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BLOG: Advancements in devices that promote diagnosis and management of retinal disorders
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New advancements in devices and technology are constantly improving our ability to more accurately diagnose issues and prescribe appropriate treatment. The following devices are a few that I have found especially beneficial in regards to early diagnosis and treatment.
OCT allows for early detection and diagnosis in numerous pathologies, including retinal edema or atrophy, retinal pigment epithelium and choroid, macular degeneration, diabetic retinopathy and glaucoma. Recent software allows for the detection of glaucomatous damage through analysis of the macular region. The ability this affords to obtain detailed retinal ganglion cell (RGC) analyses is especially useful in determining the presence and progression of disease vs. scanning the optic nerve, which has natural variations depending on the patient population being tested. In prior years, it was not uncommon for me to perform OCT testing and receive normal results only to perform a RGC analysis and detect early disease. The ability to obtain the most accurate information upfront is invaluable in providing the best possible care for my patients.
The Diopsys Nova ERG and VEP vision testing system is another device that can help detect and manage a variety of ocular conditions. While electrophysiological tests are not new, technological advancements have made it possible to conveniently perform them within the office setting. Utilizing comfortably placed sensor pads and a computer screen that shows the patients varying black and white patterns, all the patients need to do is watch.
Similar to OCT, pattern electroretinography (PERG) tests the retinal ganglion cells but objectively analyzes function instead of structure. This diagnostic is useful for multiple maculopathies, including diabetic retinopathies, Plaquenil toxicity and macular degeneration, and is significantly valuable in the early detection of glaucoma. Recording the response of electrically active retinal ganglion cells to a stronger or weaker stimulus can aid in determining the state of disease present, allowing PERG to detect early glaucoma much earlier than traditional testing.
Visual evoked potentials can be performed by the Nova to help determine subjective field loss by measuring the electrical activity of the visual cortex. The strength of the signal is measured as amplitude while the latency denotes the length of time the signal takes to travel from the retina to the visual cortex. Through this, we can better understand the health of the entire visual pathway and intervene before irreparable damage occurs. This test is useful in detecting possible ocular damage, optic nerve impairment, and conditions such as optic neuritis and amblyopia.
The Reichert Ocular Response Analyzer tonometer measures corneal hysteresis, a corneal characteristic that was not able to be measured in the past. The device is user friendly, automatically aligning and measuring with a single touch of the user interface. Measuring the corneal hysteresis provides a more accurate IOP that is independent of other factors such as whether or not the patient has undergone LASIK. This measurement provides valuable information including whether a patient is at increased risk of having glaucoma, the risk for disease progression and a patient’s likelihood of responding well to medication.
Hysteresis measures the difference between the pressure at which the cornea will bend inward and outward again during an air jet applanation. In essence, this difference tells us how well the cornea can absorb pressure. Several studies have shown that a low hysteresis is associated with a greater risk of glaucoma progression. This measurement can also indicate how well a patient is responding to a medication, which allows for the tracking of treatment efficacy. If a patient with low hysteresis responds well to one drop, you know that therapy is doing well and can monitor accordingly. Likewise, if a patient has a high hysteresis, the patient is more likely to be lower risk for progression, and you can afford to wait and see if the medication is effective before adding to the patient’s regimen.
Another significant advancement is the improved ability to test for and treat ocular surface disease (OSD) and dry eye with devices such as InflammaDry (RPS) to test for the inflammatory biomarker MMP-9, TearLab for osmolarity testing, and TearScience’s LipiView II, which can image the meibomian glands, analyze the patient’s lipid layer and perform a blink rate analysis. OSD affects all aspects of eye care and can have considerable effect on a treatment’s efficacy. However, traditional testing is not always reliable. Schirmer’s test is extremely variable, while options such as dyes can be subjective.
Current technological advances enhance our ability to more accurately diagnose and treat patients, while providing opportunities to treat early disease. With newer, more quantitative tests, we can continue to make significant improvements in outcomes across the board.
References:
Agarwal DR, et al. Br J Ophthalmol. 2012;doi:10.1136/bjo.2010.196899.
Banitt MR, et al. Invest Ophthalmol Vis Sci. 2013;doi:10.1167/iovs.12-11026.
Congdon NG, et al. Am J Ophthalmol. 2006;doi:10.1016/j.ajo.2005.12.007.
De Moraes CV, et al. J Glaucoma. 2012;doi:10.1097/IJG.0b013e3182071b92.
Medeiros FA, et al. Ophthalmology. 2013;doi:10.1016/j.ophtha.2013.01.032.
Robert J. Noecker, MD , is a leading ophthalmologist with more than 15 years developing innovations in glaucoma surgery. He currently practices with Ophthalmic Consultants of Connecticut and is on the clinical faculty at Yale University. Noecker can be reached at noeckerrj@gmail.com.
Disclosure: Noecker reports he is a consultant to Diopsys.