In tackling the issue of diabetic retinopathy (DR) Dr Marcus Kernt (Department of Ophthalmology, Ludwig-Maximillans-University,
Munich, Germany) discussed the ultra-widefield scanning laser ophthalmoscopy as a screening option at this year's World ophthalmology
Congress in Abu Dhabi, United Arab Emirates.
"The current gold standard for imaging in DR is still ETDRS type 7-field stereo colour fundus photography," revealed Dr Kernt.
"However, this method has been in place for over 25 years and has drawbacks, such as expense, time-consumption and dependence
on examiner experience." The alternative to this method is non-mydriatic ultra-widefield screening he noted.
Non-mydriatic screening
Dr Kernt and colleagues performed some research using the Optomap system (Optos, Dunfermline, UK), which is a laser ophthalmoscope,
to assess it's suitability as a valid screening tool for DR.
"Producing high-resolution images is possible with the ultra wide-field SLO, meaning it is possible to capture detailed images
of the macula region as well as the peripheral retina," Dr Kernt added. "In the system there are 3 lasers of different wavelengths.
A green (532 nm) and a red (633 nm) laser for fundus imaging, and a blue (488 nm) laser for angiography."
The red laser penetrates the deeper layers of the retina correlating to RPE. The green laser detects the superficial, neurosensory
part of the retina. Through positioning these two images Dr Kernt explained that a coloured retina image can be obtained.
"However, you can also use the two lasers separately," he noted. "In addition to colour fundus imaging, the blue laser is
angiography and the green laser is used for fundus autofluorescence."
In comparing it with the ETDRS 7-field method Dr Kernt explained that the widefield range with the Optomap enables the surgeon
to view a much larger area with one single scan.
He went on to describe the study he and his colleagues performed on a series of 66 eyes with different degrees of DR. All
patients were graded according to the images obtained from both the Optomap and ETDRS-7 field fundus photography and then
compared. Some patients were excluded as a result of poor image quality.
"The number of Optomap scans that had to be excluded due to poor image quality was significantly lower than in the ETDRS 7-field
group," asserted Dr Kernt. "In addition, the imaged area of the retina was much larger in Optomap scans than in the 7-field
ETDRS."
Summary
"In summary, there is a good agreement of Optomap retinopathy grading in ultra-widefield photography. And a good agreement
regarding detection of clinically significant macular oedema (CSME)," he continued. "The system, Optomap, shows good correlation
with what we can see from the ETDRS-7 field, and has sufficient quality able to assist in the screening of diabetic retinopathy.
The Optomap scans cover much larger areas than the ETDRS-7 field, therefore, they are of sufficient quality to assess DR and
CSME and fulfil the basic requirements of telescreening programmes."
Special Contributor
Dr Marcus Kernt is associate professor and retina specialist with a special focus on retinal imaging at the Ludwig-Maximilians-University,
Munich, Germany. He can be contacted by E-mail: marcus.kernt@med.uni-muenchen.de
Dr Kernt has indicated that he has received lecture fees from Allergan, Alcon Labs, Novartis; and he is a consultant for OD-OS
GmbH and OPTOS.
