Changes in shape and astigmatism of total, anterior, and posterior cornea after long versus short clear corneal incision cataract surgery.

PURPOSE: To compare changes in the shape and astigmatism of the total, anterior, and posterior cornea between eyes with long-length clear corneal incisions (CCIs) and eyes with short-length CCIs in cataract surgery.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

DESIGN

Prospective case series.

METHODS

Both eyes of patients having phacoemulsification with temporal CCIs were randomized to have a long-length (≥1.75 mm) or short-length (<1.75 mm) CCI. Corneal astigmatic changes were decomposed to vertical/horizontal (Jackson cross-cylinder, axes at 180 degrees and 90 degrees [J0]) and oblique changes (Jackson cross-cylinder, axes at 45 degrees and 135 degrees [J45]) using power vector analysis. Corneal shape changes were assessed using the average of the difference map on videokeratography 2 days and 2, 4, and 8 weeks postoperatively.

RESULTS

The mean J0 and J45 values of the total cornea in the 120 eyes evaluated were significantly greater in the long CCI group than in the short CCI group at all follow-ups (P ≤ .0290). The videokeratography showed a wedge-shaped flattening in the total and anterior cornea and a steepening in the posterior cornea around the CCI 2 days postoperatively in both groups. This wound-related flattening of the total and anterior cornea rapidly reduced but persisted until 8 weeks, whereas the steepening of the posterior cornea disappeared within 4 weeks. These changes extended closer to the central cornea in the long CCI group than in the short CCI group.

CONCLUSIONS

Corneal astigmatic changes were significantly greater after long CCI than after short CCI. The wound-related shape changes occurred immediately postoperatively but rapidly diminished.