Incorporating technologies to care for both glaucoma suspects and patients is critical.
Optometry’s role in medical eyecare continues to expand. As such, many in the profession are contributing in the care of chronic ocular conditions. Take glaucoma, for example. The long-term visually debilitating effects of this disease make it critical for us to identify individuals with this disease early and to provide appropriate medical therapy and referrals for surgical consultations when indicated.
Here are the tools to embrace glaucoma care as an important part of the care you deliver to patients.
This is fundamental and should be done once a year on glaucoma patients and glaucoma suspects. This gives us an indication of whether additional concerns exist with the patient, including any areas of angle recession, excessive pigment in the anterior chamber angle, the presence of narrow angles along with any other abnormalities of the iris or the angle that may influence the way aqueous leaves the eye through the trabecular meshwork.
2 THRESHOLD VISUAL FIELD TESTING
Measuring threshold visual fields and being able to monitor them over time is critical to appropriately care for both glaucoma suspects and glaucoma patients. Although this is often a difficult test for patients, it is critical to perform repeatedly to assess visual function. Standard threshold visual field testing typically involves testing 30° from the point of fixation in the nasal region and anywhere from 24° to 30° in all other areas of the field. Remember to periodically assess the central 10° of the visual field in those individuals who appear to have decreased sensitivity in this region with other testing strategies. Also keep in mind that this technology has many other clinical uses including the investigation of neurological conditions and monitoring visual function in patients taking plaquenil.
3 FUNDUS PHOTOGRAPHY
This is considered a standard of care in the management of patients who are either glaucoma suspect or diagnosed with glaucoma. It is critical in detecting subtle changes in the optic nerve head architecture that over time would be difficult to detect utilizing subjective assessments describing the cup-to-disc ratio and the rim tissue characteristics. It is often difficult to identify subtle changes in the nerve fiber layer with the physical examination and is much more easily viewed in a static image that can be viewed with a variety of filters. Interestingly, in an ocular hypertensive treatment trial, a majority of the optic nerve head hemorrhages were discovered upon optic nerve head photography inspection. This very point and its association with increased risk of developing glaucoma and also progressing glaucoma warrants regular fundus photography of the optic nerve.
4 OPTICAL COHERENCE TOMOGRAPHY
This single technology has changed the way we assess the macula, optic nerve and the anterior segment. Nerve fiber layer thickness has been a longstanding anatomical structure that we have tracked in glaucoma. With advances in optical coherence tomography (OCT) technology, our ability to measure the nerve fiber layer around the optic nerve has increased in its level of accuracy and repeatability.
The ganglion cell complex is now a common measurement that is evaluated and analyzed. This typically measures the thickness of the nerve fiber layer and the ganglion cell layer up to the inner plexiform layer in the macular region. This provides the clinician with an additional diagnostic tool to study an anatomical structure over time that may indicate treatment is warranted for a patient.
Additionally, the OCT provides the clinician the opportunity to accurately measure the central corneal thickness. It also offers the clinician views of the angle between the iris and the cornea. It is important to note that this is complementary to gonioscopy and does not take the place of performing gonioscopy on both glaucoma suspects and those being treated for this disease.
5 CORNEAL HYSTERESIS
Corneal hysteresis reflects the ability of corneal tissue to absorb and dissipate energy during a bidirectional applanation process. The Ocular Response Analyzer G3 from Reichert measures this. Clinically, low corneal hysteresis is associated with optic nerve and visual field damage in glaucoma and the risk of structural and functional glaucoma progression.
Pattern electoretinograms (pERG) measure the retinal ganglion cells response to contrast reversing visual stimuli. This test has the extraordinary ability to detect functional changes in an objective manner prior to structural changes. This is becoming increasingly integrated into eyecare practices as a strategy to detect glaucoma at an earlier phase.
7 HOME-BASED TONOMETRY
The FDA recently approved the Icare HOME, allowing patients to have the ability to measure intraocular pressure (IOP) at home. This will provide us the ability to determine whether out-of-office IOP fluctuations are greater than what would be indicated by in-office measurements. With more IOP readings, we will be better able to cater appropriate therapy to those patients who may need it most.
Through proper testing, we have access to information that will help us both educate and manage our patients. Consider incorporating these technologies to improve outcomes and provide contemporary care for your glaucoma patients. OO
Mile Brujic, OD, FAAO, is owner of Premier Vision Group in Bowling Green, OH.