Ophthalmology-Clinical skills for final
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Eye/ ophthalmology lectures for final MBBS by Dr.Saman Senanayake

Eye/ ophthalmology lectures for final MBBS by Dr.Saman Senanayake

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Ophthalmology-Clinical skills for final Document Transcript

  • 1. Basic Clinical Skills in Ophthalmology Remember  Ophthalmology does not end at the back of the eyeball  It involves the whole visual system back to the visual cortex  Many systemic diseases have ocular complications  These patients may initially present to the ophthalmologist  The commonest cause for being registered partially sighted or blind under the age of 65 years is diabetes mellitus HISTORY Common symptoms  “The red eye” (pain, redness, photophobia, discharge)  = front of eye  Painless loss of vision  = back of eye  Misty vision/glare  = cataract  Distortion of vision/central scotoma  = macula  Flashes and floaters  = vitreous/retina EXAMINATION Visual acuity  The ability of the eye to see detail  Distance acuity 1
  • 2.  each eye is tested separately using a Snellen chart  tested at a distance of 6m - normal 6/6 (in USA is 20/20 as feet used)  Near acuity  both eyes tested together  at a distance of 33cm - normal N5 Visual acuity  Snellen comprises rows of letters of decreasing size labelled 60 (top letter), 36, 24, 18, 12, 9, 6, 5  Normal distance acuity i.e. 6/6 means that the row of letters with the number 6 underneath can be read at a distance of 6m Visual acuity  numerator = distance away from the chart in metres  denominator = the number underneath that row of letters seen  if cannot see the top letter at 6 metres  then test nearer the chart (5, 4, 3, 2, 1m) Visual acuity  lower levels of visual acuity are  counting fingers (CF)  hand movements (HM)  perception of light (PL)  no perception of light (NPL, stone blind)  if visual acuity is not at least 6/9 then use the pinhole test 2
  • 3. Refractive error  Emmetropia  Myopia  Hypermetropia  Astigmatism Emmetropia  There is no refractive error and light rays from infinity are brought to a focus on the retina Myopia (short-sighted)  Light rays from infinity are brought to a focus in front of the retina:  the eye is too long - axial myopia or  (the lens is too “strong” from nuclear sclerotic cataract - index myopia) Hypermetropia (long-sighted) 3
  • 4.  Light rays from infinity are brought to a focus behind the retina - the eye is too short or  (the converging power of the cornea or lens is too weak) Astigmatism  The cornea is not spherical - rugby ball shaped rather than football shaped Accommodation  Physiological mechanism that allows close objects to be focused on the retina  In the non-accommodative state the circular ciliary muscle is relaxed - allowing the suspensory ligaments of the lens to remain taut Accommodation  Physiological mechanism that allows close objects to be focused on the retina  In the non-accommodative state the circular ciliary muscle is relaxed - allowing the suspensory ligaments of the lens to remain taut 4
  • 5. Accommodation  During accommodation the ciliary muscle contracts and the suspensory ligaments become lax causing the naturally elastic lens to assume a more globular (convex) shape Accommodation  With age (usually >45 years) the lens gradually hardens and is unable accommodate - presbyopia Accommodation  This can be corrected by a weak converging (plus) convex lens RAPD  Relative afferent pupillary defect Slit lamp microscope 5
  • 6. Front of eye  Just look  Fluorescein + blue light Cataract Surgery  Phakoemulsification and posterior chamber intraocular lens (IOL) implant  mainly LA (day case) or GA  small incision ~ 4 mm  removal of anterior lens capsule  high speed vibrating tip cuts nucleus into tiny particles and aspirates them  Phakoemulsification and posterior chamber intraocular lens (IOL) implant  irrigation and aspiration of remaining cortex  retains posterior capsule  insertion of foldable (e.g. silicone/acrylic) posterior chamber IOL into capsular bag  no sutures - reduced astigmatism  fast healing and visual rehabilitation Intra-ocular lens 6
