Democratizing Precision in Cataract Surgery

When deciding how best to manage astigmatism, we must take into account the extent of corneal astigmatism, the degree to which it can be offset by an intraocular lens (IOL), the patient's other pre-existing ocular conditions, as well as their economic constraints (1). Refractive cataract surgery has evolved by leaps and bounds in recent years (2), and the rise of femtosecond laser-assisted cataract surgery (FLACS), in particular, has made a marked impact on the field, especially regarding their use for treating corneal astigmatism by creating limbal relaxing incisions (LRIs).

While manual LRIs are simple and effective, they also produce less predictable outcomes. That said, they also require a fair amount of training to master (3). In my personal experience as a high-volume anterior segment surgeon, I’ve found the learning curve for performing consistent and effective manual LRIs to be substantial, and the training gaps and inconsistent results I’ve seen among ophthalmology residents when performing this common surgical technique have been deeply concerning.

When I saw LRIs created by FLACS for the first time, I remember being impressed at their consistency and ability to eliminate many of the variables that can lead to suboptimal surgical outcomes. However, the laser equipment is expensive, a cost which is ultimately passed on to the patient,and whether or not the benefits of femtosecond approaches for performing LRIs are worth the costs when compared to manual techniques remains the subject of ongoing debate (4, 5).

When confronted with this trade-off between precision and cost for the correction of corneal astigmatism, I knew there could be a middle path, one that offers the benefits of laser accuracy and consistency, but also has the simplicity and affordability of a manual approach. Although I am an ophthalmologist, I came to the field with a background in industrial engineering and systems optimization, and I have always held a deep fascination with the way medical technology can be refined to address the unmet needs of our patients. That’s why, in conjunction with MicroSurgical Technology, I designed the ArcDUO, a single-use, sterile ophthalmic knife (Figure 1a) that is intended to make controlled-depth, paired arcuate incisions on the cornea at or near the limbus (6).

ArcDUO: an emerging solution for the correction of corneal astigmatism

ArcDUO is available in both 9 mm and 10 mm treatment diameter options, and comes with guide templates for 15, 30, 45, and 60 degrees, offering surgeons a wide variety of options (Figure 1b). Not only can ArcDUO be used perioperatively during cataract surgery, but it can also be used postoperatively in the clinic.

When performed as an outpatient procedure, the use of ArcDUO is simple and typically does not require  anesthesia – patients usually only report feeling pressure on their eyes for about 10 seconds. This ability to treat residual or newly developed astigmatism months or even years following cataract surgery without the need for a return to the operating room or laser suite is a significant advantage, and can allow for the treatment of levels of corneal astigmatism even as low as <0.5D, especially important for modern advanced technology IOLs.

While such low levels of astigmatism are not viewed as functionally significant in a traditional ophthalmology, I believe that for patients with high visual demands or multifocal optics, the ideal target is complete correction – achieving a plano eye. Because multifocal lenses split light between focal points, any residual refractive error can meaningfully degrade patient satisfaction, and I’ve observed that correcting even miniscule levels of astigmatism leads to demonstrable improvements in subjective visual quality for my patients.

ArcDUO is a straightforward device to use with a very short learning curve. Ensuring good centration and suction of the docking ring will facilitate optimized alignment of the incisions, and the device itself regulates their depth. 

ArcDUO in practice

To evaluate its initial performance, I conducted an informal retrospective review of early cases treated with ArcDUO at one center and by a single surgeon (me) between April 2024 and January 2025. Patients included in this dataset underwent cataract surgery, had no significant corneal pathologies such as ectasia or scarring, presented with regular astigmatism of <1.5 D, and had adequate corneal thickness (i.e. central corneal thickness >500 microns and peripheral corneal thickness >600 microns at 9 mm). These patients received either standard monofocal or multifocal IOLs.

In these cases, the planned astigmatism correction with ArcDUO utilized measurements from biometry, corneal topography/tomography, and took into account the impact of lenticular astigmatism and expected corneal astigmatism after cataract surgery..

We used the Donnenfeld nomogram for LRI arc length determination throughout, using ArcDUO’s guide templates. The 30-degree arc length was the most frequently employed in this initial cohort.

The preliminary results demonstrate a reduction in astigmatism in the early postoperative phase, up to one month. Clinically, I also observed a surprising number of patients achieving plano vision on postoperative day one; however, it is important to acknowledge that LRIs may exhibit an initial overcorrection followed by regression as the cornea heals, and the incisions can be reopened if needed.

The preoperative astigmatism in this cohort ranged from 0.59 to 1.67 D, with an average of approximately 0.84 D. Because of the retrospective nature of the data collected, postoperative astigmatism in patients after treatment with ArcDUO at day one, week one, and month one were evaluated in different subsets of populations (Figure 2). It is notable that the mean degree of post-treatment astigmatism was zero across all timepoints, despite variability and relatively small sample sizes.

The mean best-corrected visual acuity (BCVA) for patients with data available was 20/22 at one week and one month (n=36 and n=21 patients, respectively; not all of the same eyes had measurements at each timepoint, and data completeness varied due to the multiple referral practices handling the postoperative follow-up).

These data suggest that, even with some residual astigmatism, patients generally achieved good vision. Subjectively, I found that patients were quite happy with the results, and no adverse events or corneal perforation were observed in any of the collected cases. 

This data analysis has its limitations, including the small population, variable and incomplete follow-up, and inconsistencies in the post-op measurement values, and further comprehensive prospective studies with longer-term data are certainly needed to draw more definitive conclusions about the predictability and stability of astigmatism correction with ArcDUO. However, even in practices equipped with FLACS capabilities, surgeons need a valuable and cost-effective solution for addressing low levels of astigmatism efficiently and affordably in situations where laser intervention is impractical.

Our patients deserve technology that delivers accuracy and reproducibility without exclusivity, and good surgical outcomes should not only be available for those who can afford it. It is my hope that the ArcDUO can significantly reduce the barrier to performing effective LRI procedures, and in doing so allow for a much wider range of individuals to enjoy better vision.