OPHTHALMIA NEONATORUM

Ophthalmia neonatorum is the name given to bilateral inflammation of the conjunctiva occurring in an infant, less than 30 days old. It is a preventable disease usually occurring as a result of carelessness at the time of birth. As a matter of fact any discharge or even watering from the eyes in the first week of life should arouse suspicion of ophthalmia neonatorum, as tears are not formed till then.
Etiology
Source and mode of infection
Infection may occur in three ways: before birth, during birth or after birth.

1. Before birth infection is very rare through infected liquor amnii in mothers with ruptured membrances.

2. During birth. It is the most common mode of infection from the

ACUTE FOLLICULAR CONJUNCTIVITIS

Acute follicular conjunctivitis is an acute catarrhal conjunctivitis"OR KNOWN AS ACUTE MUCOPURULENT CONJUNCTIVITIS" associated with marked follicular hyperplasia especially of the lower fornix and lower palpebral conjunctiva.

General clinical features
Symptoms are similar to acute catarrhal conjunctivitis and include: redness, watering, mild mucoid discharge, mild photophobia and feeling of

TRACHOMA Symptoms & Signs

Symptoms

• In the absence of secondary infection, symptoms are minimal and include mild foreign body sensation in the eyes, occasional lacrimation, slight stickiness of the lids and scanty mucoid discharge.
• In the presence of secondary infection, typical symptoms of acute mucopurulent conjunctivitis develop.

Signs
A. Conjunctival signs
1. Congestion of upper tarsal and forniceal conjunctiva.

2. Conjunctival follicles. Follicles (Fig. 1 and Fig.2) look like boiled

what is trachoma ?

Trachoma (previously known as Egyptian ophthalmia) is a chronic keratoconjunctivitis, primarily affecting the superficial epithelium of
conjunctiva and cornea simultaneously. It is characterised by a mixed follicular and papillary response of conjunctival tissue. It is still one of the
leading causes of 

CHLAMYDIAL CONJUNCTIVITIS

Chlamydia lie midway between bacteria and viruses,
sharing some of the properties of both. Like viruses,
they are obligate intracellular and filterable, whereas
like bacteria they contain both

ANGULAR CONJUNCTIVITIS

ANGULAR CONJUNCTIVITIS is a type of chronic conjunctivitis characterised by mild grade inflammation confined to the conjunctiva and lid margins near the angles (hence the name) associated with maceration of the surrounding skin.

Etiology
1. Predisposing factors are same as for 'simple chronic conjunctivitis'.
2. Causative organisms. Moraxella Axenfeld is the commonest causative organism. MA bacilli are placed end to end, so the disease is also called

CHRONIC CATARRHAL CONJUNCTIVITIS

Chronic catarrhal conjunctivitis’ also known as
‘simple chronic conjunctivitis’ is characterised by
mild catarrhal inflammation of the conjunctiva.

Etiology
A. Predisposing factors
1. Chronic exposure to dust, smoke, and chemical
irritants.
2. Local cause of irritation such as trichiasis,
concretions, foreign body and seborrhoeic scales.
3. Eye strain due to 

ACUTE MEMBRANOUS CONJUNCTIVITIS

It is an acute inflammation of the conjunctiva,
characterized by formation of a true membrane on the
conjunctiva. Now-a-days it is of very-very rare
occurrence, because of markedly decreased
incidence of diphtheria. It is because of the fact that
immunization against diptheria is very effective.

Etiology
The disease is typically caused by Corynebacterium
diphtheriae and occasionally by virulent type of

INFECTIVE & BACTERIALCONJUNCTIVITIS

Infective conjunctivitis, i.e., inflammation of the
conjunctiva caused by microorganisms is the
commonest variety. This is in spite of the fact that
the conjunctiva has been provided with natural
protective mechanisms in the form of :

•  Low temperature due to exposure to air,
•  Physical protection by lids,
•  Flushing action of tears,
•  Antibacterial activity of lysozymes and
•  Humoral protection by the tear immunoglobulins.

 BACTERIAL CONJUNCTIVITIS
There has occurred a relative decrease in the
incidence of bacterial conjunctivitis in general and
those caused by gonococcus and corynebacterium
diphtheriae in particular. However, in developing
countries it still continues to be the commonest type
of conjunctivitis. It can occur as sporadic cases and
as epidemics. Outbreaks of bacterial conjunctivitis
epidemics are quite frequent during monsoon season.

