PCO

T1

Synonyms of Retinoscopy

Skiascopy
Skiametry
Umbrascopy
Pupilloscopy
Retinoskiascopy

Skia: derived from greek meaning shadows from internal structures

Define Refracct

To change the direction of a ray of light when it passes from one medium into another of different optical density.

Determining the nature and degree of the eye's refractive errors and its correction with lenses.

Define Retinoscopy

method of determining error of refraction by illuminating the retina and observing the rays of light emerging from the eye.

Define Refractometer

optical instrument to determine in an objective manner the refractive state of the eye (autorefraction- depends on refractive indexes).

Define Refractor

instrument designed for refraction and phorometry, equipped with spheres and cylinders, prims, and other accessories for refraction and binocular vision testing

Define Phorometry

used to test oculomotor function.

Vergences, phorias.

Can be performed behind refractor or trial frame

What is the primary reflector of light during retinoscopy

The retina

What structure has the greatest index of refraction of the eye?

Cornea
(but it needs to be clear)

Layers of the Retina

1. Pigment epithelium
2. Photoreceptor layer
3. Outer limiting membrane
4. Outer nuclear layer
5. Outer plexiform layer
6. Inner nuclear layer
7. Inner nuclear layer
8. Ganglion cell layer
9. Nerve fiber layer
10. Inner limiting membrane

Waveguide Mechanism

The mechanism by which incident light rays that strike the outer limiting membrane (OLM), are transmitted to the photosensitive pigments in the outer segments of photoreceptors

Why is the fundus reflex red/orange color during retinoscopy or photorefraction?

The light that returns from the RPE and choroid is the result of competition between light absorption and backscatter

The RPE and choroid contain important light absorbers

Melanin: highest concentration in RPE

Hemoglobin: higher concentration in choriocapillaris

Xanthophyll: yellow pigment which absorbs blue light.
• Lutein and zeaxanthin
• Responsible for macular color

Retinoscopy Types/Modalities

Static Retinoscopy
Radical Retinoscopy
Hindra Mohindra Retinoscopy
Dynamic Retinoscopy

2 Types of Static Retinoscopy

Streak Retinoscopy: Uses a streak of light, converging or diverging rays, mostly used modality

Spot Retinoscopy: Uses a spot of light, with a plane mirror. Good for children. Not good if you want to refine astigmatism from the start

Static Retinoscopy

The determination of ametropic correction during fixation at a set distance with accommodation relaxed

Radical Retinoscopy

used with small pupils or media opacities that make the reflex faint and indistinct. Examiner will have to use a closer WD (20- 10cm).

Important to note new WD

Hindra Mohindra

Used for children. The patient fixates the light on the retinoscope, the WD is 50cm. When compensating the WD, 1.25D is subtracted instead of 2.00D

Dynamic Retinoscopy

when retinoscopy is performed while the patient is fixating a target at near

Instrumentation

Refractor or phoropter

Skioscopy bars

Trial lenses and trial frame

Trial lenses and trial frame

Simplest to use

±0.12D to ±20.00D

Minus cylinder from: -0.12DC to - 6.00DC

Prisms: 1-15𝝙

Occluders, pinholes, Maddox Rods, red and green lenses, neutral density (ND) filters, polarized lenses

Trial Frame

Trial lenses and frame

For children that cannot stand behind phoropter (also some elderly).

Bedridden patients: patient's home, assisted living homes, hospitals.

Lenses are larger in diameter; examiner can observe better the eye movements.

Verify distance Rx

Verify near Rx

Screenings

Mohindra's Set Up

Examiner at 50cm from the patient. Usually performed in children, have them sit in their parent's lap if unable to keep in chair.

Completely dark room.

Use loose lenses or skiaoscopy bars.

Retinoscope light intensity enough to observe the reflex, but the patient still feels comfortable

Have the patient look at the light while scoping the meridians and neutralizing., Write down the optical cross

Remove the 1.25D WD from the results to obtain Mohindra Retinoscopy

Phoropters

Interchangeable with refractor

Sphere and cylinder lenses

Jackson cross cylinder for astigmatic axis and power

Risley rotating prisms (for phorias and vergences)

Near vision tests

Objective Retinoscopy

Refractive error is determined without the input of the patient.

