Diagnostic Testing

Optimal management of many ophthalmic conditions requires reliable and accurate diagnostic testing. Modern retinal practice is particularly reliant upon diagnostic tests for best practice management of conditions such as diabetic retinopathy and macular degeneration. 

At this Perth Retina we offer the very latest in diagnostic imaging and analysis using market-leading technology and analysis to provide you with the best possible care.

  • Fluorescein Angiography
  • Indocyanine Green Angiography
  • Optical Coherence Tomography (OCT)
  • Optos Wide-Field Retinal Imaging
  • IOL Master 700 Ocular Biometry
  • Visual Field Testing: Humphrey HFA3 Field Analyzer
  • Ocular Ultrasound
  • iTrace Aberrometry

Fluorescein Angiography

An angiogram is a diagnostic procedure used in ophthalmology to image the blood vessels of the retina. It involves inserting a needle into a vein, usually in the arm or back of the hand, and injecting a contrast dye. As the dye circulates through the bloodstream, images of the retina are taken using specialised digital cameras and scanning laser technology. The procedure usually takes around 5 minutes, and the results are available immediately. The procedure is safe, with a low risk of severe adverse reactions. Fluorescein dye is most often used for retinal angiography. Fluorescein is a yellow-coloured dye that glows when excited by a certain wavelength of light, which allows for imaging of the retinal circulation.

Fluorescein angiography is useful in the diagnosis and monitoring of conditions such as age-related macular degeneration, diabetic eye disease, and retinal vascular occlusions. 

The risks of fluorescein angiography are extremely small. There is a low risk of transient nausea as the dye circulates. The skin shows mild yellowish discolouration for a few hours after the procedure, and the urine will be bright orange immediately following the procedure.

Indocyanine Green Angiography

Indocyanine green (or ICG), an iodine-based contrast dye, glows when excited by a certain wavelength of light. It is often used in conjunction with fluorescein. As in fluorescein angiography, the dye is injected through a needle into a vein. The procedure can take up to 10 minutes, and the results are available immediately.

ICG is used to assess the choroid, the layer behind the retina, and can be used in the diagnosis and management of conditions affecting this layer. These include central serous retinopathy (CSR) and types of age-related macular degeneration such as polypoidal choroidal vasculopathy.

Optical Coherence Tomography (OCT)

OCT has become the single most useful diagnostic tool in ophthalmology for evaluating the structure of the macula and optic nerve. Since many retinal diseases involve the macula, this assessment has become essential in treating retinal diseases such as macular degeneration, diabetic retinopathy, and retinal vein occlusions.

At Perth Retina we offer OCT testing with the Heidelberg SPECTRALIS®. This machine is widely recognized by ophthalmologists as the gold standard for macular assessment, providing detailed resolution of the macula down to as little as 7 micrometers. The OCT examination provides information about the condition of the different layers of the macula, or the optic nerve. The examination is completely painless and is done without touching the eye.

The OCT can detect early onset signs of retinal conditions such as macular hole, macular oedema, diabetic retinopathy, and age-related macular degeneration. This allows for earlier treatment for these conditions, which may improve the success rate of the treatment.

Optical Coherence Tomography

SPECTRALIS OCT

Preparation

At the start, you will be seated directly in front of the instrument. During the entire test, you will keep your head still with your chin resting on the chin rest and your head firmly against the instrument’s head band. You can blink normally. It takes a few minutes to acquire the images.

Examination

When the examination begins, a blue cross will appear in the instrument. You will be asked to stare at the centre of the blue cross during the entire examination. The examiner will move the instrument toward your eye without touching you. At a safe distance from the eye, the examiner is able to produce a good image of your retina or optic nerve head. A safe light beam scans the most important structures.

After the examination

After the examination, your vision will not be impaired. If your eyecare professional has not dilated your pupil to conduct the OCT test or another examination, you can drive as usual.

Are there any side effects of OCT testing?

The OCT is a non-invasive technology. It allows for the imaging of the retina without even touching the eye. The only discomfort you may feel is a flash of light when the OCT records the scan of your eye. The testing takes only a few minutes and the results are available immediately, which allows the treating ophthalmologist to discuss the results with you and to provide the best treatment possible for your condition. 

