Performing cataract surgery with phaco in patients with previous implantations

This case study presents the results and advantages of phacoemulsification, which Dr Dieter W Klass and his team applied after previous implantation of an iris-fixated phakic IOL (pIOL) (Artisan, Ophtec) for the correction of high myopia without explantation of the pIOL. The location of the procedure was the Outpatient Surgery Augenzentrum Friedberg/Augsburg in Germany.

The iris-fixated (PMMA) anterior chamber IOL is for the correction of ametropia in aphakic and phakic eyes. Twenty years ago, Dr Klass implanted these IOLs in highly myopic eyes as a refractive surgery with the aim of enabling patients to be nearly independent of spectacles.^1,2

Some of these patients developed a cataract after ten to twelve years. At first, the team had to choose between different options to treat the cataract:

·      Removal of the Artisan IOL through a mostly large incision of 6 to 7 mm dependant on the size of the IOL;³

·      Removal of the cataract with phacoemulsification through a second incision of 2.2 mm with implantation of a posterior chamber IOL on the same day;

·      Removal of the cataract with phacoemulsification through a second incision of 2.2 mm after waiting several weeks in order to obtain new data estimating the correct power of the IOL with special focus on residual astigmatism;

·      Phacoemulsification behind the Artisan IOL without explantation of the pIOL and in-the-bag implantation of a posterior chamber IOL with the advantage of only one small incision.

Methods

One of the patients was, at time of the refractive surgery, 36 years old. The refraction was: OD -18.0 - 3.5 cyl / 14° and OS -18.0 -3.5 cyl 174°. After Implantation of an Artisan IOL, the postoperative best corrected visual acuity (BCVA) was: OD -1.0 -2.75 16° =20/25 and OS -0.75 -2.25 167°=20/25.

Four months after stabile refraction, an uneventful excimer treatment of the residual astigmatism with photorefractive keratectomy was undertaken. The postoperative refraction was: BCVA OD -0.75 -0.5 / 10° = 20/25 and BCVA OS +0.25 - 0.5 / 175° = 20/25. The uncorrected visual acuity was also 20/25.

Ten years later, the patient developed a cataract in both eyes. The four surgical options outlined above, as well as possible late complications, were discussed.

“Since the corneal endothelium showed almost no loss of cells (and so was normal), we decided on the forth option,” explained Dr Klass.

“The correct power of the IOL was calculated with the help of the formulas of Gullstrand's theoretical analyses and individual corrections based on our complete IOL-master-values before and after pIOL-implantation as well as immediately before cataract surgery,” he added.

Surgical technique

A limbal 2.5-mm incision was made at the temporal superior quadrant. The corneal endothelium was protected with the use of an ophthalmic viscosurgical device (Viscoat, Alcon Laboratories) as well as the presence of the remaining pIOL as a protection shield.

No turbulences within the anterior chamber were visible. Phacoemulsification took place using the Ocusystem II Advantage (Surgical Design) with mini cobra tip; very low infusion height; low I/A values; and power settings.

Dr Klass described the surgical method as being “difficult and complex”. Placement of the incision, continuous curvilinear capsulorhexis performance (CCC); special phaco techniques, such as splitting the nucleus with viscodelineation/dissection⁴; and machine settings are described in an upcoming paper.

Refractive results, endothelial-cell-density and BCVA were analysed.

Results

The maximum follow-up time after pIOL surgery was 19 years, while after cataract surgery it was 9 years. The time of cataract incidence was 10 years. The predictability of the refraction was -0.5 +/-0.75 (SD).

There was no decrease in either BCVA (20/25) or BCVA after pIOL implantation compared with BCVA after cataract surgery.

The patient had no macular disorders. Dr Klass and his team found no significant endothelial cell density changes or loss after phacoemulsification. The maximum endothelial cell loss after 9 years was <2%.

“The main advantages of this method compared with subsequent explantation of the pIOL with a large 6.5-7-mm incision are: the small (2.5 mm) size of the incision; the lack of surgery-induced astigmatism; absence of endothelial damage due to the pIOL having an additional function as a protection shield; and all other risk factors relating to a large incision size associated with high myopia,” said Dr Klass.

Conclusion

Undertaking cataract surgery with phacoemulsification behind the pIOL without explantation of the anterior chamber lens offers the benefits of pIOL function as protection for the cornel endothelium; good predictability of the desired post-operative refraction; excellent visual rehabilitation; and, overall, fewer complication rates.

Due to the complex nature of the surgical procedure, this method is recommended mainly for experienced phaco-surgeons.

References

1. Maloney RK, Nguyen LH, John ME. Ophthalmology. 2002;109:1631–1641.

2. Tahzib NG, Nuijts RM, Wu WY, Budo CJ. Ophthalmology. 2007;114:1133–1142.

3. de Vries NE, et al.J Cataract Refract Surg. 2009;35:121-126.

4. Klaas D. Viscosplit and crack in mini-coaxial small-incision cataract surgery. Ophthalmology Times Europe. 2016;12:16-19.

Dr Dieter W Klaas, MD

E: dieter.w.klaas@gmail.com

Dr Dieter W Klaas is an ophthalmologist at Augenzentrum Friedberg, Germany. He has no financial interests to declare.