Retina !
The retina is the thin light-sensitive layer lining the back of the eye; it turns light into nerve signals and can detach or be damaged by diabetes.
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What it is
The thin light-sensitive layer lining the back of the eye.
What it does
Turns light into nerve signals; it can detach or be damaged by diabetes.
Key facts
- Where
- Inner layer of the back of the eye, from the ora serrata to the optic disc
- Blood supply
- Inner retina: central retinal artery; outer retina: choroid
- Nerve
- Output via the optic nerve
- Function
- Rods (dim light) and cones (colour, detail) turn light into signals
Relations
- In front
- Ends at the ora serrata, continuing forward as the non-pigmented epithelium of the ciliary body
- Behind
- Optic disc, where the ganglion cell axons leave as the optic nerve
- Superficial
- Retinal pigment epithelium, Bruch membrane and the choroid, which feeds the photoreceptors
- Deep
- Vitreous body, against its internal limiting membrane; the gel pulls on it in posterior vitreous detachment
How to find it
Seen with the ophthalmoscope through a dilated pupil: the disc, the macula and the vascular arcades at the back; the far periphery needs indirect ophthalmoscopy with scleral depression or wide-field photography.
Examination
- Dilated fundoscopy: direct for the disc and macula; indirect with scleral depression to find peripheral tears
- Confrontation fields and perimetry: the defect lies opposite the damaged retina (an upper detachment gives a lower field loss)
- Electroretinography: reduced rod and cone responses in inherited dystrophies such as retinitis pigmentosa
On imaging
OCT shows the layers in cross-section (fluid, oedema, holes); fluorescein angiography shows leakage, closed capillaries and new vessels; B-scan ultrasound shows a detachment when blood or a cataract blocks the view.
Common problems
- Diabetic retinopathy: damaged small vessels leak and bleed; new fragile vessels can grow.
- Retinal detachment: flashes, a shower of floaters and a curtain over vision; an emergency.
- Retinal vessel blockage: sudden painless vision loss.
How it is diagnosed
Dilated eye exam (looking at the fundus), retinal photos, OCT scans of the retinal layers and dye angiography.
Treatment
- Control of blood sugar and pressure, with yearly eye checks in diabetes.
- Laser treatment or injections into the eye for diabetic damage.
- Urgent surgery (laser, gas bubble or vitrectomy) for a detachment.
Clinical notes
- Detachment types: rhegmatogenous (a tear; more likely with myopia, age or trauma), tractional (fibrous bands in diabetic retinopathy) and exudative (fluid from inflammation or tumour)
- Retinopathy of prematurity: abnormal vessel growth in preterm babies, who are screened with fundoscopy
- Retinoblastoma, the main eye cancer of early childhood, often presents with a white pupil (leukocoria) or a squint
- Retinitis pigmentosa: rods fail first, giving night blindness and tunnel vision, with bone-spicule pigment in the fundus
- Roth spots, haemorrhages with pale centres, can accompany infective endocarditis and leukaemia
Anatomical variants
- Myelinated nerve fibres: white, feathery patches at the disc edge where axons kept their myelin in front of the lamina cribrosa; usually harmless, though they can hide other findings and enlarge the blind spot
Development
Grows out of the forebrain as the optic vesicle and cup, so it is part of the central nervous system; the outer layer of the cup becomes the pigment epithelium and the inner layer the neural retina.
Memory aid
Cones: Colour and Centre; rods: dim light and the periphery.
Related conditions
- Oculocutaneous albinism
- Tay–Sachs disease
- Refsum disease (adult)
- Leber hereditary optic neuropathy (LHON)
- Vitamin A deficiency (night blindness and xerophthalmia)
- Diabetic retinopathy
- Retinal detachment
- Age-related macular degeneration
- Type 2 diabetes mellitus
- Type 1 diabetes mellitus
- Arterial hypertension
- Digoxin toxicity
- MGUS and Waldenström macroglobulinaemia
- Toxoplasmosis
- Cytomegalovirus infection
- Toxocariasis (visceral and ocular larva migrans)
- Central retinal artery occlusion
- Retinoblastoma
- Hypertensive retinopathy
- Central retinal vein occlusion
- Ocular toxoplasmosis (retinochoroiditis)
- Endophthalmitis
- Prematurity and its complications
- Congenital (TORCH) infections: syphilis, toxoplasmosis, CMV and Zika
- Child maltreatment (physical abuse, abusive head trauma, neglect)
- Retinopathy of prematurity
Test yourself
Think of the answer, then tap the question to see it.
Between which layers does the retina separate in retinal detachment, and where is it firmly fixed?
Between the neural retina and the pigment epithelium; it is firmly fixed only at the ora serrata and the optic disc.
What are the three types of retinal detachment?
Rhegmatogenous (a tear), tractional (fibrous bands, as in diabetic retinopathy) and exudative (fluid from inflammation or tumour).
What are the fundus signs of diabetic retinopathy?
Microaneurysms, dot-blot haemorrhages, hard exudates and cotton-wool spots, then new vessels.
What is the blood supply of the inner and outer retina?
Inner retina: the central retinal artery; outer retina (photoreceptors): the choroid.
What are the classic features of retinitis pigmentosa?
Rods fail first: night blindness and tunnel vision, with bone-spicule pigment in the fundus.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- retina TA2 6776
- Official Spanish (DeCS)
- Retina DeCS D012160
- English (TA2)
- Retina
Related
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Head and Neck: Retina; Retinal Detachment.
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Representative model, for educational purposes only.
