A. Components of the Eye Exam

1. History
   1. Time of onset
   2. Symptoms when patient first noticed bluriness
   3. Unilteral or bilateral
   4. Associated conditions or events
2. Non-Ophthalmologist Visual Exam
   1. Visual Acuity
   2. Visual field
   3. Pupils
   4. Extraocular Muscle movements
   5. Anterior Segment (sclera, conjunctiva, cornea, anterior chamber, iris, lens)
   6. Posterior Segment (vitreous, retina, optic nerve)
3. Visual Acuity
   1. Test one eye at a time
   2. Glass or contact lenses on if usually used
   3. Read standard chart
   4. Pinhole occlusion used if vision <20/40
   5. If cannot read chart, ask patient to count fingers on examiner's hands
   6. If cannot count fingers, determine distance where hand motions are detect
   7. If cannot detect hand motion, determine if patient can detect light
4. Visual Field
   1. Neurologic disease or retinal detachment may change peripheral vision
   2. Test each eye separately
   3. Check nasal, temporal, superior and inferior quadrants
   4. Amsler's grid may be used: patient looks at central dot
   5. Patient then reports any areas of distortion or loss of visual field
   6. Grid is especially useful in retinal disease
5. Pupils
   1. Pupils should be black, round, of same size, and reactive to light
   2. Nonblack pupil suggests opacification of lens, usually due to cataracts
   3. Misshapen or eccentric pupils after trauma
   4. Pupillary asymmetry may be only sign of serious eye injury on penlight exam (~20%)
   5. Normally, light shined in one pupil should cause both pupils to constrict
   6. Dilation of non-illuminated pupil is called afferent pupillary defect (APD)
   7. APD is a sign of optic nerve disease or injury (nerve and/or retinal damage)
6. Extraocular Muscles (EOM)
   1. Diplopia is usually a manefestation of EOM disfunction
   2. This may be interpreted as blurry vision
   3. EOM testing should be done in all four quadrants
   4. Patient is asked to follow a penlight
   5. Movements of eyes together and separately should be smooth, unrestricted, symmetrical
   6. Limitations of gaze in any direction should be noted
7. Anterior Segment
   [Figure]: "Schematic of the Eye"
   1. Sclera, conjunctiva, cornea, anterior chamber, iris, lens
   2. Entire anterior segment can be visualized with penlight illumination and observation
   3. Sclera and conjunctiva examined for discharge, swelling, vascular prominence
   4. Corneal reflection of light is extremely important
   5. Reflection should be absolutely clear, sharp, and free of irregularities
   6. Blood collection in eye is called hyphema
   7. Pus collection in eye is called hypopyon
   8. Iris evaluated for alterations in shape and contour
   9. Lens should be clear; opacification may signify cataracts
8. Posterior Segment
   1. Consists of vitreous, retina, optic nerve
   2. Direct ophthalmoscopy with pupil dilation is required for reasonable visualization
   3. This is most difficult part of the exam
   4. Pupil dilation with 1% topicamide and 2.5% phenylephrine recommended [1]
   5. Red reflex through direct ophthalmoscope should look the same from all directions
   6. Altered red reflex in cataracts, vitreal hemorrhage, retinal or choroidal detachment
   7. Margins of optic nerve should be flat and well demarcated
   8. Arteries and veins should be free of hemorrhages, exudates, and ischemic cotton-wool spots

B. Nonpathologic Causes of Blurred Vision

1. Refractive Errors
2. Amblyopia: lazy eye (see below)
3. Strabismus: wandering eye
4. Functional (perceptual or psychological) visual loss

