AGE-RELATED MACULAR DEGENERATION

& RETINITIS PIGMENTOSA

AYESHA S ABDULLAH

17.01.2014

Learning outcomes

By the end of this lecture the students would be able to

1. Describe the epidemiology of ARMD2. Correlated the clinical presentation of age-

related macular degeneration (ARMD) with the underlying pathophysiology

3. Outline the principles of treatment of ARMD4. Describe the epidemiology and clinical

presentation of retinitis pigmentosa

Case

A 72 year old man presented to the OPD with the complaints of difficulty in recognizing faces and distortion of vision for the last one year.

When he reads the words seem distorted and wavy with the left eye.

He is a known hypertensive and smoker for the last 40 years. His elder brother has similar problem.

Physical examination

VA: 6/12 OD 6/24 OS Anterior segment: bilateral early

cataract Pupils : normal Posterior segment: fundus photograph Defect on Amsler Grid

How is ARMD caused?

What is the function of RPE? Absorb light, transport oxygen & nutrients to the

outer retina Transport cellular wastes from the outer retina to

choroid In ARMD RPE dysfunction leads to accumulation

of the waste products under the retina at the interface between the Bruch’s membrane and RPE in the form of yellowish deposits

They can be seen on ophthalmoscopy as “Drusen”

Aaetiology

Oxidative damage

Microvascular disease

Genetic predisposition

Known risk factors

Choroid

RPEBruch’s

Choroid

Bruch’sRPE

Choroid

Bruch’sRPE

It is a slow process RPE continues to slow down transport of nutrients and

wastes Overlying photoreceptors and RPE get atrophic It may continue as a slowly progressive “dry” form of the

disease In some it assumes a more aggressive “wet form” New vessels grow from the choroid underneath the retina

forming a neovascular membrane. It leaks and can bleed Resulting in severe visual damage The macula may undergo fibrosis and scarring- “diskiform

scar”

EpidemiologyWhat is the magnitude of ARMD?

Leading cause of blindness in developed countries over the age of 50 years

Whites are twice at risk as compared to blacks

Who is at risk?

Age Family history Smoking doubles the risk Hypertension Cardiovascualr disease Hyperlipidemias Variants of complement factor H Excessive exposure to sunlight

Can it be prevented?

No Risk modification

How can it be treated Risk modification Monitoring – Amsler Grid Diet . Age-Related Eye Disease Study

(AREDS), showed that those who are at high risk for developing advanced age-related macular degeneration, may be helped by taking a specific combination of antioxidants and zinc.

Vitamin C, Vitamin E, Vitamin A as beta-carotene*, Zinc , Copper in a specific dose

*with caution in smokers, increases the risk of lung cancer

Specific treatment

Anti-VEGF intravitreal injections Photodynamic therapy Thermal Laser treatment Surgical excision of the membrane

Rehab

Low vision aids

Electronic devices

Directions for using the Amsler grid

1. If you wear reading glasses, put them on for this test.

2. Hold this book at a comfortable reading distance.

3. Cover one of your eyes.

4. Look at the grid. Keep your eye focused on the white dot at the center of the grid throughout the test.

5. Without moving your eye from the center dot, notice the lines that make up the grid. All of the lines should be straight and all of the squares should look the same.

6. There shouldn’t be any blank, dark, or distorted areas on the grid.

7. Call your eye doctor right away if you notice anything unusual or abnormal in your vision.

8. Use the same procedure to test your other eye.

Retinitis pigmentosa

A degenerative retinal disease Varying pattern of inheritance

Autosomal dominant. 20% of cases (AD) Autosomal recessive (AR) X- linked. Rare with worst prognosis (XL) Isolated cases

Photoreceptor dysfunction primarily affecting rods Systemic associations and deafness 1:5000 prevalence Can have a typical or atypical clinical presentation

How can it be diagnosed?

Bilateral involvement Night blindness Loss of peripheral vision Signs

Arteriolar narrowing Bone specule pigmentary changes Waxy pale disc

ERG Perimetry

How progressive is the visual loss

Starts in childhood Progresses very slowly Rarely the person is blind by the age of 30

year ( X-linked) Rarely proceeds to complete blindness AD-best prognosis with retention of

central vision beyond the 6th decade XL has the worst prognosis with severe

visual loss by the 4th decade

Ocular associations

Cataract Glaucoma Myopia Keratoconus Macular oedema Vitreous changes Optic disc drusen Coats-like disease with exudative RD

Is it treatable?

No The associated ocular diseases like,

cataract, macular oedema , myopia and glaucoma can be treated

The person would be needing low vision aids when the visual field loss becomes more.

Needs to be differentiated from certain drug induced retinopathies ( chloroquine & thioridazine), infections (syphilis) and severe posterior uveitis