Advanced Ocular Diagnostics

Optomap

Optometrists at Barnard Levit have been using Optos technology since 2001 to examine the retina (the light-sensitive layer at the back of the eye), forming an integral part of the routine Eye Examination for all patients, from babies to the elderly.

  • Whereas conventional retinal photography takes a picture of approximately just 10% of the retina, the Optomap captures up to 85% of the retina and the anatomical layer below it, the choroid, usually without the need for dilation of the pupils.
  • Optomap technology provides an added advantage of enabling hyperfluorescent images to be taken as part of the screening process for subtle retinal disease.
  • Professor Barnard has presented numerous lectures on the Optos technology as well as publications.

Slit Lamp

The Haag-Streit BQ 900 video lit lamp enables photographs and videos to be captured of conditions of the eye lids, cornea, conjuctiva, anterior chamber, iris and lens.

  • The images below show the instrument together with the optometrist's view through the microscope of a healthy cornea.

Eye Pressure Instruments

  • The Goldmann Applanation Tonometer is used for diagnosis and monitoring of patients with Ocular Hypertension or Glaucoma. This instrument is considered to be the ‘gold standard’ and its use forms part of the NICE Guidelines for Glaucoma.
  • The Keeler Pulsair, as well as the iCare Tonometer, are used as a routine screener for patients 18 years old and above.
  • The Pascal DCT is also used by our Optometrists. This mechanism is arguably more accurate than the Goldmann, as it compensates for corneal thickness, whilst also providing a measurement of the pulse pressure associated with the systolic-diastolic cardiac cycle, which causes the eye pressure to fluctuate with the heartbeat.

OCT

  • The OCT enables us to carry out a non-invasive “biopsy” of the retina, macula and optic nerve and obtain a 3-D analysis.
  • Introduced to Barnard Levit in 2005, as the first in the UK to incorporate the OCT into primary care practice.
  • This instrument provides a non-invasive, non-contact, micron resolution analysis of eye tissues, enabling real-time imaging of tissue structure or pathology with a resolution of 5 microns.  

The OCT is used to assess a wide range of eye conditions, including:

Early Glaucoma Detection and Monitoring

It is estimated that 50% of patients with glaucoma in the UK are undiagnosed and up to about half of all patients with glaucoma have “normal” eye pressures.   OCT enables us to study in detail the structure of the optic nerve and assist detection of the most subtle changes due to glaucoma.

Whilst it does not replace conventional optic nerve examination, including Visual Field testing and the measurement of eye pressure, it helps us detect glaucoma as early as possible. OCT is suggested for patients with a risk of developing glaucoma, such as those with a family member with the condition, or patients with other signs detected by your optometrist.

Macular Degeneration and Macular Holes

Age related macular degeneration (AMD) is the commonest cause of poor vision and blindness in the UK.

Early detection is a challenge because most of us show age related changes as we get older. These early, “dry” macular changes are insidious and increase the risk of the patient developing the more serious type of AMD, (wet AMD). The latter occurs due to fine blood vessels growing deep in macula of the retina. These vessels are fragile and can leak, hence the name “wet”.
OCT assessment of the macular will assist us in monitoring the “dry” changes and detecting new vessel growth at an earlier stage. It also allows us to differentially diagnose macular holes and pseudo-holes.

Diabetes

Diabetic patients are prone to leaks of blood and plasma within the retina. One of the more difficult diabetic changes to detect is oedema (or swelling) of the macula because its appearance is very subtle.

OCT enables us to measure very accurately the thickness of the macula to help detect early changes. OCT compliments the Optos Daytona wide field imaging system and conventional indirect ophthalmoscopy, which we use routinely on all patients to view their retina.

MPS II Macular Pigment Density Screener

The Elektron Tevhnology MPS II measures the density of pigment at the macula.

  • Macular pigment affords protection against harmful blue and ultra-violet light, which can damage the retina, while also being a source of glare.
  • Reduced macular pigment density has been shown to be a risk factor for age related Macular Degeneration.
  • Detection of low levels of pigment at the maculae will enable your optometrist or ophthalmologist to provide you with nutritional advice, which may include supplements of Lutein, Zeaxanthin and Meso-Zeaxanthin.
  • Follow up tests will reveal whether the protective pigment levels increase over time with your dietary changes.

Evidence based clinical publications relating to macular piment and AMD can be reviewed at Elektron.

ERG & VEP

The Electroretinogram (ERG) measures function of the retina for ocular sequelae, results of other diseases, injury, therapy or trauma.
The Visual Evoked Potential (VEP) test measures the integrity of the complete visual pathway to the visual cortex for subclinical abnormalities caused by systemic diseases and disorders. The purpose of these tests is to differentiate ocular from systemic disorders and other conditions that affect vision.
The Diopsys® NOVA™ ERG and VEP Vision Testing System provides visual electrophysiology, components of the electroencephalogram that are specific and objective measures of visual pathway function (strength and speed).

