Eye Testing Services | Albany Eye Associates

TearLab Osmolarity System

Hyperosmolarity has been described in the literature as the primary marker of tear film integrity. When the quantity or quality of secreted tears is compromised (known as aqueous deficient or evaporative Dry Eye Disease), increased rates of evaporation lead to a more concentrated tear film(increased osmolarity) that places stress on the corneal and conjunctiva.

The TearLab Osmolarity System is the first objective and quantitative test for diagnosing and managing Dry Eye patients.

TearLab is a noninvasive test which gives fast and accurate results in seconds using only 50 nanoliters (nL) of tear film to diagnose Dry Eye Disease. It gives a clear number to help improve patient compliance. TearLab is a great aid in the diagnosis and monitoring of Dry Eye Disease.

The TearLab Osmolarity System is intended to measure the osmolarity of human tears to aid in the diagnosis of dry eye disease in patients suspected of having dry eye disease, in conjunction with other methods of clinical evaluation.

TearLab, is the first objective and quantitative measurement for diagnosing and managing Dry Eye Disease.
The osmolarity data allows patients to understand their level of disease.

What does TearLab Osmolarity tell me?

Abnormal tear osmolarity is a failure of homeostatic osmolarity regulation. Elevated osmolarity can cause less regulation of the tear film, more damage to the ocular surface, and more inflammation.

Based on the results of a 300 patient trial that was presented at the 2009 American Academy of Ophthalmology, osmolarity was found to have correctly identified 88% of normal subjects, 75% of mild/moderate disease subjects, and 95% of severe disease subjects at a diagnostic cut-off of 308 mOsms/L.1 Therefore, osmolarity values above 308 mOsms/L are generally indicative of dry eye disease.

Humphrey Visual Field

The area in space that may be visualized by the eye is known as the visual field. Plotting of the visual field is important for many disorders, particularly disorders of the optic nerve and brain. This would include glaucoma (an optic nerve disorder), strokes, and brain tumors. Testing peripheral vision with a waving hand is likely only to be useful for the most severe losses of peripheral vision, as sometimes occurs in stroke. The much more common and subtle peripheral vision deficits may only be detected by the sophisticated methodology of a computerized visual field analyzer (Automated Perimeter). This device systematically plots the field of vision using threshold testing, which allows the determination of retinal sensitivity in any given location. Your ophthalmologist then interprets the results. A visual field analyzer is most often used to evaluate and follow patients with suspected or actual glaucoma.

In order to have the automated visual field testing, you sit in front of a concave dome and stare at a central target within the dome. A computer-driven program flashes small lights at different locations within the dome's surface, and you press a button when you see the small lights in your peripheral vision. Your responses are compared to age-matched controls to determine the presence of defects within the visual field.

Humphrey Matrix Visual Field

The Humphrey Matrix represents the latest breakthrough in visual field testing. Using Frequency Doubling Technology, the Humphrey Matrix will help you conduct a thorough visual field evaluation and assess treatment alternatives. This new product is a clinically validated glaucoma management tool that enables the ophthalmologist to diagnose visual field loss early and accurately.

The frequency doubling effect occurs when black and white gratings are flickered at a high rate, resulting in the patient's perception that the grating has twice the original number of bars. The physiological substrate believed to cause this frequency doubling illusion represents approximately 2% of all ganglion cells in the retina and these specific cells are believed to be the earliest damaged by glaucoma.

Digital Ophthalmic Photography

Ophthalmic photography is a highly specialized form of medical imaging dedicated to the study and treatment of disorders of the eye. Through the use of our highly specialized digital photographic cameras and equipment we can document parts of the eye like the cornea, iris, and retina. The retina is the "film" of the eye. Images passing through the clear structures of the cornea and lens are focused there to give us our sight. Special instruments called fundus cameras, used by our skilled photographer, Michel Mehu, can document the condition of this anatomical structure.

When fundus photography is performed after the injection of a fluorescent dye into the bloodstream via a vein in the patient's arm, the procedure is called Fluorescein Angiography. With special colored filters, only the dye is photographed as it travels through the vessels in the retina. These studies, performed by our ophthalmic photographer and interpreted by your ophthalmologist, may be used in differentiating one retinal disease from another and in determining appropriate courses of treatment.

A horizontally mounted microscope, coupled with special illumination devices is used to photograph the cornea. This photo slitlamp produces high magnification views of disorders that would be impossible to observe with the naked eye.

Fluorescein Angiography

Fluorescein Angiography is an imaging technique that allows for a view of the circulation of the retina and the layers beneath the retina highlighting any abnormalities. The test consists of injecting a small amount of a vegetable-based dye (sodium fluorescein) intravenously using a small needle in the arm. Blue colored flash photographs are then taken of the back of the eyes over the next ten minutes on film. These photographs highlight the circulation through the eye. Examination of these photographs can then give further information about one's eye condition. Note that this test is virtually painless and side effects are uncommon; occasionally, though, persons will get nauseous or get hives. Rarely a more severe reaction may occur.

The information derived from this study is very helpful in determining the cause of many retinal diseases and most commonly in evaluating Diabetic Retinopathy and Age-related Macular Degeneration.

Corneal Topography

Of all the technology currently available, corneal topography provides the most detailed information about the curvature of the cornea. A corneal topographer projects a series of illuminated rings onto the corneal surface, which are reflected back into the instrument.The reflected rings of light are analyzed by very sophisticated computer and software and a topographical map of the cornea is generated. The color topographical map and computerized analysis reveals any distortions of the cornea, such as is keratoconus or corneal scarring, as well as the corneal curvature and meridians of astigmatism. The corneal map allows the physician to formulate a "3-D" perspective of the cornea's shape. This diagnostic procedure is essential for patients being considered for refractive surgical procedures (such as Epi-LASIK) and may even be helpful with fitting contact lenses and calculating intraocular lens power for cataract surgery.

Ophthalmic Ultrasound

Ultrasonography is a non-invasive method to examine and measure the eye and is not associated with pain or side effects. The eye is a perfect organ to be examined by ultrasound because of its' anterior location and its anatomical structures and shape, which enhance the echograms produced by the ultrasound. We provide two types of ultrasound used in ophthalmology:

A-Scan Biometry is used to measure the axial length of the eye in order to make the intraocular lens (IOL) calculations for patients who will be undergoing cataract surgery. B-Scan Biometry is used for diagnosis in the posterior eye segment.

Optical Coherence Tomography (OCT)

Optical Coherence Tomography (OCT) is a promising new class of diagnostic medical imaging technology that combines the principles of ultrasound with the imaging performance of a microscope. This enables the ophthalmologist to look at the eye in microscopic detail in a clinical setting. Whereas ultrasound produces images from backscattered sound "echoes," OCT uses infrared light waves that reflect off the internal microstructure within the biological tissues. This results in greatly increased image resolution - 8-25 times greater than any other existing modality.

While standard electronic techniques are adequate for processing ultrasonic echoes that travel at the speed of sound, interferometric techniques are required to extract the reflected optical signals from the infrared light used in OCT. The output, measured by an interferometer, is computer processed to produce high-resolution, real time, cross sectional or 3-dimensional images of the tissue. This powerful technology provides in situ images of tissues at near histological resolution without the need for excision or processing of the specimen.

As a result of this high level of resolution, OCT is particularly suitable for retinal thickness measurements. OCT images can be presented as either cross sectional images or as topographic maps. Cross-sectional images take advantage of the well defined boundaries in optical reflectivity at both the inner and outer margins of the neurosensory retina allowing for retinal thickness measurement. Retinal thickness can then be assessed longitudinally using serial OCT images.