Dry Eye Severity, Persistence Related to Neuropathic Pain
Dry Eye Severity, Persistence Related to Neuropathic Pain
Objective Studies of patients with non-ocular pain suggest that it is therapeutically useful to identify those with features of neuropathic pain. No data is available, however, on whether this approach has similar utility in dry eye. The purpose of this study was to determine whether severity and persistence of dry eye symptoms associate with self-reported symptoms of neuropathic ocular pain (NOP).
MethodsDesign: Cohort study. Participants/setting: 102 men seen in the Miami Veterans Affairs eye clinic. A baseline evaluation was performed consisting of the dry eye questionnaire 5 (DEQ5) and ocular surface evaluation. Patients were contacted ≥2 years later to repeat the DEQ5 and complete questionnaires that further characterised their eye pain. Main outcome measure: The relationship between dry eye symptom severity and persistence (DEQ5) and additional measures of ocular pain (NOP).
Results Of 102 patients with variable dry eye symptoms, 70 reported at least mild symptoms on both encounters (DEQ5≥6). Fifty-four of 70 (77%) reported ≥1 NOP feature, and the number of NOP features correlated moderately with dry eye symptoms at both encounters (r=0.31–0.46, p<0.01). Patients with any symptom of NOP had higher dry eye symptom scores at both encounters (p<0.05), but similar ocular surface parameters. Hypersensitivity to wind and photoallodynia were associated with having mild or greater symptoms on both encounters (OR 3.4, 95% CI 1.2 to 10.0, p=0.02; OR 15.6, 95% CI 2.0 to 123, p=0.009, respectively).
Conclusions NOP features are common in patients with symptomatic dry eye and these features correlate with symptom severity and persistence.
Dry eye affects the quality of life of millions of Americans. One challenge to effectively managing dry eye is that patients given the diagnosis have a heterogeneous group of disorders. We believe that an important first step in individualising the treatment of dry eye is to classify patients with dry eye by clinical signs, and by symptoms, an approach largely not taken by eye care providers. In fact, the most commonly used dry eye questionnaires arrive at a symptom score by combining a variety of different types of symptoms, including visual disturbances, tearing and pain, rather than using these symptoms to categorise patients.
Data from other chronic pain conditions may shed light on improved ways to classify symptoms of patients with dry eye. As defined by the International Association for the Study of Pain, pain is "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage." Based on this broadly accepted definition, some dry eye symptoms (eg, burning, aching) should be classified as pain.
Pain disorders are broadly classified into two categories: nociceptive pain, which is the normal physiological response to a noxious stimulus and which typically stops when the noxious stimulus terminates; and neuropathic pain, which is pain that persists in the absence of the initiating insult. Neuropathic pain is caused by a wide array of disorders of the somatosensory nervous system and includes conditions such as postherpetic neuralgia, diabetic neuropathy and phantom limb pain. Neuropathic pain is frequently chronic in nature.
There is a growing understanding that many patients diagnosed with dry eye describe features of neuropathic pain, including spontaneous pain, dysaesthesias (unpleasant, abnormal sensation), hyperalgesia (exaggerated pain response to suprathreshold noxious stimuli) and allodynia (pain response to normally non-noxious stimuli). Furthermore, some patients diagnosed with dry eye have abnormal corneal nerve morphology and sensitivity. It is not known, however, what proportion of patients with dry eye symptoms report features of neuropathic pain, and whether these symptoms associate with disease severity. The goal of this study was to evaluate whether severity and persistence of dry eye as assayed by the dry eye questionnaire 5 (DEQ5) associated with self-reported symptoms of neuropathic ocular pain (NOP).
Abstract and Introduction
Abstract
Objective Studies of patients with non-ocular pain suggest that it is therapeutically useful to identify those with features of neuropathic pain. No data is available, however, on whether this approach has similar utility in dry eye. The purpose of this study was to determine whether severity and persistence of dry eye symptoms associate with self-reported symptoms of neuropathic ocular pain (NOP).
MethodsDesign: Cohort study. Participants/setting: 102 men seen in the Miami Veterans Affairs eye clinic. A baseline evaluation was performed consisting of the dry eye questionnaire 5 (DEQ5) and ocular surface evaluation. Patients were contacted ≥2 years later to repeat the DEQ5 and complete questionnaires that further characterised their eye pain. Main outcome measure: The relationship between dry eye symptom severity and persistence (DEQ5) and additional measures of ocular pain (NOP).
Results Of 102 patients with variable dry eye symptoms, 70 reported at least mild symptoms on both encounters (DEQ5≥6). Fifty-four of 70 (77%) reported ≥1 NOP feature, and the number of NOP features correlated moderately with dry eye symptoms at both encounters (r=0.31–0.46, p<0.01). Patients with any symptom of NOP had higher dry eye symptom scores at both encounters (p<0.05), but similar ocular surface parameters. Hypersensitivity to wind and photoallodynia were associated with having mild or greater symptoms on both encounters (OR 3.4, 95% CI 1.2 to 10.0, p=0.02; OR 15.6, 95% CI 2.0 to 123, p=0.009, respectively).
Conclusions NOP features are common in patients with symptomatic dry eye and these features correlate with symptom severity and persistence.
Introduction
Dry eye affects the quality of life of millions of Americans. One challenge to effectively managing dry eye is that patients given the diagnosis have a heterogeneous group of disorders. We believe that an important first step in individualising the treatment of dry eye is to classify patients with dry eye by clinical signs, and by symptoms, an approach largely not taken by eye care providers. In fact, the most commonly used dry eye questionnaires arrive at a symptom score by combining a variety of different types of symptoms, including visual disturbances, tearing and pain, rather than using these symptoms to categorise patients.
Data from other chronic pain conditions may shed light on improved ways to classify symptoms of patients with dry eye. As defined by the International Association for the Study of Pain, pain is "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage." Based on this broadly accepted definition, some dry eye symptoms (eg, burning, aching) should be classified as pain.
Pain disorders are broadly classified into two categories: nociceptive pain, which is the normal physiological response to a noxious stimulus and which typically stops when the noxious stimulus terminates; and neuropathic pain, which is pain that persists in the absence of the initiating insult. Neuropathic pain is caused by a wide array of disorders of the somatosensory nervous system and includes conditions such as postherpetic neuralgia, diabetic neuropathy and phantom limb pain. Neuropathic pain is frequently chronic in nature.
There is a growing understanding that many patients diagnosed with dry eye describe features of neuropathic pain, including spontaneous pain, dysaesthesias (unpleasant, abnormal sensation), hyperalgesia (exaggerated pain response to suprathreshold noxious stimuli) and allodynia (pain response to normally non-noxious stimuli). Furthermore, some patients diagnosed with dry eye have abnormal corneal nerve morphology and sensitivity. It is not known, however, what proportion of patients with dry eye symptoms report features of neuropathic pain, and whether these symptoms associate with disease severity. The goal of this study was to evaluate whether severity and persistence of dry eye as assayed by the dry eye questionnaire 5 (DEQ5) associated with self-reported symptoms of neuropathic ocular pain (NOP).