Requires either a (an):
Human operator with a retinoscope
Automated refractor-several. Pros and cons.
Photorefractor

Purpose of Retinoscopy

To determine the distance refractive status of the patient's eyes. The goal is to locate the far point of the spherical eye or the two far-point planes of an astigmatic one.

It is an objective measurement, Used as the starting point for subjective refraction. Know your working distance

Retinoscopy brings the patient's far point to a location that is a predetermined distance from the patient, the working distance, in front of the eye, with the use of lenses

Retinoscopes

The most widely used retinoscopes are the Copeland, Keeler, Heine, and the Welch -Allen.

They consist of an optical head, a sleeve, and a battery handle.

Streak vs Spot Retinoscopy
Streak: more accurate-fast. Developed by Copeland.
Spot: external light source, very fast, for estimation.

Spot Retinoscopy

Optic are the same, except that cylinder axis and power determination is more accurate with the streak method.

For some, the brightness of the reflex is much better with the spot retinoscope.

Meridional axis control are not necessary and not present with spot retinoscopy.

Will look at the center of a diverging light through the patient's pupil.

Not manufactured anymore

Retinoscopic Reflexes to Determine the Principal Meridians

The principal meridians correspond to the orientation of the streak that provide the thickest and the thinnest reflexes or the brightest and dimmest reflexes.

Spherical error: same thickness reflex in all meridians

Astigmatic error: thickness varies in different meridians
Break phenomenon
Thickness phenomenon
Skew phenomenon

Astigmatic Reflex

Skew phenomena is used more to refine the axis of small cylinders (astigmatism)

When the streak is of the axis, the reflex and intercept move in different directions (their motion is skewed)

The reflex moves parallel to the intercept when the streak is on the axis.

Straddling

Used to confirm the axis

Perform with the estimated cylinder in place. Then the streak is turned 45° off axis in both directions.

Results: if the axis is
Correct: widths are equal in both positions
Incorrect: widths are not equal in positions

Scissor reflex

Sometimes one half of the reflex goes with the other half goes against

Confusing Fundus Reflex

Motion will be confused, according to the:
Number of separate optical areas existing and
Degree of ametropic refractive differences between these areas.

Possibilities are the patient is having:
Irregular astigmatism
Distorted corneas- ex. Keratoconus, PMD
Monochromatic optical aberrations (especially coma and spherical aberration, which are the most common)

When do Confusing Fundus Reflex usually occur?

When spherical and coma aberrations coexist, and the refracting power of the eye is greater throughout the periphery than the center of the pupil.

Then the eye is relatively myopic in the periphery and becomes more myopic peripherally when the pupils dilates (dim or by pharmacological agents)

Scissor Motion

The retinoscopy reflex moves more quickly in the center than in the periphery of the pupil as neutrality is approached from less minus/more plus direction and appears to have a wider streak in the central area than in the periphery.

Scissor Motion is most common in?

very myopic eyes
Light irises
Younger adults

Neutralizing Scissor Motions

Best to neutralize the central portion and rely on bracketing to reduce the error in neutralization

Neutrality is reached first in the center of the pupil and more minus is needed to neutralize the periphery.

False Neutrality

Can be created by focusing the incident beam on the entrance pupil. •

The beam is well focused on the iris, which is approximately in the same plane as the entrance pupil.

Must do this in slit lamp/biomiocroscopy evaluation, for retro illumination technique

Sources of Error in Ret

Incorrect working distance
Failure to remove the working distance
Scoping off the patient's visual axis
Failure to obtain reversal
Failure to locate the principal meridians
Failure to recognize the scissors motion
Failure of the patient to fixate the distance target, looking at you will cause accommodation, making it a dynamic retinoscopy

Interpupillary Distance (PD)

the distance from the center of one pupil to the center of the other pupil, in mm.

Measured From temporal limbus OD to nasal limbus OS or Measured from center to center of pupils

Corneal reflex IPD

Method to be used of patients with strabismus or only having one eye.

