Part 1: Streamlining the cataract workflow from preoperative assessment to post-surgery


1.1 Increasing efficiency through digitalization

Wolfgang J Mayer

Coping with the workforce demands associated with the increasing number of patients needing cataract surgery places a burden on surgeons and staff in the clinic and operating room and highlight interest in tools that can streamline preoperative and intraoperative workflow. Importantly, any strategy implemented to gain a benefit of increased efficiency should at least preserve and better yet also improve surgical safety and efficacy.

In our high volume university hospital setting, we have looked at the use of a digital workflow system as a solution for enhancing efficiency while maintaining our commitment to delivering maximum care. Our experience shows that it results in time savings throughout the entire cataract surgery journey along with excellent surgical results (Video 1).

Video 1. Streamlining the cataract workflow

The IOLMaster® 700 from ZEISS is the entry point into the digital workflow. Biometry data acquired with the ZEISS IOLMaster 700 can be seamlessly imported to EQ Workplace® from ZEISS. The latter platform is a central hub that offers convenient access to our patient data. It also allows surgeons to do IOL power calculation remotely. The system contains a full complement of modern power calculation formulae, and relevant data for each formula are automatically populated into the appropriate fields. After selecting the IOL model and power, the application gives me the convenient opportunity to automatically order the lens by email.

On the day of surgery, the patient’s data and reference image acquired with the ZEISS IOLMaster 700 are digitally transferred to my ZEISS surgical devices in the OR. The electronic importation saves time by eliminating the need to upload data manually or with a USB memory stick, avoids the potential for transcription errors that can occur with manual data entry, and makes it unnecessary to bring printouts into the OR.

ZEISS FORUM®, another component of the digital workflow system, is an ophthalmic data management software program that connects these various technologies to streamline processes and that serves us from the point of data acquisition at the beginning of the cataract surgery journey and into the planning, intraoperative, and postoperative phases.

Documenting efficiency

In a prospective study published in 2017, we reported that using ZEISS CALLISTO eye® for digital guidance of toric IOL implantation had advantages for significantly reducing overall surgical time and significantly improving alignment accuracy.1 Taking our research a step further, we subsequently conducted a study comparing time spent for surgical planning and in the OR in toric IOL procedures performed using ZEISS EQ Workplace versus a conventional manual approach for data collection and transfer (Video 2).2

Video 2. Time saving using a digital workflow

The results of our more recent study showed digitalization had benefits for improving both preoperative and intraoperative workflow efficiency. We documented that the digital approach was associated with statistically significant time savings for each of the diagnostic and surgical steps we analyzed that together translated into a total time savings of about 4 minutes per case (Figure 1). Consistent with our previous study, we also found that use of the digital approach for guiding IOL alignment was associated with excellent results when analyzing surgical outcomes that included IOL alignment accuracy, cylinder reduction, prediction error, and visual acuity.

Figure 1. Using a digital workflow for planning and performing toric IOL surgery increased efficiency overall and for all steps

Enabling the task of optimization

Optimizing refractive and functional results for patients undergoing cataract surgery is an ongoing process that should include consideration of the need for updating the values for lens constants and surgically-induced astigmatism used in IOL power calculations. ZEISS EQ Workplace also facilitates this task of optimization.

Postoperative data for corrected and uncorrected visual acuity, sphere, cylinder, and axis entered for individual patients into the postoperative surveillance screen are uploaded into ZEISS FORUM with the click of a button. Whenever I choose, I can easily select from this database a series of recent cases for analysis. Then, with another click, the calculations are quickly completed (Video 3).

Video 3. Post-operative optimization


Digital technologies and seamless data workflows increase efficiency throughout the entire cataract surgery journey (Figure 2). Our formal analyses prove that when implanting toric IOLs, the use of a digital workflow results in significant time savings compared to a conventional manual workflow and excellent outcomes. From a practical perspective, these benefits allow for increased productivity, which can help surgeons meet the growing demand for cataract surgery services, and also make for happy patients.

Figure 2. Benefits of a digital workflow for cataract surgery

1. 2 Digital planning and IOL power calculation for toric IOL surgery

Nino Hirnschall

Allowing patients to enjoy independence from glasses after cataract surgery depends on effective correction of both sphere and cylinder. Importantly, at least one-third of eyes are affected by visually significant corneal astigmatism.3 Toric IOL implantation is accepted as a safe and effective method for astigmatic correction during cataract surgery, and use of toric IOLs has been increasing.4 Compared with procedures performed with a standard non-toric IOL, however, planning and executing cataract surgery with a toric implant is a little more time-consuming and poses some additional challenges for achieving the targeted refractive outcome. Having a smooth and efficient workflow for obtaining corneal measurements, performing IOL power calculation, ordering IOLs, and guiding proper alignment is important for helping surgeons overcome these issues.

Residual astigmatism after toric IOL surgery can occur for multiple reasons, but according to our research, inaccurate measurement of preoperative corneal astigmatism is the main source and is followed by implant misalignment.5 Precise assessment of preoperative corneal astigmatism requires the use of reliably accurate technology and accounting for posterior corneal astigmatism (PCA). Although IOL misalignment can occur as the result of implant movement postoperatively, incorrect positioning intraoperatively is the more common underlying cause.5Utilizing the digital workflow described by Prof. Wolfgang Mayer in the above section addresses these issues and offers additional advantages for increasing workflow efficiency and surgical accuracy.

