Presbyopia is a multifactorial physiologic aging mechanism that leads to progressive functional loss of near vision. Increased patient demand for spectacle independence at both distance and near have forced ophthalmologists to search for new solutions for presbyopia correction at the corneal1-3 or lens plane.4 Now, a growing number of patients who have undergone a corneal procedure for restoring near vision are presenting for cataract surgery with deteriorated far and near vision, as a result of the normal aging process.5-8 As a result, questions concerning the viability of cataract surgical procedures, biometry, and IOL power calculation have arisen. Below is a description of our experience performing bilateral cataract surgery in a patient 5 years after implantation of the Flexivue Microlens intracorneal inlay (Presbia Coöperatief U.A.) in the nondominant eye.9,10
The central 1.6-mm zone of the Flexivue Microlens refractive corneal inlay is plano, and the peripheral zone has a fixed positive refractive power that is customized to the addition required in the eye, with an available base power range of 1.50 to 3.50 D. At the center of the disc, there is a 0.15-mm diameter hole that permits the transfer of oxygen and corneal nutrients through the lens. The inlay, implanted inside a corneal stromal pocket in the nondominant eye, provides two focal points, one for far vision and the other for near. A femtosecond laser is used to create the corneal pocket.11
The lens’ bifocal optical system provides a modified monovision (so-called smart monovision). When the eye is focused on a far object, the rays pass through the central zone of the inlay without refractive effect and are sharply focused on the retina. Rays passing through the refractive peripheral zone focus in front of the retina. When the eye is focused on a near object, the rays that pass through the central zone become out of focus behind the retina, and the rays that pass through the peripheral refractive zone are focused on the retina.
A 63-year-old woman attended a scheduled follow- up examination 5 years after implantation of a +2.50 D Flexivue Microlens in her nondominant (left) eye. Distance UCVA was 20/40 in her right eye, 20/50 in her left eye, and 20/32 binocularly. Near UCVA was 20/80 and 20/32 in her right and left eyes, respectively, and 20/30 binocularly. Distance BCVA was 20/30 in her right eye, with a refraction of 1.25 D. In her left, distance BCVA was 20/32 with -2.50 -1.00 X 170º. Slit-lamp examination showed nuclear sclerosis-type cataract in both eyes. Because the patient was unhappy with her vision but wanted to preserve spectacle independence, we proposed bilateral cataract surgery starting with her left eye.
After we discussed other options that included inlay removal (with monovision technique or accommodating or multifocal IOLs to address presbyopia), we agreed to proceed with cataract surgery, targeting emmetropia, without removing the Flexivue Microlens in order to restore both far and near vision after surgery. Written informed consent was obtained.
Routine preoperative evaluation including corneal topography was performed with unremarkable findings except for the nuclear cataract in both eyes. Biometry was performed with the IOLMaster (Carl Zeiss Meditec), and emmetropia was targeted in both eyes. IOL power calculation with the SRK/T formula (axial length: OD 22.93 mm and OS 22.96 mm) was used for a one-piece monofocal IOL (AcrySof IQ SN60WF; Alcon Laboratories, Inc.).
The patient underwent cataract extraction in her left eye, followed 6 weeks later by extraction in her right eye. During both procedures, phacoemulsification was performed and a posterior chamber IOL was implanted under topical anesthesia. The clear corneal incision was made in the steepest meridian according to topography. Surgery was uneventful in both eyes, and postoperative topical therapy included antibiotic-steroid drops four times daily that were tapered for 4 weeks.
Examinations were performed at 1 day and 1 and 3 months postoperative. On the patient’s last follow-up visit, distance UCVA was 20/20 in her right eye, 20/50 in her left eye, and 20/20 binocularly. Near UCVA was 20/63 and 20/20 in her right and left eyes, respectively, and 20/20 binocularly. Distance BCVA was 20/20 in her right eye, with a refraction of +0.25 -0.25 X 170º, and 20/32 in her left eye, with a refraction of -2.50 -0.50 X 180º. No complication was recorded on any follow-up visit. The patient was very satisfied with her final visual outcome.
Despite restoration of near vision and preservation of binocular far vision after Flexivue implantation, it is likely that years after this refractive surgical procedure patients will develop cataract as a result of the normal aging process. This can lead to progressive deterioration of far and near vision and the need for surgical management of cataract.
We have found that neither preoperative evaluation of the anterior and posterior segments nor cataract surgery itself is affected in these eyes, as the inlay is transparent and intraocular structures can therefore be visualized without difficulty. During the procedure, the surgeon has good visibility under the microscope and can perform common surgical manipulations throughout routine phacoemulsification under topical anesthesia. Additionally, postoperative treatment and follow-up examinations are not different from those after routine cataract surgery.
In light of the latest developments in cataract surgery, it may be important to note that the transparency of the inlay allows the use of laser cataract surgery as an optional surgical technique.
IOL power calculation is still based on axial length and keratometry measurements, as they are not significantly altered by pocket creation and intrastromal inlay implantation. Therefore, biometry and IOL power calculation in patients with the Flexivue Microlens are easy and accurate with the IOLMaster.
Furthermore, the intrastromal corneal inlay is not an obstacle in selecting the type of IOL. If a monofocal lens is selected, the refractive target should be emmetropia, given that the intrastromal corneal inlay is a refractive lens with a positive power chosen based on the patient’s needs. The potential reversibility of inlay implantation is beneficial if the patient elects a multifocal or accommodating IOL, rather than retaining the implant, to compensate for presbyopia.
Cataract surgery in patients with the Flexivue Microlens intracorneal inlay does not differ from routine cataract surgery in regard to surgical technique or pre- and postoperative surgical approaches. Furthermore, the reversibility of the method allows any other option, including accommodating or multifocal IOLs, for restoration of the patient’s far and near vision after cataract surgery.
Dimitrios I. Bouzoukis, MD, FEBO, practices in the Department of Ophthalmology and the Institute of Vision and Optics, University of Crete, Greece. Dr. Bouzoukis states that he has no financial interests in the products or companies mentioned. He may be reached at tel: +30 2810 371800; fax: +30 2810 394653; e-mail: Dbouzoukis@ hotmail.com.
Aliki N. Limnopoulou, MD, MSc, practices in the Department of Ophthalmology, Vardinoyannion Eye Institute of Crete, Institute of Vision and Optics, University of Crete, Greece. Dr. Limnopoulou states that she has no financial interest in the products or companies mentioned. She may be reached at tel: +30 2810371800; fax: +30 2810394653.
Ioannis G. Pallikaris, MD, PhD, is a Professor of Ophthalmology at the University of Crete, and Director of the Institute of Vision and Optics, Heraklion, Greece. Dr. Pallikaris states that he is Chair of the Medical Advisory Board of Presbia. He may be reached at tel: +30 2810371800; fax: +30 2810394653; e-mail: firstname.lastname@example.org.
Nela R. Stojanovic, MD, MSc, FEBO, is a refractive surgery fellow at Vardinoyannion Eye Institute of Crete, Institute of Vision and Optics, University of Crete, Greece. Dr. Stojanovic states that she has no financial interest in the products or companies mentioned. She may be reached at tel: +30 2810 371800; fax: +30 2810 394653; e-mail: email@example.com.
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