“How many times will I need to keep coming back here?”

A few weeks after his baseline glaucoma suspect evaluation, a 71-year-old, semi-retired local farmer asked at his return appointment, “How many times will I need to keep coming back here?”

Although he may have been focused on the upcoming fall harvest, he was also wisely questioning the practicality and purpose of his follow-up testing. Such insightful, proactive questions reflect increased patient awareness, and prompt us to take the time for the following patient education, which answers this gentleman’s question:

AGE

A patient’s residual life expectancy should be considered when developing a testing strategy and any treatment plans.

Chang et al says, “The primary goal of glaucoma therapy is to slow visual deterioration such that the patient experiences no symptoms from the disease during the course of his or her lifetime…”¹

To accomplish this primary goal, and to have the most representative functional information to prevent such visual deterioration, the World Glaucoma Association provided the following guiding consensus principles:²

1. “A good baseline of reliable VFs is essential to be able to monitor for progression.”
2. “The frequency of follow-up VFs should be based on the risk of clinically significant progression (based on extent of damage and life expectancy).”
3. “In clinical scenarios, where the lifetime risk of visual disability is high…three baseline VFs may be necessary.”
4. “Perform sufficient [VF testing] to detect change.”

In addition to performing sufficient VF testing, Keltner et al reminds us to carefully examine the optic nerve to monitor for glaucoma development or progression: “Both the VF and the optic disc must be monitored with equal diligence, because either may show the first evidence of glaucomatous damage.”³

Close monitoring with sufficient VF testing and optic nerve evaluations, with equal diligence in the context of the patient’s age and their residual life expectancy, helps preserve visual function throughout their lifetime.

STAGE

Disease stage determines the type of testing that may be most useful in diagnosing glaucoma and/or detecting glaucomatous progression.

Several studies show that struct-ural testing may be relatively more effective in earlier stages of glaucoma than functional testing with current testing strategies. This disparity decreases as the disease progresses, with both approaches showing more correlating/confirming damage in moderate glaucoma — and then flips, with functional testing generally being more informative in advanced glaucoma stages.^4-6

Performing the right type of testing, and at the right frequency, helps us detect glaucoma development earlier and more quickly, and accurately quantify the potential rate of progression.

TESTING RELIABILITY

We should be aware that, with advancing age and disease stage, there is a recognized decrease with testing reliability in both structural and functional testing. Even in healthy adults without glaucoma, one study shows that there is still a greater than 1 in 4 chance that the OCT retinal nerve fiber layer scan will show false positives⁷ and a more than 1 in 3 chance⁸ that the OCT scan may have some degree of artifacts — and that’s just for objective structural testing.

Let’s also remember that the reliability of functional testing is influenced by so many factors — and both the patient and the provider must be aware of these potential false positives or negatives and analyze them accordingly. Regardless of the type of testing, my mantra is: “If in doubt, repeat.” Good, reliable testing increases certainty. (For a recommended flowchart, timeline, and summary of evaluations for “controversial clinical dilemmas,” see https://bit.ly/3qU37h0 .)

TRIAD APPROACH

This testing triad approach helps prevent both under- and over-testing and, as a result, precludes under- and over-treatment, while helping to diagnose glaucoma earlier and detect progression sooner. OM

REFERENCES

1. Chang R, Singh K. Glaucoma Suspect: Diagnosis and Management. Asia Pac J Ophthalmol (Phila). Jan-Feb 2016;5(1):32-7. doi: 10.1097/APO.0000000000000173.
2. Weinreb R, World Glaucoma A. Progression of Glaucoma: The 8th Consensus Report of The World Glaucoma Association. Amsterdam: Kugler Publications; 2011.
3. Keltner JL, Johnson CA, Anderson DR, et al. The association between glaucomatous visual fields and optic nerve head features in the Ocular Hypertension Treatment Study. Ophthalmology. 2006 Sep;113(9):1603-12. doi: 10.1016/j.ophtha.2006.05.061.
4. Zhang X, Dastiridou A, Francis BA, et al. Comparison of Glaucoma Progression Detection by Optical Coherence Tomography and Visual Field. Am J Ophthalmol. 2017;184:63-74. doi: 10.1016/j.ajo.2017.09.020.
5. Hood DC, Raza AS. On improving the use of OCT imaging for detecting glaucomatous damage. Br J Ophthalmol. 2014; 98 Suppl 2(Suppl 2):ii1-9. doi: 10.1136/bjophthalmol-2014-305156.
6. Abe RY, Diniz-Filho A, Zangwill LM, et al. The Relative Odds of Progressing by Structural and Functional Tests in Glaucoma. Invest Ophthalmol Vis Sci. 2016;57(9):OCT421-8.
7. Kim NR, Lim H, Kim JH, et al. Factors associated with false positives in retinal nerve fiber layer color codes from spectral-domain optical coherence tomography. Ophthalmology. 2011;118(9):1774-1781. doi: 10.1016/j.ophtha.2011.01.058.
8. Asrani S, Essaid L, Alder BD, Santiago-Turla C. Artifacts in spectral-domain optical coherence tomography measurements in glaucoma. JAMA Ophthalmol. 2014;132(4):396-402. doi: 10.1001/jamaophthalmol.2013.7974.

DR. LIFFERTH practices at Center for Sight, in Carmel, Ind. He is a member of the Optometric Glaucoma Society and a Glaucoma Diplomate of the American Academy of Optometry. For additional glaucoma cases, you can also follow Dr. Lifferth on his Instagram account: glaucomaqd. Email him at glaucomaqd@yahoo.com.