AMD

Overview

Eye Cells

Video 2.1 : The normal eye: The retina and the macula​

A thin membrane which lines the inner part of the eye

Consisting of​ :

  • Visual cells sensitive to light or photoreceptors
    • Rods: responsible for night-time vision.
    • Cones: responsible for day-time vision and differentiate between colours.
  • Nerve cells enable transmission of visual information to the brain via the optic nerve

Organised in two areas :

  • The peripheral retina is involved in peripheral vision, i.e. spatial vision involved in perception of the environment.
  • The macula or macula lutea (the yellow spot) (central retina)
    • Located at the centre of the retina, in the optic axis of the eye
    • Transmits 90% of visual information processed
    • Responsible for visual acuity and for central vision: precise vision involved in reading, writing, recognition of details and of colours. 

Age-related macular degeneration

  • A degenerative disorder of the macular retina  
  • Acquired
  • Onset most commonly after 50 years of age.
  • Results in irreversible alteration of central vision
    • Central vision: precise vision involved in reading, writing, recognition of details and of colours.
  • Does not lead to complete blindness, peripheral vision is conserved
    • Peripheral vision: spatial vision involved in perception of the environment. (2) (3)

Epidemiology

  • The 3rd leading cause of visual deficiency world-wide
  • Accounts for 8.7% of causes of visual deficiency
  • The leading cause of decreased visual acuity in the industrialised countries (3)
  • Prevalence in the population of France: 8% (4)
  • The incidence increases in the population with ageing (5)
    • 1% of persons 50 to 55 years,
    • about 10% of subjects 65-75 years
    • of 25 to 30% of subjects over 75 years of age
  • A disease which risks becoming wide-spread world-wide as the result of increasing life span (3)

Aetiology and risk factors

  • Age: +50 years
  • Smoking
  • Genetic susceptibility (6):
    • Multifactorial, polygenetic
    • Family heredity
    • Identification of genetic areas associated with the disease (Complement Factor H)
  • Diet:
    • A healthy and balanced diet, high in green vegetables and in fresh fruits and fish may delay onset of the disease
  • Repeated exposure to UV radiation is a suggested risk factor.
  • Arterial hypertension, cardiovascular disease, hypercholesterolaemia. (2) (4)

Clinical Presentation

Video 2.2 : AMD: Dry form

Characteristics

  • The most common form
  • The least serious form
  • Not reversible
  • Atrophy of the macula. (2)

Progression

  • Progression generally over several years, progressive, not painful
  • Late onset of scotomas that sometimes can become severe
  • Generally bilateral symptoms.(2)

Video 2.3: AMD: Wet form​

Characteristics

  • The least common form
  • Results in rapid loss of vision
  • Development of choroidal neo-vessels, under the macula, responsible for exudates and haemorrhage in fundoscopic examination. (2)

Progression

  • Progression in a few days to weeks.
  • First symptoms, generally visual distortion
    • Scotoma
    • Inward distortion of straight lines
  • Generally unilateral symptoms (2)
 

 

Video 2.4: AMD: Visual symptoms​

Visual symptoms

  • An asymptomatic disease in the early stages

Then,

  • Decrease in sensitivity to contrasts
    • Need to have better lighting for reading or for any precision work.
  • Decrease in visual acuity and increased blurring of central vision
    • Alteration of the perception of colours,
    • Distortion of straight lines (which appear deformed and bowed).
  • Occurrence of a central dark spot (scotoma)
    • Difficulty in recognising faces,  
    • Visual hallucinations (2)
 

Diagnostic

World Cells

Figure: the Amsler Grid Test​

Diagnostic approach

  • Diagnosis established by an ophthalmologist
  • Elements of suspicion in a patient + 50 years of age (2)
    • Decrease in visual acuity
    • Abnormalities in the Amsler grid test
      • Vision with deformed, interrupted or broken lines or sometimes blurred areas or blind spots. (4)
    • Decreased perception of contrasts
    • Impairment of night-time vision
  • Laboratory examinations:
    • Measurement of visual acuity
    • Fundoscopy to guide diagnosis (2) (7)
  • Elements of the fundoscopy suggestive of AMD
    • Optical coherence tomography (OCT)
    • Fluorescein angiography to confirm the existence of choroidal neovessels
    • +/- Indocyanine green angiography (ICG)
    • +/- Ultrasound (2) (7)

Fundoscopy

  • Performed with a bio-microscope after dilatation of the pupil with eye drops.
  • Alterations in fundoscopy that can be observed: drusen, irregularities of the deep layer of the retina, alteration of the pigmentary epithelium, haemorrhage, exudates (liquid deposits). (2)(7)

OCT (Optical Coherence Tomography)

  • Technique based on reflection of infrared light
  • A painless examination, not requiring injection of a contrast medium.
  • Makes it possible to assess the thickness of the retina by providing images in section ranging from the superficial layers to the deepest layers:
    • To analyse alterations of the retinal tissue (dry and wet forms of AMD)
    • To visualise the processes of exudation and neovascularisation (wet form). (2) (7)

Fluorescein angiography

  • Performed using a retinograph with photographs of vessels in the retina, after administration of a contrast medium.
  • Precautions related to the use of fluorescein (allergic subjects). (2)(7)
    • Clarifying the form and severity of AMD.

