JUL 13, 2012
This interesting article reports promising results, with minimal complications, for the treatment of moderate to high myopia with a new implantable collamer lens with a central hole (Hole ICL). The authors present in the March issue of the British Journal of Ophthalmology results of its implantation in 20 patients (20 eyes) with moderate to high myopia. They found that it was safe and effective, with no vision-threatening complications and predictable and stable refractive results through the first six months following surgery. They conclude that this new surgical approach, which does not require additional iridectomies, may be a good alternative to current corneal refractive procedures.
I find it rather interesting that the ICL was designed with a central hole to minimize pupillary block and reduce the need for iridotomies/iridectomies when being implanted. I would have thought that the hole would be problematic for vision, but evidently it is not.
Mean spherical equivalent (± SD) among the patients was -7.36 ± 2.13 D before ICL implantation. Six months after surgery, logMAR UCVA was 0.20 ± 0.12 and BSCVA was -0.25 ± 0.06. The safety index (mean postoperative BSCVA/mean preoperative BSCVA) was 1.13 ± 0.24. The efficacy index (mean postoperative UCVA/mean preoperative BSCVA) was 1.03 ± 0.30. At six months, 95 percent of eyes were within ±0.5 D of the targeted correction and 100 percent were within ±1.0 D. The change in manifest refraction from one week following surgery until six months was 0.06 ± 0.28 D.
No eye experienced a significant rise in IOP (including pupillary block), even without preoperative or intraoperative peripheral iridectomy. The authors say this may support the view that postoperative pupillary block can be prevented by the presence of the central hole in the ICL, since conventional ICL implantation inevitably requires preoperative laser iridectomies or intraoperative peripheral iridectomy in order to prevent the occurrence of pupillary block. The former is frequently accompanied by some pain, especially in younger subjects, resulting in patient dissatisfaction; and the latter is sometimes accompanied by iris hemorrhage, adding to the difficulty of the surgical procedure. Hole ICL implantation may have many advantages over conventional ICL implantation in the management of preoperative pain, intraoperative iris hemorrhage and IOP because it does not require these additional procedures.
The authors say that the fact that no eye experienced a secondary cataract during follow-up suggests that the central hole's presence may contribute to the improvement of aqueous humor circulation to the anterior surface of the crystalline lens, resulting in less cataract formation. However, further research is required to clarify this issue and the long-term safety of Hole ICL implantation.