This article is part of Ophthalmology Advisor’s Dry Eye Disease In-Depth coverage from the 2021 meeting of the American Academy of Ophthalmology, held in New Orleans from November 12 to 15, 2021. The team at Ophthalmology Advisor will be reporting on a variety of the research presented by the dry eye disease experts at the AAO. Check back for more from the AAO 2021 Meeting.


Conditioned pain modulation (CPM) is a measure of descending (inhibitory) pain pathway, using noxious conditioning. A presentation at the American Academy of Ophthalmology 2021 shows, when dry eye metrics rise, patients have a more robust CPM response.    

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The study reviewed the cases of 268 patients, who presented between October 2017 and August 2018 with dry eye disease. Dry eye metrics were evaluated using the 5-Item Dry Eye Questionnaire (DEQ-5) and an ocular surface exam. 

Conditioning involved exposure to a noxious thermal stimulus followed by a water bath that served as a conditioning stimulus, and finally exposure to the original thermal stimulus applied to the forehead and forearms. The expected normal response is pain inhibition. 

Results of the study indicated that CPM intensity and discomfort at the forehead was significantly associated with elevated DEQ-5 scores (r=-0.21, P <.05 and r=-0.18, P <.05, respectively) and significantly associated with average eye pain intensity for 1 week (r=-0.20, P <.05) and tear breakup time (r=-0.21, P <.05). 

At the forearm, CPM intensity was significantly associated with average eye pain intensity for 1 week (r=-0.26, P <.05), evoked pain to wind (r=-0.21, P <.05) and light (r=-0.24, P <.01). 

Visit Ophthalmology Advisor’s conference section for the complete Dry Eye Disease coverage from the AAO 2021.



Huang A, Galor A, Felix ER. Role of conditioned pain modulation in dry eye. Paper presented at: The American Academy of Ophthalmology 2021 Annual Meeting; November 12-15, 2021; New Orleans. Abstract PA028.