Contact lenses, migraine, and allodynia.

Clinical trials and electrophysiologic studies demonstrated increased perceptual sensitivity in patients suffering from migraines. At least, one triggering factor is described in 85% of migraine patients. The aim of this report was to investigate the relationship between contact lens (CL) usage and migraine attacks in two cases. Two patients who were diagnosed with migraine reported that the frequency of migraine attacks increased after they switched to using CL with different base curves (BCs). These two patients, who began using CL with different BCs experienced discomfort and dryness of the eye. The ocular complaints were followed by migraine attacks. CL intolerance was also developed during migraine attack in one of the cases. The frequency of migraine attacks decreased and allodynia relieved significantly when flatter BCs were selected. CL related stimulus could have triggered the migraine attack. CLs should be well fitted in migraine patients with allodynia.

Introduction

Migraine is an idiopathic pain in which any tissue injury or detectable pathology cannot be found.[1] It is the most commonly observed neurological disorder. Migraine is continuously investigated due to its high prevalence and socioeconomic influence and the hope for better treatment increases as pathophysiologic mechanisms are enlightened. Recent evidence indicates dysfunction in brainstem pathways in the etiopathogenesis of migraine.[2]

Most migraine patients showed at least one triggering factor.[3] Clinical trials and electrophysiologic studies showed increased perceptual sensitivity in patients suffering from migraines compared to the patients without migraine.[4] Increased sensitivity is seen towards light, voice, movement, smell, and other perceptional stimuli during migraine attacks or in-between attacks.[3] For these reasons, it is not surprising that a system with an already low excitatory threshold is easily stimulated by internal or external triggering factors. Herein, we presented two cases who experienced discomfort and dryness preceded by migraine attacks after using contact lens (CL), with the base curves (BCs) different from the ones they are previously accustomed to.

Case Reports

Case 1

A 35-year-old female patient was diagnosed with migraine with aura 21 years ago. Her aura history included prolonged visual auras that involved obscuration of the outer halves of each visual field, just like looking through a tunnel and could last up to 30-60 min followed by a headache. She has been using CL for more than 1 year and she complained of sensations of ocular discomfort and dryness associated with wearing her new CLs for the last 2 weeks; although, she did not change either the brand or the power of the CL. Ocular discomfort and dryness were the initial complaints followed by pain surrounding the eyes, eyebrows, and upper eyelids. She reported that the migraine attack started at the same time with a slight pain around the eyes. While the frequency of migraine attack was 0.25-0.5 per month according to her medical history, it was identified that the use of the new boxes of CL increased the frequency to 1.5-2 per week. She was diagnosed to have axial myopia, and her best-corrected visual acuity was 20/20 in both eyes using Snellen chart at 6 m with a prescription of − 3.75D in OD and − 3.75D in OS. She was wearing a silicone hydrogel CL of 8.3 mm BC. It was observed that the BC of the CL was different from the previous one but the brand, material, power, water content, and diameter were the same. A slit lamp biomicroscopic examination revealed the lenses were tightly fitted. She had been wearing this CL of wrong BC for 1½ months. The CL was observed to be resistant to movement on push-up test with lower lid. Vertical post blink movement was seen to be <0.2 mm. Conjunctival indentation was not detected. There was no bulbar or limbal hyperemia. However, there was a mild superficial punctuate epithelial corneal staining in the peripheral cornea in the 3 and 9 o’clock position. The existing 8.3 curved base CL was thought to be too tight and replaced that with a flatter BC of 8.6 mm. In the follow-up visits after using 8.6 mm BC CL, her complaints were completely relieved, and the frequency of migraine attacks returned to its previous pattern. Slit-lamp biomicroscopic examination revealed clear corneas those did not stain with fluorescein and well-centered CLs with appropriate movement in each eye.

Case 2

A 36-year-old male patient who was diagnosed with migraine without aura 16 years ago, reported that he began to experience ocular discomfort, and the frequency of his migraine attacks increased after he began wearing a new brand of CL. Subsequently, his migraine attacks increased from 1/month to twice a week. His new CL brand had a BC of 8.5 mm and was made from silicone hydrogel material (narafilcon A, dia 14.2 mm) while his previous CL brand had an 8.7 mm BC (nefilcon A, dia 14 mm). He described his ocular discomfort as intermittent burning sensation, dryness during CL use and stinging and pain on the ocular surface following CL use. He reported that the pain around the eye frequently transforms to migraine attacks. He stated that he could not tolerate CLs during migraine attacks, and he had to remove the lenses. Axial myopia was detected on his ocular examination. His best-corrected visual acuity was 20/20 in both eyes. The CL with an 8.5 mm BC was seen to be a bit tightly fitted during the slit lamp biomicroscopic examination. The CL was seen to be resistant to movement on the push-up test. Vertical post blink movement was seen to be <0.2-0.3 mm with the blinking of the eye. There were no other signs of tightly fit soft CLs such as conjunctival indentation and bulbar or limbal hyperemia. Soon after, he returned to using his previous CL brand that had a BC of 8.7 mm, his ocular discomfort improved and at the 2-month follow-up visit the frequency of migraine attacks returned to its baseline frequency.