Etiology
A. Predisposing factors for bacterial conjunctivitis,
especially epidemic forms, are flies, poor hygienic
conditions, hot dry climate, poor sanitation and dirty
habits. These factors help the

Structure of conjunctiva

Histologically, conjunctiva consists of three layers
namely, (1) epithelium, (2) adenoid layer, and (3)
fibrous layer (Fig. 1 below ).


1. Epithelium. The layer of epithelial cells in
conjunctiva varies from region to region and in its
different parts as
follows:

• Marginal conjunctiva has 5-layered stratified squamous type of epithelium.
• Tarsal conjunctiva has

Refractive surgery for astigmatism

Refractive surgical techniques employed for myopia
can be adapted to correct astigmatism alone or
simultaneously with myopia as follows:
1. Astigmatic keratotomy (AK) refers to making
transverse cuts in the mid periphery of the steep
corneal meridian (Fig. 1).

Fig. 1. Astigmatic keratotomy. (A) showing flat and deep meridians of cornea; (B) paired transverse incisions to flattern
the steep meridian; (C) showing correction of astigmatism after astigmatic keratotomy.

AK can be performed
alone (for astigmatism only) or along with RK (for
associated myopia).
2. Photo-astigmatic refractive keratotomy (PARK)
is performed using 

Types of contact lenses

Depending upon the nature of the material used in
their manufacturing, the contact lenses can be divided
into following three types:
1. Hard lenses,
2. Rigid gas permeable lenses, and
3. Soft lenses.

1. Hard lenses are manufactured from PMMA
(polymethylmethacrylate). The PMMA has a high
optical quality, stability and is light in

varieties of myopia

Clinical varieties of myopia
1. Congenital myopia
2. Simple or developmental myopia
3. Pathological or degenerative myopia
4. Acquired myopia which may be: (i) post-traumatic; (ii) post-keratitic; (iii) drug-induced, (iv)
pseudomyopia; (v) space myopia; (vii) night myopia; and (viii) consecutive myopia.
 
1. Congenital myopia
Congenital myopia is present since birth, however, it is usually diagnosed by the age of 2-3 years. Most of the time the error is unilateral and manifests as anisometropia. Rarely, it may be bilateral. Usually the error is of about 8 to 10 which mostly remains constant. The child may develop convergent squint in order to preferentially see clear at its far point
(which is about 10-12 cms). Congenital myopia may sometimes be associated with

What is APHAKIA

APHAKIA

Aphakia literally means absence of crystalline lens from the eye. However, from the optical point of view, it may be considered a condition in which the lens is absent from the pupillary area. Aphakia produces a high degree of hypermetropia.

Causes
1. Congenital absence of lens. It is a rare condition.
2. Surgical aphakia occurring after removal of lens is the commonest presentation.
3. Aphakia due to absorption of lens matter is noticed rarely after trauma in children.
4. Traumatic extrusion of lens from the

Treatment of hypermetropia

Treatment
A. Optical treatment. Basic principle of treatment is to prescribe convex (plus) lenses, so that the light rays are brought to focus on the retina (Fig. 1). Fundamental rules for prescribing glasses in hypermetropia include:
 
1. Total amount of hypermetropia should always be discovered by performing refraction under
complete cycloplegia.

2. The spherical correction given should be comfortably acceptable to the

Optical aberrations of the normal eye

The eye, in common with many optical systems in practical use, is by no means optically perfect; the lapses from perfection are called aberrations. Fortunately, the eyes possess those defects to so small a degree that, for functional purposes, their presence is immaterial. It has been said that despite imperfections the overall performance of the eye is little short of astonishing.
 Physiological optical defects in a normal eye include the following :
1. Diffraction of light. Diffraction is a bending of light caused by the edge of an aperture or the rim of a lens. The actual pattern of a diffracted image point produced by a lens with a circular aperture or pupil is a series of concentric bright and dark rings (Fig.1).
At the centre of the pattern is a bright spot known as the Airy disc.

Fig. 1. The diffraction of light. Light brought to a focus
does not come to a point,but gives rise to a blurred disc
of light surrounded by several dark and light bands (the
'Airy disc').

2. Spherical aberrations. Spherical aberrations occur owing to the