Phakic intraocular lenses: An overview

Phakic intraocular lenses (pIOLs) are a common solution for the surgical correction of high myopia and myopia in thin corneas. Global trends result in increasing rates of patients with high myopia which will result in increased rates of pIOL implantation. Three types of lenses can be distinguished: anterior chamber angle-supported, anterior chamber iris-fixated, and posterior chamber phakic IOLs. The efficacy of phakic intraocular lenses is generally very good, but pIOLs have undergone many changes over the years to improve the safety profile and decrease pIOL-related complications such as endothelial cell loss, corneal decompensation and cataract formation. This article describes the efficacy and safety profiles of the most recent pIOLs, as well as suggests gaps of knowledge that are deserve additional research to optimize the results of pIOLs.

Long-term changes in visual outcomes and ocular morphometrics after myopic and toric phakic intraocular lens implantation: Five- and 10-year results

PURPOSE

To evaluate the long-term refractive and visual, anterior chamber depth, and axial length (AL) changes and complications after rigid iris-fixated phakic intraocular lens (pIOL) implantation to treat myopia or astigmatism.

SETTING

University Eye Clinic Maastricht, Maastricht UMC+, the Netherlands.

DESIGN

Prospective case series.

METHODS

The study evaluated patients who had implantation of an Artisan myopic or toric iris-fixated pIOL as of January 1998. Changes were measured annually and reported after 1, 5, and 10 years postoperatively.

RESULTS

The study comprised 460 eyes (250 patients; mean age 41.1 years ± 10.7 [SD]). Over 10 years, the mean myopization was -0.79 diopters (D) (P < .001), with 52% of eyes within ±1.0 D of target. The mean increase in the logarithm of the minimum angle of resolution (logMAR) corrected distance visual acuity (CDVA) over 10 years was 0.05 (P < .001); 95% of eyes had a CDVA of 20/40 or more and 7% lost 2 or more lines of CDVA. The mean logMAR uncorrected visual acuity (UDVA) increased by 0.14 over 10 years (P < .001); 96% had a UDVA 20/40 or better. The AL increased by 1.14 mm over 10 years (P = .009). Ten percent of pIOLs were explanted because of cataract formation after a mean of 97.9 ± 34.9 months. A higher preoperative age (hazard ratio [HR], 1.08; P < .001) and longer AL (HR, 1.34; P < .001) were risk factors for shorter survival because of cataract formation.

CONCLUSION

Ten years after rigid iris-fixated pIOL implantation, the CDVA and UDVA decreased significantly as a result of significant myopization caused by an increased AL unrelated to the pIOL.

The rising incidence of Acanthamoeba keratitis: A 7-year nationwide survey and clinical assessment of risk factors and functional outcomes

Purpose

To evaluate the incidence of Acanthamoeba keratitis in the Netherlands between 2009 and 2015 and to analyse predicting factors for treatment outcome.

Methods

Patient characteristics, diagnostic methods, diagnostic delay, therapy prior to and after diagnosis, and visual outcome were obtained from medical files of all patients diagnosed with Acanthamoeba keratitis in the Netherlands between 2009 and 2015. A logistic regression analysis on treatment failure, defined as a best corrected visual acuity of less than 20/40 Snellen decimals (i.e. >0.3 logMAR or an approximate loss of three lines of visual acuity) and/or the need for keratoplasty, was performed to determine predicting factors.

Results

Two hundred and twenty-four eyes of 224 patients were included. Ninety-five percent of the patients were contact lens wearers, of whom 74% wore soft contact lenses. The number of cases increased from 16 in 2009 to 49 in 2015. This resulted in an estimated incidence of 1 in 21,000 for soft contact lens wearers in 2015. Eighty-seven eyes (39%) met the criteria for treatment failure. In a multivariable regression analysis, higher age at presentation, a higher severity stage and corticosteroid use before diagnosis were positively correlated with treatment failure. Early referral to a cornea specialist was associated with better clinical outcomes.

Conclusions

Although Acanthamoeba keratitis is still a relatively uncommon disease, the incidence in soft contact lens wearers has increased to reach 1 in 21,000 in 2015. Treatment failure occurred in 39% of cases, with age, higher severity stage, corticosteroid use before diagnosis and indirect referral to a cornea specialist as important risks factors.

Endothelial cell decay after descemet's stripping automated endothelial keratoplasty and top hat penetrating keratoplasty

PURPOSE

To analyze endothelial cell density (ECD) decay after Descemet's stripping automated endothelial keratoplasty (DSAEK) and top hat keratoplasty (THPK) in patients with Fuchs' endothelial dystrophy (FED) and/or pseudophakic bullous keratopathy (PPBK).

METHODS

Patients underwent either THPK (n = 33) or DSAEK (n = 39) at the Erasmus Medical Center, Rotterdam. For each nonrandomized cohort, a biexponential regression model for ECD decay was fitted. Factors associated with higher ECD decay were evaluated.

RESULTS

Median follow-up was 31.2 months (range, 11-91) in the THPK cohort, and 23.4 months (range, 6-61) in the DSAEK group. The early ECD decay was much higher after DSAEK (half time, 2.2 months) than after THPK (half time, 12.8 months). The late ECD decay after DSAEK was less steep (half time, 75.5 months) than after THPK (half time, 62 months). The 1-, 3- and 5-year endothelial cell losses derived from the models after DSAEK were 56%, 66%, and 73%, respectively, and after THPK were 24%, 50%, and 64%, respectively. For the DSAEK cohort, PPBK as an indication for surgery was associated with significantly higher late-phase decay rates. For the top-hat cohort, a significantly lower late-phase decay rate was found in PPBK. FED and same-session cataract surgery were confounding variables in the DSAEK cohort. Regarding DSAEK, postoperative re-bubbling was not found to have significant effects on early or late ECD decay rates. However, the small sample size and other limitations related to the method of evaluation may have influenced these findings.

CONCLUSIONS

After DSAEK, early ECD decay was stronger than after THPK, as opposed to late decay. Late decay was faster for PPBK than for FED after DSAEK.

Long-term follow-up of hydrogel intracorneal lenses in 2 aphakic eyes

We report the outcome of hydrogel intracorneal lens implantation in 2 patients. The lenses were implanted at approximately 50% depth in the cornea to correct high hyperopic refractive errors of 10.5 diopters (D) and 14.0 D, respectively. Both patients were contact lens intolerant and not suitable for intraocular lens implantation. Surgery was performed in 1988, and the patients were followed until early 2010. The patients showed good tolerance for the intracorneal lenses, but both developed opacities around the implant, leading to reduced visual acuity in 1 patient. Long-term patient monitoring is essential since corneal opacities can develop after many years. Removing the implant is not necessary as the lens can easily be rinsed by lifting the corneal cap.