Chapter-10 The Lens

BOOK TITLE: Basic Ophthalmology

1. Jogi Renu
Publishing Year
Author Affiliations
1. MGM Medical College, Indore (MP), Pt. Jawahar Lal Nehru Memorial Medical College, Raipur, Chhattisgarh, India, India, Mahatma Gandhi Memorial Medical College, Indore, Madhya Pradesh, India, Pandit Jawahar Lal Nehru Memorial Medical College, Raipur, Chhattisgarh, India
Chapter keywords


Lens is a transparent, biconvex, crystalline structure placed between the iris and vitreous, having dioptric power of 15 to 18 D. The inner nucleus is surrounded by cortex which in turn is enveloped by the capsule. Any opacity in the lens is termed cataract which may be congenital or acquired. Congenital cataract may be hereditary, due to maternal causes (malnutrition, infection), foetal causes (deficient oxygenation, metabolic or chromosomal abnormalities) or may be idiopathic. If visually significant, it should be operated at the earliest to avoid development of amblyopia, by lens aspiration or by lensectomy followed by visual rehabilitation. Senile cataract is the commonest type of acquired cataract. It may be cortical or nuclear type. Senile cortical cataract progresses through the stages of lamellar separation, incipient cataract, intumescent cataract, followed by mature and hypermature (Morgagnian) cataract. Senile nuclear cataract has a comparatively slow progression with sclerosis of the nucleus. Cataract can also develop as a complication of inflammatory diseases or degenerative diseases of the eye. Diabetes, galactosemia, certain drugs and trauma are other causes of cataract. Interference with the routine of a patient’s life is the most important indication for cataract surgery. An extracapsular cataract extraction (ECCE) is the treatment of choice which may be done by conventional ECCE, manual small incision cataract surgery (SICS) or phacoemulsification. An incision in the cornea or sclera, anterior capsulotomy, hydroprocedures, nucleus management, aspiration of cortex, followed by intraocular lens implantation are the basic steps of any ECCE procedure. Any opacity persisting or following an ECCE procedure is termed a secondary or after cataract. It is usually managed by YAG laser capsulotomy or by needling.

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