What is Direct Ophthalmoscopy ?

Direct Ophthalmoscopy

❑ Direct ophthalmoscope is a hand held instrument used to examine the fundus.

❑ It is used monocularly.

❑ It can be used to examine central 7 to 10 degree of retina.

❑ It gives a magnification of 15x which makes the 1.5mm disc appear much larger.

Direct ophthalmoscope consist of two system

❑ Illuminating system

❑ Viewing system

Illumination system consist of:

❑ Bulb

❑ Condensing lens

❑ A reflector/ prism

❑ Apertures stop and filters

Viewing system consist of:

❑ Sight hole

❑ Focusing system

❑ Rack of lenses of different powers in the form of a wheel or chain to compensates for the refractive states of the examiner and the patient and accessory filters.

Filters In Direct Ophthalmoscopy

❑-Red free filter

❑-Cobalt blue filter

Apertures In direct Ophthalmoscopy

❑ Large aperture

❑ Small aperture

❑ Semicircle

❑ Streak

Uses of Direct Ophthalmoscopy

❑ The red free in the ophthalmoscope is use to differentiate between retinal and choroidal lesion.

❑ It also makes small macro aneurysms and small hemorrhage standout more clearly and helpful in estimating C/D ratio.

❑ Large aperture is used to examine the fundus through the dilated pupil.

❑ Small aperture is used to examine the fundus with small pupil.

❑ Semi circle aperture is used to avoid fundus reflection while examining the fundus.

❑ The grid with small star in the centre is used to find out the eccentric fixation

Optic Disc examination on direct ophthalmoscope

❑ The optic disc is oval/ round & measure about 1.5mm.

❑ Healthy optic disc appears pinkish orange in color.

❑ Yellowish appearance of the optic disc is suggestive of optic atrophy.

❑ The small spot of light in direct ophthalmoscope intended to be approximatly one disc diameter in size.

❑ Place the spot on the disc & observe how much of the disc is filled up.

❑ If the disc is fully fills the spot of light & matches its size this would indicate a normal disc size.

Examine the disc for its

❑ Shape

❑ Color

❑ Clarity of margins

❑ Cup-Disc (C/D)ratio

Macula and Foveal Reflex

❑ The fovea is located approximately 3mm temporal.

❑ It should always recorded as FR present or absent.

❑ If is dull, it is recorded as Dull FR.

❑ Macula is dark pigmented area around the foveal reflex.

Retinal Vessels Examination on Direct ophthalmoscope

❑ Examine the vessels & branches as they come out of disc.

❑ Examine atery to vein (A/V) ratio, branching of vessels to all four quadrants crossing etc.

❑ Normal A/V ration is 2/3

Procedure Of Direct Ophthalmoscopy

❑ First you have to explain the patient about the procedure.

❑It should be perform in a semidark room.

❑ The patient's right eye should be examine with the examiner right eye & right hand.

❑ Give the pt a fixation target.

❑ Start from a one arm length & move as close as possible to the pt's.

❑ First trace the optic disc & follow the vascular arcades & finally move to the macula & other as you wish to examine.

Advantages Of Direct Ophthalmoscopy

❑ It is relatively easy procedure to master as compare to Indirect Ophthalmoscope.

❑ It has the greatest magnification of any procedure used for fundus examination.

❑ By using the lens wheel to adjust focus, the examiner is able to examine the various structures of the eye.

❑ It can be used in non dilated pupil.

Disadvantages of Direct Ophthalmoscopy

❑ Limited field of view & monocular view.

❑ A steroscopic view is not possible.