Indocyanine green angiography

  • To obtain information in addition to that obtained with fluorescein angiography.
  • Use of a different dye than fluorescein.
  • Very well-tolerated.
  • Contraindication: during the first 3 months of pregnancy. (2)(7)

Ultrasound

  • Useful in case of opacity of a medium (cataract: an opaque lens).
  • Swelling in the macula caused by accumulation of deposits that accumulate under the retina that can be visualised with ultrasound. 

Treatment

Eye Cells

Therapeutic approach

General measures

  • To date, there is no curative treatment for atrophic AMD.
  • The utility of dietary supplementation with Zinc, Copper, Vitamin C and E and Lutein and with pro-vitamin A for patients with a progressive risk (dry or unilateral wet form)
  • Utility for concomitant measures:
    • Utility of objects with appropriate ergonomics and technologies of accessibility: lighted magnifying glasses, synthetic voice software, etc.
    • Rehabilitation for limited vision:  All techniques designed to maximise the remaining vision. (2)(7)

Management of exudative AMD

  • The initiation of treatment with anti-VEGF as early as possible after diagnosis of retrofoveolar exudative AMD.
  • In case of contraindication to anti-VEGF, the following therapeutic alternatives can be considered on a case by case basis:
    • Dynamic phototherapy with verteporfin;
    • Argon laser photocoagulation (2) (7)

Principle of laser treatments

Dynamic phototherapy using verteporfin: Photodynamic therapy (PDT)  

  • Consists of activating by means of a low intensity laser, a dye previously injected in to a vein in the patient’s arm. This dye selectively binds to the neo-vessels. Its activation by laser creates a thrombosis within the blood vessel and thus results in its disappearance.
  • Can be repeated every three months, after re-evaluation (visual acuity, fundoscopy and/or retinophotographs, optical coherence tomography, fluorescein angiography).
  • Makes it possible to reduce risk of loss of vision, but visual improvement is exceptional.
  • Can cause chorioretinal atrophy, responsible for scotomas and for decreased visual acuity.
  • Direct exposure to sunlight should be avoided during 48 hours, due to risk of photosensitisation. (7)

Laser photocoagulation

  • Consists of use of a laser to burn lesions of the retina which lie in the proximity of the central region. The objective is to prevent these lesions from reaching the centre of the retina and of causing permanent decreased vision.
    • Performed after dilatation of the pupil with eye drops.
    • It is recommended to keep the eyes fixed during the intervention.
  • Carries little risk. The impact of laser light however can leave marks on the retina perceived as transient dark spots in the visual field. In one person out of six, the laser generates light or coloured phenomenon, or even true visual hallucinations. (8)

References

Cells
  1. Cohen SY, Desmettre T. Comment fonctionne l’œil et la rétine ? Dans : DMLA – Dégénérescence liée  l’âge, Bash 2008, p 36.
  2. Porter RS, Kaplan JL. Chapter 68. Retinal Disorders. The Merck Manual of Diagnosis & Therapy, 19th Edition,  Merck Research Laboratories 2011, p. 719-721.
  3. Organisation mondiale de la santé. Prévention de la cécité et des déficiences visuelles.  Maladies oculaires prioritaires. Dégénérescence maculaire liée à l'âge (DMLA). http://www.who.int/blindness/causes/priority/fr/index8.html
  4. Instituts Thématiques INSERM en collaboration avec F. Sennlaub. Dégénérescence maculaire liée à l’âge (DMLA) http://www.inserm.fr/thematiques/neurosciences-sciences-cognitives-neurologie-psychiatrie/dossiers-d-information/degenerescence-maculaire-liee-a-l-age-dmla, Juin 2014
  5. Leveziel et al. Epidémiologie de la dégénérescence maculaire liee a l’age. Journal Français d’ophtalmologie, 2009, 32 :440-451.
  6. Instituts Thematiques INSERM. Léveillard T. et Sahel J.A. Sept facteurs de risque génétiques associés à la DMLA. http://presse-inserm.fr/sept-facteurs-de-risque-genetiques-associes-a-la-dmla/7121/, Mars 2013
  7. Haute Autorité de Santé. Dégénérescence maculaire liée à l’âge : prise en charge diagnostique et Thérapeutique Méthode « Recommandations pour la pratique clinique », Juin 2012
  8. Cohen SY, Desmettre T. Quelles sont les effets secondaires du laser ? Dans : DMLA – Dégénérescence liée à l’âge, Bash 2008, p 118.