Download Ocular Instrumentation - Heart of America Contact Lens Society

Ocular Instrumentation
Lynn E. Konkel, M.S., CPOT
Heart of America – February 2013
Overview
 Identify most commonly used equipment
 Identify the reason for use
 Note: there are many different brands of the same type
of equipment, all the brands are not depicted in this
presentation
 Recommend maintaining the manuals for all equipment
in a central location. The manuals are very helpful for
use, calibration, care and servicing of equipment
Pretesting Equipment
Transilluminator
• Handle that contains a rechargeable
battery
• Preferred over a penlight
• Dial control for the brightness of the
light
• Recommended for assessing pupil
reflexes
• Also may be used to provide
additional light source when needed
• Maintain back up light bulb
Pinhole Disk
• Instrument that looks like an
occluder but has multiple holes 0.5
to 2mm in diameter.
• Used to assess whether the
reduced visual acuity is due to
refractive error or some other
condition.
• If the visual acuity improves with
the pinhole then usually expect a
refractive error.
Maddox Rod
• A group of either red or colorless
parallel glass rods
• Used to dissociate the eyes,
prevent fusion
• Used to detect or measure amount
of heterotropia or heterophoria.
•
Rods held vertically
•
Rods held horizontally
• Stereopsis plates
• Color vision plates
•
Ishihara
•
Pseudoisochromatic
Keratometer
• Kera is the root word for cornea;
meter is the suffix for measure
therefore this is a instrument that
measure the corneal curvature.
• Obtains the curvature in diopters
along the area of least and most
curvature.
• Ex: 44.50@175; 45.25@ 85
• Available in manual or automated
versions
• Maintain a stock of replacement
bulbs
Tonometer
• Tono = pressure, meter again is to
measure. This instrument
measures the intraocular pressure.
• Many styles of tonometers, manual
and automated versions.
• Pictured here is the noncontact
tonometer = automated, “air puff”.
• Readings are stated in millimeters
of mercury (mmHg)
• Record time of day
•
Diurnal variation
Tonometer cont.
• Tonopen
•
Maintain supply of tip covers and batteries
•
Use with corneal anesthetic
• Goldmann
•
Needs no electricity or special supplies to
maintain however, needs an operating slit
lamp unless using the hand-held model
•
Use with combo drug of corneal anesthetic
and fluorescein, brand name = Fluress
Visual Field
Testing
• Eye maintains steady fixation and
•
•
•
•
tests the retina for areas of
decreased (or absent) vision.
Typically used to test area outside
the macula (central vision)
Compare/contrast visual field
testing to visual acuity testing
Typically need to use trial lenses
when testing the central visual field
(lenses removed for area outside
the central 30°)
Equipment is complicated, keep
manual handy.
Visual Field
Testing - cont.
• Amsler grid
•
Used when you want to assess the macular
area of the retina.
•
Can detect
•
Central scotomas
•
Paracentral scotomas
•
Distortion = metamorphopsia
Auto-refractor
• Instrument used to estimate a
refractive error. Automated version
of a retinoscope
• Can be in combination with an
auto-keratometer.
Examination Room
Projector & Slides
• Projector – used to project letters,
characters, shapes on a silver
screen
• Slides
•
Snellen letters
•
Landoldt rings
•
Numbers
•
Tumbling E’s
•
Worth 4-dot
• Means to isolate lines/letters
• Filters – red/green
Retinoscope
• Obtains an estimate of the patient’s
refractive error without any input
needed from the patient (objective
measurement)
• Projects light onto the retina,
moving the light back and forth
gives the doctor input as to
whether the patient has
myopia/hyperopia/astigmatism.
• Use lenses in the phoropter to
neutralize the movement of the
light.
Ophthalmoscope
• Instrument used to exam the retina.
• Eyes are typically dilated for wider
view.
• Direct (pictured on left)
•
Uses internal lenses to assist in focus
•
Can magnify 15x
• Indirect
•
Monocular – greater magnification then direct,
not used much today.