Patients who would benefit most:
  • Have special needs, difficulty taking standard vision tests (e.g. pediatric, non-verbal), or
  • May require more specific testing due to the nature of subclinical effects on the visual pathway,
    • Vascular diseases- systemic hypertension, diabetes mellitus, vasculitis, hematologic diseases, cerebrovascular disease, increased intracranial pressure
    • Endocrine- thyroid eye disease, metabolic storage diseases
    • Neurological-multiple sclerosis, Pupillary function, optic nerve disorders (e.g., optic nerve glioma), chiasmal tumors, myasthenia gravis, central nervous system defects or aneurysm, drug or heavy metal toxicity
    • Toxicity- hydroxychloroquine, tamoxifen, or phenothiazines,tamoxifen, or phenothiazines, Nutritional ON, Toxic ON, drug or heavy metal toxicity
    • Infectious- acquired immunodeficiency syndrome, tuberculosis, syphilis, histoplasmosis, toxoplasmosis
    • Neoplastic- primary or metastatic tumors, orbital tumor
    • Trauma- Cerebral Oedema, compression of brain Cerebral disorder, TBI, Optic Nerve/Pathway disorder
    • Autoimmune- sarcoidosis, immune-mediated diseases

We are pleased to receive referrals from other optometrists or medical practitioners to carry out these tests. Our new visual electrophysiology diagnostic testing benefits us both for appropriate referral, co-management and treatments.

Intuitive Colorimetry:

  • This diagnostic test is used to determine the optimum tint to help alleviate or reduce symptoms of perceptual distortions, associated with Visual Stress Syndrome.
    This condition is reported by some patients who have dyslexia, migraines or photosensitive epilepsy.
  • The instrument independently changes the 3 parameters of colour, hue, saturation and brightness, while the eyes are colour adapted.
  • Barnard Levit Optometrists was one of the first practices in the world to use the Intuitive Colorimeter, from August 1993. This technology is supported by peer reviewed research studies and controlled trials. However, it is deemed controversial by some clinicians and scientists. For this reason, the practice will usually follow a step-by-step diagnostic process when assessing children, to try and rule out any placebo effect.

Contrast Sensitivity

Contrast Sensitivity technology assesses the quality of vision.

  • Contrast Sensitivity measures visual sensitivity at various contrast levels and can therefore detect and quantify visual performance problems better, and at a much earlier stage than the standard visual acuity testing.
  • Contrast sensitivity is particularly useful in documentation of visual performance in the presence of:
    • Cataract
    • Early detection of Glaucoma
    • Macular pathologies
  • Used to monitor treatment efficacy in glaucoma, cataracts, macular degeneration, and diabetic eye disease.
  • Useful tool in understanding visual difficulties after all types of refractive surgery and contact lens vision correction.
Background
  • Research shows that the standard visual acuity assessment only tests one’s ability to see black on white high contrast letters.
  • Many ocular and visual problems remain undetected when only high contrast vision is tested.
  • Standard acuity measurement was originally designed as a tool to quantify optical blur and prescribe spectacles, it does not represent an accurate and representative measure of visual function in the real world.
  • At Barnard Levit we utilise the CSV1000E, manufactured by VectorVision USA. This is a research grade standardised and fully validated Contrast Sensitivity testing equipment.

Cone Contrast Test

  • The Rabin Cone Contrast Test (CCT) is a revolutionary new color vision test sensitive enough to detect both hereditary and acquired deficiency.
  • Barnard Levit Optometrists were the first clinic in the UK to introduce the Rabin Cone Contrast Test to enable precise evaluation of their patients' colour vision.
  • Research shows Cone Function loss is affected early, as a result of numerous diseases, including:
    • Macular Degeneration
    • Diabetic Retinopathy
    • Glaucoma
    • Multiple Sclerosis
    • Parkinson’s Disease
    • Optic Neuritis
    • high-risk medications, such as Plaquenil,
    • Macular pigment density loss.

This test is approved as the sole colour vision test by the US Air Force. The CCT has sensitivity and specificity comparable to anomalascope testing and exceeds Pseudo Isochromatic Plate testing in experienced observers. The CCT provides a rapid, clinically expedient measure of colour vision for quantifying normal colour performance, diagnosing and quantifyng severity of heriditary colour vision deficiency, and detection of aquired colour vision sensitivity loss, due to ocular, neurological and/or systemic disease, as will as injury or physiological stressors such as altitude and fatigue. (Invest Ophthalmol Vis Science, 2011, 52; 816-820).

Barnard Levit Optometrists use this test to:
  • Diagnose the type and severity of heriditary colour vision defects to enable advice to be provided regarding career choice and to enable parents to inform the school of the colour vision anomaly
  • Assist in the diagnosis of a wide range of eye, neurological and systemic conditions
  • Provide accurate information to patients wishing to obtain a commercial or private pilot's licence.