Blurring of Vision in a 14-Year-Old

Common Causes

1. Refractive Errors (Most Common)

• The most frequent cause in this age group. The eye is too long, focusing light in front of the retina, causing blur for distant objects.
• Typically discovered when children cannot see the blackboard.
• Myopia usually progresses until age 20–25 years.
• Fully correctable with glasses, contact lenses, or (later) LASIK.
• Rapidly progressing myopia after age 25 warrants investigation for diabetes, trauma (cataract), or corticosteroid use — but at 14, progression is expected.

• Eye is shorter than average; light focuses behind the retina.
• Young patients may compensate with lens accommodation, masking the condition.

• Unequal curvature of the corneal surface causes blurred vision at all distances.
• Corrected with cylindrical glasses/contact lenses.

Refractive errors requiring eyeglasses affect almost 20% of the pediatric population before full growth is attained. — Textbook of Family Medicine, 9e

2. Amblyopia ("Lazy Eye")

• Reduced vision in one eye due to abnormal visual development, often from uncorrected refractive error or strabismus.
• Must be identified and treated before visual maturity (~age 7–9 ideally, but some benefit up to teenage years).
• Can present as blurring in one eye.

3. Keratoconus

• Progressive thinning and conical deformation of the cornea.
• Often presents in adolescence with progressive, irregular myopia and astigmatism that is not well corrected by glasses.
• Slit-lamp examination and corneal topography confirm the diagnosis.

4. Pediatric Cataract

• Lens opacity can cause blurred vision.
• In children, causes include: trauma (~40%), inherited (~1/3), systemic disease, or medications (corticosteroids).
• Posterior subcapsular cataracts are associated with corticosteroid use, atopic dermatitis, and inflammatory diseases.
• Traumatic cataract is the most common cause of unilateral cataract in children.

5. Increased Intracranial Pressure (ICP) / Papilledema

• Raised ICP can cause transient visual obscurations — brief episodes of blurred/lost vision, often postural.
• Associated symptoms: headache, pulsatile tinnitus.
• Papilledema (disc swelling) on fundoscopy is the key finding.
• Causes in adolescents: idiopathic intracranial hypertension (pseudotumor cerebri — more common in obese females), intracranial mass.

6. Optic Neuritis

• Inflammation of the optic nerve causing acute visual loss, often with pain on eye movement.
• Can be associated with demyelinating disease (e.g., multiple sclerosis) even in teenagers.
• Distinguished from papilledema by severe acute visual loss accompanying it.

7. Other Causes to Consider

Red Flag Features (Urgent Referral)

• Sudden, painless loss of vision
• Associated headache + vomiting (↑ ICP)
• Eye pain with visual loss (optic neuritis, acute glaucoma)
• Flashes and floaters (retinal detachment)
• Diplopia (double vision)
• Asymmetric red reflex (cataract, retinoblastoma — though rare at 14)
• Papilledema on fundoscopy

History Pearls

• Blurred at distance only, near only, or both?
• One eye or both?
• Constant or intermittent? Sudden or gradual onset?
• Associated pain, redness, headache, floaters, flashes?
• Holding objects very close to see them?
• Family history of myopia, amblyopia, strabismus, glaucoma
• Medications (steroids)?
• Recent trauma?

Workup

1. Visual acuity — Snellen chart (each eye separately)
2. Refraction (ideally cycloplegic refraction in children)
3. Cover test — for strabismus/amblyopia
4. Red reflex — retinoscopy for lens opacities
5. Slit-lamp exam — cornea, lens, anterior chamber
6. Fundoscopy — disc, macula, retina
7. IOP measurement — rule out glaucoma
8. Corneal topography — if keratoconus suspected

Management Summary

Blurring of Vision in a 14-Year-Old with History of Fever

Key Differential Diagnoses

1. Para-infectious (Post-viral) Optic Neuritis — Top Priority in This Age Group

"Optic neuritis may be associated with viral infections such as measles, mumps, chickenpox, rubella, whooping cough, and glandular fever and may also occur following immunization. Children are affected much more frequently than adults. Presentation is usually 1–3 weeks after a viral infection, with acute severe visual loss generally involving both eyes. Bilateral papillitis is the rule." — Kanski's Clinical Ophthalmology, 10th ed.

• Occurs 1–3 weeks after febrile illness
• Usually bilateral in children (unlike adults)
• Prognosis is excellent — spontaneous recovery is the rule
• IV steroids considered only if visual loss is severe or bilateral
• Look for: reduced visual acuity, reduced color vision, pain on eye movement, disc swelling (papillitis)

2. Uveitis (Anterior, Intermediate, or Posterior)

"Presents most frequently in adolescent girls; weight loss, fever, anemia, and hyperglobulinemia often occur before ocular and kidney manifestations." — National Kidney Foundation Primer, 8e

3. Herpes Zoster Ophthalmicus (HZO)

"Dermatomal pain, paresthesias, and skin rash or discomfort. May be preceded by headache, fever, or malaise, and accompanied or followed by blurred vision, eye pain, and red eye." — Wills Eye Manual

4. Measles / SSPE

• Acute measles: conjunctivitis + epithelial keratitis; rarely retinitis with macular and disc edema
• SSPE (Subacute Sclerosing Panencephalitis): rare but critical
  • Affects children and teenagers, onset 6–15 years after measles infection
  • Starts with personality change → involuntary movements
  • Posterior uveitis, papilledema, optic neuritis can occur
  • Retinal vein occlusion secondary to vasculitis reported in teenagers

5. Increased Intracranial Pressure from CNS Infection

• Meningitis / Encephalitis with fever → raised ICP → papilledema → visual obscurations
• Associated: headache, neck stiffness, vomiting, altered consciousness
• Urgent — neuroimaging + LP needed

6. Dengue / Leptospirosis (Tropics)

• Dengue: can cause uveitis, macular edema, optic neuritis during or after febrile phase
• Leptospirosis: classic triad of fever + jaundice + uveitis
• Consider based on geographic context

Fever + Blurred Vision: Diagnostic Approach

Fever + Blurred Vision in 14-yr-old
          ↓
Is the fever CURRENT or PAST (resolved)?
          ↓
PAST (1–3 weeks ago):          CURRENT/recent:
Para-infectious optic neuritis  → Uveitis workup
(most likely)                   → CNS infection
                                → Systemic infection
                                  (dengue, typhoid, lepto)

Workup

Red Flags Requiring Urgent Referral

• Papilledema + fever + headache → CNS infection/raised ICP
• Severe acute bilateral visual loss post-fever → Para-infectious optic neuritis
• Floaters + retinal whitening → Acute retinal necrosis (herpes)
• Personality change + vision loss in teenager → SSPE
• Skin rash around eye + blur → Herpes Zoster Ophthalmicus