Postoperative Keratometric Astigmatism Axis Shift in Cataract Operated Adult Patients in National Eye Centre, Kaduna.

ABSTRACT

Cataract surgery incisions distort corneal curvature at meridian of incision with tendency to change the orientation of astigmatism. In this article, we determine the pattern of astigmatism types in cataract operated adult patients in National Eye Centre, Kaduna. This was a prospective randomized interventional study involving 150 patients with cataract distributed into three groups for cataract surgery with posterior chamber intraocular lens (PCIOL) implantation. In group I, 41 patients had extracapsular cataract extraction (ECCE), group II, 68 patients had manual small incision cataract surgery (MSICS) by superior incision and group III, 41 patients had manual small incision cataract surgery by temporal incision. The patients were evaluated with autokeratometer for keratometric astigmatism preoperatively, at 1 week and 6 weeks after surgery. Data were analyzed using SPSS Version 16 and P-value less than or equal to 0.05 was considered statistically significant. The preoperative type of astigmatism for each of the groups was similar: WTR; 12(29.3), 21(30.9), 12(29.3), (P 0.99) and ATR; 22(53.7), 34(50.0), 21(51.2), (P 0.91) with predominantly ATR. There was a shift in the type of astigmatism from Against-the-rule (ATR) to With-the-rule astigmatism (WTR) in 29(70.7%) extracapsular cataract surgery and 21(51.2%) manual small incision cataract surgery by temporal incision. Increased Against-the-rule (ATR) in 41(60.3%) manual small incision cataract surgery by superior incision (Msup) was found in the first week after surgery. This pattern was statistically significant at 6 weeks after surgery. Astigmatism is predominantly against the rule in adults but changes depending on the procedure used in cataract operated eyes.