cataract

CATARACT

* By dr. Omar S. Mahmood M.B.CH.B F.I.C.M.S ( Opht.)

The crystalline lens

Anatomy of the lens The crystalline lens is a biconvex, avascular transparent structure enclosed by a capsule. The lens consists of: 1- Nucleus: 2- Cortex: 3- The capsule: What is zonules? What is "Accommodation"

Ciliary muscle Innervation: 3rd CN Function ? Ciliary process Attaches to the lens by suspensory ligament (zonular fibers) Secrete the Aqueous humor into the post. chamber

Definition of cataract

Opacification of crystalline lens

Epidemiology

Cataracts remain the leading cause of blindness. Age-related cataract is responsible for 48% of world blindness, which represents about 18 million people Cataracts are also an important cause of low vision in both developed and developing countries.

Causes of cataract

Old age (commonest) Ocular & systemic diseases DM Uveitis Previous ocular surgery Systemic medication Steroids Phenothiazines Trauma & intraocular foreign bodies Ionizing radiation X-ray UV
CongenitalDominantSporadicPart of a syndromeAbnormal galactose metabolismHypoglycemiaInherited abnormalityMyotonic dystrophyMarfan’s syndromRubellaHigh myopia *


Age -related cataract
It is the Most commonly occurred.Classified according to:Morphological ClassificationNuclearCorticalSubcapsularChristmas tree – uncommonMaturity classificationImmature Cataract Mature Cataract Hypermature Cataract


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Mature Cataract

Lens is completely opaque. Vision reduced to just perception of light Iris shadow is not seen Lens appears pearly white
Right eye mature cataract, with obvious white opacity at the centre of pupil

Liquefactive/Morgagnian Type

Cortex undergoes auto-lytic liquefaction and turns uniformly milky white. The nucleus loses support and settles to the bottom.

Symptoms

A cataract usually develops slowly, so: Causes no pain. Cloudiness may affect only a small part of the lens People may be unaware of any vision loss. Over time, however, as the cataract grows larger, it: Clouds more the lens Distorts the light passing through the lens. Impairs vision
Reduced visual acuity (near and distant object) Monocular diplopia. Altered colours ( white objects appear yellowish) Not associated with pain, discharge or redness of the eye. Cataract can improve vision?!



Signs
Reduced acuity. An abnormally dim red reflex is seen when the eye is viewed with an ophthalmoscope. Reduced contrast sensitivity can be measured by the ophthalmologist. Only sever dense cataracts causing severely impaired vision cause a white pupil. After pupils have been dilated, slit lamp examination shows the type of cataract.

Gradual loss of vision

DDX: Cataract Glaucoma Diabetic retinopathy Hypertensive retinopathy Age related macular degeneration Retinitis pigmentosa OnTrachoma chocerciasis (river blindness) Vitamin A deficiency

Treatment

SURGERY● there is NO effective medical treatment Indications of surgery: 1- Visual improvement:is the most common indication, whether it is mature or immature. 2- Medical indications ? Types of cataract surgery: 1- Intracapsular cataract extraction (ICCE) ± AC IOL (anterior chamber, intraocular lens): 2- Extracapsular cataract extraction (ECCE) ± PC IOL (posterior chamber intraocular lens):3- Phacoemulsification:


Phacoemulsification in cataract surgery involves insertion of a tiny, hollowed tip that uses high frequency (ultrasonic) vibrations to "break up" the eye's cloudy lens (cataract). The same tip is used to suction out the lens
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Summery

Cataract is opacification of crystalline lens Cataract can be congenital or acquired Cataract presents with gradual painless loss of vision Senile cataract is the most common cause Treatment of cataract is only surgical when indicated

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