Considerations in the management of aphakia.

Dear Editor,

Can et al. describe their modification of an ab interno technique of transscleral suturing of one-piece posterior chamber intraocular lenses (IOLs) by injecting the IOL implantation in the through a clear corneal incision.[1] We believe that discussion of their proposal highlights relevant issues.

The article does not mention the increasingly popular techniques of secondary IOL implantation in aphakia management, namely intrascleral sutureless haptic fixation (SSF) and iris-claw lenses.[23]

Sutureless scleral fixation uses a three-piece lens, often implanted by injector and avoids the risk of suture breakage. Also, when the eye moves, it acquires kinetic energy from the muscles and attachments, and the energy is distributed to the internal fluids as it stops. Thus, pseudophakodonesis is the result of oscillations of the fluids in the anterior and posterior segment of the eye. In a scleral-fixated IOL suspended with the suture, there is more pseudophakodonesis, and this may lead to posterior segment complications in the long-term. This is seen by the incidence of retinal detachment (4.9%) and chronic macular edema (CME) (7.3%).[4] However, no significant retinal problems are seen in the follow-up of SSF techniques potentially because a large part of the haptic is buried in scleral tunnels in these techniques and so the IOL is inherently more stable and less prone to pseudophakodonesis.

The choice of IOL is of concern for two reasons. Firstly, a one-piece IOL with square cross-section of haptics is not suitable for placement in the sulcus as it can lead to future problems. Their bulky haptics is large and thick enough to contact the posteriori iris and were shown, when implanted into the sulcus to lead to pigment dispersion syndrome, secondary IOP elevation, recurrent iridocyclitis, and CME.[5] Also, a hydrophobic material is probably preferable in these eyes. In addition, the use of 10–0 prolene, because of the risk of breakage over years, has largely been replaced by 9–0 prolene to reduce the rate of late suture breakage. Polytetrafluoroethylene CV-8 (Gore-tex) is also being used off-label in place of 10–0 prolene and has very good longevity. Authors of the article[1] do not mention the rates of late suture breakage, which has been significant with all sutured scleral fixated techniques reported to-date with intermediate/long follow-up. The proposed fixation is two-point, and there is probably no argument why the risk of IOL tilt is less than that from any other two-point fixation of three-piece lenses. In addition, authors propose to leave the sutures subconjunctivally which is also a cause for concern. It is well accepted that in any scleral suture-fixation technique, a scleral flap, scleral pocket or patch graft to cover the external suture is required to protect the suture and prevent the external suture erosion.