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Ophthalmology Management

Article

Diagnosing glaucoma: COVID-19 and beyond

The pandemic has changed glaucoma care, but traditional tools still have their place.

By: Cheryl N. Zimmer, OD
Ophthalmology Management March 1, 2021 Vol 25, Issue March 2021 Page(s): 34-36, 39

Never have the words “Necessity is the mother of invention” been truer than when managing glaucoma during the COVID-19 pandemic. Glaucoma patients consist of a vulnerable population with an average age of approximately 60 years.1 For the purposes of diagnosis and management, those with glaucoma are usually seen for follow-up every 3 to 6 months.

Considering we have been dealing with the global pandemic in North America for more than a year now, these patients have either been lost to follow-up or have had to leave the safety of isolation to be monitored and treated. Either option can lead to devastating consequences. Fortunately, the ophthalmology community has adapted using a combination of changes in workflow and technology to limit the risks of COVID-19 exposure and vision loss.

While the coronavirus is dominating the conversation today, once it is safe, some aspects of practice may return to their pre-pandemic state. However, a few new diagnostic technologies are likely to be part of ongoing glaucoma care.

VISUAL FIELD TESTING

An important consideration right now in diagnostic equipment is the disinfecting process (see “COVID-era changes”). To assist ophthalmologists, Zeiss created a guideline for disinfecting the Humphrey Field Analyzer (HFA) which can be found online, along with other sanitization support, at www.zeiss.com/meditec/int/med-support-now/disinfecting-ophthalmic-devices.html .2 The bowl surface may be sprayed with a 70% isopropyl alcohol using an atomizing sprayer to avoid drips and to achieve good coverage. Rubbing the bowl is not recommended, as this may damage the surface. Zeiss recommends leaving the room door partially open while doing perimetry to increase airflow and ventilation, provided light is not shining directly on the HFA bowl. The instrument is calibrated to alert the operator if the room lighting is too bright. Additionally, Zeiss offers HFA models with internal fans to circulate air through the front of the bowl.

Reza Razeghinejad, MD, a glaucoma specialist at Wills Eye Hospital says his group added the Octopus 600 (Haag-Streit), which does not bring potential concerns of perimeter bowl contamination and damage to the bowl coating by disinfecting agents. The Octopus 600 does not have a bowl, so it can be cleaned with disinfecting wipes. This device does fast, central, standard white-on-white perimetry, with HFA formatted printouts available.3

“Alternative methods of visual field testing have been something we have always wanted,” says Oluwatosin Smith, MD, of Glaucoma Associates of Texas. “COVID-19 helped accelerate the process, forcing us to look for efficient, yet safe perimetry. We chose to purchase 10 VisuALL Field head-mounted, virtual reality devices from Olleyes for our practice.” Olleyes offers the following benefits:4

  • It is portable and can be worn in any position.
  • Light levels are controlled internally, so there is no need for a separate darkened examination space.
  • Eye-tracking allows for uninterrupted fixation control.
  • It is worn over the patient’s habitual correction, with no need for trial frames or eye patches.
  • It is technician independent, offering a demo video at the beginning of the test to educate the patient.
  • All results are saved to the cloud so the physician can access them, irrespective of the testing location.

Dr. Razeghinejad and his team at Wills Eye Hospital published the first study on the VisuALL.5 “Retinal sensitivity measured by the VisuALL was similar to that of the HFA. The mean sensitivity of the entire visual field and all quadrants correlated significantly in both the control and glaucoma groups (25 subjects in each group). Although the receiver operating characteristic curve of the mean sensitivity for the VisuALL (0.98) was greater than that of the HFA (0.93), there was good agreement and difference was not statistically significant.”

Dr. Smith says her team has done more than 1,100 fields using the VisuALL virtual reality visual field system. “The results for pre-perimetric and mild cases are definitely comparable to the HFA,” she says. “These are the predominant cases for whom we have chosen to use this technology for the time being. We need more data with regard to progression analysis, as well as advanced glaucoma.”

