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Ophthalmology Emphasizing Corneal and Refractive Issues

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The Canrobert “C” Procedure

The “C” procedure was developed by Canrobert Olivera of Brazil. The procedure consists of 6 incisions as shown in figure A and figure B. The pattern was developed after Dr Olivera observed the pattern shown in figure C after performing relaxing incisions. He observed sufficient relaxing to control astigmatism in the central cornea but “leaking” of the astigmatic pattern around the incisions in the midperiphery resulting in an “X” astigmatic pattern which he dubbed keratopyramis. Persitant keratopyramis can be a disturbing visual problem with diminished best corrected astigmatism and side effects such as glare. His solution was to make a set of 4 additional incisions outside the 2 primary incisions to prevent “bleeding” around the primary incisions. The procedure which resulted was successful in preventing keratopyramis but also has other admirable properties. In the nomogram provided below we note that no single incision is longer than 60 degrees. These relatively short incisons heal well and result in a stable correction after healing.

Markers for this operation are available from Mastel Precision.



“C” Procedure Nomogram

2 Diopter Correction

Optical Zone 7.5/8.5 mm

Arc Length 45/22.5 degrees



3 Diopter Correction

Optical Zone 7.0/8.0 mm

Arc Length 60/22.5 degrees



4 Diopter Correction

Optical Zone 6.5/7.5 mm

Arc Length 60/30 degrees



5 Diopter Correction

Optical Zone 6.0/7.0 mm

Arc Length 60/30 degrees



6 Diopter Correction

Optical Zone 6.0/7.0 mm

Arc Length 60/45 degrees