Fundal examination
Until the invention of direct ophthalmoscope by von Helmoltz, the retina of the livings was not visible to men. The first ophthalmoscope was invented in 1851.
Direct ophthalmoscope is portable and easy to use. However, studies showed that it has low sensitivity, though high specificity in diabetic retinopathy screening. The main reason being the limited field of view of the retina.
Slit-lamp is routinely used by ophthalmologists in the detection of diabetic retinopathy. It allows a wider view and therefore more sensitive. It is the 'Gold standard' method for ophthalmoscopic detection of diabetic retinopathy.
For effective screening of diabetic retinopathy, the British Diabetic association proposes the following criteria:>80% sensitivity, >95% specificity, <5% technical failure 
Section 4 Screening for Diabetic Retinopathy
4.1 Methodology and Validation
The Diabetic Retinopathy Study Group26 and the British and Study 
Group 27 have shown that photocoagulation is effective in the treatment 
of proliferative retinopathy. Treatment is particularly effective when 
given early and adequately and joint initiatives for screening for diabetic 
retinopathy as shown by the Brunel study1.
Similarly the British and Study28 and the Early Treatment of Diabetic 
Retinopathy Study14 have shown that visual loss due to diabetic 
maculopathy can be reduced, especially when the lesion are early, and 
the vision still good.
As the earliest forms of retinopathy, when treatment is also most 
effective, are not associated with visual symptoms, it is essential that 
these should be detected. DR therefore represents an excellent paradigm 
for screening as laid out in the principles for screening of human disease29
Screening for diabetic retinopathy is cost effective in health economic 
Comprehensive screening programmes for DR in the UK are difficult 
to put in place since there is as yet no complete register of all diabetics 
in all health regions. however, attempts should be made to achieve full 
coverage of the patient population through the establishment of district 
wide diabetes registers.
Screening may be undertaken for two reasons: the detection of disease 
of any severity and the detection of disease of sufficient severity to 
require consideration for treatment. The latter constitutes the 
"indications for referral to the ophthalmologist" and is dealt with below.
Screening modalities include fundoscopy, which can be performed by 
various individuals with different levels of expertise, and photography 
with a fundus camera with or without mydriasis.
Several studies on the value of screening11,30,32-39 have led to the 
following general recommendations proposed in a parallel guidelines 
document in preparation by the European Consensus Document and the 
conference of Scottish Royal Colleges:
  • all patients aged over 12 years and/or entering puberty 

  • should be screened
  • screening should be performed annually and should 

  • include a measurement of visual acuity and examination 
    of the fundus through a dilated pupil
  • screening should be performed in the most appropriate 

  • and comprehensive manner and will involve a combination of:
    a. diabetologists for patients attending hospital diabetic 
    b. optometrists, usually in densely populated urban areas, 
        as primary screeners for diabetic patients being treated 
        by their general practitioner, if the GP does not wish to 
        perform the screening him/herself
    c. photographic screening for patients for whom neither of 
        the above is available eg. in rural communities. Photographs 
        would be evaluated by primary screeners at diabetic clinics 
        or GP practices.
Combined modality screening may be useful in certain circumstances. 
In this case the opinion of a trained ophthalmoscopist, whether 
physician, ophthalmologist or optometrist, is combined with photography 
through a dilated pupil, the photographs being evaluated by a trained 
observer. While labour intensive, the number of missed is greatly reduced. 
Whichever screening method is employed in any region, it is important 
that the results of screening and indeed treatment outcomes from the 
screening programme, are audited and validated.
With rapid advancement of technology, new methods for screening are 
now available including digital photographic and computerized methods for 
detection and assessment of retinopathy. While opinions remain divided 
as to the best screening modalities, it should dbe possible to develop an 
effective screening programme based on a single modality, thereby 
reducing duplication, cost and sources of error. A number of research 
programmes are currently in progress to evaluate the various modalities. 
All new screening methods however, should be tested for sensitivity and 
specificity against known standards. In addition, the screening procedure 
in each centre should be audited regularly by independent assessors to 
ensure uniform standards of care.
4.2 Indications for referral to an ophthalmologist
The main purpose of screening is to detect patients who require treatment 
and to refer them to the ophthalmologist in good time, when vision can be 
saved, or possibly improved.
Urgent referral is indicated in the following conditions:
  • new vessels on the disc
  • new vessels elsewhere
  • preretinal and/or vitreous haemorrhage
  • rubeosis iridis
  • retinal detachment

  • .
    These patients should be seen on the same day in the case of retinal 
    detachment and vitreous haemorrhage and within 2-3 days in the 
    case of new vessels.
Early referral is indicated in the following conditions:
  • "high risk", pre-proliferative retinopathy
  • non-proliferative retinopathy with macular involvement
  • haemorrhages and/or hard exudates within one disc diameter from 

  • the centre of the fovea
  • reduced visual acuity not corrected pinhole, suggestive of macular oedema.
  • These patients should be seen within 3-4 weeks.
Routine referral for an ophthalmological opinion should be made for 
the following conditions:
  • non-proliferative retinopathy with large circinate or plaque exude 

  • within the major temporal arcade but not threatening the macula
  • retinal findings that are not characteristic of diabetic retinopathy
  • background retinopathy with reduced vision but without maculopathy 

  • to determine cause of visual loss.
Epidemiology Clinical features Risk factors Screening
Lasers and lenses. NVD,, NVE.. Maculopathy
Vitrectomy. Cataract Special problems Counselling
References.. AAO guidelines Atlas of Retinopathy Contact lenses
Main index Main page.