Ophthalmology Clinical Pearls

Visual Acuity: 

  • Visual acuity is recorded as chart distance (numerator) over the number of lowest line read (denominator)
  • What does 6\12 mean?
    • Means what the pt sees at 6 meters, is what a normal person sees at 12 meters
    • If you bring the patient closer to 3 meters from the chart and then he finally sees the biggest row -> his vision is recorded as 3\60
  • You can add +1\-1 if the patient can\can’t see one letter of the next smaller\previous larger row
  • What does +1 means? The patient can see only one letter in the next smaller line
  • What does -1 means? The patient can’t see only one letter in that same line
    • If the pt gets more than 2 letters wrong, then the previous line should be recorded as their acuity
  • If the patient can’t see -> try using a pinhole; if it improves, it suggests a refractive error
  • If can’t read the top line at 6 m -> reduce the distance to 5,4,3,2, 1 m -> counting fingers (at 70, 50, 30 cm) -> hand motion -> light perception (by dimming the room)
    • If can’t see; say “no light perception” (avoid saying the patient is blind)
  • If the patient can see hand motion -> do light projection in quadrantes (only if the patient can see hand motion), and record as either hand motion with good\poor projection

 

Pupillary Reflex: 

  • If the patient has optic atrophy in the right eye and you:
    • Shine a light on the right eye -> no direct reflex in the right + no consensual reflex in the left
    • Shine a light on the left eye -> direct reflex in the left + consensual reflex in the right
  • When doing the pupillary reflex, come with the light temporally, why? Bc if you shine the light straight -> this is the Near reflex: (1) pupillary constriction, (2) accommodation, (3) convergence

 

Intra-ocular Pressure: 

  • Normal IOP? 10-21 mmHg
  • How to measure intraocular pressure? Via two principles:
    • Indentation: “a force or a weight will indent or sink into a soft eye further than into a hard eye”
      • Digital\manual palpation: soft, firm, hard
      • Tono-pen
      • Schoitz tonometer
    • Applanation: by flatting the cornea
      • Goldmann tonometry
      • Air puff tonometer

Ophthalmology overview 3 

Cataracts:

  • MCC: senile, pre-senile (DM), some diseases and medications (steroids)
  • Degree of visual acuity loss depends on:
    1. Location: cortical (peripheral) < nuclear < posterior subcapsular (steroids)
    2. Density: mild < moderate < severe
  • If the patient has mature cataract (the last and worst stage) their visual acuity will be: hand motion with good light projection
    • How does this matter? Bc if the pt with mature cataract and has vision less than hand motion w\ good light projection -> suspect another pathology which won’t be corrected by cataract surgery (e.g. DM retinopathy, macular degeneration, optic atrophy, retinal detachment)
  • If a patient sustained blunt trauma (which can cause both mature cataract (quickly) and retinal detachment) with visual acuity less than hand motion w\ good projection, how do we confirm if the cause of severe drop in visual acuity is secondary to retinal detachment (since we can’t simply look through a fundoscope bc no clear media due to the cataract)?
    • Pupillary reflex (unlike cataracts, retinal detachment leads to afferent pupillary defect)
    • Ultrasound
  • When to treat? If the pt can’t perform his\her normal life (depends on pt’s needs and occupation)
  • Surgical techniques:
    1. Phacoemulsification (the best and most commonly used)
    2. Extracapsular cataract extraction

Ophthalmology overview 4

 

Anterior Chamber: 

  • We evaluate 2 things:
    • DEPTH:
      • Dislocation of the lens -> deep AC
      • Subluxation of the lens (trauma, Marfan, homocystinuria, Weill-Marchesani syndrome) -> here, due to a break in some of the zonules causing some part of the lens to subluxate and irregular depth of the AC
      • A-phakia or pseudophakia -> deep AC
      • Myopia -> long axial length -> deep AC
      • Hyperopia -> short axial length -> shallow AC (high risk of AACG)
    • CONTENT:
      • Normally -> clear aqueous humor
      • Uveitis -> cells and flares

