Swept-source OCT, faster perimetry and home IOP monitoring are some of the latest advances in diagnosing glaucoma.

In ancient Greece, eye color was often used as a diagnosis of glaucoma, and it was thought of as a disorder of the crystalline lens.1 Glaucoma diagnosis has come a long way since, with knowledge about changes to the optic nerve, diurnal IOP, and the advent of automated perimetry and optical coherence tomography (OCT). And, new technologies continue to come into play to improve the diagnosis and monitoring of individuals who have glaucoma. Here are three such examples.

Swept-source optical coherence tomography (SS-OCT) is the third generation of OCT imaging, following spectral domain (second) and time domain (first). SS-OCT uses interferometry to create depth profiles, or A-scans, which provide cross-sectional and volumetric images. The major advantages of SS-OCT are faster scan speed and higher-resolution images, thought to provide improved disease protection.

SS-OCT is an exciting prospect for practices that heavily utilize OCT, especially retina practices, as SS-OCT can improve efficiency. Early reports indicate that OCT-Angiography also shows dramatic improvements with SS-OCT.

Last month, Topcon Medical Systems, Inc. announced that its DRI OCT Triton Series has received 510(k) clearance from the FDA. The DRI OCT Triton offers easy image capture and a 1μm, 1050nm light source with a scanning speed of 100,000 A-scans/second. The DRI OCT Triton penetrates ocular tissues to visualize deeper pathology and displays high-resolution fundus images with clear retinal vessel and macular mapping to allow Pin-Point Registration of the deepest pathology. The instantaneous capture of a high-density data cube, comprised of 512 B-scans, reduces interpolation between slices and allows the most revealing imagery.

SS-OCT provides thicknesses measurements of the macular retinal nerve fiber layer and the ganglion cell layer plus inner plexiform layer in the macular area. The ability to measure the macular inner layer thicknesses using SS-OCT may aid in the diagnosis of glaucoma.2

In open-angle glaucoma patients, one study found, decreased peripapillary choroidal thickness in glaucoma patients, though this was not affected by glaucoma severity. Also, macular choroidal thickness was not significantly decreased, and choroidal thickness did not show any global or localized relationship with glaucoma severity.3

Humphrey Field Analyzer SITA Faster, or ZEISS HFA3, enables patients to complete 24-2 testing in about two minutes. A company white paper states that the SITA Faster 24-2 test has been shown to run 30% faster compared to SITA Fast, and 50% faster compared to SITA Standard.4 As a result, patients may be more willing to present for frequent visual detection which, in turn, allows earlier detection of progression.

Shorter visual field test times have been a frequent request from both patients and practitioners. The dilemma was that shorter often meant less sensitive and more variable. SITA-FASTER appears to have found the best middle ground.

Given that IOP fluctuates throughout the day, measurement of diurnal intraocular pressure is important in glaucoma diagnosis and management, as single in-office measurements may miss the peak or highest IOP in 69% to 75% of patients.5 While continuous IOP monitoring during the day and night may have been outside the realm of everyday practice, new devices have made it possible for patients to monitor IOP from home.

In March 2017, for example, the Icare HOME tonometer received FDA clearance for use in the U.S. The Icare HOME features patented rebound technology, automatic right eye/left eye, red and green light signals to help patients correctly position the tonometer, and an automated measuring sequence that can take either a single measurement or a series of six measurements with one touch of a button. The Icare HOME involves no puff of air and requires no drops.

One study found that IOP, as measured with Icare HOME for four to six weeks peaked upon awakening and at mid-day and that diurnal IOP measured in the first seven days showed strong correlation to diurnal IOP across the entire study period. Also, patients rated the system as easy to use.6 Another study declared monitoring with Icare HOME was “feasible,” but reported that IOP measured about 0.21mm Hg higher on Icare HOME than Goldmann applanation tonometry.7

Full assessment of diurnal IOP in glaucoma patients has taken a major step forward with the Icare HOME tonometer. Identifying the peaks and troughs of the IOP curve is critical toward developing an individualized treatment and recognizing those patients that are at high risk for progression. Solely relying on in-office IOP measures is simply too limiting.

Another home monitoring device, a soft silicone contact lens called SENSIMED Triggerfish, received FDA approval in 2016. This lens, from Sensimed AG, is intended for one-time use to detect even tiny changes or fluctuations in IOP. During the 24 hours the patient wears the lens, it transmits data wirelessly from the sensor to an adhesive antenna worn around the eye. The patient wears a portable data recorder that receives and transfers data from the antenna to the ECP’s computer via Bluetooth.

It is important to realize that the device does not measure IOP. Rather, it shows the range of time during the day in which IOP may increase so that ECPs can determine the most critical time of day to measure the patient’s IOP.

Evidence suggests that Triggerfish is safe, well tolerated and provides reproducible results, yet some studies show that it only provides data on relative changes in intraocular pressure rather than absolute intraocular pressure.8 In addition, its validity at estimating intraocular pressure compared to other methods is still controversial. The most common temporary side effects were pressure marks from the contact lens, ocular hyperemia and punctate keratitis.

Glaucoma diagnosis obviously has come a long way since ancient Greece.

Michael Chaglasian, OD, FAAO, is the chief of staff of the Illinois Eye Institute and associate professor at the Illinois College of Optometry and is the current President of the Optometric Glaucoma Society.


  1. Leffler CT, Schwartz SG, Hadi TM, Salman A, Vasuki V. The early history of glaucoma: the glaucous eye (800 BC to 1050 AD). Clin Ophthalmol. 2015 Feb 2;9:207-15.
  2. Lee KM, Lee EJ, Kim T-W, Kim H. Comparison of the Abilities of SD-OCT and SS-OCT in Evaluating the Thickness of the Macular Inner Retinal Layer for Glaucoma Diagnosis. Gonzalez P, ed. PLoS ONE. 2016;11(1):e0147964.
  3. Song YJ, Kim YK, Jeoung JW, Park KH. Assessment of Open-Angle Glaucoma Peripapillary and Macular Choroidal Thickness Using Swept-Source Optical Coherence Tomography (SS-OCT). PLoS One. 2016 Jun 16;11(6):e0157333
  4. Callan T, Lee GC, Larson E. HFA3 SITA Faster Results Are Equivalent to SITA Fast and SITA Standard Carl Zeiss Meditec, Inc., Dublin, CA.
  5. Huang J, Katalinic P, Kalloniatis M, Hennessy MP, Zangerl B. Diurnal Intraocular Pressure Fluctuations with Self-tonometry in Glaucoma Patients and Suspects: A Clinical Trial. Optom Vis Sci. 2018 Feb;95(2):88-95.
  6. Huang J, Katalinic P, Kalloniatis M, Hennessy MP, Zangerl B. Diurnal Intraocular Pressure Fluctuations with Self-tonometry in Glaucoma Patients and Suspects: A Clinical Trial. Optom Vis Sci. 2018 Feb;95(2):88-95.
  7. Takagi D, Sawada A, Yamamoto T. Evaluation of a New Rebound Self-tonometer, Icare HOME: Comparison With Goldmann Applanation Tonometer. J Glaucoma. 2017 Jul;26(7):613-618.
  8. Dunbar GE, Shen BY, Aref AA. The SENSIMED Triggerfish contact lens sensor: efficacy, safety, and patient perspectives. Clin Ophthalmol. 2017 May 8;11:875-882.

Icare USA
888.422.7313 |
Sensimed AG
41.21.621.9191 |
Topcon Medical Systems, Inc.
800.223.1130 |
Carl Zeiss Meditec, Inc.
800.342.9821 |


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