Other head-mounted perimetry systems include the imo (Crewt Medical Systems)6 and the C3 Field Analyzer (Remidio).7 Similar to the VisuALL, the imo is able to track fixation and thereby reduce fixation losses. A 2019 study by Goukon et al showed that there was no significant difference in the mean deviation, visual field index and pattern standard deviation between the imo and HFA for 54 subjects with glaucoma and pseudo-fixation loss.8 Additionally, the results were well correlated between the two devices.

Although the C3 Field Analyzer looks more like the VisuALL than the imo, a study published in 2020 conducted by Mees et al found that it is only moderately reliable with a receiver operating characteristic curve for mean sensitivity and specificity of 0.77 for mild glaucoma and 0.86 for moderate to advanced glaucoma.9

“The appeal of head-mounted perimetry systems would be even greater with the inclusion of other functional tests,” says Dr. Razeghinejad. Examples might include visual acuity, color vision, contrast sensitivity and even fundus photography, that could be administered in the office or at home without requiring full technician supervision. According to Olleyes, the company now offers the VisuALL H for home monitoring of perimetry, which is covered by Remote Patient Monitoring (RPM) billing codes.4

COVID-era changes

If you consider how well exam rooms are being cleaned now — washing chairs and arm rests, wiping down the entire slit lamp and table, sanitizing keyboards and handhelds — it is a wonder that we used to believe it was sufficient to just swab the chin and head rest in the pre-COVID-19 era. “Before COVID-19, all patients who needed supplemental testing following their examination were escorted to the testing rooms, leaving that exam room available for the next patient,” says Reza Razeghinejad, MD. “The original patient was seen after testing in any other available room to discuss the results. Now, the same examination room is used before and after testing, for the entire length of the patient’s visit.”

At Glaucoma Associates of Texas, they structure things a little differently. “After the initial 6-week lock-down in 2020, we looked at the use of our space and decided to convert our business office into a separate testing center. Now, patients are seen in the exam room for their examination and return at a later date for auxiliary testing, as well as a visual acuity and IOP check, at the new testing suite,” says Oluwatosin Smith, MD. The physicians review and interpret the results within a week and determine if the next visit can be conducted via telemedicine or if an in-office follow up is needed. “I have always kept an eye on the length of each patient’s visit using our EMR flow page, with the goal of having them in and out within an hour. By reorganizing our schedule, reducing or eliminating waiting room time and introducing our testing facility, this is now easily achievable.”

In addition, glaucoma specialists, like many physicians, are turning to telemedicine. “It has allowed us to learn a lot about our patients’ lives and problems, which could adversely affect their glaucoma care,” Dr. Razeghinejad explains. “Some lost their jobs and had issues with purchasing their medications. Some were not taking their eyedrops properly. Telemedicine helped us to get closer to our patients — from a distance — establishing a better foundation of communication, which is needed for treating a chronic disease like glaucoma.”

MONITORING IOP

“With regard to IOP,” says Dr. Razeghinejad, “research has demonstrated that mean IOP, maximum IOP and IOP fluctuations can lead to significant changes in the visual field. We need to learn about the diurnal IOP of our patients. However, checking the ‘modified’ diurnal IOP during office hours only (8:00 a.m. to 4:00 p.m.) misses the key measurements of the early morning, evening and late at night.”

With regard to the ongoing COVID-19 crisis, bringing patients into the office for repeated measurements carries its own risks. At-home IOP monitoring is a solution.

“We were using iCare HOME tonometer before the COVID-19 pandemic,” informs Dr. Razeghinejad. The iCare HOME tonometer is a hand-held, anaesthetic drop-free instrument that calculates IOP based on the deceleration and rebound time over a series of consecutive measurements (Figure).10 According to a 2017 article in the Journal of Glaucoma, the IOP readings from the iCare HOME tonometer are not statistically or clinically different when measured by the physician or the patient (0.21 mm Hg). However, the IOPs are statistically higher as compared to Goldmann applanation tonometry (>3 mm Hg in 9.4% of cases and >5 mm Hg in 2.3% of cases).11 Diurnal fluctuations in IOP, however, will still be evident.

Figure. A print-out of a patient’s measurement history, provided by the iCare HOME tonometer.
Figure. A print-out of a patient’s measurement history, provided by the iCare HOME tonometer.