•
Binocular – allows for stereoscopic and wider
view of the retina, worn on head and used with
handheld condensing lens. Image is inverted
(upside down and reversed left/right). Very
commonly used today especially for patient’s
with disease.
Ophthalmoscope
• Binocular indirect
Phoropter
• Used to obtain patient’s correction
for refractive error
•
Distant Rx
•
Near Rx
• Used to measure phoria’s,
accommodation, etc.
• Contains concave, convex,
cylindrical lenses along with prisms
and various other lenses (Maddox
rod for example)
Trial Lenses
• Tray of lenses and accessories
•
Lenses – sphere & cylinder
•
Prisms
•
Occluders
•
Pinhole disk
•
Maddox Rod/red lens
•
Frame
• Uses:
•
Test refractive error of an eye
•
Let the patient test how a potential Rx will
be
•
Used with other instruments such as visual
field bowl analyzers
Slit Lamp –
Biomicroscope
• Instrument used to examine the
external and anterior structures of
the eye under magnification.
• Can have attachments such as:
•
Goldmann tonometer
•
Camera
•
Observation tube
•
Handheld lenses used in conjunction with slit
lamp can be used to examine the retina.
Slit Lamp
“Accessories”
• Hruby lens – 55 D lens
• Goniolens – consists of a contact
lens and a mirror. Use a corneal
anesthetic and a gel (goniogel).
• Goldmann tonometer
Ancillary Testing
Instruments
Pachymeter
• Measures the corneal thickness
• Used to assist in the diagnosis of
glaucoma
•
Do thinner corneas mean increase risk of
developing glaucoma?
•
Do thinner corneas mean we are
underestimating the IOP?
•
Do thicker corneas mean we are
overestimating the IOP?
• Evaluated prior to refractive
surgery
• Need a corneal anesthetic
A-scan Ultrasound
Biometry
• Measure the length of the eyeball
• Used to calculate the power of the
lens implant needed for cataract
surgery
• Requires corneal anesthetic
• Test being replaced by automated
instruments such as the IOL Master
•
Noncontact = no anesthetic
Fundus Camera
• Instrument that takes a picture of
the patient’s retina.
• Documents what is seen on
ophthalmoscopy.
• Can center picture on various parts
of the retina – disk, macula,
periphery
• Nonmydriatic versus mydriatic
Automated optic
nerve/retina
instruments
• Heidelberg Retina Tomograph
(HRT).
•
Used to assist in the diagnosis and
management of glaucoma
• GDx Nerve Fiber Analyzer
•
Used to assist in diagnosis and management
of glaucoma.
• Ocular Coherence Tomography
(OCT).
•
Used to assist in diagnosis of retinal pathology
Corneal
Topography
• Advanced analysis of the corneal
curvature
• Measures the cornea’s shape fro
apex to the periphery
• Used to:
•
Treat and monitor patient’s with corneal
disease
•
Prior to refractive surgery
Lasers
• Tunable dye lasers
•
Used in the anterior segment
•
Trabeculoplasty
•
Iridoplasty
• Photodisruptive lasers
•
YAG laser (pictured), used for secondary
cataract, iridotomy.
• Thermal photocoagulation
•
Argon blue-green/argon monochromatic
green/krypton red
•
Extensively used to treat diabetic retinopathy,
CRVO, retinal holes, retinal detachments
• Excimer laser
•
Used in phtorefractive keratotomy
•
Ablates a small amount of the corneal stroma to
flatten the corneal
Optical Dispensary
Lensometer
• Lens gauge/clock
• Lens thickness gauge
• Corneal reflex pupilometer
• PD stick
Where to obtain more
information on this subject:
 AOA Paraoptometric Section, Self-Study Course for
Paraoptometric Assistants and Technicians, Revised
3rd Edition Butterworth-Heinemann 1997
 Stein, Stein, Freeman, The ophthalmic assistant (8th
edition) Mosby 2006
 Cassin, Rubin, Dictionary of eye terminology (6th
edition) Traid 2011
Questions?