C. Pathologic Causes of Sudden Blurred Vision

1. Sudden, Unliteral, Painless Vision Loss
   1. Often from abnormality in posterior segment of eye
   2. Vitreous hemorrhage (usually in diabetics)
   3. Serous elevations of macula, including choroidal neovascular membranes
   4. Age-related macular degeneration (AMD)
   5. Retinal detachments
   6. Retinal-vein occlusions
   7. Retinal artery occlusion (temporary = amaurosis fugax)
   8. Central retinal artery occlusion - APD, cherry red spot on macula, plaque may be seen
2. Sudden, Unliteral, Painful Vision Loss
   1. Usually involve cornea and anterior chamber
   2. Typically with red eye
   3. Corneal causes: abrasion, infection, edema
   4. Corneal infections with ulceration are emergencies
   5. Inflammaiton of iris, ciliary body, anterior uveal tract often associated with photophobia
   6. Traumatic hyphema usually associated with pain and reduced visual acuity
   7. Acute glaucoma causes pain and corneal edema
   8. Temporal (giant cell) arteritis (vasculitis) - presents in older patients, sometimes with scalp pain and arthropathy, very high erythrocyte sedimentation rate (ESR)
   9. Optic neuritis presents in younger persons, often associated with multiple sclerosis
   10. APD is present in temporal arteritis and optic neuritis
   11. Orbital cellulitis can be vision threatening, potentially life threatening
3. Sudden, Bilateral, Painless Vision Loss
   1. Extremely rare
   2. May occur in poorly controlled diabetes
   3. Medications with anticholinergic agents or cholinergic agents
4. Sudden, Bilateral, Painful Vision Loss
   1. Trauma to anterior segment: foreign bodies, chemicals, welder's exposure to UV radiation
   2. Corneal infections, iritis, and acute glaucoma may be biliateral

D. Pathologic Causes of Gradual Visual Loss

1. Gradual, Unliteral, Painless Vision Loss
   1. Cataracts are most common cause, particularly in elderly
   2. Age-related macular degeneration (dry form)
   3. Rarely caused by slow compression on optic nerve (with optic atrophy)
   4. This may be caused by a pituitary or other brain tumor, or sinus tumor
   5. Vasculitis - giant cell arteritis (visual loss may be sudden), other vasculidites [2]
2. Gradual, Unliteral, Painful Vision Loss
   1. Rare cause of vision loss
   2. Slowly progressive inflammatory or neoplastic disease
   3. Orbital granulomas or optic neuromas
3. Gradual, Bilateral, Painless Vision Loss
   1. Cataracts and macular degeneration as above
   2. Ethambutol or hydroxychloroquine (very rare) toxicity
4. Gradual, Bilateral, Painful Vision Loss
   1. Exceedingly rare
   2. Usually chronic inflammatory disease including sarcoidosis and autoimmune disorders

E. Amblyopia (Lazy Eye) [3,4]

1. Defined as reduction in best-corrected visual acuity that is not directly attributable to any structural abnormality of the eye or visual path
2. Most common cause of uncorrectable loss of vision in children
   1. Prevalance of 2%
   2. Usually occurs in children <3 years old (but can occur in ages 4-6)
   3. Screening at least by school entry (age 5-6) for all children is standard
   4. Earliest possible screening (when child can undertake visual acuity measurement) has been advocated, which is typically ~3 years old in many states in the USA
3. Visual outcome ranges from 20/25 (nearly normal) to 20/200 (legally blind)
   1. Anisometropic amblyopia - only one eye is involved (most commonly)
   2. Isometropic amblyopia - both eyes are involved
4. Three Categories
   1. Strabismic amblyopia: most common
   2. Refractive amblyopia: most difficult to detect
   3. Deprivation amblyopia: most severe in terms of vision loss
5. Strabismic Amblyopia
   1. Deviating eye may turn in (esotropia), out (exotropia), up (hypertropia), down (hypotropia)
   2. Deviating eye input to brain is suppressed to prevent double vision
   3. This suppression may progress until all visual potential is lost in deviating eye
6. Refractive Amblyopia
   1. Occurs when two eyes have significantly different refractive states
   2. Young child may rely on sight of the more focused eye
   3. The other eye will lose its visual potential
7. Deprivation Amblyopia
   1. Typically affects children with unilateral or bilateral congenital cataracts
   2. May also occur with corneal or vitreous opacity or severe ptosis
   3. Excessive patching of one eye may similarly lead to deprivation amblyopia
8. Treatment
   1. Appropriate optical correction using eye glasses or contact lenses
   2. Refractive error correction with spectacles may take up to 6 months
   3. Main choices are patching and atropine drops
   4. For strabismus, nearly full time occlusion of normal eye is prescribed
   5. Atropine may also be instilled into the normal eye to cause blurring ("penalization")
   6. Careful pediatric ophthalmological examination is critical
   7. Treatment is effective and results in better visual outcomes than no treatment

References

1. Shingleton BJ and O'Donoghue MW. 2000. NEJM. 343(8):556
2. Kathiresan S, Kelsey PB, Steere AC, et al. 2005. NEJM. 352(19):2003 (Case Record)
3. Holmes JM and Clarke MP. 2006. Lancet. 367(9519):1343
4. Simon JW and Kaw P. 2001. Am Fam Phys. 64(4):623