Optos Wide-Field Retinal Imaging

Perth Retina Clinic offers assessment with the Optos P200C Ultra-Widefield Retinal Imaging System. This revolutionary ultra-widefield digital scanning laser technology acquires images that support the detection, diagnosis, analysis, documentation and management of ocular pathology that may first present in the retinal periphery. These conditions may otherwise go undetected using traditional examination techniques and equipment. Simultaneous, non-contact central pole-to-periphery views of up to 82% or 200 degrees of the retina are displayed in one single capture, compared to 45 degrees achieved with conventional methods. The Optos P200C is able to image the peripheral retina through an undilated pupil (including through most cataracts) in under 1 second. It is particularly useful in evaluating and monitoring eye tumours.

This may result in more accurate detection and monitoring of peripheral retinal and vitreous disorders and earlier diagnosis and treatment of sight-threatening conditions, leading to improved patient outcomes.

IOL Master 700 Ocular Biometry

Biometry refers to measurements of the eye which are necessary to calculate the correct lens for implantation during cataract surgery. Perth Retina Clinic uses the Zeiss IOL Master 700, which is the very latest technology for ensuring the correct lens is chosen for your surgery.

Visual Field Testing:  New Humphrey HFA3 Field Analyzer

The visual field refers to your total area of vision, from the centre to the periphery in all directions. Visual field tests (perimetry) are used to measure the integrity of the visual field, and are important for evaluating the retina, optic nerve and visual pathways within the brain.

Visual Field Testing

The gold standard of visual field testing is automated perimetry, using the Humphrey Field Analyzer. Perth Retina Clinic uses the newest available model of this device, the HFA3. This machine utilises Liquid Lens technology to reduce chair time and provide streamlined and faster workflow.

You are seated in front of a concave dome or screen and instructed to stare at a fixation target in the centre with one eye whilst the other eye is occluded. When the testing begins, a small light or pattern stimulus will appear, one at a time, in random locations of the peripheral visual field. You are asked to press a button when you observe one of these lights or patterns. Based on your responses, the computer analysis can determine whether the peripheral visual field is within normal limits or abnormal. Your doctor will interpret the results and discuss them with you.

Ocular Ultrasound

Ophthalmic ultrasonography uses high-frequency sound waves, which are transmitted from a probe into the eye. As the sound waves strike intraocular structures, they are reflected back to the probe and converted into an electric signal. The signal is subsequently reconstructed as an image on a monitor, which can be used to make a dynamic evaluation of the eye or can be photographed to document pathology.

Even in an era of high-tech OCT scanning and digital imaging, ultrasound is the only means to obtain a crucial view of the posterior segment of the eye when there is a dense cataract or vitreous hemorrhage  – making it one of the most fundamental diagnostic tools in ophthalmology. Detection of disorders like posterior vitreous detachment (PVD) in opaque ocular media is easily achieved with B-Scan ultrasound. It is an essential tool in diagnosing and assessing intraocular tumours such as uveal melanoma, and planning treatment.

Perth Retina Clinic offers assessment with the Ellex Eye Cubed unit, the gold-standard in high-resolution ultrasound of the posterior segment. In addition, we offer the UBM mode, allowing visualisation and assessment of anterior structures such as the cornea, iris, ciliary body, crystalline and intraocular lens more clearly than ever before.

iTrace Aberrometry

The iTrace is the newest acquisition to the diagnostic services offered by Perth Retina Clinic. This machine uses ray-tracing technology to analyse aberrations and thus the total visual function of the eye. It is able to measure and quantify the total refractive power of the eye and identify the cause of imperfections in the visual system.

The iTrace sequentially sends 256 individual light rays through the pupil, then detects where each of these light rays lands on the retina. By analysing the spot pattern, the cause and location within the eye of optical aberrations can be identified. This information is crucial in determining which patients might be suitable for cataract surgery, or in identifying the loss of vision due to vitreous floaters, and hence whether a patient can be expected to benefit from YAG laser vitreolysis.