By Muhd Ariff B Mahdzub

CATARACT

CATARACT

• Cataract is one of the most common cause of gradual visual loss but is usually treatable.

• It refers to “clouding” or loss of clarity of the crystalline lens, with a resultant of decrease in visual acuity.

• When it lies on the visual axis or is extensive, it gives rise to visual loss.• A cataract may occur congenitally, but elderly cataracts are much more

common as a result of cumulative exposure to environmental and other influences, such as smoking, UV radiation and elevated blood sugar levels.

• A cataract is a very common cause of blindness, but patients may initially experience glare (with the cortical type), monocular diplopia or a change in refraction, usually a “myopic shift” because of nuclear sclerosis.

• Cataracts are recognised by a decrease in the red reflex with resultant poor visualisation of the retina on attempted fundoscopy.

• It is important to exclude other co-existing ocular pathologies which may limit the chances of visual recovery after surgery.

• A cataract is also the most common cause of leukocoria (white pupil).• Cataract blindness is reversible by microsurgery which aims to improve

visual function and is safe, quick and cost-effective

• Causes of Cataract Primary- Congenital- Age-related Secondary- Trauma- Systemic diseases – diabetes mellitus- Drugs s/a steroid- Others

• Types of age-related cataracts include:A subcapsular cataract occurs at the back of the lens. People

with diabetes or those taking high doses of steroid medications have a greater risk of developing a subcapsular cataract.

A nuclear cataract forms deep in the central zone (nucleus) of the lens. Nuclear cataracts usually are associated with aging.

A cortical cataract is characterized by white, wedge-like opacities that start in the periphery of the lens and work their way to the center in a spoke-like fashion. This type of cataract occurs in the lens cortex, which is the part of the lens that surrounds the central nucleus.

Mature cataract (with absent red reflex) visible through the dilated pupil

Phacoemulsification: • An ultrasound probe is used to emulsify the cataract and aspirate it

through a small scleral or corneal wound which needs no sutures.• This surgical technique requires a shorter recovery time. • More recently, femtosecond laser has been introduced to perform

some of the steps of the procedure.

Ultrasound probe used for phacoemulsification

MANAGEMENT

Cataract extraction can be performed in two basic ways, 1. intracapsular cataract extraction (ICCE), whereby the lens is

removed together with its capsule2. extracapsular cataract extraction (ECCE), whereby the lens is

removed leaving the capsule behind, which is the preferred technique.

INTRAOCULAR LENSES (IOL) TYPES

5. AGE-RELATED MACULAR DEGENERATION (ARMD)

Anatomical Landmarks• The macula is a round area at the posterior pole, lying inside the temporal

vascular arcades. It measures between 5 and 6 mm in diameter, and subserves the central 15–20° of the visual field.

• Histologically, it shows more than one layer of ganglion cells, in contrast to the single ganglion cell layer of the peripheral retina.

• The inner layers of the macula contain the yellow xanthophyll carotenoid pigments lutein and zeaxanthin in far higher concentration than the peripheral retina (hence the full name ‘macula lutea’ – yellow plaque).

• Retinal pigment epithelium composed of a single layer of cells that are hexagonal in cross-section. The cells consist of an outer non-pigmented basal element containing the nucleus, and an inner pigmented apical section containing abundant melanosomes.

• The cell base is in contact with Bruch membrane and at the cell apices multiple thread-like villous processes extend between the outer segments of photoreceptors.

• Functions of RPE :- Prevent extracellular fluid leaking into subretinal space from the chorio

capillaries and actively pump ions and water out of the subretinal space. Facilitation of photoreceptor. Maintenance of the outer-blood retinal barrier ; inward transport of

metabolites and outward transport of metabolic waste products. Storage, metabolism and transport vitamin A in the visual cycle. To absorb stray light

INTRODUCTION

• ARMD is a degenerative disorder affecting the macula and is a disease of the elderly.

• Characterized by the presence of specific clinical findings, including drusen which are pale deposits in the macular area, and retinal pigment epithelium (RPE) changes, in the absence of another disorder. Later stages of the disease are associated with impairment of vision.

• Initially, drusen do not interfere with vision. • Age-related macular degeneration is a very common cause of bilateral

visual loss in the developed world, especially in patients over the age of 65 years.

CLASSIFICATIONDry (non-exudative, non-

neovascular) AMD

Most common form. Comprising around 90%

Geographic atrophy (GA) is the advanced stage of dry AMD; it has

been authoritatively suggested that the term ‘dry AMD’ be used only to

describe GA rather than earlier stages of AMD.

Usually associated with gradual vision loss (due to collection of

drusens formed)

Wet (exudative, neovascular) AMD

Much less common than dry, but is associated with more rapid

progression to advanced sight loss. The main manifestations are

Choroidoneovascularization and Pigment epithelial detachment.

Retinal angiomatous proliferation (RAP) and polypoidal choroidal vasculopathy (PCV), have been included under the umbrella of

neovascular AMD by many authorities.

Drusen around the fovea (centre of the macula). Exudates and haemorrhage in “wet” age-related macular degeneration.

• Sclerosis of arteries that nourish the retina sensitive retinal tissue oxygen and nutrients that needs to function and thrive atrophic thinning macular tissues, amorphous deposits, pigmentation in macula.

MANAGEMENT• No specific treatment yet for non-exudative (dry) ARMD.• Treatment starting at intermediate ARMD, by giving VitaLux, an ocular

multivitamin to help delay the progression of the disease and to help maintain healthy vision.

• In wet ARMD :- anti-VEGF such as Ranibizumab (Lucentis) or Bevacizumab (Avastin) could

be injected intravitreously to prevent new vessels forming.- Photodynamic therapy (PDT) : light-sensitive medicine is injected into the

bloodstream. The medicine collects in the abnormal blood vessels under the macula. Laser light is then shone into the eye, which activates the medicine and causes it to create blood clots that block the abnormal blood vessels.

refference• Kanski's Clinical Ophthalmology - Eighth Edition • Opthalmology an illustrated colour text 3rd edition• Opthalmology at a glance • Lecture Notes Ophthalmology, 11th Edition - James, Bruce, Bron,

Anthony• http://www.aao.org/eye-health/diseases/what-is-glaucoma• http://patient.info/doctor/• http://www.emedicinehealth.com/glaucoma_overview/page7_em.ht

m#glaucoma_surgery