Dr Chris Kennedy
MBBS PhD FRANZCO FRACS
St John of God Eye Clinic, Subiaco WA
Takagi 700GL LED slit lamp with digital imaging system
Our busy clinic in Perth is mainly concerned with retinal disease and cataract surgery but we also deal with complicated lens surgery and other anterior segment issues that are worth documenting.
My staff performs all of our retinal imaging. Because there are so many different variables involved in selecting the best method of illuminating the points of interests, I have found it difficult to delegate imaging of the anterior segment of the eye.
To get the anterior segment images that you want, you really have to take them yourself. With experience, optometrists and ophthalmologists develop an almost innate ability to select the optimal lighting method to evaluate eyes and highlight points of interest. This may involve combinations of diffuse lighting, direct illumination with the slit beam, use of back-scattered light, retro-illumination, and use of the red reflex.
The Takagi 700GL is an excellent stand-alone slitlamp, even without the imaging system attached. It has dual dials next to the joystick on the slitlamp to permit separate control of diffuse background lighting and slit beam intensity. It uses bright LED lighting, so there are no halogen globes to replace.
The slit beam height extends to 14 mm, which exceeds those of many other slitlamps and provides a slit beam that comfortably straddles the cornea. Aesthetically, the device itself is attractive; the cords are concealed, its construction is solid and it delivers excellent optical quality.
The imaging system that seamlessly integrates with the Takagi 700GL is my choice of imaging system for several reasons.
Ease of use
The operator illuminates the subject, just as they usually do during an eye examination, and then presses the capture button on the slitlamp’s joystick to take the photo. The computer monitor previews the images that are about to be taken and the operator can rapidly scroll through the images that have just been taken in seconds. Some like to install a second monitor diagonally above the patient’s head or on an adjacent wall for previewing shots and to demonstrate and explain eye problems to patients and relatives.
Figure 2. Pigmented iris naevus
This system is fast. It turns on with the flick of a switch and date and time-stamped images are saved straight to the computer as each photo is taken. No wasted time entering patient data first. My system is automatically set to capture a series of multiple photos per second in machine-gun style for as long as the joystick button is depressed.
No complicated knowledge of cameras is needed. Set the camera settings to ‘Auto’ and just take the photos. This is good for clinicians who know how to illuminate their subject matter but who get a headache from reading camera manuals.
Figure 3. Corectopia with spontaneous inferior subluxation of a clear crystalline lens
Figure 4. Nuclear cataract: slit beam with diffuse illumination
Figure 5. Nuclear cataract: slit beam alone with no diffuse illumination
Figure 6. Cortical vacuolar lens opacities
Figure 7. Feathered posterior subcapsular cataract
Figure 8. Anterior and posterior subcapsular cataract with cortical vacuoles
Images taken with systems that are based on video stills and eye-piece adaptors simply cannot compete with the clarity and depth of colour and lighting in the images taken with the Canon 70 D digital camera body, the image capture device at the heart of the Takagi 700GL imaging system.
In addition to the high resolution of the attached Canon camera, the bursts of photos taken by depressing the joystick button will inevitably include several photos in which the patient’s eye is absolutely stationary between microsaccades, enhancing the clarity of the shots.
Figure 9. Chronic neurotrophic corneal ulceration with inferior pannus
Figure 10. Fluorescein staining showing persistent ulcer
Figure 11. Multifocal IOL with split pupil sphincter
Figure 12. Subluxed anterior chamber IOL with haptic through peripheral iridectomy
Figure 13. Lens zonule rupture with IOL subluxation, direct illumination
Figure 14. Retro-illumination of subluxed IOL highlighting edge of IOL optic
This complete combination of slitlamp and imaging system costs less than $20,000. It compares very favourably with systems that cost considerably more.
The cases shown here demonstrate how well the system performs with a variety of illumination methods. Figures 2 to 16 are all raw, unenhanced photos that I have taken within the past three months.
Figure 15. Total exudative retinal detachment from choroidal tumour
Figure 16. Rare case of recurrent transient visual loss: bleeding angioma on pupil margin