Ophthalmology overview 5Ophthalmology overview 6

Iris:

  • Normal pattern -> crypts and farrows
  • Neurofibromatosis -> Lisch nodules
  • Coloboma -> part of the iris is missing (it can be in the iris, lens, choreo-retinal layer, or all 3 together)
  • Diabetic neuropathy -> Rubeosis iridis; new vessels on iris (due to ischemia -> VEGF -> new vessels)

Ophthalmology overview 7

 

Corneal Abrasion:

  • Discontinuity of the corneal epithelium
  • MCC: contact lenses, fingernail, paper
  • Nerve supply of the corneal -> CN V (ophthalmic division) -> runs beneath the epithelial layer, so when there’s an erosion in the epithelium, it becomes exposed and causes:
    • Severe pain
    • Ciliary spasm (afferent CN5, efferent CN3)

Ophthalmology overview 8

  • Treatment:
    • Patch (to relieve pain, allow healing by preventing lid movement, and prevent infection)
    • Cyclopentolate: to relax ciliary muscle (cycloplegic)
    • Ointment: to lubricate and prevent infection
    • If you suspect infection: don’t patch it and apply abx and lubricant frequently

 

Corneal Ulcer:

  • An infected corneal abrasion with inflammatory infiltrates in the corneal stroma
  • Organism:
    • Viral: slight discomfort, no discharge, Hx of w\ URTI
      • Adenovirus
      • Herpes zoster -> CNS ganglion, reactivates due to decreased immunity
      • Herpes simplex -> dendritic ulcers
      • Treatment: topical antiviral (acyclovir) + abx (to prevent 2ndry bacterial infection)
    • Microbial: severe pain, decreased vision, edema and congestion, colored mucopurulent discharge, hazy cornea w\ infiltrates
      • Bacterial: most common is S. epidermis, most aggressive is gram negative bacilli
        • Treatment:
          1. Admit (esp if centrally involved, good-eye involvement)
          2. Corneal scraping -> decrease bacterial load and to send for gram stain, culture and sensitivity
          3. Abx: ceftazidime + vancomycin (to cover for gram positive and negative)
          4. Cyclopentolate
          5. Don’t patch the eye
          6. Daily F\U: pain, visual acuity, AC infiltrates -> if present; do US to make sure no vitreous involvement (endophthalmitis)
      • Fungal: mainly chronic, can result by an injury from a wooden piece, r\out systemic cause, never ever give steroids!
      • Protozoal

 

Fundus Exam: 

  • Either direct or indirect

Ophthalmology overview 9

 

Disc: 

  • Contour: normally, it should be sharp and clear
  • Cup: normal cup-to-disc ratio is 0.3
    • Filling of the cup -> one of the earliest signs of papilledema
  • Color: normal is orange-pink
    • If grey or pale -> optic nerve atrophy
    • Hyperemic (tortuous vessels) -> optic disc swelling; either due to papilledema or optic neuritis
      • How to differentiate? Optic neuritis: afferent pupillary defect and poor vision 

Ophthalmology overview 10

 

Vessels: 

  • Obliterated -> branch vein\artery occlusion
  • Nicking\narrow -> hypertensive retinopathy
  • Dilated and tortuous -> papilledema, post uveitis, sarcoidosis, DM retinopathy

 

Retina:

Diabetic Retinopathy

1. Non-Proliferative: 

  • Ischemia -> micro-angiopathy (vessels are losing their layers) -> first thing: micro-aneurysm
  • Signs on fundoscopy: 1. microaneurysm, 2. hemorrhages, 3. hard exudates (lipid deposits), edema
    • Dot-blot hemorrhages: deep, impacted layers
    • Flame-shed hemorrhage (elevated on the retina): superficial in nerve fiber layer (more with HTN)
  • Classification:
    1. Mild non-proliferative: if 1 or all 4 signs are found in 1 quadrant
    2. Moderate non-proliferative: if 1 or all 4 signs are found in 2 quadrants
    3. Severe non-proliferative: if 1 or all 4 signs are found in 3 or all quadrants
  • Signs of ischemia:
    • First thing: tortuous veins
    • IRMA: intra-retinal microvascular abnormality: collateral from non-ischemic areas to ischemic areas: normal walls and flat on the retina
    • Cotton wool spots due to edema causing micro-infarctions (what differentiates mild from moderate non-proliferative)

2. Proliferative:

  • Formation of new abnormal vessels with abnormal layers (very fragile, no normal branching) coming from the venous site -> random tufts of fibrovascular tissue -> can pull on the retina and cause retinal tears, vitreous hemorrhages, Sub-hyaloid hemorrhage (between the vitreous and retina -> “boat-shaped”)
  • Location:
    • On the optic disc itself -> new vessels on the disc (NVD)
    • Outside the disc -> new vessels elsewhere (NVE)
    • On the iris -> new vessels on the iris (NVI)

Treatment: (the vision is intact, so it’s sometimes difficult to convince the pt they need treatment!)

  • Non-proliferative: control of DM, and other risk factors (HTN, DLP), by medications and lifestyle (diet and exercise):
    • Mild: f\u every 6 month
    • Moderate: f\u every 4 months
    • Severe: f\u every 2 months
  • Proliferative:
    • Argon laser panretinal photocoagulation (laser ablation); destroys the normal peripheral retina (visual field and night vision) for the sake of the central retina (central vision, acuity, color). How? less surface area -> less demands -> less ischemia

 

Diabetic Maculopathy: (edema of the macula)

  • Unlike diabetic retinopathy, it leads to poor visual acuity
  • It has no relation of the severity of the diabetic retinopathy, can happen at any stage of the retinopathy (mild, moderate, severe)
  • Treated by anti-VEGF (sometimes we use laser, but risk of scarring of the macula and permanent loss of vision)

Ophthalmology overview 11

Squint; Strabismus: 

Pseudo-strabismus:

  • When you look at both eyes straight, they appear as if the pt has squint, but when you do the cover\uncover test -> the eyes don’t move (eso, exo, hyper, hypo-tropia)
  • Can be pseudo-esotropia -> due to the appearance of epicanthal folds
  • Can be pseudo-exotropia -> due to diversion of the globe externally (extorsion)

True strabismus:

  • Latent: Heterophoria (eso-, exo-, hyper-, hypo-\phoria)
    • If you look at both eyes, they’re both straight, but when you interrupt binocular vision by covering one eye -> the heterophoria appears. And comes back when you uncover
  • Heterotropia (eso-, exo-, hyper-, hypo-\tropia): unilateral vs alternating:
    • If you look at both eyes straight, the left eye is straight, while the right is esotropia -> if cover the left, the right will fix and centralize
    • If you uncover:
      • And the right comes back to esotropia; then the squint is unilateral (in the right eye only)
      • If it’s remains fixed; then the squint is bilateral (alternating)
    • Treatment:
      • Unilateral: surgery to the affected eye only, risk of amblyopia
      • Alternating (bilateral): surgery to both eyes, no risk of amblyopia

 

Random notes:

  • Most common retinal tumors:
    • In pediatrics -> Retinoblastoma
    • In adult -> choroidal melanoma
  • Retina -> 10 layers; their blood supply:
    • Inner layers: retinal vessels
    • Outer layers: diffusion from choroid (highest vascularized organ in the body)
  • Bell’s phenomenon is protective reflex in which the globe is turned upwards and slightly outwards during the eyelid closure to avoid corneal exposure (CN 3 and CN 7)

 


Download the PDF version: here


References:

  • Dr Galmady’s clinical notes
  • Dr Aly’s clinical notes
  • Toronto notes

 

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