“We have had a handful of patients who had elevated IOPs with the iCare HOME tonometer despite stable office IOPs, who benefited from laser or surgical interventions,” advises Dr. Razeghinejad. The major limitation to home tonometry is the patient’s ability to use the device. For example, patients with musculoskeletal or memory issues are not ideal candidates.

Both Wills Eye Hospital and the Glaucoma Associates of Texas offer patients the opportunity to borrow the device for a week. “We charge $150 per week, which includes eight probes and the required training,” explains Dr. Smith. “Training increases the accuracy of the measurements.” Dr. Smith has found at home monitoring of IOP particularly useful when there is a question of compliance or if visual field loss continues to progress with no obvious reason.

OCTA

Although neither Dr. Razeghinejad nor Dr. Smith routinely use optical coherence tomography angiography (OCTA) to manage glaucoma, they concur that, because there is an associated loss of retinal vessel density in glaucoma and apoptosis of retinal cells, OCTA, may provide insight regarding glaucoma management in the future.

“With more advancements in OCTA to address issues such as motion artifact, sensitivity to media, reproducibility and the lack of normative databases, as well as employing artificial intelligence to combine the results of structural and functional testing, we may be able to detect minimal changes at a very early stage and modify treatment accordingly,” says Dr. Razeghinejad. A 2018 systematic review of 80 references on OCTA for glaucoma concluded that it can accurately differentiate normal eyes from glaucomatous eyes, even in early cases.12

CONCLUSION

“With future advancements, having reliable home-based or even implantable tonometers is not impossible,” Dr. Razeghinejad says. “Receiving a tonometer and head-mounted device in the mail to check visual acuity, contrast sensitivity, perimetry and acquire fundus photos, along with automated data transfer to the ophthalmologist, is a distinct possibility.” The future of glaucoma management may be different, but out of necessity that future may be just around the corner. OM

REFERENCES

  1. Zhao Y, Fu JL, Li YL, Li P, Lou FL. Epidemiology and clinical characteristics of patients with glaucoma: An analysis of hospital data between 2003 and 2012. Indian J Ophthalmol. 2015;63:825-831.
  2. Zeiss. Cleaning and disinfecting ZEISS ophthalmic devices. https://www.zeiss.com/meditec/int/med-support-now/disinfecting-ophthalmic-devices.html . Accessed Jan. 9, 2021.
  3. Haag-Streit USA. OCTOPUS 600 Perimetry simplified. https://www.haag-streit.com/haag-streit-usa/products/haag-streit-diagnostics/octopus-perimetry/octopus-600/ . Accessed Jan. 6, 2021.
  4. Olleyes. Olleyes virtual visual field products. https://olleyes.com/ . Accessed Jan. 9, 2021.
  5. Razeghinejad R, Shukla AG. In the field. How does a novel portable head-mounted perimeter compare with the gold standard in visual field testing? The Ophthalmologist. https://olleyes.com/wp-content/uploads/2020/09/Reza-Artic-The-Ophthalmologist__Text.pdf . Accessed January 9., 2021.
  6. CREWT Medical Systems, Inc. Products. https://www.crewt.co.jp/en/products/ . Accessed Jan. 9, 2021.
  7. Remidio. CFA C3 Field Analyzer. https://www.remidio.us/images/c3fa.pdf . Accessed Jan. 9, 2021.
  8. Goukon H, Hirasawa K, Kasahara M, et al. Comparison of Humphrey Field Analyzer and imo visual field test results in patients with glaucoma and pseudo-fixation loss. PLoS One. 2019;14:e0224711.
  9. Mees L, Upadhyaya S, Kumar P, et al. Validation of a head-mounted virtual reality visual field screening device. J Glaucoma. 2020;29:86-91.
  10. iCare. iCare HOME. https://www.icare-world.com/product/icare-home-tonometer/ . Accessed Jan. 10, 2021.
  11. Takagi D, Swada A, Yamamoto T. Evaluation of a new rebound self-tonometer, Icare HOME: Comparison with Goldmann Applanation Tonometer. J Glaucoma. 2017;26:613-618.
  12. Van Melkebeke L, Barbosa-Breda J, Huygens M, Stalmans I. Optical coherence tomography angiography in glaucoma: A review. Ophthalmic Res. 2018;60:139-151.

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