Abstract
Purpose :
Preloaded IOL injectors are commonplace in cataract surgery. A variety of preloaded IOL injectors have been developed with differing designs and varying clinical outcomes. Additionally, there are subtle differences in the recommended incision and the actual clinical reports. Hence, to clarify the effect of different injector tip shapes on the incision, a laboratory set up was used to determine the relationship between the insertion resistance and tip shape, and an ex-vivo study of porcine eyes was performed to determine the postoperative incision width.
Methods :
The following injectors were investigated: XY-1 (HOYA), AU00T0 (Alcon), YP2.2R (KOWA), SZ-1 (NIDEK), and NSP-1 (NIDEK).
Bevel angle, slit length, tip angle, and outer circumference length of the injector tips were measured with a shape measuring device. A slit knife was used to create a 2.0±0.08 mm incision in a 0.4 mm silicone rubber sheet that mimicked corneal properties. Subsequently, the tip was inserted at 2 mm/sec with a testing machine to measure the maximum insertion resistance values for each injector. Preloaded IOLs with the same power were inserted from each of the injectors into a 2.0 mm corneal incision in porcine eyes. The post-insertion incision widths were measured with intraocular calipers.
Results :
The range of values for tip shapes were:
Bevel angle: 27° (SZ-1) to 48.7° (YP2.2R)
Slit length: 3.3 mm (XY-1 and YP2.2R) to 4.3 mm (NSP-1)
Tip angle: 64.1° (NSP-1) to 96.6° (AU00T0)
Outer circumference length: 5.21 mm (XY-1) to 6.09 mm (SZ-1)
The range for maximum insertion resistance was 0.155 ±0.018 N (SZ-1) to 0.248 ±0.022 N (YP2.2R)
Incision width on porcine eyes ranged from 2.30±0.10 mm (XY-1) to 2.50±0.00 mm (SZ-1).
There was no correlation between the postoperative incision width and the maximum resistance to insertion (r=0.030). The circumference length had the highest correlation coefficient with respect to the postoperative incision width and tip shape (r=0.962).
Conclusions :
The outcomes of this study indicate that shorter outer circumference can mitigate enlargement of incision width. A “sharp bevel angle” and “long slit length” of the injector tip are the main determinants for preventing enlargement. A “sharp bevel angle” is more conducive to overcoming insertion resistance of the cornea.
This is a 2021 ARVO Annual Meeting abstract.