Care Of Ophthalmic Instruments

1. Care Of Ophthalmic
Instruments

2. Primary Eye CareOD-104
Sahibzada Hakim Anjum Nadeem
Departmental Coordinator,
Department of Optometry and Vision Sciences
CEO Anjum Eye Care & Optical Company
Optometrist, Al-Khair Eye Hospital Lahore
Co-Incharge OTTC, Optician, Refractionist, COAVS
Phone:03344496480, Email: shanjum92@gmail.com

3. Direct Ophthalmoscope
A diagnostic instrument to
look at the fundus in the
eye

4. Parts
–Handle
–Cells / Battery (use and throw, rechargeable) / power
supply
–On-off switch and brightness control
–Head
–Bulb
–Aperture, filter systems
–Lenses, reflectors, windows, shutter
–Disc lens + extra lenses
–Screws, springs, steel balls
–Shutter, pouch / box

5. Problem – No light or dim light – Level I
• Battery / cells not placed properly or rundown
- check their position, their voltage, recharge or
replace them (all cells)
• Power supply problems
- check input and output voltages, the switch,
connecting wires and the circuit and rectify
faults noticed
• Bulb fused or darkened - check and replace
• On off switch and brightness control not functioning
- check and clean rheostat & switch
• Head not mounted properly on the handle
- check and fix properly

6. Problem - No Light or dim light - Level II
– little more involved
- Reflector dislocated
- Window shutter stuck up
- Disc lens, aperture / filter system broken or
stuck up
- Lenses broken or dislocated
- Too much dust (particles of smoke) or
moisture inside the head
- The remedy for all these is to open the head
- clean and fix or replace the parts

7. Extra information for technicians
- The blue (red free) filter is used to cut out the red glare
of the retina.
- Polarizing filter is used to cut out reflection from cornea
- Small aperture is used for undilated (small) pupil
- Regular aperture is used otherwise.
- Slit aperture is a used as in slit lamp
- The special aperture with concentric circles and the plus
sign is used to detect any bulge projection on the
surface of retina
- If the tiny steel balls in the instrument are lost one can
replace them with a steel balls used in the bearings of
bicycle
- Small springs can be wound using thin wires

8. Maintenance Tasks
- Keep the instrument in the box / pouch when not in use
to avoid collection of dust on the instrument
- Make sure the on-off switch is fully turned off ( a click
sound will be heard) before placing the instrument in
the box / pouch.
- Recharge rechargeable cells at the end of each day after
work
- When the instruments is not likely to be used for a few
days remove the battery / cells keep them out of the
handle to avoid leakage
- Avoid smoking. Smoker’s breath carries fine smoke
particles into the instrument that reduce illumination

9. Bulb
Condensing
lens
Image forming lens
Slit, filters apertures Reflector
Optics of direct ophthalmoscope
The bulb is filament type halogen bulb that gives more
light.The reflector is a front silvered mirror (fully reflecting),
or a total reflecting prism except and in Welch Allyn
Ophthalmoscopes in which it is a partially reflecting mirror.
Total reflecting prism

10. Indirect Ophthalmoscope
A diagnostic instrument used to look at the
retina in the eye
Also used as therapeutic instrument to
deliver laser pulses at required spots in the
retina

11. Comparison
Indirect ophthalmoscope
I. Binocular
II.Stereoscopic (Three
dimensional image)
III.Magnification is less (3X with
a 20 D lens)
IV.Field of view is more and can
be increased by using a
depressor
V.Observer remains at a
distance from the patient
VI.Darkening of the room
required
VII.Inverted image
Direct ophthalmoscope
I. Monocular
II.Flat image ( Two
dimensional image)
III.Magnification is more 15X
IV.Field of view is less
V.Observer has to be close to
the patient
VI.Can be used in day light
VII.Erect image

12. Parts
I. Head band / spectacle mounted
II. Power supply, battery box, cable, switch
III. Illumination system – bulb, lenses,
reflecting mirror, filters, apertures
IV. Viewing system – lenses, reflecting prisms
or front silvered mirrors, screws
V. Teaching mirror
VI. 20D / 30 D lens
VII.Depressor

13. Problems – No light
I. Check on-off switch - rectify defects if any
II. Check power supply voltage (input / output)
and rectify defects if any
III. Check battery pack voltage - recharge if
necessary
IV. Check connecting wires for continuity or
short circuit - replace if necessary
V. Check the fuse - if blown out replace
VI. Check the bulb - if fused or blackened
replace

14. Other problems and Maintenance tasks
I. Spot of light not in focus – lenses, filters, reflector,
aperture in the illumination system disturbed - check
and rectify
II. Diplopia (Double image) – mirrors / prisms and lenses
in the viewing system disturbed. – check and align
them properly looking at an object at a distance of a
meter
III. Head band problems – cleanliness, padding, fitting
screws and connecting wire should all be checked
cleaned often and defects removed
IV. Keep the 20D lens clean

15. Optics of Indirect Ophthalmoscope
IPD
20D lens

16. Streak Retinoscope
Along with the lenses in a trial
set it is used in objective
refraction for the measurement
of spectacle power and for fixing
the axis of astigmatism if
present.

