STURMS CONOID

By

Yasir Maqsood

STURMS CONOID 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.

ETIOLOGY 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.

Lenticular causes It is comparatively rare. It may be

Curvatural…..lenticonusPositional…….congenital tilting & traumatic

subluxation of lens Index……………developing cataract/nuclear

sclerosis/index astigmatism.

FOCUS OF STURMS CONOID ACCORDING TO THE TYPES OF ASTIGMATISM Regular astigmatism The astigmatism is said to be regular

when horizontal and vertical meridians are at right angle to each other. Simple astigmaism

Simple myopic astigmatism Simple hyperopic astigmatism

Compound astigmatism Compound myopic astigmatism Compound hyperopic astigmatism

Mixed astigmatism Oblique astigmatism

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.

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.

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.

Irregular astigmatism There are so many irregularities in the

curvature of cornea that no geometrical figure of focus is formed on the retina.

SIGNS AND SYMPTOMS Asthenopia Blurring of vision Decrease vision Headache Half closure of lid occurs due to achieve

good vision. Head tilt possible

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

ASSESSMENT Examination VA, pinhole examination Keratometry Astigmatic fan test Cycloplegic refraction

CORRECTION 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.