Opthalmoscopy

Question 1

purpose of ophthalmoscopy

Answer 1

• examine retina /fundus (by placing scope in body that veins and arteries can be seen )
• provide clinically valuable information (ocular /systemic condition )

Question 2

3 types of fundus examination

Answer 2

Direct ophthalmoscopy
indirect ophthalmoscopy
fundus biomicroscopy

Question 3

advantages of direct ophthalmoscopy

Answer 3

portable 
easy to use 
upright image 
magnification ~ 15 x 
can use without dilation

Question 4

disadvantages of ophthalmoscopy

Answer 4

small field of view (5 degree of the retina)
lack of stereopsis(3D view )
tricky in small pupil
medial opacities can degrade the image

Question 5

Principle of ophthalmoscopy

Answer 5

light source is reflected through the subject pupil to illuminate an area of fundus

this illuminated area is the object for observation system of ophthalmoscope

Question 6

Factors affecting Field of view

Answer 6

pupil size ( small -smaller field of view , large - bigger field of view )

distance -examiner to sight hole and examiner to patients

refractive error - hyperope increase filed of view , myope decrease field of view (shrink eyeball/elongated eyeball)

Question 7

Auxiliary lens wheel , wear spec ?

Answer 7

is use to adjust power of the ophthalmoscope by adding the total refractive error of both patient and examiner together

however this power value is not very accurate and it is not the final numbers as accommodation takes place so there’s a correction of plus minus 1 and also because the wheel only provide power with whole number so there will be power uncorrected and this will affect the full view of the fundus

patient can choose to wear spec / contacts
pro:

• don’t need click the dial
  cons:
• more reflection and worser field of view

Question 8

granticule control

Answer 8

Aperture :

wide angle beam - illuminate largest fundus for best possible general diagnosis through a dilated pupil

intermediate beam - permit easy assess through undulated pupil in peripheral examination (useful in paediatric examination)

macular beam - design for viewing macular area , decrease pupillary reaction and increase patient comfort

slit (fixed/standard size ) - to determine , retinal elevation , depression and anterior chamber depth

glaucoma - project graticule on retina to assess optic disc / cup ratio as an aid to glaucoma diagnosis and monitoring

fixation cross - projects a graticule on retina for assessment of degree and direction of eccentric fixation for Binocular vision and it’s useful for examining children

Filters :
red free green filters - examine blood vessel in fine detail , green filter block red rays showing blood vessel as black against dark green background (useful to diagnose diabetic retinopathy)

cobalt blue : used in conjunction with fluorescein dye for detection and examination of cornea scar and abrasion

Question 9

small pupil what type of beam should we use ?

Answer 9

small beam !
large beam -> pupil to construct more

however the usage of small beam is difficult to see and we need to scan more .

also the techniques of ophthalmoscope is dependent on examiner’s competency !!!

Question 10

what to record while using ophthalmoscope ?

Answer 10

Disc colour - healthy - orange pink abnormal - pale

disc margin
-distinct is healthy
blurry - indicated swollen

Neuroretinal rim (ISNT rule )

• thinning ; possible glaucoma dmg
• notching ; definite glaucoma
• vertical should always be thicker than horizontal due to the papillomacular bundle

venous pulsation
-rhythmic pulsation occurring on central retinal veins due to change in pressure along the retina veins as it traverse the laminate cribrosa

cup disc ratio
can be measured both vertically and horizontally
clinical pearls to look at location where blood vessel turns out to demarcate the CDR instead of using the pallor of the optic disc

retinal vessel
-veins should be thicker than arteries due to veins carry the deoxygenated blood note: arteries are narrower and brighter red in colour

( AV ratio should be 1:2/2:3) usually conduct after second bifurcation of vessels )

mid periphery
regions of posterior pole outside macular area - any lesion or signs ?

macular and fovea

macular- healthy = evenly pigmented with no lesion
fovea - fovea light reflex is present when light is reflected and converge by the fovea pit (look like bright light ! )

absence of this fovea light reflex indicated swelling in fovea BUT in elderly absence of these light reflect is normal due to the shallow fovea pit (due to anatomical variation)