Measure from the center of the nose bridge to the corneal reflex

Also gives you Monocular PD

Which meridian do you normally neutralize frist?

The meridian with the most WITH motion (thicker reflex)

This is the most plus meridian

You see a with motion doing ret, what do you do?

Add plus lenses, black numbers, wheel down

You see an against motion doing ret, what do you do?

Add minus lenses, red numbers, wheel up

Which meridian do you neutralize first?

1st Meridian WITH + 2nd Meridian AGAINST

Neutralize the WITH first

Which meridian do you neutralize first?

1st Meridian SLOW WITH + 2nd Meridian FAST AGAINST

Neutralize the SLOW WITH first

Which meridian do you neutralize first?

1st Meridian SLOW AGAINST + 2nd Meridian FAST AGAINST

Neutralize the FAST AGAINST first

What does it mean if you neutralize one axis and the other axis is also neutral?

The patient does not have an astigmatism, they are only spherical

Both meridians are neutralized, what does that number indicate?

the GROSS retinoscopy

Both meridians are neutralized and the working distance has been removed, what number does that indicate?

the NET retinoscopy

Photorefraction

A photographic technique that can measure the refractive error and accommodative response.

It is rapid and objective

Only requires the patient to pay attention for short periods of time

Aspecific photographic pattern, which varies with the degree of eye defocus with respect to the plane of the camera.

Photorefractive methods are not as accurate as retinoscopy but can be very useful for testing infants and young children.

What does Myopic photorefraction show?

Reflects a bright half-moon over the top of the pupil.

What does Hyperoptic photorefraction show?

The light reflects as a brighter crescent moon in the bottom half of the eye

What does Paraxial Photorefraction show?

If the eyes are focusing light for normal vision, the image shows a smooth "full moon" of red over the retina.

How to perform photo refraction

3 photos will be taken at an axial plane
1st: at 75cm: to determine pupil size
2nd: at 50cm
3 rd: at 150cm

2 nd and 3rd photos are compared to see which pupil is larger.
If pupil is larger at 150cm, then eye is hyperope.
If larger at 50cm, then the eye is myope.

4 characteristics of the streak reflex

Break
Width
Intensity
Skew

Streak reflex:
Break

A break is seen when the streak is not parallel to one of the meridians. The orientation of the reflex streak in the pupil is not the same as that of the streak.

Streak reflect:
Width

the width of the streak varies as it is rotated around the correct axis. It appears narrowest when the streak aligns with the axis.

Streak reflex:
Intensity

the intensity of the line is brighter when the streak is on the correct axis.

Streak reflex:
Skew

skew (oblique motion of the streak reflex) may be used to refine the axis in small cylinders

Opacities

anything that interferes with the light returning from the retina will be seen as a black opacity or an irregularity of the red reflex

Floaters
Corneal Scars
Cataracts
Lens Pigmentation

Opacity movement:
Same direction of gaze

It lies anterior to the pupil plane (i.e. cornea or anterior chamber)

ex. tear film debris

Opacity movement:
Stationary

IN the pupil plane

ex. cataract, mittendorf dot

Opacity movement:
Opposite direction of gaze

It lies posterior to the pupil plane

ex. PVD, floaters

What lens is best to see vitreous floaters with?

+6.00D or +10.00D

As the patient moves their eyes the vitreous floaters will be seen

Swirling across as dark cobwebs or filaments within the retinal glow

What is a lens Mittendorf dot?

A small congenital lens opacity, remanent of the Hyaloid artery. Seen as a dark spot with no movement

What are the categories during an ONH eval

Disc shape
Disc Margins
Neuroretinal Rim (NRR)
Cup/Disc (C/D) ratio
Spontaneous Venous Pulsation (SVP)
Crescents
Peripapillary area NFL appearance
Depth

ONH Eval:
Disc Shape

round, oval, small, larges, tilted

ONH Eval:
Disc margins

distinct vs indistinct (blurry)

ONH Eval:
Neuroretinal Rim (NRR)

salmon pink vs pallor, follow the ISNT rule, notching

ONH Eval:
CupDisc (C/D) ratio

H/V
Horizontal/Vertical dimensions

ONH Eval:
Spontaneous Venous Pulsation (SVP)

present (+) or absent (-)

