Keratometer or Ophthalmometer 3.pptx
- 2. Definition: Measures radius of curvature of central cornea app (3mm) One of the classic method for refraction, astigmatic Assesses curvature, Power and toricity of the cornea It may be used to asses the integrity of corneal/tear surface
- 4. Optical principle: The anterior corneal surface acts as a convex mirror Doubling system to obtain accurate measurement of image size Keratometric formula Types: 1. Bausch & Lomb(adjust image size), one position 2. Javal Schoitz(adjust object size)two position
- 7. Basic components: Adjustable eyepiece Adjustable chin and forehead rest Knob to raise and lower the instrument Two power wheel to measure corneal power in each meridian An axis scale Targets known as mires Joystick
- 8. Procedure: Focusing the eyepiece Adjust the instrument to the patient Aligning the instrument Instruct the patient Finding the primary meridians Taking the reading Recording the findings
- 9. Interpreting: R:42.00 at 180 ; 43.00 at 90 L:42.25 at 170 ; 43.00 at 80 Interpretation: R: -1.00 x180 L: -1.25 x170 With the rule astigmatism 180 Against the rule astigmatism 90 Oblique astigmatism
- 10. Refractive astigmatism: Total astigmatism Increase with against the rule: 1. In the absence of corneal astigmatism -0.50 ag 2. In corneal -0.50 c rule no astig expected 3. If corneal -2.00 c refractive also -2.00 D c 4. If corneal -2.00D x the refractive -3.00 against
- 11. Indications: Contact lens fitting Keratoconus detection 48.00 or 50.00
- 12. Any question