  • 7. Intra-ocular pressure (IOP)  maintained at 10-21 mm Hg  dynamic balance between secretion and drainage of aqueous humour  high IOP (glaucoma)  leads to loss of visual field and eventual blindness OPHTHALMOSCOPY Back of eye  Direct ophthalmoscopy:  What are you trying to achieve?  How do you do it? What are you trying to achieve?  To see the fundus  Optic disc  Retina  Macula  Blood vessels  Also  Media opacities  Cornea  Lens  Vitreous 7
  • 8. Ophthalmoscopy for dummies  What is an ophthalmoscope?  How do I  Hold it?  Know what settings to put it on?  Know where to look?  Know what I’m looking at? What is an ophthalmoscope?  Instrument with three essential components  Lenses  Light  Diaphragm The direct ophthalmoscope  Magnification approx. 15 x  Field of view 6.5 - 10 degrees  With an undilated pupil  You will not see the macula  The disc will take up the whole field of view  Don’t ask the patient to look into your light as the patient will accommodate and together with the bright light from your ophthalmoscope will make the pupil even smaller 8
  • 9. What lens should I set it on?  Do you wear glasses? - If so, keep them on  Set the ophthalmoscope to zero THEN  Adjust the lens according to the patient’s refractive error What lens should I set it on?  Ask the patient if they wear glasses  If only for reading then do not adjust the lens further  If for the distance (driving, TV) then ask if they are short sighted or long sighted BUT  Many patients get confused and may give you the wrong answer What lens should I set it on?  Pick up the patient’s glasses and hold them about 4 inches from you  With one eye look through one lens at a distant object  If the object appears smaller then they are myopic  If the object appears larger then they are hypermetropic What lens should I set it on?  The smaller the object and thicker the lens the higher the degree of myopia and the higher the lens number (red) on the ophthalmoscope  The larger the object and thicker the lens the higher the degree of hypermetropia and the higher the lens number (black) on the ophthalmoscope 9
  • 10. Direct Ophthalmoscopy  Ophthalmoscope with bright light - halogen bulb if possible, bulb not broken, recharged or new (ish) batteries  Your right eye for the patient’s right eye  Your left eye for the patient’s left eye  Patient sitting comfortably  Ask patient to fixate on distance object  Do not block vision to fellow eye  Semi-dark room, no bright lights or reflections Direct Ophthalmoscopy  Do not put your hands on the top of a patient's head  Women and many men would not like you to mess up their hair  You cannot do much about your patient's breath or personal hygiene, but you can yours so make sure to pay some attention to both Direct ophthalmoscopy  Remove the patient’s glasses (if they are wearing any)  Hold ophthalmoscope with your index finger on the lens dial  Set ophthalmoscope lens to see fundus  Approach from an angle of about 15 degrees temporal to the patient  You must be at the same height as the patient Direct Ophthalmoscopy  Start with your dominant eye  Close your non-dominant eye (with more experience you will be able to keep both eyes open) 10
  • 11.  Use the diaphragm dial to set the small white beam for an undilated pupil and large white beam for a dilated pupil  Shine the light at the pupil and observe the red reflex (yellow/orange glow)  The greater the refractive difference between you and the patient the more blurred will be the red reflex Direct Ophthalmoscopy  Aim about 15 degrees nasal and get nearer to the patient keeping the red reflex as your guide  This is where the optic disc is and it should not be uncomfortable for the patient as it is their blind spot  About a few inches from the patient the fundus should come into view What should I look at?  Optic disc (think of the 3 Cs: cup, colour and contour)  Colour  Cup:disc ratio  Contour (margins)  New vessels (if diabetic)  Retinal blood vessels  Arterioles and veins  Calibre  New vessels, collateral vessels  Tip: If you cannot see the disc follow the blood vessels towards their apex 11
  • 12. What should I look at?  Macula (if pupil dilated)  Foveal reflex  Haemorrhages  Microaneurysms  Exudates  Cotton wool spots  Drusen  Atrophy What should I look at?  Elsewhere  Haemorrhages  Microaneurysms  Exudates  Cotton wool spots  New vessels 12