Purpose: To assess the occurrence and magnitude of corneal topographic changes in phakic
eyes undergoing Transconjuctival Cannulated 20 gauge Vitrectomy (TC20V) without scleral
buckling or silicone oil tamponade.
Setting: Prospective randomized controlled study done at Egyptian Eye Academy.
Methods: Forty eyes of 40 patients underwent TC20V for a variety of vitreo-retinal conditions
over a 1 year follow-up period. Corneal keratometric readings were obtained using Oculus
Pentacam before surgery, 1 week after, and 1 month after surgery; neither scleral buckling nor
silicone oil tamponade were used in order to not affect the final corneal changes. Cases with
postoperative hypotony were excluded.
Results: The mean preoperative K1 (vertical keratometry) was 44.87 ± 3.55, the mean
K2 (horizontal keratometry) was 44.57 ± 3.68; the mean postoperative K1 after
1 week was 45.1 ± 6.82 while the mean postoperative K2 after 1 week was 45.7 ± 3.97. Using
paired t-test analysis, the P-value of the K1 change was 0.01 and P-value of the K2 change was
0.02. Both indicate minimally significant differences. One month postoperative the mean K1
was 45.2 ± 2.53 and the mean K2 was 45.1 ± 1.56 and P-values of both K1 and K2 changes
after 1 month were .0.05, which indicates insignificant changes.
Conclusion: The results showed that minimal corneal topographic changes were encountered
with the use of TC20V owing to the tunnel configuration of the wound, and these changes also
decrease within the first month.