Autologous Serum Tears for Treatment of Photoallodynia in Patients with Corneal Neuropathy: Efficacy and Evaluation with In Vivo Confocal Microscopy

Abstract

Objective Patients suffering from corneal neuropathy may present with photoallodynia; i.e., increased light sensitivity, frequently with a normal slit-lamp examination. This study aimed to evaluate the efficacy of autologous serum tears (AST) for treatment of severe photoallodynia in corneal neuropathy and correlate with corneal subbasal nerve alterations by in vivo confocal microscopy (IVCM). Methods Retrospective case control study with 16 patients with neuropathy-induced severe photoallodynia compared to 16 normal controls. Symptom severity, clinical examination and bilateral corneal IVCM scans were recorded. Results All patients suffered from extreme photoallodynia (8.8±1.1) with no concurrent ocular surface disease. Subbasal nerves were significantly decreased at baseline in patients compared to controls; total nerve length (9208 ±1264 vs 24714 ±1056 μm/mm2; p<.0001) and total nerve number (9.6±1.4 vs 28.6±2.0; p<.0001), respectively. Morphologically, significantly increased reflectivity (2.9±0.2 vs 1.8±0.1; p<.0001), beading (in 93.7%), and neuromas (in 62.5%) were seen. AST (3.6±2.1 months) resulted in significantly decreased symptom severity (1.6±1.7; p=.02). IVCM demonstrated significantly improved nerve parameters (p< .005), total nerve length (15451±1595 μm/mm2), number (13.9±2.1), and reflectivity (1.9±0.1). Beading and neuromas were seen in only 56.2% and 7.6% of patients. Conclusion Patients with corneal neuropathy-induced photoallodynia show profound alterations in corneal nerves. AST restores nerve topography through nerve regeneration, and this correlated with improvement in patient-reported photoallodynia. The data support the notion that corneal nerve damage results in alterations in afferent trigeminal pathways to produce photoallodynia.

Neuropathic symptoms of the ocular surface: dryness, pain, and itch

“…Treatments that target nerve function may improve symptoms of dryness, ocular pain, and itch in those whose symptoms are partially neuropathic in origin (Table 1). While some therapies, such as autologous serum tears, have been found to improve symptoms of dryness and evoked pain to light [94], their effect on ocular itch are not known. We have anecdotally used gabapentin and pregabalin in several patients with symptoms of dryness and ocular pain not responsive to traditional therapies.…”

La douleur oculaire chronique : mieux la comprendre pour mieux la traiter

“…Les symptômes de la sécheresse oculaire regroupent des troubles visuels et des douleurs d'intensité variable qui deviennent souvent chroniques, voire permanentes. Les patients souffrant de douleur oculaire se plaignent également d'une sensibilité accrue à la lumière (ou photoallodynie) [36]. Il est nécessaire de distinguer la douleur oculaire physiologique nociceptive de la douleur oculaire neuropathique [3,37].…”

Neuropathic Corneal Pain

“…20 The hallmark of central sensitization is pain that is disconnected from ongoing peripheral signs. Sensitization may results in allodynia 7 , photoallodynia (pain due to non-noxious stimuli or light), 6 or hyperalgesia 11 (enhanced pain response to infra-threshold noxious stimuli), causing unpleasant sensations. NCP may have a peripheral origin (e.g, ocular surgery 9,21 or herpes zoster ophthalmicus 22 ) or a systemic origin (e.g, small-fiber polyneuropathy or fibromyalgia).…”

“…While recent articles have attempted to elucidate the pathophysiology behind NCP, very limited literature exists on the management of NCP. 6,13 This review article provides an evidence-based approach on management strategies for NCP, and further reflects our own extensive clinical experience on a large cohort of NCP patients. We have been treating NCP patients since late 2008.…”

“…2 Neuropathic pain can also occur in the cornea, 3–7 the most richly innervated tissue in the body. 8 Neuropathic corneal pain (NCP) remains an ill-defined entity (also termed corneal neuralgia, keratoneuralgia, corneal allodynia or corneal neuropathy), 3–7 and can be perceived as pain, 9 discomfort, 10 aching, 11 photoallodynia, 6 burning, 10 irritation 10 , dryness, 11 and grittiness; 11 symptoms that may overlap with diseases such as dry eye disease (DED). 12 NCP can result from both peripheral nerve injury 5–7, 9 or systemic etiologies, 4,10, 9,13 and owes much of its understanding to advances in the pathophysiology and neurobiology of systemic neuropathic pain.…”