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6 Cards in this Set
- Front
- Back
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Contact/ applanation |
-Ultrasound prove tip is placed directly on anesthetised cornea -Makes gentle contact w/ cornea and may slightly indent the surface -Hand held or mounter -5 Peaks probe and cornea= 1 peak |
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Non-contact/ immersion |
- Ultrasound probe does not touch the cornea, prevents identation - Plastic cone sits on the sclera surrouding the cornea - It is filled with fluid and the sound waves travel through the fluid -More reproducible and therefore increase in accuracy - 6 peaks probe and cornea are not demonstrated as one |
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Good A-scan |
-Retinal peaks should be sharp and straight at 0- degrees at baseline -5 high amplitude spikes -Always measure both eyes -Delete unreliable scans |
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Bad A-scan |
- Incorrect gain: gain is too high and resolution of separate retinal and scleral spikes is lost, results in one thick flattened spike - Corneal compression: More shallow ACD. Note AL will be shortened. Av. ACD 3.10mm+/- 0.3mm -Misalignment: Peaks need to be sharp and perpendicular |
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Normal Results |
Av. AL= 23.5mm Av. k reading= 44D 1d k reading error = 1d refraction error 1mm AL error= 3d refracn error Av. LT= 4.7mm Av. ACD= 3.1+/- 0.3mm Av. emmetropic IOL power for PCIOL= 19D |
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Validating Results |
- Aim for SD< 0.09mm -AL < 0.3mm difference bw OU -AL 21-30-26.30 -Ensure refractn and AL are consistent: Myope- longer AL > 24.0mm HT- Shorter AL<24.0mm if above not reached, get 2nd orthoptists to recheck |
