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Is intraoperative aberrometry an essential tool in cataract surgery?
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A value-add in challenging cases
ORA (Alcon) is a powerful tool, and the dual abilities of calculating IOL power and measuring and adjusting total refractive astigmatism are compelling reasons to utilize this technology.
IOL calculations in patients with prior keratorefractive surgery have become less difficult with recent improvements in IOL formulas and corneal imaging devices. Some surgeons have also relied on intraoperative aberrometry for confirmation of IOL power and guidance with astigmatism management in these cases. There are studies that clearly demonstrate the value of ORA in these patients. There are also other reasons to consider utilizing ORA in this setting.
We understand that it is necessary to account for posterior corneal astigmatism either by utilizing formulas that theoretically account for posterior corneal astigmatism or by direct or indirect measurement. A number of Scheimpflug-based devices have posterior corneal astigmatism measurement capability, but not all surgeons may have access to this technology. There are also questions due to the inherent difficulty of directly measuring the posterior cornea. ORA allows measurement of the aphakic refraction of the total optical system, therefore theoretically accounting for all sources of astigmatism, including the posterior cornea.
In managing lower amounts of astigmatism, which is predominant in the cataract population, corneal relaxing incisions (CRIs), either femtosecond or manual, are extremely effective. The value of aberrometry in guiding CRI placement has been demonstrated in reducing enhancement rates after cataract surgery. Additionally, surgeons are able to utilize ORA to guide the opening of femtosecond CRIs to titrate their impact.
Most surgeons now use a centroid surgically induced astigmatism value; however, studies demonstrate significant variability in surgically induced astigmatism. In patients with lower amounts of astigmatism, a change in surgically induced astigmatism may sometimes negate the need for a toric IOL or cause a higher power toric IOL to be necessary.
If I could only pick one advanced technology tool to improve my ability to provide better surgical outcomes for my patients, ORA would certainly be in the discussion.
- References:
- Abulafia A, et al. J Cataract Refract Surg. 2018;doi:10.1016/j.jcrs.2018.07.027.
- Cao DM, Al-Mohtaseb Z, Wang L, Weikert MP, Koch DD. Chapter 185: Incisional keratotomy. In: Mannis MJ, Holland EJ, eds. Cornea. 5th ed. Elsevier; 2020 (in press).
- Ianchulev T, et al. Ophthalmology. 2014;doi:10.1016/j.ophtha.2013.08.041.
- Packer M. J Cataract Refract Surg. 2010;doi:10.1016/j.jcrs.2009.11.029.
- Wang L, et al. BMC Ophthalmol. 2017;doi:10.1186/s12886-017-0661-6.
- Yesilirmak N, et al. J Refract Surg. 2016;doi:10.3928/1081597X-20151210-02.
Quentin B. Allen, MD, is from Florida Vision Institute, Stuart, Florida. Disclosure: Allen reports he is a consultant for Alcon.
Not essential and slows you down
I have been using the ORA (Alcon) since its inception, and I am a big fan of this technology. I do think that in some instances such as post-refractive cases it helps surgeons make sure they get a more accurate IOL power, but in most cases, I do not think its use is essential. The first reason is the nature of the device, which depends on your input of biometry readings. The data you upload dictate the output of that machine. ORA is not independent of your preoperative biometry, and accuracy depends on the quality and consistency of preoperative data. Good data in, good data out; bad data in, bad data out.
The second reason is economics. In the U.S., a lot of surgeons use the ORA as a profit center for their practice. Patients might be prepared to pay for it, but personally I think that the extra income that may come with it is neutralized by the additional time it requires for each procedure. If you are a fast surgeon in a high-volume practice, it is not financially advantageous to add 5 minutes to each case. ORA slows me down; therefore, I like to use it only when it is truly needed, when I feel I need to confirm my biometry data, like in post-RK or some post-LASIK patients. Routinely, in post-refractive eyes, I use the American Society of Cataract and Refractive Surgery calculator to measure IOL power. The ORA helps, but it is not essential. And it is certainly not essential in routine cases.
Ehsan Sadri, MD, is from Atlantis Eyecare, Newport Beach, California. Disclosure: Sadri reports no relevant financial disclosures.