In this episode of Dry Eye Fireside Chat, Damon Dierker, OD, FAAO, and Jessica Steen, OD, FAAO, Dipl-ABO, discuss neuropathic pain management in optometry, highlighting diagnostic challenges and the importance of identifying underlying neuropathic conditions in patients with complex medical histories.
They support a multidisciplinary approach that aims to improve ocular surface health and involves collaborating with diverse healthcare providers to effectively address symptoms.
Corneal neuropathic pain
Corneal neuropathic pain (CNP) is a type of neuropathic pain caused by damage to the corneal nerves. CNP is a poorly understood condition marked by an abnormal response to normally harmless non-painful stimuli.1
Dr. Steen states that neuropathic pain is challenging to diagnose and typically requires multiple visits before it is considered. Diagnosing CNP is challenging because it has multiple causes, lacks distinct clinical signs, and has limited ancillary testing options, such as in vivo confocal microscopy and esthesiometry, which are often unavailable or cannot definitively confirm the diagnosis.
Its symptoms can resemble those of severe, chronic dry eye disease (DED), frequently resulting in misdiagnosis and ineffective treatment. Symptoms of CNP include itching, irritation, burning, dryness, a foreign body sensation, and related feelings of pressure.1
The impacts can be mild, with minimal effects on activities of daily living, or severe, with the patient experiencing debilitating symptoms that can lead to a deterioration in their physical and social well-being.1 According to Dr. Steen, for some patients, it can be difficult to describe what they are experiencing, but there are signs and symptoms that doctors can identify to help manage this condition.
Is it ocular inflammation, OSD, or CNP?
Dr. Steen recounts a patient encounter she had as a resident. The patient was a woman in her mid-60s who was 12 months post-op for glaucoma filtration and cataract surgery. She had an excellent outcome, but her glaucoma drainage device had failed, and she was back on topical glaucoma medications.
When Dr. Steen entered the room, the lights were off despite the patient being undilated, and she had a hat pulled down over her face. The intern working with her reported having difficulty examining her, and even when the patient’s eyelids were touched, she visibly flinched.
Although she was 12 months post-op, Dr. Steen decided to check for active intraocular inflammation. Her anterior chamber and vitreous were quiet, and her pressure was normal. After ruling out intraocular inflammation, the next step was to evaluate ocular surface disease, which was found to be significant. Her systemic history also revealed rheumatoid arthritis, fibromyalgia, and type II diabetes mellitus.
Assessing patients with corneal neuropathic pain
One of the things that doctors need to consider in situations such as these is that there could be a neuropathic component. Will instilling topical proparacaine in her eye and asking her about symptoms improve it?
Application of a topical anesthetic is useful for distinguishing peripheral from central pain, as it decreases peripheral pain, has no effect on central pain, and may have a reduced effect if both types of pain occur together.1
Another point to consider is that her clinical findings did not align with her complaints, which included light sensitivity and burning. Sometimes, when a patient describes burning eyes, doctors automatically think about ocular surface burning or irritation. However, this patient reported a burning sensation around the eyes. Understanding the patient's main concern can sometimes require extensive open-ended questioning.
Dr. Dierker comments that there are many patients like this with histories of multiple surgeries and systemic diseases that put them at risk for this type of condition.1 Their degree of photophobia may not match the clinical exam findings, and it is important to clearly communicate the management process with these patients, as the condition can be difficult to manage.
Multidisciplinary management of CNP
Treatment of CNP is complex. When managing patients with neuropathic pain, the first step is to optimize the ocular surface.
Consider topical therapies such as anti-inflammatory agents and autologous serum eye drops to improve the ocular surface and support nerve healing and regeneration.1 For this patient, Dr. Steen started with preservative-free artificial tears, as the patient had to continue using her preserved glaucoma medications and a topical immunodulator.
The most important part of management is taking a multi-disciplinary treatment approach. This team can include primary care physicians, pain specialists, neurologists, and psychologists.1 Dr. Steen made sure her patient’s rheumatologist and primary care physician were part of the plan.
She also wanted her to be under the care of a pain management specialist who could employ a holistic, empathetic approach. This doctor prescribed her a selective serotonin reuptake inhibitor (SSRI) and gabapentin.
Considerations for clinical practice
Dr. Steen stresses that an important aspect is how we diagnose and assess these patients. When we instill proparacaine into an uncomfortable eye, and the eye remains uncomfortable, it doesn't automatically indicate neuropathic pain. Instead, it suggests that the pain isn't nociceptive.
We should consider other possible causes of ophthalmic pain, such as referred pain, inflammatory pain, vascular pain, or other factors. Remember, this doesn't necessarily mean the pain is neuropathic. Recognizing this is a key clinical insight that can help us improve pain management and ensure accurate assessment of these patients.
Key takeaways
- Diagnosing CNP can be difficult due to its varied causes and lack of definitive clinical signs.
- A thorough patient history is vital, as many patients have complex medical backgrounds that can contribute to neuropathic pain. Open-ended questioning can help uncover the nature of their symptoms.
- Effective management involves collaboration among healthcare professionals, including optometrists, primary care physicians, pain specialists, and neurologists, to address the complex aspects of the condition.
- Initial treatment should aim to enhance ocular surface health, using options such as topical anti-inflammatory agents and preservative-free artificial tears.
