Comparison of toric intraocular lens axis measurement by slit lamp versus photography.

PURPOSE: To investigate the accuracy of slit lamp measurement of toric Intraocular lens (IOL) axis compared with photography and software measurement of the same IOL.

METHODS

The medical charts of 102 eyes of 86 patients who underwent cataract surgery with toric IOL implantation in Ein-Tal eye center, Israel, were retrospectively reviewed. Preoperative data includes demographics, biometry, and calculated IOL. Post-operative data includes visual acuity, refraction, and the IOL axis as measured at the slit lamp and using the Goniotrans eye photograph software. The difference between the two measurements was calculated.

RESULTS

The mean absolute difference between the slit lamp and the photography measurement was 2.13 ± 1.9o (range 0.0-9.0o). In the against the rule (ATR) cases (n = 50) 48% were counterclockwise (CCW), 32% were clockwise (CW) and in 20% there was no difference, the average absolute deviation was 0.4 ± 1.8o CCW, range 0.5-7.0o. In the with the rule (WTR) cases (n = 40), 52% were CCW, 23% were CW and in 25% there was no difference, the average absolute deviation was 1.0 ± 2.0o CCW, range 0.5-9.0o. In the oblique cases (n = 12) 58% were CW, 25% were CCW and in 17% there was no difference, the average absolute deviation was 0.37 ± 1.9 o CW, range 0.5-5.5o.

CONCLUSIONS

Average discrepancy between the slit lamp and photography measurement was small, but in an individual case it was found to be as high as 9.0o. It can be significant when rotation of toric IOL is needed. When photography is not available slit lamp measurements should be used as is.