Editors Selection IGR 21-1

Medical Treatment: The Importance of Being Adherent

Adeleh Yarmohammadi
Sally Baxter

Comment by Adeleh Yarmohammadi & Sally Baxter on:

84925 The Association between Medication Adherence and Visual Field Progression in the Collaborative Initial Glaucoma Treatment Study, Newman-Casey PA; Niziol LM; Gillespie BW et al., Ophthalmology, 2020; 127: 477-483

See also comment(s) by Fotis Topouzis

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Reduced adherence to therapeutic plans remains a significant global healthcare concern in many chronic diseases, including glaucoma.1 In this study, Newman-Casey et al. evaluated a spectrum of adherence among patients with glaucoma in the Collaborative Initial Glaucoma Treatment Study (CIGTS), finding a statistically significant relationship between medication adherence and glaucomatous visual field progression among the participants randomized to the medication arm of the trial.

Authors found that adherent patients who reported not missing any medication doses had 0.62 dB of visual field loss (ascertained by mean deviation, MD) on average over the seven years of follow-up, consistent with reported rates of age-related changes in MD.2 In contrast, patients who reported missing doses at 1/3 of follow-up visits lost an average of 1.42 dB of MD; those who reported missing doses at 2/3 of visits lost an average of 2.23 dB. Factors associated with non-adherence were of younger age, non-married status, black race, depression, a lower degree of education, and worse baseline MD.

This study showed a significant dose-response relationship between the extent of medication adherence and rate of glaucomatous visual field progression (p = 0.005)

This study showed a significant dose-response relationship between the extent of medication adherence and rate of glaucomatous visual field progression (p = 0.005). However, several issues require further consideration. First, the assessment of medication adherence via self-reported data could have been confounded by overestimation of true adherence. Patients generally overestimate their own adherence when compared to device-measured or pharmacy refill data,3 and the rates of adherence in CIGTS participants exceeded those reported in prior studies.4 Therefore, the magnitude of the reported association may have been underestimated.

Second, visual field progression in non-adherent patients could have been secondary to factors other than medication adherence; association does not equal causation. However, overall this study offers strong secondary analysis of clinical trial data to provide further support for the importance of evaluating patient adherence in glaucoma.


  1. Quigley HA. 21st century glaucoma care. Eye (Lond). Published online October 10, 2018. doi:10.1038/s41433-018-0227-8 PMID: 30305707
  2. Chauhan BC, Malik R, Shuba LM, Rafuse PE, Nicolela MT, Artes PH. Rates of glaucomatous visual field change in a large clinical population. Invest Ophthalmol Vis Sci. 2014;55(7):4135-4143. doi:10.1167/iovs.14-14643 PMID: 24917147
  3. Friedman DS, Quigley HA, Gelb L, et al. Using pharmacy claims data to study adherence to glaucoma medications: methodology and findings of the Glaucoma Adherence and Persistency Study (GAPS). Invest Ophthalmol Vis Sci. 2007;48(11):5052-5057. doi:10.1167/iovs.07-0290 PMID: 17962457
  4. Newman-Casey PA, Blachley T, Lee PP, Heisler M, Farris KB, Stein JD. Patterns of Glaucoma Medication Adherence over Four Years of Follow-Up. Ophthalmology. 2015;122(10):2010-2021. doi:10.1016/j.ophtha.2015.06.039 PMID: 26319441

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