It is very difficult to precisely size a pIOL. In my experience, I would rather have more space than less space between the crystalline lens and the pIOL. It seems that in this case, the pIOL is slightly larger than it should be.
Regarding the preferred treatment for the left eye (excimer laser enhancement or pIOL replacement), the patient is young with a current uncorrected visual acuity of 20/20 for distance and J1 for near. It has been only 6 months since pIOL implantation. I recommend waiting another 6 months. Before any reoperation, I would suggest a +1.25 D contact lens trial to make sure the symptoms decrease. If the patient is very happy with the +1.25 D correction, one should weigh the pros and cons of a pIOL exchange, including endothelial and lens trauma. Before deciding on a pIOL exchange, the brimonidine tartrate should be discontinued to reassess the pupil size and pIOL position. If the pupil size is similar to that in the contralateral eye and the pIOL is in the same position, laser vision correction should be considered.
I would replace the pIOL only if I knew the size and power of the current pIOL. Once I knew the size, I would use a pIOL of the next smaller size down. It is difficult to know (but it seems likely) whether the consecutive hyperopia is due to the more anterior position of the pIOL. I would also decrease the power of the pIOL by 0.50 D.
I would not leave the patient on brimonidine tartrate for the rest of his life.
Sizing problems (a too large PC pIOL) can cause anterior bowing of the iris with a subsequent increase in pupil size and latent hyperopia. Especially for PC pIOLs, the use of adequate diagnostic methodologies (very-high-frequency UBM) appears mandatory. Similarly, we now know that for AC pIOLs, the use of AS-OCT technology is indicated to determine safe distances from the lens edges to the corneal endothelium.
Disparity between the pIOL optical zone and the mesopic pupil size has been suggested as a cause of halos, and pupil-constricting eyedrops suggested as a potential treatment. However, there appears to be no definite evidence in the literature for this presumed correlation. The use of pupil-constricting eyedrops is not effective as a long-term treatment in my experience. However, a permanent surgical solution (exchange or excimer laser enhancement) must be balanced against the potential complications of cataract induction and regression of a hyperopic laser treatment.
This case illustrates that access to adequate preoperative diagnostic technology is mandatory for defining the correct indication for implantation of (PC) phakic IOLs.
Rudy Nuijts MD