Absent is apprx. 10-20% of normal individuals

ONH Eval:
Crescents

pigmentary, scleral

ONH Eval:
Peripapillary area NFL appearance

NFL drop out or intact, PPA

ONH Eval:
Depth

of physiological cup

Neuroretinal Rim (NRR) Colors:

Typical, Moderate Glaucoma, Advance Glaucoma, Neuro-ophtha case

Typical: Yellow-orange

Moderate glaucoma: Thinner but still yellow-orange

Advanced glaucoma: Still yellow-orange

Neuro-ophtha case: Pale

Elsching's Classification:
Type I

Flat no physiological cup, same place as retina

Elsching's Classification:
Type II

Physiological cup and is cylindrical in shape

Elsching's Classification:
Type III

Saucer-shaped cup

Elsching's Classification:
Type IV

Typical myopic cupping, retinal artery and vein are pushed nasally, is wide and deep cup, deeper nasally and more shallow temporally

Elsching's Classification:
Type V

Miscellaneous category that includes:

Glaucoma: fully developed, cup almost at disc margin, vessels seem to disappear, excavated

Atrophic disc
Edematous disc
Myelinated disc

A/V Crossing:
Gunn's Sign

Tapering of vein on either side of crossing

Thinner on one end, vein appears to taper down either side of the artery

A/V Crossing:
Bonnet's Sign

Banking of vein distal to the crossing site.

Thicker on one end, vein is twisted on the distal side of the artery and forms a dark, wide knuckle

A/V Crossing:
Salus' Sign

Deflection of veins at crossing site

A/V Crossing:
A/V Nicking

Due to compression of hard artery on veins

Vein thinner on both ends, the vein appears to stop abruptly on either side.

What happens if the arterial wall becomes sclerotic?

The light streak in the artery is accentuated and widened

It can acquire a copper wire or silver wire appearance

What percentage of SVP is normal and seen in patients?

80%

Is pulsation of the central retinal artery normal or abnormal?

Abnormal, it occurs when IOP exceeds the diastolic pressure of the retinal artery and indicates a patient suffering a glaucoma attack

Extravascular changes:
Microaneurysms

Most visible by Fundus Fluorescein Angiography (FAN)

Occur at localized areas of capillary wall weakness

Extravascular changes:
Retinal Hemorrhages

pre-retina, intra-retina, sub-retinal

Each characteristic of certain systemic conditions

Extravascular changes:
Retinal and Macular edema

Due to either transudation of choroidal fluids after breakdown of RPE or failure of autoregulation of retinal capillaries

Extravascular changes:
Retinal Lipid Deposit

Hard exudates

Elsewhere and also in the macula

Extravascular changes:
Cotton wool spots

Due to focal nerve fiber infarcts/sign of ischemia, hypoxia

Macula Evaluation

Normally appears darker than the rest of the retina

If there is pigment clumping, hypopigmentation (salt and pepper), beaten bronze appearance, bull's eye appearance all of this is NOT NORMAL

Should not present hemorrhages, yellow or white deposits

There should be a foveal pit, but not a "hole "in the area

If the area does not present abnormalities record as healthy and presence or absence of foveal reflex

Recording +FR or BFR is not enough!!

Fundus Background

Thinning of the retinal pigment epithelium towards the periphery, this makes choroidal vessels more visible

Fundus Background:
Even Red Fundus

Dense even pigmentation, choroidal vessels obscured

Fundus Background:
Tessellated Fundus

Tigroid, Brunette
Choroidal vessels are visible as red and intervascular spaces are black/brown

Fundus Background:
Blonde Fundus

Albinotic
Visible choroidal vessels seen as red net on yellow-white scleral background

The 5-Rs in Glaucoma Suspect ONH

Scleral Ring
Rim
Retinal Nerve Fiber Rim & Layer (NRR/NFL)
Region of Peripapillary Area
Retinal and Optic Disc Hemorrhages

The 5-Rs in Glaucoma Suspect ONH:
Scleral Ring

Observe the scleral ring to identify the limits of the optic disc and its size

Blurred or defined margins