The correct answer is B.
This patient has a corneal abrasion, suggested by her acute eye pain, tearing, photophobia, foreign body sensation, and fluorescein uptake showing an epithelial defect. The cornea is densely innervated by sensory fibers from the ophthalmic division of the trigeminal nerve (cranial nerve V1). Under normal conditions, these nerve endings are protected by the corneal epithelium. When a corneal abrasion occurs, this protective barrier is disrupted, leaving the superficial nociceptive nerve terminals directly exposed to the external environment.
As a result, even minimal stimuli such as blinking, tear film movement, or light exposure can activate these nociceptors. This leads to the characteristic severe pain and foreign-body sensation that patients often describe, which may be out of proportion to the size of the epithelial defect. Additionally, the constant motion of the eyelid across the corneal surface further amplifies discomfort. This mechanical irritation, combined with the high sensitivity of corneal nerves, explains why patients experience persistent symptoms even with small abrasions. Fluorescein staining highlights areas of epithelial disruption, helping confirm the diagnosis. The lack of stromal infiltrate, corneal haze, or purulent discharge makes infectious keratitis less likely, although clinical suspicion for infectious keratitis increases in contact lens wearers.
Choice A is incorrect because although cytokines may contribute to inflammation, the intense foreign-body sensation is due to exposed corneal sensory nerves. Choice C is incorrect because increased intraocular pressure causes symptoms of deep eye pain, headache, halos around lights, nausea, and vomiting. These symptoms are present in acute angle-closure glaucoma, not in a corneal abrasion. Choice D is incorrect because although reflex tearing can certainly occur in a corneal abrasion as a response to irritation of the ocular surface, it is not the primary cause of pain and foreign-body sensation. Choice E is incorrect because bacterial toxin-mediated damage would suggest infectious keratitis. Although infectious keratitis is more common in those who wear contact lens and can cause epithelial defects, the lack of infiltrate, discharge, worsening redness, or stromal involvement suggests a corneal abrasion.
Source: Domingo E, Moshirfar M, Zeppieri M, et al. Corneal Abrasion. [Updated 2024 Jan 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532960/
Photo: https://www.apexvisionslc.com/conditions/corneal-abrasion/
