Conventional Surgery vs. Verion/VerifEye

Overview

Nowadays cataract patient's expectations are closer to those of refractive surgery patients. Patients want to be spectacle independent. However, fifteen to twenty percent of cataract surgery patients have from 1.00 to 3.00 diopters (D) of corneal astigmatism which makes achieving spectacle independence unlikely in this patients unless the astigmatism is treated at the time of cataract surgery. Option to treat this astigmatism include corneal or limbal incisions (LRIs), the use of toric intraocular lenses (IOLs) or LASIK. Regardless of the treatment of choice to correct the astigmatism at time of cataract extraction, a treatment plan has to be calculated preoperatively. This planning include: keratometry measurements and the use of a calculator to estimate the treatment and orientation of IOL and/or placement of the LRIs. New technology has been developed and is widely used. Among this technology, we have the VERION Image Guided System. This system encompasses a reference unit that takes a picture of the eye with the patient in the sitting position creating image of the patient's eye, capturing scleral vessels, limbus and iris features. It measures keratometry as well as the corneal diameter (limbus) and pupil size. The information captured is transferred automatically to its planner where IOL power calculation and astigmatism correction calculation are completed. Additionally, intraoperative wavefront aberrometry has been used in the last couple of years with increase success.

Nowadays cataract patient's expectations are closer to those of refractive surgery patients. Patients want to be spectacle independent. However, fifteen to twenty percent of cataract surgery patients have from 1.00 to 3.00 diopters (D) of corneal astigmatism which makes achieving spectacle independence unlikely in this patients unless the astigmatism is treated at the time of cataract surgery. Currently available treatments include corneal or limbal incisions, the use of toric intraocular lenses (IOLs) or LASIK. Limbal relaxing incisions (LRIs) are the most commonly used manual method Traditionally, LRIs have been made manually (with a surgical knife). With the introduction of femtosecond laser to assist during cataract surgery, a new alternative is available for creating corneal incisions. The stability of the LRIs and visual outcomes using toric IOLs have been shown. Regardless of the treatment of choice to correct the astigmatism at time of cataract extraction, a treatment plan has to be calculated preoperatively. This planning include: keratometry measurements and the use of a calculator to estimate the treatment and orientation of IOL and placement of the LRIs. Keratometry can be measured using a variety of devices including manual keratometers (i.e. Javal-Shiotz), automated keratometers, corneal topography, and optical biometry ( IOL master and Lenstar). Once keratometry to be used has been selected, if the treatment of choice are LRIs, a calculator is used to determine the location and size of the LRI. Many nomograms have been developed; the choice of nomogram is the surgeon's prefer one, usually based on prior experience, and their preferred knife. LRIs calculators are available on line. Nomograms specify the location, length, size, and number of incisions based on the patient's age, the type of astigmatism, and the amount of astigmatism correction needed. If a toric IOL has been chosen then planning the appropriate orientation of the toric IOL is accomplished by using online calculators. The calculator selects the optimal toric power and location based on the keratometry and the surgically induced astigmatism (SIA) values entered by the surgeon. Intraoperatively, marking the eye and placing the incisions or aligning the toric IOL in the right axis are key steps for the success of astigmatism correction. Marking of the eye can be done using a variety of instruments using ink and it is routinely done with the patient in the upright position to avoid cyclorotation. Once patient is on the table in supine position, axis should be checked once again. Additional suggested methods to mark the eye include taking pictures preoperatively to identify anatomical landmarks similar to iris registration in refractive surgery. The use of iris registration during LASIK was introduced in 2008. Several publications have shown that patients undergoing wavefront-guided LASIK with iris recognition achieved better visual and refractive outcomes compared to conventional LASIK. Recently, Alcon introduced VERION Image Guided System: Digital Surgical Planning and Positioning Tools. This system encompasses a reference unit that takes a picture of the eye with the patient in the sitting position creating a high-resolution digital image of the patient's eye, capturing scleral vessels, limbus and iris features. It measures keratometry as well as the corneal diameter (limbus) and pupil size. The information captured is then transferred automatically to the planner where additional information including target refraction, manifest refraction, axial length, anterior chamber depth, and lens thickness is entered for IOL power calculation and astigmatism correction planning. Astigmatism correction options include corneal incisions, toric IOL and a combination of both. Intraoperatively, The VERION Digital Marker displays patient information and images from the VERION Reference Unit. Additionally it positions all incision locations and assists with lens alignment in real time while accounting for the variable impact of cyclorotation and patient eye movement. In the OR, it displays a reticle that helps to align the IOL to the axis according the surgical plan. It also helps to position manual LRIs. Intraoperative wavefront aberrometry has been used in the last couple of years to confirm spherical and toric power as well as lens position. The Optiwave Refractive Analysis (ORA) system can refract the eye in phakic, aphakic, and pseudophakic states at any time during cataract surgery and assists in IOL power selection and recommendations for toric IOL positioning before and after implantation as well as LRIs confirming the surgery plan calculated preoperatively. Furthermore, VerifEye, an ORA hardware upgrade, provides continuous assessment of the patient's eye allowing for more precise measurements; therefore, more accurate results and improved refractive outcomes and VerifEye +, the latest upgrade that provides streaming information on the refractive status and correct IOL positioning through the right ocular of the surgical microscope. This enables the surgeon to visualize all the information without having to look up at the monitor screen during the surgical procedure. This new technology is an alternative to plan and treat astigmatism at the time of cataract surgery. It could make this treatment easier for less experience surgeons by facilitating the calculations and making the identification of the correct axis easier by reducing the need for manual marks. The main objective of this study is to evaluate spherical and astigmatism outcomes post routine cataract surgery when the complete VERION Image Guided System packet + ORA System with VerifEye or VerifEye + are used in the treatment of pre-existing astigmatism using toric intraocular lens (IOL) or corneal incisions compared to the surgeon's standard of care.