Anatomy of the Retina

Thin, semi-transparent, multilayered neural tissue lining the inner wall of the posterior two-thirds of the eye.

Inner and outer layers of the embryonic optic cup

10 layers

10 mm

Optic nerve and macula

Transmits visual information to the brain

Macula lutea, area centralis, or yellow spot

5.5 mm

5 mm

Nasal ora serrata

Temporal ora serrata

Long ciliary nerve, short ciliary nerve, and ampulla for vortex veins

Area where vessels meet

15 mm

Near periphery

10–15 mm anterior to the posterior pole and posterior to the equator

Less than 10 mm

1.5 mm

Region inside the perifovea encircling the fovea

0.5 mm

Ganglion cell, inner nuclear, and Henle layers

Fovea centralis

1.5 mm

Fovea

0.35 mm

Inner nuclear layer and ganglion cell layer

Central floor of the fovea and area of most acute vision

Absence of inner retinal layers and blood vessels minimizes light scattering

Foveal avascular zone, a capillary-free region within the fovea

0.35 mm

Center of the foveola

Light reflex

Produces cross-sectional images of retinal layers

Bright bands representing reflected light

Dark bands representing absorbed or less-reflected light

Internal limiting membrane through external limiting membrane

Photoreceptor layers through the choroid

Outer plexiform layer through retinal pigment epithelium

Inner nuclear layer through nerve fiber layer

Outermost pigmented retinal layer responsible for photoreceptor support and maintenance

Synthesizes and stores retinoids

Vitamin A

11-cis-retinaldehyde

Red-orange pigmentation of the RPE

Phagocytosis of photoreceptor outer segments and waste removal

Necessary nutrients and ions

Tight junctions or zonula occludens between RPE cells

Active fluid transport and pumping keep it dry

Retinal detachment

Melanin

Acts as a free-radical scavenger

Lipofuscin

Atrophy of overlying photoreceptors and underlying choriocapillaris

Light-sensitive photoreceptor elements: rods and cones

Mitochondria, cilia, and discs

Photoreceptor integrity

They are modified sensory cilia

Junctional site between photoreceptors and Müller cells

Nuclei and cell bodies of rods and cones

Synapses between photoreceptors and bipolar and horizontal cells

Bipolar, horizontal, and amacrine cell bodies and nuclei

Synapses between bipolar cell axons and ganglion cell dendrites

Ganglion cell nuclei

Foveola

Parafovea

Ganglion cell axons

Optic nerve

Nasal perifovea

Fused Müller cell foot processes

Structural support and sensory retinal metabolism

Inner nuclear layer

First-order neurons in the visual pathway

Provide horizontal interconnections between photoreceptors and bipolar cells in the OPL

Connect with ganglion cell axons

Rods and cones

120–130 million

6 million

$20:1$

Fovea

Approximately 20 degrees from fixation

It decreases

Cylindrical

Conical

Photopsin and iodopsin

Scotopic and peripheral vision

Photopic, color, and high-resolution vision

Rods

Cones

Internal carotid artery

Ophthalmic artery

Short posterior ciliary arteries

Central retinal artery

Four

Superonasal, inferonasal, inferotemporal, and superotemporal

Cilioretinal artery

Area between the optic nerve and center of the macula

It may enlarge, causing decreased visual acuity

Make it disappear due to fluid extravasation

Tight junctions between barrier cells

Ciliary body epithelium, iris capillary endothelium, retinal capillary endothelium, and RPE

Non-fenestrated retinal capillary endothelial cells

Tight junctions between RPE cells

Tracer substances such as fluorescein dye

Edema, exudation, and neurosensory detachment

RPE

RPE

Cornea → lens → vitreous body → retina

Conversion of light energy into electrochemical energy

Photoreceptors → integrator neurons → ganglion cells → optic nerve → visual cortex

It is reflected back toward the nerve fiber layer and optic nerve

Distortion of visual images

Objects appear smaller than their actual size

Objects appear larger than their actual size

Abnormal color vision

Visual field defect or blind spot

Night blindness

Floaters

Flashes of light

Helps characterize the onset and progression of retinal disease

To determine whether central or peripheral vision is affected

Pain

Glaucoma

Timing, sequence, duration, and interval

Which eye was affected first and the temporal relationship between eyes

Medications, surgery, laser, and injections

Hypertension, diabetes, kidney disease, cardiopulmonary problems, cancer, and blood dyscrasias

Hereditary eye and systemic diseases

Occupation, travel, chemical exposure, sports, pets, diet, drugs, smoking, and alcohol

