Frequent follow-up visits are necessary to monitor for endothelial cell loss in patients in whom phakic IOLs have been implanted, according to one surgeon who has 5 years of experience with the lens.
Careful patient selection and use of the latest technology, such as anterior segment optical coherence tomography (OCT), to ensure selection of a good-fitting lens are other keys to success with phakic lens implantation.
Dr. Piovella developed these guidelines after 5 years of experience with an anterior chamber phakic IOL (Vivarte, IOL Tech) but emphasized that they can be extrapolated to all anterior and posterior chamber phakic lenses as well as iris-fixated models. Selection criteria for implantation of the phakic IOL in Dr. Piovella's study: minimum anterior chamber depth of 3.2 mm; endothelial cell counts greater than 2,500/mm2; patient age less than 50 years; open anterior chamber angle; and no cataract, angle hyperpigmentation, vessels in the angle, or eccentrical pupil.
Using anterior segment OCT to verify the anterior chamber size, they determined that the correct lens size had been implanted in only 38% of the 34 study eyes. But contrary to their expectations, only 11.8% of the IOLs (n = 4) had been explanted. Explantation occurred only when the endothelial cell count dropped to 1,500/mm2 and the procedure was necessary to preserve the cornea, Dr. Piovella said. No cases of corneal decompensation occurred in this series.
In 12 cases, the preoperative and postoperative endothelial cells counts were the same, and these cases probably were those in which the lens size was best matched to the eye, Dr. Piovella said.
Although first-year results showed a mean endothelial cell loss of 3%, which is a satisfactory rate, a change was noticed after 5 years. Patients may develop iritis or conjunctivitis, rub their eyes frequently, or sleep on one side, all of which can affect endothelial cell count.
Clinicians must remain alert to the risk of endothelial cell loss, Dr. Piovella said, recommending follow-up visits every 6 months for patients in whom phakic lenses have been implanted. The necessity of these visits may require explanation to patients who are reluctant to make frequent visits to the clinic if they are experiencing no problems with the implantation, and a clause about these visits should be included in the informed consent, he added. In this series, the mean preoperative refraction was –15 ± 4.6 D spherical equivalent (SE) with best-corrected visual acuity of 0.7 ± 0.3. The final best spectacle-corrected visual acuity was 0.9 ± 0.2 with –0.67 ± 1.22 D SE. Pupil ovalization was observed in 20.6% of eyes (n = 7) at 127 ± 106 days.
Results of a survey showed that all of the patients were satisfied with the results of their surgery, Dr. Piovella said.