Astigmatism is an optical condition where the cornea and lens have different refractive powers in different meridians, resulting in two focal points instead of one. The distance between focal points is called the Sturm's conoid interval. Astigmatism can be caused by abnormalities in the cornea or lens. It can be regular, where the meridians are perpendicular, or irregular. Symptoms include blurry vision, asthenopia, and headaches. Treatment options include glasses, contact lenses, and refractive surgery like LASIK or LASEK.

1. By
Yasir Maqsood

2.  It
is an optical condition in which refractive
power of cornea and lens is not the same in
all meridians therefore instead of single focal
point there are two focal points separated by
focal interval,this is called sturms conoid.
 The
distance between two focal points is
called sturms conoid interval.

4.  Corneal
causes
 It occurs due to abnormalities of curvature of
cornea.
 Most common cause of astigmatism
 e.g eyelid pressure,pterygium,corneal
scars,corneal degeneration,keratoconus,mild
corneal opacities.

5.  Lenticular
causes
 It is comparatively rare.
 It may be
 Curvatural…..lenticonus
 Positional…….congenital
tilting & traumatic
subluxation of lens
 Index……………developing cataract/nuclear
sclerosis/index astigmatism.

6.  Regular
astigmatism
 The astigmatism is said to be regular when
horizontal and vertical meridians are at right
angle to each other.

Simple astigmaism



Compound astigmatism




Simple myopic astigmatism
Simple hyperopic astigmatism
Compound myopic astigmatism
Compound hyperopic astigmatism
Mixed astigmatism
Oblique astigmatism

7. Simple astigmatism
 In simple astigmatism,one of the foci falls on
retina & other foci falls infront or behind the
retina.
 This leads to one meridian being emmetropic
& other being myopic(one focus on retina &
other focus falls infront of retina) or
hyperopic(one focus falls on retina & other
falls behind the retina)so called as simple
myopic astigmatism and simple hyperopic
astigmatism respectively.


9. Compound astigmatism
 Neither of two foci falls on retina.


If both foci are infront of retina,the
condition is known as compound myopic
astigmatism.

If both foci are behind the retina, the
condition is known as compound hyperopic
astigmatism.

11. Mixed astigmatism
 In mixed astigmatism,one of the two foci lies
at the back while other at infront of retina.

Oblique astigmatism
 A type of astigmatism in which principle
meridia are not horizontal or vertical but are
at right angle to each other.


13.  Irregular
astigmatism
 There are so many irregularities in the
curvature of cornea that no geometrical
figure of focus is formed on the retina.

14.  Asthenopia
 Blurring
of vision
 Decrease vision
 Headache
 Half closure of lid occurs due to achieve
good vision.
 Head tilt possible

15.  History
Blurring of vision
 Asthenopia : near or distance
 Distorsion
 Head tilt
 Diplopia
 Family history ; glasses,squint.


16.  Examination
VA, pinhole examination
 Keratometry
 Astigmatic fan test
 Cycloplegic refraction


17.  Non
surgical treatment
 Glasses
 Contact lens
 Cylindrical lens;correct simple astigmatism
 Spherocylindrical lens;correct compound and
mixed astigmatism
 Surgical treatment
 Refractive surgery including
 Arcuate keratotomy,
 LASIK correct upto 5D.
 LASEK correct upto 3 Dioptre.