OPTOMETRIC EQUIPMENTS IN REFRACTION ROOM

Presented by

T.Muthuramalingam

Contents• Torch• Retinoscope• Trial set • Trial frame• JCC• Autorefractometer

• RAF Ruler• Prism Bar• IPD scale• Snellen’s near &

distance chart• Illuminated bulb• Mirror• PC

Torch• Used to see the corneal

reflex, the ocular movement, the abnormality of ocular surface

Retinoscope

• It is a hand-held instrument that is used to objectively determine the refractive power of the eye

• It has a light source & a way to shine light into patients eye & observe its reflection from patients retina

Trial Set• Trial lenses• Pinhole• Occluder• Stenopaic Slit• Red & Green glass• Maddox Rod• Prism

Trial lenses

• Trial lenses are sets of lenses of two types sphere and cylinder.

• To measure the refractive state of the eye.

Occluder• Is a opaque disc• Used to take Vision uniocularly

Trial Frame

• Trial frame is an adjustable frame that is used with trial lenses when measuring the patients for spectacle lenses.

• The pupillary distance,lens height ,cylinder axis can be set to accommodate the patients size

• It consist of 4 case. Front case is for cylindrical lens, back case for high myopic lens, other for additional lens and Occluder

Pinhole• Pinhole accessory consist

of an opaque disc with a Pinhole (PH)  • Optical function of Pinhole: Pinhole allows

the passage of central rays of light. This permits the formation of clear image.

Uses of Pinhole:If patient’s vision improves with pinhole,

patient is having uncorrected refractive error.If patient’s vision is not improving then

patient may have any pathological defect or neurological defect of the eye

Stenopic Slit• The Stenopaic slit consists of a

rectangular aperture ranging from 0.5mm to 1.0mm in width and up to 15mm in length.

• Stenopaic slit reduce the size of blur circle in the meridian at right angle to the slit, yet allows blur circle size to be unchanged in the meridian coincident with it

Uses of Stenopic Slit• To find out astigmatic power and axis.• To measure vertex distance.

Red & Green glass• Red and green lenses are primarily

use before an eye to interrupt fusion in the assessment of binocularity. These are used for worth four dot test, FRIEND test and stereopsis.

Maddox Rod• Maddox rod

consists of a series of powerful convex cylindrical lenses, mounted side by side in a trial lens. The glass of Maddox rod is tinted red

Uses of Maddox Rod Maddox rod is used in the diagnosis of

extra ocular muscle imbalance.•  Maddox rod is placed in front of right

eye.•  A distance white spot light source

viewed through both eye•  Right eyes see red line at 900 to the

axis of Maddox rod, left eyes sees spotlight.

•  Two eyes sees dissimilar images and dissociated, allowing any muscle imbalance to become manifest.

Prism• Prism is a triangular geometrical figure

having two refracting surface meeting at an apex joined by a base

• Used in treatment of diplopia and to overcome the residual deviation in squint.

• In trial set, Prisms are ranging from 1/2prism diopter to 12prism diopter

JCC• A sphero-cylinder lens • The power of the cylinder is twice the

power of the sphere and of the opposite sign.

• Used to refine power and axis of cylindrical power

Snellen's Chart• Used to assess Vision.• Can be used at 3mtr & 6mtr.• Also used for near vision

assessment

Autorefractometer• Autorefractometer is an optical

instrument that can automatically determine the refractive measurement of the eye.

• It has a chin rest, forehead rest, viewing screen for the observer to monitor fixation.

Prism Bar• Prism bar are sets of plastic

prisms that are attached to each other in ascending order of power.

• Prism bar can be horizontal and vertical

• Used to measure the vertical and horizontal amplitude of fusion of patients

RAF Ruler• Royal Air force Ruler• Used to measure the

amplitude of accommodation, near and far point of accommodation, near point of convergence

IPD Scale & Pupillometer• Used to measure the

Inter Pupillary Distance uniocularly and binocularly

• Illuminated bulb: it is kept just above and behind the patient’s head to provide the illumination for near vision assessment

• Mirror: it is used for maintaining the 6m distance placed at 3m

• PC: A palmtop computer. to provide the printed prescription of glasses and to collect the data of glass prescription prescribed per day

Other accessories