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Femtosecond laser used for dense cataract in eye with previous cornea transplant
The patient also had high corneal astigmatism and poor vision.
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The bar for postoperative vision quality after refractive cataract surgery has been raised in the recent past, especially with cataract surgery technology advancements, surgical technique improvements, keratorefractive surgery and modern-day foldable IOLs that correct presbyopia and astigmatism. Patients’ expectations regarding the way they see after cataract surgery have been set at levels never seen before, and the surgeon is expected to deliver and fulfill patient satisfaction.
The introduction of femtosecond laser-assisted cataract surgery has expanded the horizon of surgical options and the way cataract surgery can be performed utilizing such technology. Femtosecond laser-assisted cataract surgery decreases phacoemulsification time and energy and also provides an accurate and precise capsulorrhexis with regard to centration, size and shape, which is not possible with manual techniques. Femtosecond laser-assisted cataract surgery is expected to deliver improved clinical outcomes, with predictable and reproducible results.
When dealing with a cataract in the presence of a previous penetrating keratoplasty graft, in addition to the cataract contributing to compromised vision, the iatrogenically induced corneal astigmatism from the corneal graft is an added hurdle that needs to be overcome to improve the patient’s postoperative vision. Astigmatism degrades visual quality, and every effort should be made to minimize it. In addition, cataract surgery can compromise the corneal endothelial cells on the graft. Hence, when dealing with both corneal graft-induced astigmatism and cataract, femtosecond laser-assisted cataract surgery may be a choice to consider to deliver optimal visual results.
In this column, Dr. Chen describes his technique in the management of a patient with significant corneal astigmatism, corneal graft and cataract.
Thomas “TJ” John, MD
OSN Surgical Maneuvers Editor
This is a case of high corneal astigmatism and poor vision secondary to penetrating keratoplasty and cataract that was effectively treated using a technique of laser-assisted cataract surgery (LACS) and a toric IOL.
The patient sustained a traumatic injury to his right eye 27 years ago and underwent PK. His vision in the operated right eye remained poor and worsened secondary to increasing cataract formation. He elected to undergo surgery in his right eye to improve vision.
Examination
Best corrected vision in his right eye was 20/100 with –8.75 +7.75 × 23. The right corneal graft was clear, and there was a 3+ nuclear sclerotic cataract. Corneal topography revealed 13.5 D of against-the-rule astigmatism at 180°.
There were several considerations preoperatively because of the dense cataract with an old, uneven corneal graft with 13.5 D of against-the-rule astigmatism.
- Too much phaco energy may damage the corneal endothelium of the corneal graft.
- How do you achieve maximum reduction of this 13.5 D of astigmatism?
- If the high power of a toric IOL and limbal relaxing incisions (LRIs) will be used, the capsulorrhexis needs to be perfect to ensure ideal lens position, with perfect marking of the axis.
- LRIs need to be adjustable to refine the correction of a large amount of astigmatism.
- Due to a history of injury and surgery in the patient’s right eye, the integrity of the zonules may be compromised.
The decision was made to use LACS combined with toric IOL implantation and LRIs for several reasons.
- LACS can offer less energy for phacoemulsification.
- LACS can be better than the manual technique in marking of the astigmatic axis and performing the capsulorrhexis for implanting an SN6AT9 toric IOL (Alcon).
- LACS can be used to perform adjustable LRIs to enhance more cylinder correction with control.
- LACS can be better in protection of zonules.
Surgical technique
On July 11, 2013, the patient was admitted to a surgical suite in Honolulu. Diazepam 5 mg was given orally upon admission. Under the slit lamp, with the left eye covered and the right eye focusing at the middle of the two beams, marking was done at 90° and 180° with a marking pen. The right pupil was then dilated with 1% tropicamide, 2.5% phenylephrine and proparacaine. The LenSx SoftFit patient interface (Alcon) was used for LACS. A 5.5-mm capsulorrhexis was performed using an energy setting of 5 µJ. Lens fragmentation was performed at a 4 mm diameter with a two chop and three cylinder technique using an energy of 7 µJ. An arcuate incision with 40° arc was carried out at a 9 mm diameter and on axis at 180° with 80% corneal depth. Primary and secondary incisions were done as routine. The patient’s right eye then was prepped and draped in the usual manner.
Primary and secondary wounds were easily opened using a Sinskey hook. The capsulorrhexis was carefully checked for completion without any tag (Figure 1). The nucleus was easily dislocated out of the capsular bag due to the air behind the nucleus (Figure 2). Cumulative dissipated energy was 3.19 seconds after supranucleus phacoemulsification (sandwich technique, Figure 2) was completed. An Alcon SN6AT9 +6 D toric IOL was inserted into the capsular bag after cortical cleanup and polishing of the posterior capsule. The marker on the toric IOL was carefully aligned against the center of the arcuate incision that was set at 180° (Figure 3). At the end of surgery, after removing all the viscoelastic and hydrating the wounds, the IOL appeared well centered and the cornea was clear (Figure 4).
Figure 1. Perfectly round 5.5-mm capsulorrhexis.
Images: Chen M
Figure 2. Sandwich phacoemulsification technique.
Figure 3. Dialing SN6AT9 toric IOL marker to align against 180° axis.
Figure 4. The end of surgery.
Figure 5. Postop 1 day.
Postoperatively, the 3-week examination revealed a refraction of –2.00 +6.50 × 260 with vision of 20/50. The arcuate incision was opened with a Sinskey hook under the slit lamp in the office. The refraction at 1 month after surgery was –2.00 +5.50 × 260 with vision of 20/30.
Discussion
LACS was safe and effective in this patient who had a previous PK in his right eye. In this case, LACS was thought to have a better outcome than conventional phacoemulsification. However, cost may be an issue to some patients when considering LACS.
In this case, LACS facilitated safe removal of a dense cataract with less energy to maintain the clarity of the existing corneal graft and correct a total of 10 D of cylinder at 3 months after surgery with a toric IOL. The corrected vision improved from 20/100 to 20/30. Final refraction at 3 months was +0.50 +3.50 × 280.