The lens is a biconcave structure located behind the iris that helps refract light and allow for accommodation. It has an outer capsule surrounding softer cortical and nuclear layers. Cataracts occur when the lens becomes opaque due to fluid accumulation in the lens fibers. Cataracts can be congenital or acquired through aging, diabetes, steroid use, trauma or infections. They are classified based on which layer is affected and symptoms include blurred vision, glare sensitivity, and reduced visual acuity. Cataracts are diagnosed via visual acuity and slit lamp exams and are generally treated with surgical removal of the opaque lens.

1. HUMAN LENS AND
CATARACT
BY TINA

2. INTRODUCTION
 The lens is a biconcave, a vascular, colorless
structure.
 Its about 4mm thick and 9mm in diameter.
 Refractive power of 18-20D
 It is suspended by zonule which connect it to the
ciliary body.

3. ANATOMY
 Now in order to understand its anatomy, think of a
lens as a M&M peanut which has;
 An outer crystal coating resembling the lens capsule,
 The chocolate part as a lens cortex,
 Its inner peanut as the lens nucleus
 Anterior to lens the is aqueous humor and posterior
to it vitreous. (main supplier of nutrients to the lens)

5.  The lens capsule is semi permeable membrane so can
allow water and electrolytes to pass.
 The lens consists of about 65% water and 35%
protein (tissue with high protein content), it also has
mineral like potassium.
 Glucose is the main source of energy

6.  As the age increase sub capsular epithelium which
is anterior increase production of sub epithelial
lamella fibers which makes the lens became larger
and less elastic.

7. FUNCTION
 Together with the cornea it helps to refract the light
so as it can be focused on the retina.
 It does a greater function known as accommodation
in which it change its shape so as the image from
various distance (focus) can be formed on the retina.

8. CATARACT
 Cataract is opacity of the lens in the eye, which occur
when fluid accumulate in the lens fibres.

9. CAUSES
Causes of cataract can be;
 Congenital
 Acquired

10. CONGENITAL CAUSES
syndrome example
 Marfan’s syndrome,
 lowe’s syndrome

11. ACQUIRED CAUSES
 Old age
 Associated with other ocular or systemic disease eg
diabetes
 Associated with systemic medication eg steroids,
phenothiazine.
 Trauma and intraocular foreign bodies
 Infection eg Rubella

12. CLASSIFICATIONS
Cataract is classified according to the part of the lens
that is opacified;
 Cortical (affect the edge of the lens)
 Posterior sub capsular ( affect the back of the lens)
 Nuclear sclerotic ( affect the center of the lens)

13. Symptoms
 Blurred vision
 Glare (sensitivity to light)
 Diplopia
 Clouding of vision
 Reduced best corrected visual acuity less than 6/9

14. DIAGNOSIS
 Visual acuity test
 Slit lamp examination
Note: cataract patients will have normal pupil
reflexes if no other ocular/ optic nerve
diseases

15. MANAGEMENT
 Glasses can be used in early stage of the disease but
the effective treatment is cataract surgery.

16. THANK YOU