17. Parts
I. Handle
II. Cells / Battery (use and throw, rechargeable /
power supply)
III. On-off switch and illumination control
IV. Head
V. Bulb
VI. Beam width adjustment
VII.Beam orientation adjustment
VIII.Lenses, reflector and window

18. Problem – no light
I. Battery / cells not properly placed or run
down- check and replace battery / cells
II. Power supply problems - check input output
voltages, switch & connecting wires and the
circuit
III. Bulb fused or darkened - check and replace
IV. Head not mounted properly on the handle-
check and fix properly
V. Lenses disturbed - check and correct
VI. Reflector disturbed - check and correct

19. Other Problems
I. Light flickering - loose electrical contact at
the bulb holder and illumination control -
check and clean
II. Beam width adjustment problem - check,
clean and gently lubricate shaft movement in
the head
III. Beam orientation adjustment problem -
check, clean and lubricate the turning knob
IV. Dust on reflector, window - clean

20. Maintenance Tasks
• Keep the retinoscope in the box when not in use
• While turning it off turn the switch all the way till a
click sound is heard
• If the retinoscope is not likely to be used for a few
days keep the battery / cells outside. This will avoid
leakage of battery / cells
• The handle of streak retinoscope and direct
ophthalmoscope are the same. Some manufacturers
supply the two heads with a single handle for
economy and convenience in carrying them in a single
box
• The bulbs of direct ophthalmoscope and streak
retinoscope are not the same. Retinoscope bulbs have
a straight filament.

21. Keratometer
Used in measurement of the corneal
power required in the calculation of IOL
power in cataract surgery
&
Used in contact lens fitting

22. Parts-Optical
I. Bulb , bulb holder
II. Switch and connecting cable
III. Reflector
IV. The mire
V. Telescope (objective and eye piece)
VI. The prisms
VII.Model cornea

23. Parts - Mechanical
I. Base
II. Up - down movement screw
III. Left - right rotation with a lock for fixing
IV. Forward - backward movement (focusing)
screw
V. Power reading drums - horizontal / vertical
VI. Circular scale to measure the axes for
astigmatism
VII.The chin and head rest

24. Maintenance tasks
I.Keeping the instrument covered when not
in use.
II.Cleaning the body & the optics (removal of
dust).
III.Periodic lubrication of all moving parts.
IV.Replacement of bulb when required.
V.Checking the on-off switch and the power
cable replacing them when necessary.

25. Calibration check
•Check the calibration every day before
using the instrument using the model
cornea. If the calibration is disturbed
correct it immediately.
•Correct power of IOL to be used in a
cataract surgery depends on the power of
the cornea. Correct Keratometer readings
are very important.

26. What NOT to do???
While cleaning do not disturb the
optics especially the two prisms
inside used to get the extra
images.

27. Slit Lamp
An instrument used to examine all parts of
the eye
Also used to deliver laser pulses into the
eye for treatment
Convenient instrument for photographing
different parts of the eye

28. Types
I.Bulb located at the top –
tilting type
• Uses a front silvered
mirror to reflect light
in the direction of the
patient
II.Bulb located at the
bottom – fixed type
• Uses a total reflecting
prism to reflect light
in the direction of the
patient
III.Inclined optics
• consists of two
objectives looking at
an angle.
Magnification change
achieved by changing
the objective
IV.Parallel optics
• Single objective lets
two beams of light
into the instrument at
an angle. Has 3 or 5
step magnification
using Galilean set-up

29. Parts
I.Illumination system
• Bulb, condensing lens, slit, slit width adjustment, slit height
adjustment, slit orientation adjustment, filters, power supply
illumination control and power card
II.Magnification system
• Stereo compound microscope. With a prism arrangement that
lets adjustment of eye pieces separation to suit the IPD of the
observer. The final image is erect without left right inversion
III.Mechanical system
• Table movement up / down (manual / electrical)
• Joystick movement up / down, forward / backward, left /
right
• Chin and head rest movement up / down
• Illumination system tilting arrangement / slit adjustments
(width, height and orientation with respect to the vertical)

30. Maintenance tasks
• Keep the instrument covered when not in use
• Replace bulb when necessary
• Remove of dust and stain
• Lubricate and check all mechanical movements
periodically
• Check electrical parts

31. Other instruments used with Slit
Lamp
•78D / 90D lens to look at the fundus
•Gonio lens to look at the angle of the eye
•Applanation tonometer to measure the
IOP
•Micromanipulator to used to deliver the
laser beam at required spots
•Camera

32. Optics Cleaning
-Clean optics is needed for good vision.
-Optics get dirty due to dust and stain

33. Removal of dust
I. By blowing air
II. Using soft brush
III. Using cotton swab and mild soap
solution

34. Removal of stain
I. Using cotton swab and distilled water
II. Using cotton swab and mild soap
solution
III. For hard stain use cotton swab and
acetone.
IV.Don't use acetone on plastic optics.
You may use alcohol