Discussion

Allodynia (derived from ancient Greek “other pain”) is a pain due to a stimulus that does not usually provoke pain.[5] Theoretically, it refers to central pain sensitization caused by a nonnociceptive stimulus, but this definition cannot be used in the clinical setting because it would be impossible to state whether a stimulus is capable of activating nociceptors or not.[67]

Allodynia is a clinical feature of many painful conditions. One of these conditions is a migraine.[89] Allodynia may be seen in the course of migraine attacks and usually includes the scalp, face, and extremities.[8] In the literature a case that relates migraine to the use of CL was reported. In that case, reported by Maggioni et al., it was suggested that the frequency of migraine attacks increased with CL use, and CL-related visual stimuli were effective to trigger pain.[10] It was reported in another study that ocular surgery could be a trigger for a migraine attack.[11] There was no complaining of visual discomfort in either of our cases. In both cases, complaints started after the BCs of the CL's were changed and the resulted ocular discomfort was followed by migraine attacks. In addition, the male patient during migraine attacks had CL intolerance, a condition known as allodynia.

Both patients had pain on and around the upper eyelid following discomfort during CL use. The pain's arousal without the presence of a nociceptive stimulus (trauma, extremely hot, inflammation, etc.) or neuropathic stimulus (trauma, infection, or ischemia-related nerve injury) suggests the concept of dysfunctional pain. The pain around the eye before the migraine attacks may be explained by dysfunctional pain. Development of hyperalgesia and allodynia despite the absence of any body injury or neuronal injury that may cause pain are the characteristic findings of migraine. Migraine headache is considered to be a brain condition reflecting the response of the trigeminovascular system with a differentiated stimulus threshold in genetically susceptible individuals.[89] Burstein et al. reported that peripheral sensitization arises in the early period, and central sensitization arises in the late period of migraine attack.[8] The clinical indicator of this sensitization is the spontaneous pain development and the induction of pain with a painless stimulus.[12] Herein, there is a CL use-related nonnoxious stimulus on the ocular surface. We consider that the condition arising as a CL-related discomfort is initially perceived as pain with time due to peripheral dysfunction in trigeminal system. CLs intolerance may be explained with allodynia which is the indicator of central sensitization following the stimulus.

Performance, comfort, and response to the ocular surface of the CL are evaluated in clinical CL practice. These features are evaluated by assessing lens centration, movement and tightness of the lens using slit lamp biomicroscope. Staining with sodium fluorescein is done to evaluate the effects of CL on the ocular surface. Changes in the BC are known to negatively affect the patient's comfort as it changes the lens-cornea fitting relationship.[1314] Tight fitted CLs may cause burning sensations, stinging, watering and the symptoms are known to continue after the removal of CLs. CLs with inappropriate BCs may cause mechanical trauma to the cornea and tight fitted lenses may lead to hypoxia.[15] Studies report the effects of borderline fitted soft CLs on ocular surfaces such as corneal staining and bulbar or limbal hyperemia, comparing them to well-fitted CLs.[16] A poorly fitted CL, especially with a wrong BC, may cause an adverse effect on the cornea and compromise the comfort either due to tight contact or excessive movement. Many parameters of the lens such as power, material, thickness, water content, O2 permeability, diameter, and edge thickness have important roles in comfort.[13141516171819] Lens solution, the frequency of change, quality of tear, age, gender, drug use, humidity of the environment, and even the ethnicity are also known to affect CL comfort.[13141516171819]

The relationship between CL and migraine attacks may easily be overlooked because uncomfortable CL-related disorders are usually temporary and fitting of CL is not usually evaluated by neurologists. We consider that every migraine patient who uses CL should be questioned for CLs comfort before a treatment plan is made considering the high prevalence of migraines, headaches, and CL use. Furthermore, it is possible that a CL-related stimulus could have triggered the migraine attack and allodynia since we observed that the frequency of migraine attacks decreased and ocular allodynia relieved significantly when proper, well-fitted CLs were selected.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.