Retinal examinationwithout dilation The Optos Panoramic 200

The Optomap Retinal Exam, produced by the company Optos, was the brainchild of Scot Douglas Anderson. He had been inspired to do so when his five-year-old son, Leif, had lost the sight of one eye due to an undetected retinal tear. After seeing his son undergo numerous unsuccessful dilated ophthalmoscopy examinations that still failed to detect any lesion, Anderson and his team developed a system using low-powered lasers to scan a wide area at the back of the eye in just 0.25 of a second.
American optometrist William Jones has been reviewing Optomap images since 1998 when Optos had the Panoramic 200 in a pre-production phase. He has reviewed thousands of Optomap images, illustrating a variety of retinal conditions, and has first-hand experience of using it in his own clinical practice.
Jones is one of six practitioners in a city centre private optometric practice in Albuquerque where a comprehensive eye exam, including an Optomap exam, costs approximately $195 (£120). The patient pays a percentage of this fee, while the remaining amount is met by insurance companies or healthcare plans such as Medicare.
Although well equipped, he had no access to any form of digital imaging at the practice before the Optomap was introduced. Its arrival meant a change in practice behaviour for Jones Ð mydriasis was a common procedure for almost all his patients prior to the eye exam. Since the introduction of Optomap, the number of patients being dilated has fallen to around 5 per cent of the total patient base. This is justified by the very large fundus field of view that the Optomap is able to represent.
The practice caters for a varied age group and population. Interestingly, for an authority on peripheral retinal disease, Jones sees a higher percentage of children than is typical for other practitioners.

The Instrument
The Panoramic 200 ultra widefield scanning laser ophthalmoscope (SLO) is the technology behind Optomap images. It is a highly complex medical imaging device, that contains approximately 11,000 components.

How it works
A spinning polygon (at 30,000rpm) produces a rapid scan of the component laser. This scanning is known as a raster, and is similar to the way images are produced on a television set or VDU. Mirrors reduce the scan raster from approximately 1m2 to a 1mm2 raster. They also produce a virtual image of the raster at a fixed point in front of the instrument. The image of the raster must be placed within the patient's pupil, therefore head positioning is critical.
Two lasers, green and red, simultaneously scan the retina to provide detailed information about the retinal layers. The green laser light penetrates from the sensory retina to the retinal pigment epithelium (RPE) while the red wavelength light penetrates deeper, gathering information from the RPE to the choroid.
Advantages of SLO technology
Lasers offer exceptionally 'high contrast' illumination of the retinal structure and deeper layers. This is very significant in visualising small vessels and outperforms broad spectrum white light (for the same pixel density).
The passage of a laser beam through a media opacity produces much less light scatter than white light flash or flood illumination. This greatly improves the clinician's ability to visualise the retina in patients over 50 years of age or with cataracts and vitreous abnormalities.
The absence of white light, commonly used in other digital imaging equipment, does not adversely affect the ability to see the retina in clear detail. Indeed, in many conditions, the absence of white and blue light actually improves visualisation of the retina as there is no bleaching of details. Light scatter is also minimised, allowing successful imaging to take place in conditions such as keratoconus, cataract and in patients with small pupils.
Colour-specific light detectors sense the reflected red and green lasers and transform them into electronic signals which are transmitted to the computer (Figure 2). Very little laser light is reflected back from the fundus. Proprietary software transforms the electronic signals into an easily interpreted image (the Optomap image) which is then displayed alongside the SLO on a monitor screen.

Acknowledgements
optician thanks Kathy Jones of Optos for supplying technical information.

A virtual lecture based on the use of the Optos Panoramic 200, written by Dr William Jones, will appear on optometry online.net in the coming weeks.The Optomap Retinal Exam, produced by the company Optos, was the brainchild of Scot Douglas Anderson. He had been inspired to do so when his five-year-old son, Leif, had lost the sight of one eye due to an undetected retinal tear. After seeing his son undergo numerous unsuccessful dilated ophthalmoscopy examinations that still failed to detect any lesion, Anderson and his team developed a system using low-powered lasers to scan a wide area at the back of the eye in just 0.25 of a second.
American optometrist William Jones has been reviewing Optomap images since 1998 when Optos had the Panoramic 200 in a pre-production phase. He has reviewed thousands of Optomap images, illustrating a variety of retinal conditions, and has first-hand experience of using it in his own clinical practice.
Jones is one of six practitioners in a city centre private optometric practice in Albuquerque where a comprehensive eye exam, including an Optomap exam, costs approximately $195 (£120). The patient pays a percentage of this fee, while the remaining amount is met by insurance companies or healthcare plans such as Medicare.
Although well equipped, he had no access to any form of digital imaging at the practice before the Optomap was introduced. Its arrival meant a change in practice behaviour for Jones Ð mydriasis was a common procedure for almost all his patients prior to the eye exam. Since the introduction of Optomap, the number of patients being dilated has fallen to around 5 per cent of the total patient base. This is justified by the very large fundus field of view that the Optomap is able to represent.
The practice caters for a varied age group and population. Interestingly, for an authority on peripheral retinal disease, Jones sees a higher percentage of children than is typical for other practitioners.

The Instrument
The Panoramic 200 ultra widefield scanning laser ophthalmoscope (SLO) is the technology behind Optomap images. It is a highly complex medical imaging device, that contains approximately 11,000 components.

How it works
A spinning polygon (at 30,000rpm) produces a rapid scan of the component laser. This scanning is known as a raster, and is similar to the way images are produced on a television set or VDU. Mirrors reduce the scan raster from approximately 1m2 to a 1mm2 raster. They also produce a virtual image of the raster at a fixed point in front of the instrument. The image of the raster must be placed within the patient's pupil, therefore head positioning is critical.
Two lasers, green and red, simultaneously scan the retina to provide detailed information about the retinal layers. The green laser light penetrates from the sensory retina to the retinal pigment epithelium (RPE) while the red wavelength light penetrates deeper, gathering information from the RPE to the choroid.
Advantages of SLO technology
Lasers offer exceptionally 'high contrast' illumination of the retinal structure and deeper layers. This is very significant in visualising small vessels and outperforms broad spectrum white light (for the same pixel density).
The passage of a laser beam through a media opacity produces much less light scatter than white light flash or flood illumination. This greatly improves the clinician's ability to visualise the retina in patients over 50 years of age or with cataracts and vitreous abnormalities.
The absence of white light, commonly used in other digital imaging equipment, does not adversely affect the ability to see the retina in clear detail. Indeed, in many conditions, the absence of white and blue light actually improves visualisation of the retina as there is no bleaching of details. Light scatter is also minimised, allowing successful imaging to take place in conditions such as keratoconus, cataract and in patients with small pupils.
Colour-specific light detectors sense the reflected red and green lasers and transform them into electronic signals which are transmitted to the computer (Figure 2). Very little laser light is reflected back from the fundus. Proprietary software transforms the electronic signals into an easily interpreted image (the Optomap image) which is then displayed alongside the SLO on a monitor screen.

Acknowledgements
optician thanks Kathy Jones of Optos for supplying technical information.

A virtual lecture based on the use of the Optos Panoramic 200, written by Dr William Jones, will appear on optometry online.net in the coming weeks.