A healthy dose of paranoia can help in glaucoma management and treatment

I ask myself throughout every exam, “Does this patient have any signs of glaucoma?” I feel that the repetition of this question (in real time) is a healthy dose of paranoia that may help me diagnose and detect glaucoma earlier.

Here are some other cautious questions ODs can continually consider during the exam.

IS IT REALLY GLAUCOMA?

Not every retinal nerve fiber layer defect (RNFL) or VF defect is glaucomatous. Fortunately, a thorough, personal medical and ocular health history, combined with a systematic evaluation of the optic nerve, can help differentiate glaucoma from other nonglaucomatous optic neuropathies, such as high myopia, neuroretinal vascular occlusive/ischemic diseases, or neurological conditions, that may also cause RNFL or VF defects. While each may present very differently, the former two are usually relatively stable over time, while the latter condition is likely to progress with characteristic VF defects.^1-5

In general, if a person younger than age 40 presents with reduced vision, neuroretinal rim pallor, and/or uncharacteristic VF defects with faster disease progression than expected and that do not correlate with the optic nerve or retinal appearance, optometrists should suspect other neurological etiologies and employ appropriate blood work and/or imaging.^2-3

IS THE IOP REALLY LOW ENOUGH?

Because mean IOP is the greatest modifiable risk factor in the development^6-7 and the progression of glaucoma,^8-11 and because IOP reduction decreases the risk of development^6-7 and progression of glaucoma,^8-11 even among patients who have IOP within the statistically normal range,¹² primary treatment is focused on IOP reduction. Although proposed target pressure ranges exist,¹³ I feel that determining whether a patient’s IOP is low enough comes down to one word: testing. If a patient shows reliable structural or functional progression at their mean IOP level, ODs should seek to further lower their IOP.

HAS THIS PATIENT DONE ENOUGH VFS?

Despite their importance and relatively easy accessibility, in general, optometrists do not do enough perimetry testing as recommended¹⁴ to establish a baseline and/or to readily (and reliably) detect progression.¹⁵ While recognizing the reality of limited patient satisfaction with VF testing¹⁶ and limited clinic personnel or available appointments for such testing, I find the World Glaucoma Association’s Consensus Statements¹⁷ helpful principles to strive for:

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

As a related side note, when interpreting VF results, optometrists should remember that, in general, the defects will get worse where the VF is the worst. So, ODs should look for deepening and widening of these defect areas, in addition to new correlating VF defects. Because the VF should look the same as, or better than, the optic nerve appearance, additional workups are needed if defects appear outside these areas and, particularly, if they are progressing quickly.

PARANOIA THERAPY

Timely and patient-tailored testing and treatment is the therapy for this paranoia, allowing you to help with certainty. OM

REFERENCES:

1. Choudhari NS, Neog A, Fudnawala V, George R. Cupped disc with normal intraocular pressure: the long road to avoid misdiagnosis. Indian J Ophthalmol. 2011;59(6):491–497.

2. Greenfield D. Glaucomatous versus nonglaucomatous optic disc cupping: clinical differentiation. Seminars In Ophthalmology.  June 1999;14(2):95-108.

3. Greenfield, David S et al. The cupped disc: Who needs neuroimaging? Ophthalmology, Volume 105, Issue 10, 1866 – 1874. 

4. Dias DT, Ushida M, Battistella R, Dorairaj S, Prata TS. Neurophthalmological conditions mimicking glaucomatous optic neuropathy: analysis of the most common causes of misdiagnosis. BMC Ophthalmol. 2017;17(1):2. Published 2017 Jan 10.

5. Tan NYQ, Sng CCA, Jonas JB, Wong TY, Jansonius NM, Ang M. Glaucoma in myopia: diagnostic dilemmas. Br J Ophthalmol. 2019;103(10):1347‐1355.

6. Kass MA, Heuer DK, Higginbotham EJ, et al. The Ocular Hypertension Treatment Study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma. Arch Ophthalmol. 2002;120(6):701–830. 

7. Miglior S, Zeyen T., Pfeiffer N, et al.  Results of the Europrean Glaucoma Prevention Study.  Ophthalmology 2005.  112: 366-375.

8. Heijl A, Leske MC, Bengtsson B, et al. Reduction of intraocular pressure and glaucoma progression: results from the Early Manifest Glaucoma Trial. Arch Ophthalmol. 2002;120(10):1268–1279.

9. Musch DC, Gillespie BW, Niziol LM, Lichter PR, Varma R; CIGTS Study Group. Intraocular pressure control and long-term visual field loss in the Collaborative Initial Glaucoma Treatment Study. Ophthalmology. 2011;118(9):1766–1773
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10. The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration.The AGIS Investigators. Am J Ophthalmol. 2000;130(4):429–440.

11. Sommer A., Tielsch J.M., Katz J., et al.  Relationship between intraocular pressure and primary open angle glaucoma among white and black Americans.  The Baltimore Eye Survey.  Arch Ophthalmol. 1991;109:1090-1095.

12. Comparison of glaucomatous progression between untreated patients with normal-tension glaucoma and patients with therapeutically reduced intraocular pressures.  Collaborative Normal-Tension Glaucoma Study Group.  Am J Ophthalmol.  1998.  126:487-497.

13. Sihota R, Angmo D, Ramaswamy D, Dada T. Simplifying "target" intraocular pressure for different stages of primary open-angle glaucoma and primary angle-closure glaucoma. Indian J Ophthalmol. 2018;66(4):495–505.

14. Chauhan BC, Garway-Heath DF, Goñi FJ, et al. Practical recommendations for measuring rates of visual field change in glaucoma. Br J Ophthalmol. 2008;92(4):569–573.

15. Fung SSM, Lemer C, Russell RA, et al Are practical recommendations practiced? A national multi-centre cross-sectional study on frequency of visual field testing in glaucomaBritish Journal of Ophthalmology 2013;97:843-847.

16. Glen FC, Baker H, Crabb DP. A qualitative investigation into patients' views on visual field testing for glaucoma monitoring. BMJ Open. 2014;4(1):e003996. Published 2014 Jan 10.

17. Weinreb R, World Glaucoma A. Progression of Glaucoma: The 8Th Consensus Report of The World Glaucoma Association. Amsterdam: Kugler Publications; 2011.
 

DR. LIFFERTH practices at Center for Sight. 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.