Internal Medicine Board Review: Ophthalmology

Ophthalmology is one of the topics to understand for the USMLE Step 3, ABIM, and on other medical exams where internal medicine is a major focus. The following is an excerpt out of Cracking the USMLE Step 3.


Ophthalmology is a very specialized field that can get very complicated very quickly.  This field is full of a variety of pathology affecting the eye.  However, we have gone through all these disease states and have compiled the following diseases that are most common and have a higher likelihood of appearing on the USMLE Step 3 examination.  We have also included high quality pictures to add another dimension to this chapter.  Please read and enjoy.


Macular Pathology 


Age-Related Macular Degeneration (ARMD)

Internal Medicine Macular Degeneration

Exclusive visual from the Knowmedge QVault


  • Painless loss of central vision
  • See drusen (i.e., yellow deposits) in the macula on ophthalmoscopic exam
  • Treatment is low-vision aids, antioxidants and sometimes laser photocoagulation to delay loss of vision in exudative macular disease
Optic Disc Pathology  


Closed-Angle Glaucoma (Acute Glaucoma)
  • Acute onset -Typical history is person sitting watching a movie in dark theater with sudden blurry vision that is usually unilateral
  • Signs and symptoms include:
    • Tender, hard eye
    • Red eye
    • Dilated pupil that is semi-responsive to light
  • Obtain stat ophthalmologic consult
  • Conduct tonometry (i.e., measure pressure in the eye) for diagnosis
  • Treat with IV acetazolamide or acetazolamide eye drops
    • Carbonic anhydrase inhibitors – decrease the production of bicarbonate
  • Can also give β blocker eye drops (i.e., timolol)
  • Consider cholinergic eye drops (i.e., pilocarpine)
    • Never give anticholinergics to patients with glaucoma
  • Definitive treatment is laser iridotomy
Open-Angle Glaucoma (Chronic Glaucoma)
  • Occurs more gradually as vision is lost
  • Painless
  • Treatment is to decrease intraocular pressure with topical eye drops (i.e., acetazolamide, timolol, or pilocarpine)
    • Never give anticholinergics
  • Definitive treatment is laser iridotomy
Lens Pathology 


  • Clouding of the lens
  • Patients may present with loss of visual acuity
  • Requires ophthalmologic follow-up with slit-lamp examination
  • Treatment is usually surgical if vision loss is progressive and discomforting
  • Difficulty for lens to focus
  • Decrease in near-sightedness
  • Presbyacusis – loss of hearing with age (i.e., usually high frequency sounds)
  Vessel Pathology 


Central Retinal Artery Occlusion

Internal Medicine Retinal Artery Occlusion

Exclusive visual from the Knowmedge QVault
  • May be from emboli
  • May be from atherosclerosis or Diabetes
  • Sudden blurry vision or loss of vision in one eye
  • Painless -May respond poorly to light, but will constrict abruptly when light shined in other eye
  • See cherry red spot on the macula and a pale fundus
  • Treat with thrombolysis if within 8 hours since symptom onset
  • Consider IV acetazolamide or timolol to decrease intraocular pressure
  • Prescribe aspirin daily
  • If suspect may be secondary to temporal arteritis, start IV prednisolone immediately and schedule temporal artery biopsy
Central Retinal Vein Occlusion
  • Visual loss is painless and occurs gradually
  • Ophthalmologic exam is critical
    • Dilated tortuous veins
    • Retinal hemorrhages
    • Cotton-wool spots
    • Macular edema
  • Treat with laser photocoagulation
    • Especially for diabetic retinopathy with neovascularization and branch retinal vein occlusion
  • Prescribe aspirin daily
Amaurosis Fugax

Internal Medicine Amaurosis Fugax

Exclusive visual from the Knowmedge QVault
  • Sudden, transient loss of vision
  • Usually unilateral
  • Described as a curtain coming down vertically over the visual field
  • Caused by transient ophthalmic artery (i.e., branch off internal carotid artery) occlusion
  • Ultrasound carotids to detect degree of stenosis
    • If greater than 70 % stenosis with symptoms (i.e., amaurosis fugax), carotid endarterectomy is indicated
  • May also do Stenting or balloon angioplasty
  • If carotid stenosis greater than 60 % and patient asymptomatic, carotid endarterectomy indicated
  • Prescribe aspirin daily




Lesions along Visual Processing Circuit
  • Lesion of Right Optic Nerve
    • Blindness in right eye
    • No reaction to light in right eye
    • Left eye does not constrict with light in right eye
  • Lesion at Optic Chiasm
    • Patients present with bitemporal hemianopsia
    • Seen in pituitary tumors, craniopharyngiomas, or Rathke’s cleft cyst
  • Lesion of Right Optic Tract
    • Causes a contralateral homonymous hemianopsia with loss of macular vision
  • Lesion of Right Optic Tract in Meyer’s Loop in Temporal Lobe
    • Causes a left superior quadrantonopsia (i.e., “pie in the sky”)
  • Lesion of Right Optic Tract in Parietal Loop in Parietal Lobe
    • Causes a left inferior quadrantonopsia
  • Lesion in Right Occipital Lobe
    • Causes a left homonymous hemianopsia with macular sparing  Seen in posterior cerebral artery (PCA) distribution infarctions


  • Autosomal recessive
  • Mutation of RB1 gene(Tyrosine kinase)
  • Mutation on chromosome 13
  • Most distinctive sign is leukocoria
    • White spot present in the patient’s pupil upon light testing
    • If detected on ophthalmoscopic exam, treatment is stat ophthalmology consult
  • Treatment is enucleation

Got something to add?

Please log In or register for a free account to write a comment.