Delirium

Disease Description (Causes and Symptoms)

• Definition·Causes: Snow blindness (photokeratitis) is an acute radiation (ultraviolet) injury in which intense ultraviolet (UV) rays enter the eyes after reflecting off surfaces such as snow, damaging the epithelial cells on the surface of the cornea. It can also occur after exposure to strong artificial light sources such as welding arcs.
• Pathophysiology: Ultraviolet rays (UV‑B, UV‑C, etc.) are absorbed by corneal epithelial cells, causing cell death, inflammation, and edema, which lead to pain and reduced vision. Symptoms usually appear after a delay of several hours (typically 6–12 hours) after exposure, and most cases recover within several days.
• Main symptoms: Eye pain (in severe cases, difficulty opening the eyes), photophobia, tearing, foreign-body sensation, conjunctival redness, temporary blurred vision, and cloudiness on the eye surface (when there is a corneal epithelial defect). Rarely, severe cases may result in persistent vision loss.

Treatment Methods

• General principles: Most cases recover with conservative treatment (symptomatic treatment). Relieving symptoms is the top priority, and evaluation by an ophthalmologist is necessary in severe cases.
• Acute management
  • Protect the eyes immediately after exposure (block light), move indoors, close the eyes, and rest.
  • Remove contact lenses immediately.
  • Frequently use cold compresses (a wet, cold towel placed over the eyes) and preservative-free artificial tears.
  • Control pain with oral analgesics (e.g., acetaminophen or NSAIDs).
  • Topical antibiotic ointment (e.g., erythromycin ointment) — may be considered to prevent infection in people with a corneal epithelial defect or contact lens users. However, the physician should determine whether it is necessary.
  • A mydriatic agent (injectable or topical cycloplegics) may be used to relieve severe eye pain (ciliary spasm) under a physician’s instructions.
• Contraindications/Precautions
  • Do not self-use topical anesthetics (eye drops) — they can mask pain, causing worsening, and interfere with wound healing.
  • Eye patching is not generally recommended, but may be applied for a short period at the physician’s discretion.
• Specialist treatment and additional management
  • Immediate referral to an ophthalmologist is required if symptoms are severe or there is reduced central vision, persistent pain, purulent discharge, or worsening symptoms.
  • If severe corneal infiltration/clouding or infection is suspected, specialist treatment with antibiotics, steroids, or other treatments may be necessary (as directed by a physician).
• Lifestyle management and precautions
  • Avoid strong light and direct sunlight until recovery, and wear UV-blocking goggles.
  • Do not wear contact lenses until symptoms improve.
  • Do not rub the eyes with your hands until the injury has healed.

Prognosis: Most cases improve within 24–72 hours and recover completely. Repeated or chronic UV exposure may increase the risk of conjunctival abnormalities, pterygium, corneal clouding, and cataracts.

Complications: Secondary infection (corneal ulcer), persistent epithelial defect, reduced vision due to scarring, and chronic photophobia and pain (rare).

Prevention: Wear UV-blocking sunglasses/goggles, use side shields, wear a hat, and take particular care when exposed to highly reflective surfaces (snow and ice).

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Outpatient Visit Checklist (Including Preparations and Sample Questions)

• Materials and items to prepare
  • A list of all medications currently being taken (including prescription drugs, over-the-counter medications, and supplements)
  • Relevant ophthalmic history (contact lens use, previous corneal disease or surgery, etc.)
  • The time symptoms began and the exposure circumstances (when and for how long exposure occurred)
  • How symptoms have progressed (degree of pain, vision changes, presence of tearing/discharge, and sensitivity to light)
  • If possible, photos taken when symptoms occurred (the appearance of the eye or the exposure environment)
  • Contact lenses (bring them to the visit if worn)
• Items the physician checks during the consultation
  • Visual acuity test, slit-lamp examination (to check for a corneal epithelial defect), and, if necessary, slit-lamp and fluorescein staining examinations
  • Culture or additional tests if infection is suspected
• Prohibited actions and preparations before the outpatient visit
  • Do not use anesthetic eye drops on your own
  • If symptoms worsen, an immediate visit to the emergency room is recommended

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Examples of General Questions to Ask the Doctor

• "What is the expected healing time for this condition?"
• "What are the side effects of the prescribed medication, and what precautions should I take when taking or applying it?"
• "Are antibiotics or steroids necessary, and if so, why?"
• "When can I start wearing contact lenses again?"
• "What specifications for protective equipment (sunglasses or goggles) do you recommend to prevent exposure to the same environment again?"

Examples of Condition-Specific Questions

• "Could you tell me whether a corneal injury has occurred in my case (based on the fluorescein staining results) and whether there is a risk of damage to my central vision?"
• "In the future, what type of sunglasses do you recommend for reflective environments such as mountains or ski resorts (lens rating, UV protection, etc.)? (e.g., UV400, goggles with side shields)"