Sexual history

Visual acuity

Refractive error from retinal disease

Refractive error

Retinal problem

Corneal astigmatism and cataract

No

Direct and consensual

Red-orange reflex

Cataract, vitreous hemorrhage, or corneal opacity

White pupillary reflex

Retinoblastoma

Normal

Exotropia

Poor fixation due to impaired vision

Similar firmness to tapping the nose

Softer than the nose

Retinal detachment, choroidal detachment, and ciliary body inflammation

Harder than the nose

End-stage proliferative diabetic retinopathy

Erect, highly magnified image

15x

5 degrees

1–2 inches

No

Inverted and laterally reversed image

3.5x

35–45 degrees

Arm's length

Yes

Indirect ophthalmoscope

Direct ophthalmoscope

Vitreous, retina, and optic disc

Anatomic relationships of the vitreous, retina, and choroid

When media opacity prevents adequate fundoscopy

Hypoechoic

Hypoechoic

Hyperechoic

Choroidal thickening and hyperechoic or moderate-echoic vitreous densities

Absence of choroidal thickening

V-shaped membrane continuous with the optic nerve

Imaging of retinal and choroidal circulation using sodium fluorescein dye

Antecubital vein

Appearance of the retina and fundus

Cross-sectional imaging of retinal structures

Electrical activity and function of retinal layers

Retinal function through electrical activity measurements

Diabetic retinopathy, hypertensive retinopathy, CRVO, CRAO, AMD, retinal detachment, vitreous hemorrhage, retinitis pigmentosa, ROP, and retinoblastoma

90%

60%

Strict glucose control

Diabetes Control and Complications Trial

United Kingdom Prospective Diabetes Study

76%

54%

50%

60%

31%

Blood pressure control

Vitreous hemorrhage from abnormal new vessels

Transient exophoria

Microvascular changes within the neurosensory retina

Chronic elevation of blood sugar

Microaneurysms, intraretinal hemorrhages, exudates, macular edema, and macular ischemia

Enlargement of the foveal avascular zone

Inner blood-retinal barrier

New blood vessel growth outside the retina

Fibrous tissue

Thick fibrous membranes pulling on the retina

Neovascular glaucoma

New vessels obstruct the trabecular meshwork, increasing intraocular pressure

Laser photocoagulation

Regression of neovascularization by treating ischemic retinal areas

Ischemic retina produces chemicals that stimulate abnormal vessel growth

For neovascularization and macular edema

No, repeated injections may be necessary

Advanced disease with retinal detachment or persistent vitreous hemorrhage

More than 3 months

Good blood glucose control

Early detection

At the time of diagnosis

Yearly

Five years after onset

Yearly from diagnosis

Before conception or early in the first trimester

Every 3–12 months

Every 1–3 months

95%

No, usually asymptomatic

Precapillary arterioles and capillaries

$2:3$

Reduction in the caliber of retinal arterioles

Ischemic areas of retinal nerve fibers

Retinal hemorrhages also seen in diabetic retinopathy

Arteriovenous crossing abnormality or disconnection of vessels

Lipids in the retina

Swelling and elevation of the optic nerve head

Widening and brightening of the central arteriolar light reflex, producing a copper appearance

No retinal changes

Mild to moderate arteriolar narrowing

Marked arteriolar narrowing, increased central light reflex, intermittent constrictions, and AV crossing defects

Stage I and II changes plus cotton wool spots, hard exudates, hemorrhages, and macular star

All previous changes plus disc edema

Branch retinal artery occlusion and central retinal artery occlusion

Combined capillary and precapillary injury may produce more severe complications

Mainly clinically

Systemic blood pressure management

Central retinal vein occlusion, also called venous stasis retinopathy

Partial or complete blockage of the central retinal vein

Thrombosis and compression of the central retinal vein

Vessel damage, stasis, and hypercoagulability

Arteriovenous crossing

At or just proximal to the lamina cribrosa

Four quadrants

One or two quadrants

Acute unilateral blurring or loss of vision

Older age, hypertension, hyperlipidemia, diabetes, high IOP, smoking, oral contraceptives, and hypercoagulability

Perfused retina with generally better visual acuity and prognosis

Non-perfused retina with severe visual impairment and poorer prognosis

Better than 20/200

Worse than 20/200

Yes

Mild or absent

Visual field defect

Extent of retinal capillary non-perfusion

More than 10 disc areas

Reduced B-wave amplitude

Generally good

Poor, with increased risk of neovascular glaucoma

Neovascular glaucoma

Macular edema

Transient visual obscurations, blurry vision, and distorted vision

Clinical examination

Fluorescein angiography

Optical coherence tomography

Treatment of extensive capillary non-perfusion

When macular edema is present

When vitreous hemorrhage occurs

Sudden, painless, severe monocular vision loss

Transient loss of vision lasting seconds to minutes

White or gray

Younger than 40 years

Carotid artery cholesterol emboli

Platelet-fibrin emboli

Vasculitis and intravenous particulate medications

It can cause irreversible retinal damage

Within 90 minutes

Permanent retinal damage

Surrounding retinal edema and whitening make the central foveal reflex prominent

Clinical examination

Delayed or sluggish retinal arterial blood flow

Hyperreflective, thickened, edematous inner retinal layers

Diminished B-wave amplitude

No

22%

10%

Attempt to dislodge emboli