Phakic intraocular lens surgery shares the same possible risks and complications as other forms of IOL surgery. However, the most relevant potential complications include raised IOP, persistent anterior chamber inflammation, traumatic PIOL dislocation, cataract formation, and endothelial cell loss. Some of these complications do not manifest for years, thus necessitating long-term follow-up.
Iris-fixated phakic intraocular lens
At 1-year follow-up in an FDA clinical trial of 662 patients who had an iris-fixated PIOL implanted for myopia, 1 patient had a hyphema, 5 had IOL dislocations, and 3 had iritis. Night-vision concerns about glare, starbursts, and halos were reported in 13.5%, 11.8%, and 18.2%, respectively, in patients who did not have these symptoms preoperatively. However, improvement in symptoms occurred 12.9%, 9.7%, and 9.8%, in patients after PIOL implantation. In general, nighttime symptoms were worse in patients with larger pupil diameters.
Stulting and colleagues reported a 3-year follow-up study on 232 eyes of the 662 eyes enrolled in the FDA study. A total of 5 lenses dislocated and required reattachment, and an additional 20 lenses required surgery for insufficient lens fixation. No eyes required IOP-lowering medications after the first month. The mean decrease in endothelial cell density from baseline to 3 years was 4.8%. Six eyes required retinal detachment repair (rate, 0.3% per year), and 3 eyes underwent cataract surgery.
Pop M, Payette Y. Initial results of endothelial cell counts after Artisan lens for phakic eyes: an evaluation of the United States Food and Drug Administration Ophtec Study. Ophthalmology. 2004;111(2):309–311.
Stulting RD, John ME, Maloney RK, Assil KK, Arrowsmith PN, Thompson VM; U.S. Verisyse Study Group. Three-year results of Artisan/Verisyse phakic intraocular lens implantation. Results of the United States Food and Drug Administration clinical trial. Ophthalmology. 2008;115(3):464–472.
Posterior chamber phakic intraocular lens
In addition to the potential risks associated with implantation of other types of PIOLs, implantation of posterior chamber PIOLs increases the risk of cataract formation and pigmentary dispersion. If the posterior chamber PIOL is too large, vaulting increases, and iris chafing with pigmentary dispersion could result. If the PIOL is too small, the vaulting is reduced, decreasing the chance of chafing but increasing the risk of cataract. Incorrect PIOL vault can necessitate exchange of the implanted lens for one with a better fit.
In an FDA clinical trial for 1 posterior chamber PIOL model, the incidence of nighttime visual symptoms was approximately 10%, but a similar percentage showed improvement in these symptoms after surgery. The incidence of visually significant cataract development in the FDA clinical trial as reported by Sanders and colleagues was 0.4% for anterior subcapsular cataracts and 1% for nuclear sclerotic cataracts.
Kamiya and colleagues reported 4-year follow-up results on 56 eyes of 34 patients with implanted posterior chamber PIOLs. No eyes developed pupillary block or a significant increase in IOP. The mean central endothelial cell loss was 3.7%. Symptomatic cataracts requiring surgery developed in 2 eyes, and asymptomatic anterior subcapsular cataracts developed in 6 other eyes. In a study of more than 500 eyes monitored for an average of 4.7 years, Sanders reported that anterior subcapsular opacities developed in 6%–7% of eyes, and visually significant cataracts developed in 1%–2% of eyes.
The incidence of retinal detachment after posterior chamber PIOL insertion is very low. In a series of 418 eyes that underwent a posterior chamber PIOL procedure, rhegmatogenous retinal detachment developed in 3 eyes (0.7%) at a mean of 19.8 months postoperatively, a rate comparable to the expected natural history of detachment in eyes with similar degrees of myopia.
Al-Abdullah AA, Al-Falah MA, Al-Rasheed SA, Khandekar R, Suarez E, Arevalo JF. Retinal complications after anterior versus posterior chamber phakic intraocular lens Implantation in a myopic cohort. J Refract Surg. 2015;1;31(12):814–819.
Kamiya K, Shimizu K, Igarashi A, Hikita F, Komatsu M. Four-year follow-up of posterior chamber phakic intraocular lens implantation for moderate to high myopia. Arch Ophthalmol. 2009;127(7):845–850.
Kohnen T, Knorz MC, Cochener B, et al. AcrySof phakic angle-supported intraocular lens for the correction of moderate-to-high myopia: one-year results of a multicenter European study. Ophthalmology. 2009;116(7):1314–1321.
Sanders DR. Anterior subcapsular opacities and cataracts 5 years after surgery in the Visian Implantable Collamer Lens FDA trial. J Refract Surg. 2008;24(6):566–570.
Sanders DR, Vukich JA, Doney K, Gaston M; Implantable Contact Lens in Treatment of Myopia Study Group. U.S. Food and Drug Administration clinical trial of the Implantable Contact Lens for moderate to high myopia. Ophthalmology. 2003;110(2):255–266.
Angle-supported phakic intraocular lens
The complications reported most frequently for angle-supported PIOLs are nighttime glare and halos, pupil ovalization, and endothelial cell loss. The risk of pupillary block is low with the use of modern PIOL designs and of iridotomies when needed.
Glare and halos, the most commonly reported symptoms after angle-supported PIOL insertion, occurred in 18.8%–20.0% of patients, but these symptoms appear to decrease by as much as 50% over a postoperative period of 7 years. Endothelial cell loss occurring 1–7 years after angle-supported PIOL insertion ranges from 4.6% to 8.4%. Pupil ovalization can occur because of iris tuck during insertion, or it can occur over time as a result of chronic inflammation and fibrosis around the haptics within the anterior chamber angle. The incidence of pupil ovalization ranges from 5.9% to 27.5% and is directly related to the postoperative interval studied. Ovalization is more likely when the implant is too large. In contrast, endothelial damage and decentration are most often associated with movement of a lens that is too small.
Knorz and colleagues reported on the 6-month to 3-year results of an angle-supported PIOL in 360 eyes with moderate to high myopia. No eyes experienced pupillary block, pupil ovalization, or retinal detachment. The annualized percentage loss in central and peripheral endothelial cell density from 6 months to 3 years was 0.41% and 1.11%, respectively.
Knorz MC, Lane SS, Holland SP. Angle-supported phakic intraocular lens for correction of moderate to high myopia: Three-year interim results in international multicenter studies. J Cataract Refract Surg. 2011;37(3):469–480.
Excerpted from BCSC 2020-2021 series: Section 13 - Refractive Surgery. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.