How to determine prognosis and progression

A healthy 73-year-old female recently returned to our clinic for repeat VF testing for her early primary open-angle glaucoma OU. Her IOPs were stable in the mid-teens, an improvement from pre-treatment levels in the low 20s, as was her optic nerve and OCT testing. After the patient’s VF testing and while reviewing her summary VF graph with her, as shown below, she asked, “Will that get worse and, if so, will I go blind?”

Here, I explain what information I used to give answers to each of the patient’s questions, and I provide two additional scenarios to contemplate.

“WILL THAT GET WORSE?”

Several population-based studies show sufficient IOP reduction helps prevent both the development of glaucoma and glaucomatous progression.^1-4 Additionally, high-peak IOP, older age, pseudoexfoliation and advanced baseline VF damage are risk factors for further progression.^5-7

The verdict: Because this patient has only mildly elevated pre-treatment IOP levels, currently controlled IOPs, no pseudoexfoliation OU and overall normal baseline (and overall stable) VF testing, the odds are in her favor that her condition is unlikely to worsen significantly with her current treatment.

“WILL I GO BLIND?”

The Early Manifest Glaucoma Trial (EMGT) compared the natural course of glaucomatous progression among treated patients to those without treatment. As one of its many findings, the trial shows patients with pseudoexfoliation had a relatively faster rate of progression than both high-tension primary open-angle glaucoma patients and normal tension glaucoma patients with a mean rate -3.13, -1.31, and -0.36 dB/year, respectively.⁸

The verdict: So, as this patient has a mean deviation of about -1dB, and an estimated rate of progression, as shown above, that is nearly zero, progression to total blindness (-30dB) at her age during her lifetime is also very unlikely.

TWO SCENARIOS

Let us consider two different scenarios for this patient, based on the previously mentioned EMGT rates of progression, if insufficiently (or not) treated.

Scenario one: With a mean rate of -1.31 dB/year, it would take just over 22 years for this patient to reach total blindness from a baseline MD of -1.0dB.

Scenario two: If she had pseudoexfoliation and, thus, a faster rate of progression of -3.13dB/year, the patient would reach -30dB in about nine years, with a baseline MD of -1.0dB. So, she could potentially progress to blindness in her lifetime.

IS RATE UNDERRATED?

Regular VF testing (ideally six within the first two years⁹) helps us more accurately detect the rate of VF progression unique for each patient. This rate of progression, when taken in the context of the expected longevity of the patient, helps us better understand their visual function, so that we can initiate (or adjust) treatment appropriately. OM

REFERENCES

1. 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.
2. 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.
3. 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.
4. The Advanced Glaucoma Intervention Study (AGIS): The relationship between control of intraocular pressure and visual field deterioration. The AGIS Investigators. Am J Ophthalmol. 2000;130(4):429–440.
5. Kim JH, Rabiolo A, Morales E, et al. Risk Factors for Fast Visual Field Progression in Glaucoma. Am J Ophthalmol. 2019;207:268-278
6. Bommakanti N, De Moraes CG, Boland MV, et al. Baseline Age and Mean Deviation Affect the Rate of Glaucomatous Vision Loss. J Glaucoma. 2020;29(1):31-38.
7. Rao HL, Kumar AU, Babu JG, Senthil S, Garudadri CS. Relationship between severity of visual field loss at presentation and rate of visual field progression in glaucoma. Ophthalmology. 2011;118(2):249-253
8. Heijl A, Bengtsson B, Hyman L, Leske MC; Early Manifest Glaucoma Trial Group. Natural history of open-angle glaucoma. Ophthalmology. 2009;116(12):2271-2276.
9. 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. doi:10.1136/bjo.2007.135012

DR. LIFFERTH practices at Grossnickle Eye Center as a consultative optometrist with an emphasis in glaucoma management, and he is a member of the Optometric Glaucoma Society. For additional glaucoma cases, you can also follow Dr. Lifferth on his Instagram account: glaucomaqd. Disclosures: None. Email him at austinlifferth@yahoo.com.