excretion
Yes
Wait until resolved
No
No
Repeat in 1 year
Test for microalbumin gt 30 mg/24h
Yes
Repeat microalbumin test twice within 3 months
period
2 of 3 tests gt 30 mg/24h ?
Yes
Microalbuminuria, begin treatment
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SPECIMEN COLLECTION

• Collect freshly voided urine in a clean, dry
  container
• Preservatives should be avoided
• Samples which cannot be tested within 3 days of
  collection should be refrigerated
• Samples should not be frozen
• The test should be free from significant
  interference from glucosuria, pH, ketonuria or
  bacterial contamination

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SCREENING FOR MICROALBUMINURIA
Three methods
Albumin to creatinine ratio in random spot
collection 24 - h urine collection with
creatinine Timed collection (4-h or overnight)
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DEFINITION OF MICROALBUMINURIA
Stage 24h Timed
Spot collection collection
collection
Normoalbuminuria lt 30 mg/24h lt20?g/min
lt30?g/mg creat
Microalbuminuria 30-300 mg/24h
20-200?g/min 30-300?g/mg creat
Clinical albuminuria gt300 mg/24h
gt200?g/min gt300?g/mg creat
ADA, Diabetes Care, 1998
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ADVANTAGES AND DISADVANTAGES
METHODS OF MICROALBUMINURIA ANALYSIS
Random spot collection
Easy to perform Generally provides accurate
information
First void or morning collection
Preferred due to diurnal variation in albumin
excretion
Gold standard Notoriously labour and time
intensive Patients co-operation difficult
Timed collection
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SPECIFICITY AND SENSITIVITY FOR MICROALBUMINURIA
Timed urine collection - gold standard
Sensitivity
Specificity
() ()
Random spot specimen 89
85 First morning void
70 93
Schwab et al, Diabetes Care, 1992
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SHORTENED TIMED CLEARANCES
SUGGESTIONS ..
3 -hour collections
Brodows et al, Diabetes Care, 1981
4 -hour collections
Steno study group, Lancet, 1982
1 -hour timed collections
Sochett et al, J.Pediatr,1988
Overnight collections
Viberti et al , Lancet, 1982
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ASSAYS FOR MICROALBUMINURIA
Qualitative
Dipstick method
Quantitative
Radioimmuno assay
Immunoturbidometric assay
Enzyme linked Immunosorbant assay
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MICRAL STRIPS
Micral strip screening tests offer a
cost-effective method of screening Dip sticks
show acceptable sensitivity (95) and specificity
(93) All positive tests should be confirmed by
more specific methods
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FALSE POSITIVES FOR ALBUMINURIA
Hyperfiltration (Newly diagnosed
diabetes) Exercise Marked hypertension Congestive
Heart Failure Urinary Tract Infection Acute
febrile illness
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CONCLUSIONS
Screening for retinopathy
Sensitive, specific and safe screening tests are
available for retinopathy
Retinal photography is the gold standard, which
can be modified from seven to four field
Training is necessary to grade retinal photographs
Newer technologies including digital imaging may
reduce the cost of screening
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PRIORITIES
For preventing blindness due to diabetes

• Screening
• Diagnosis
• Treatment
• Counseling
• Education

For all diabetic patients
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CONCLUSIONS
Screening for nephropathy
Screening tests for microalbuminuria are safe,
simple at the same time specific and sensitive
Timed urine collection is the gold standard.
However spot urine testing has also proved to be
equally sensitive
Micral dip sticks are cost effective
Microalbuminuria provides information not only
about nephropathy,but also generalized vascular
disease (endothelial dysfunction)
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PRIORITIES
For preventing nephropathy due to diabetes

• Annual screening of Microalbuminuria
• Glycemic control
• Treatment modalities to slow down the rate of
  progression of nephropathy

in all diabetic patients