POSTERIOR CHAMBER PHAKIC INTRAOCULAR LENS IMPLANTATION USING 2.4MM SMALL INCISION

The current standard incision for implantation of phakic posterior chamber intraocular lenses is 2.8mm in width. To reduce postoperative astigmatism and improve refractive results we tested different injectors suitable for 2.4mm IOL implantation in a wet-lab setting using IPCL (Care Group) phakic intraocular lenses. Main targets were finding an injection system with controlled implantation and predictable IOL unfolding characteristics. After positive results in testing we implanted twelve IPCLs using a 2.4mm small incision. Postoperative results were evaluated one day, one week and three month after surgery. 

All IPCLs were planed, implanted und followed-up at DrWehrmann Augenheilkunde in Miesbach, Germany. 

Injector testing was done using sample lenses equivalent to products for patients. Unfolding characteristics were evaluated in an artificial chamber filled with methyl cellulose. 

Six patients had IPCL implantation on both eyes. Alle patients were myopic, two with astigmatism above 0.5 diopters on both eyes, one with monocular astigmatism. Eyes with astigmatism less than or 0.5 diopters were treated with spherical IPCL, above with toric IPCL (IPCLv2 in all cases). The spherical equivalent range was -3.5 up to -14 diopters. Implantation was done using a main 2.4mm incision (Mani MSL24SH) at 90° and two 0.9mm incisions at 45° and 135°. Medicel Ergojet injector was used for IOL implantation. All IOLs were placed on the horizontal 180° axis in the sulcus. Postoperative astigmatism was measured using the Nidek AR360 autorefractor and Heidelberg Anterion anterior segment optical coherence tomography. 

IOL unfolding characteristics were favorable in all cases (see video). No IOLs showed defective haptics or other signs of damage after implantation. Postoperative astigmatism on day one in autorefraction was was less than or 1.0 diopter in all cases, less than or 0.5 in six cases. One week and three month after surgery measured astigmatism was less than or 0.75 diopters in all cases. One toric IOL had to be rotated two weeks after surgery. Anterior segment OCT showed usual swelling of the cornea at the main incision on day one after surgery. As far as corneal tomography is evaluable on surgically induced astigmatism, no eye showed noteworthy irregularities sometimes seen with bigger incisions after surgery. Total corneal power stayed within 0.5 diopters of the preoperative values and axis stayed within 6° deviation in all cases. 

Safe and predictable phakic IOL implantation was possible in all our cases. Noteworthy surgically induced astigmatism was not present in our twelve cases. As surgically induced astigmatism is hard to eliminate and can be particularly disturbing in refractive cases, we can encourage using a smaller incision in phakic IOL cases, similar to what is already very common in cataract surgery. Still further evaluation with more patients and all lens powers is needed.