際際滷

際際滷Share a Scribd company logo

Sturms conoid

Download as PPTX, PDF
Yasir Maqsood
Yasir Maqsood

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 of 18
Downloaded 24 times
By Yasir Maqsood
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.
Sturms conoid
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..lenticonus Positional.congenital tilting & traumatic subluxation of lens Indexdeveloping cataract/nuclear sclerosis/index astigmatism.
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
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.
Sturms conoid
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.
Sturms conoid
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.
Sturms conoid
Irregular astigmatism There are so many irregularities in the curvature of cornea that no geometrical figure of focus is formed on the retina.
Asthenopia Blurring of vision Decrease vision Headache Half closure of lid occurs due to achieve good vision. Head tilt possible
History Blurring of vision Asthenopia : near or distance Distorsion Head tilt Diplopia Family history ; glasses,squint.
Examination VA, pinhole examination Keratometry Astigmatic fan test Cycloplegic refraction
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.
Sturms conoid

More Related Content

Sturms conoid

  • 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 Indexdeveloping 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.