MEDICAL ACADEMY NAMED AFTER S.I. GEORGIEVSKY

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MEDICAL ACADEMY NAMED AFTER S.I. GEORGIEVSKY

DEPARTMENT OF OPHTHALMOLOGY

Head of the Department Professor N.V. Ivanova

A lecture by the Department of Ophthalmology is used to prepare this material Lecture theses

Diseases of the Lens

The lens is a transparent, biconvex, crystalline avascular structure placed between iris and the vitreous

Ø The accomodative power of the lens ≈ 20 D

Ø The thickness varies from 3,6 to 5 mm

Ø it consists of proteins (≈ 35%) and water (≈ 65%)

Structure :

Ø Anterior capsule

Ø Single layer of cuboidal cells

Ø Lens fibres: nucleus and cortex

Ø Posterior capsule

Classification of the lens anomalies

1. CATARACTS

2. DISPLACEMENTS OF THE LENS

3. CONGENITAL ANOMALIES OF THE LENS.

CONGENITAL ANOMALIES

Ø Lenticonus

Ø Lens coloboma

Ø Micro- and spherophakia

Ø Biphakia

Ø aphakia

Ø remnant of the fetal hyaloid vascular system

Ø remains of pupillary membrane

Classification of Cataracts

I. By Anatomic Location

A. Cortical

B. Nuclear

C. Posterior subcapsular

D. Mixed

E. Other

II.By Etiology

A. Senile or age-related

B. Congenital and juvenile

C. Traumatic

D. Associated with intraocular diseases: uveitis/inflammation, glaucoma, retinal detachment, retinal degeneration (retinitis pigmentosa, gyrate atrophy), persistent hyperplastic primary vitreous, aniridia, Peters' anomaly, sclerocornea, micro-ophthalmus, Norrie's disease, retinoblastoma, retrolental fibroplasia, highmyopia, retinal anoxia (Buerger's disease, Takayasu's arteritis), anterior segment necrosis

E. Associated with systemic diseases:

1. Metabolic disorders: diabetes; galactosemia; hypoparathyroidism/hypocalcemia; Lowe's, Albright's, Wilson's, Fabry's, and Refsum's diseases; homocystinuria

2. Renal disease: Lowe's and Alport's diseases

3. Skin disease: congenital ectodermal dysplasia;Werner's and Rothmund-Thomson syndromes; atopic dermatitis

4. Connective tissue/skeletal disorders: myotonic dystrophy; Conradi's and Marfan's syndromes; bone dysplasias; dislocated lenses

5. Central nervous system: Marinesco Sjogren's Marinesco-Sjцgren's syndrome, bilateral acoustic neuroma (neurofibromatosis type 2)

F. Caused by noxious agents:

1. Ionizing radiation: x-ray, ultraviolet rays, infrared rays, microwaves

2. Pharmaceuticals: steroids, naphthalene, triparanol, lovastatin, ouabain, ergot, chlorpromazine, thallium (acetate and sulfate), dinitrophenol, dimethyl sulfoxide, psoralens, miotics, paradichlorobenzene, sodium selenite

Any opacity in the lens of the eye is the condition termed cataract.

By Anatomic Location:

1. Anterior polar

2. Posterior polar

3. Spindle-shaped

4. Lamellar (zonular)

5. Nuclear

6. Cortical

7. Posterior subcapsular (cup-shaped)

8. Total cataract

Stages of maturation:

incipient senile cataract

Immature cataract

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