Phaco without presbyopic inlay explantation viable option

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Two patients underwent cataract surgery and implantation of a monofocal IOL with a small aperture corneal inlay (Kamra, AcuFocus) in place. The surgery was uneventful, presented no new technical challenges, and resulted in spectacle-free near, intermediate, and distance vision.

By Cheryl Guttman Krader; Reviewed by Jodhbir S. Mehta, MD

Singapore-Phacoemulsification can be performed without removing a presbyopia-correcting small aperture corneal inlay (Kamra, AcuFocus), said Jodhbir S. Mehta, MD.

Dr. Mehta presented two such cases he performed: one was at 19 months after the inlay procedure and the other after 6 years. The cataract surgery was done under local anesthesia through a 2.60 mm temporal clear corneal incision with implantation of a single-piece, aspheric, acrylic monofocal IOL (Tecnis ZCB00, Abbott Medical Optics). It was completed uneventfully in 15 minutes, and both patients achieved good uncorrected near, intermediate, and distance vision.

“We found that the cataract surgery was not technically more difficult than in an eye without a corneal inlay,” said Dr. Mehta, associate professor, head, corneal and external eye disease, and senior consultant, refractive service, Singapore National Eye Centre, Singapore. “No extensive modifications were necessary to the procedure, but we did find visualization through the 1.6 mm central aperture of the inlay was improved during capsulorhexis and phacoemulsification by some additional ocular rotations.

“Based on our outcomes, it appears that the biometry readings were reliable and that the SRK/T formula was accurate for determining IOL power,” he continued. “Therefore, we conclude that phacoemulsification without presbyopic inlay explantation is a viable option for maintaining spectacle independence across the full range of vision. However, longer follow-up and more experience are needed to properly evaluate safety, visual outcomes, and the best method for IOL power calculation.”

Additional details on these cases are described in a published paper [Clin Ophthalmol. 2013;7:1899-903].

Details of the study

The patients were aged 53 and 62 years at the time of their inlay procedure. Both individuals had the inlay placed under a lamellar flap, which was created using a microkeratome in one patient (depth 151 µm) and a femtosecond laser in the other (depth 190 µm).

Both patients had good distance uncorrected visual acuity preoperatively, and at 1 month after the inlay procedure, they had good near, intermediate, and distance vision.

One patient developed ghosting and slight monocular diplopia in the inlay eye 12 months postimplantation that resolved with surgical repositioning of the inlay. Seven months later, near vision had deteriorated significantly and the patient was diagnosed with a LOCSIII grade NC3P3 cataract. The second patient developed a cataract after 4 years (grade NC2) without significant decrease in vision. However, 2 years later, the cataract had progressed (grade NC4), and while near vision remained well, the patient’s distance vision was significantly decreased.

“Other management options for these patients include removing the implant before cataract surgery and then replacing it after, or removing the inlay and implanting a presbyopia-correcting pseudophakic IOL. All three approaches were discussed, and the patients chose to have cataract surgery with the inlay in situ after its excellent centration was confirmed using the AcuTarget,” said Dr. Mehta.

Surgical pearls

Dr. Mehta noted that since the procedures were performed under local anesthesia, the patients themselves were able to voluntarily make the extra ocular rotations.

“We felt that these rotations did not significantly increase the risk of complications. A 5 mm capsulorhexis was made in both cases without difficulty, albeit by a surgeon with significant experience,” he said.

Providing a few other tips, Dr. Mehta noted the importance of achieving good mydriasis.

He recommended making the main incision as limbal as possible to avoid the inlay flap, creating the capsulorhexis by starting the radial tear in the center and initiating the circumferential tear outside the implant, and keeping the phaco probe tip in the center of the aperture.

Postoperatively, Dr. Mehta performed back-calculations using the Haigis, Holladay 1, and Hoffer Q formulae to see if they would have been a better choice for IOL power calculation. However, the SRK/T was associated with the best result for one patient and was the second most accurate, following the Haigis formula, in the second patient.

“We cannot make any conclusions about what the best power formula is for these patients, but it appears the SRK/T is a reasonable choice. There are also patients who may come to need cataract surgery after undergoing inlay placement combined with LASIK, and in those individuals, a different IOL power formula may be required,” Dr. Mehta said.

Calculations to determine biometry data prior to inlay implantation were also performed retrospectively, and the results indicated the inlay had no significant effect on axial length.

Jodhbir Mehta, M

E: jodhbir.s.mehta@snec.com.sg

Dr. Mehta has no financial interest in any of the products mentioned.