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• What is the purpose of direct ophthalmoscopy?


  To assess ocular health and the fundus of the eye
• What parts of the eye are assessed during direct ophthalmoscopy?


  The anterior and posterior parts of the eye
• Which internal eye diseases can be screened for using direct ophthalmoscopy?


  Cataract, glaucoma, and maculopathy
• What systemic diseases can be assessed through direct ophthalmoscopy?


  Diabetes and hypertension
• What happens to pupils when brighter light is used during direct ophthalmoscopy?


  Pupils constrict
• What is the overview of the image produced by direct ophthalmoscopy?


  It produces a real and erect image
• What conditions are ideal for performing direct ophthalmoscopy?


  A dim room with no light reflections
• What is the optic disc?


  Where retinal ganglion cells exit the eye to form the optic nerve
• What does the optic cup to disc ratio measure?


  The size of the optic cup
• What is the significance of the optic cup being paler and larger in glaucoma patients?


  It indicates potential optic nerve damage
• What does the ISNT rule refer to in the context of the neuroretinal rim?


  Inferior ≥ superior ≥ nasal ≥ temporal thickness
• What is the function of the macula?


  Responsible for central vision and fine detail
• What is the fovea?


  The central depression of the inner retinal surface
• What is the average power of the eye?


  60 D
• What is the magnification for an emmetropic eye using a direct ophthalmoscope?


  $M =$$x15$
• How is the magnification calculated for a myopic eye?


  $M =$$> x15$
• How is the magnification calculated for a hyperopic eye?


  $M =$$< x15$
• What is the formula for calculating magnification in an ametropic eye?


  $M =$$\frac{Fe}{4} \times \frac{1}{1 - (W \times K)}$
• What is the working distance for a direct ophthalmoscope at a distance of 25mm?


  $W =$$-0.025m$
• What is the magnification for a -10D myope at a distance of 25mm with a dioptric power of the eye of 60D?


  $M =$$x20$
• What is the linear extent of the useful field of view for a 10D myope with a 4mm pupil size at a distance of 25mm?


  $j =$$0.002m$
• What factors affect the field of view and magnification in direct ophthalmoscopy?


  • Pupil size
  • Sighthole size
  • Working distance
  • Subject’s ametropia (hyperope, myope, astigmatism)
• What are the requirements of a good ophthalmoscope?


  • Clear, uniform light patch
  • Field of view coincident with light patch
  • Minimize corneal reflections
  • Absence of sighthole flare
  • Range of target apertures
  • Extra targets
• What is the vitreous body and its function?


  It comprises ~80% of the eyeball volume and transmits light
• What is the refractive index of the vitreous body?


  About 1.33
• What mechanical support does the vitreous body provide?


  It supports the posterior surface of the lens and retina
• What are the components of the vitreous body structure?


  Cortex, lenticular fossa, retrolental space, tracts, and zones
• What is the role of hyalocytes in the vitreous body?


  They produce hyaluronic acid and collagen
• What happens to the vitreous body with aging?


  Liquefaction occurs, increasing from about 20% at age 18 to about 50% at age 80
• What are vitreous floaters and their common causes?


  They are shadows cast on the retina, caused by embryonic remnants or clumps of collagen fibers
• What is the risk factor for posterior vitreous detachment?


  Age, myopia, retinal disease, and ocular surgery
• What is Schafer’s sign?


  Brown pigment cells seen in the anterior third of vitreous indicating a retinal break
• What is asteroid hyalosis?


  Particles suspended in vitreous gel that generally do not cause visual symptoms
• What is synchysis scintillans?


  Cholesterol crystals that cause floaters and are more reflective than asteroid hyalosis
• What is vitreous hemorrhage and its causes?


  Blood located in the space between retina and vitreous cortex, caused by diabetes or retinal traction
• What is the overview of the retina?


  It is the innermost layer of the eye that sends light-induced nerve impulses to the brain
• What are the anatomical relations of the retina?


  Bruch’s membrane is external and the vitreous body is internal
• What are the layers of the neural retina?


  There are ten layers including the internal limiting membrane and photoreceptors
• What is the function of the retinal pigment epithelium (RPE)?


  It absorbs scattered light and maintains the outer blood-retinal barrier
• What is the distribution of rods and cones in the retina?


  Rods are about 120 million and cones are about 6 million in each retina