Considering PCA

The importance of including the contribution of the posterior corneal surface to corneal astigmatism when performing toric IOL power calculations has been recognized for many years (Video 4). Research reported by Dr. Doug Koch and colleagues in 2012 showed that ignoring PCA in toric IOL cases could lead to undercorrection in most eyes with against-the-rule anterior surface astigmatism and overcorrection in eyes having with-the-rule anterior surface astigmatism.6

Video 4. Why is the posterior surface of the cornea important?

Accounting for PCA in toric IOL power calculations can be performed using either the measured values (anterior and posterior radii and pachymetry) or by using formulae that use an estimated value for the posterior surface. Results from various research groups differ regarding whether measuring or estimating the posterior surface of the cornea is preferred. There are two explanations for this lack of agreement. First, recent improvements in methods for corneal measurement methods have led to better results when using the measured values. Second, the estimated values for the posterior cornea include not only the estimation for the posterior surface, but also a corrective element for other errors. Therefore, using measured PCA for toric IOL calculations is more likely to be the standard for the future.

Video 5. Case examples

Posterior corneal astigmatism can be directly measured using Scheimpflug, OCT, and other diagnostic imaging technologies. With the ZEISS IOLMaster 700, however, PCA is directly measured during routine biometry, avoiding the need for additional imaging (Video 5).

The ZEISS IOLMaster 700 is a swept source optical coherence tomography biometer that analyzes the anterior surface of the cornea using telecentric, 3-zone keratometry along with corneal thickness and the posterior corneal surface with swept source OCT technology. The data are then combined to Total Keratometry (TK), which is the vector sum of the front and back surface astigmatism. Because TK is comparable to the mean keratometry value, it can be used for toric and non-toric IOL calculations. This represents another benefit of using the ZEISS IOLMaster 700 with TK as not all power calculation formulae allow for direct input of the PCA value measured with other technologies.

A study we conducted analyzing outcomes data from 49 eyes that underwent toric IOL surgery showed that using TK for IOL power calculation instead of standard keratometry resulted in higher prediction accuracy and a higher percentage of patients with ≤0.5 D of residual cylinder (Figure 3).7

Figure 3. Outcomes data from 49 eyes with toric IOL surgery that shows higher prediction accuracy using TK7

In addition to cases involving toric IOL implantation, TK provided by the ZEISS IOLMaster 700 has important value for optimizing the accuracy of IOL power calculations in eyes with a history of corneal refractive surgery for which a refractive surprise is likely when using anterior keratometry alone.

Digitalization for improving accuracy and efficiency of toric IOL implantation

As mentioned earlier, IOL misalignment due predominantly to incorrect positioning intraoperatively is the second most common cause of residual astigmatism after toric IOL surgery.5 Manual axis marking adds an additional step on the day of surgery and can result in IOL misalignment as the ink marks lack precision and can fade or even disappear during surgery.8 As reported in the studies described by Dr. Mayer and other researchers, the use of digital tools for cataract surgery enables accurate toric IOL alignment while simultaneously increasing workflow efficiency.


My use of toric IOLs for correcting astigmatism during cataract surgery has increased significantly over the last few years. To deal with this higher work load it is helpful to have a digital workflow that increases efficiency at every step of the surgical journey from preoperative evaluation to the planning stage and into the operating room. In addition to saving time, approaching toric IOL surgery with a digital workflow has advantages of eliminating errors that can occur with repeated manual data entry and provides a more reliable method for guiding accurate IOL alignment compared to manual marking.

Optimizing predictability of refractive outcomes in cases involving toric IOLs also requires taking into account the contribution of the posterior corneal surface to total corneal astigmatism when performing the IOL calculation, and my preference is to use a direct measurement of PCA rather than an estimation. The ZEISS IOLMaster 700 meets this need and does so efficiently with its integrated Total Keratometry and through seamless data transfer to software for power calculation using the latest formulas.


  1. Mayer WJ, Kreutzer T, Dirisamer M, et al. Comparison of visual outcomes, alignment accuracy, and surgical time between 2 methods of corneal marking for toric intraocular lens implantation. J Cataract Refract Surg. 2017;43(10):1281-1286.
  2. Brunner BS, Luft N, Priglinger SG, et al. Saving of time using a software-based versus a manual workflow for toric intraocular lens calculation and implantation. J Clin Med. 2022; 11(10):2907.
  3. Hoffmann PC, Hutz WW. Analysis of biometry and prevalence data for corneal astigmatism in 23,239 eyes. J Cataract Refract Surg. 2010;36(9):1479-1485.
  4. ESCRS Clinical Trends Survey 2022 results. Supplement to EuroTimes. September 2022. Accessed February 21, 2024.
  5. Hirnschall N, Findl O, Bayer N, et al. Sources of error in toric intraocular lens power calculation. J Refract Surg. 2020;36(10):646-652.
  6. Koch DD, Ali SF, Weikert MP, et al. Contribution of posterior corneal astigmatism to total corneal astigmatism. J Cataract Refract Surg. 2012;38(12):2080-2087.
  7. Zeiss. Trilogy: Getting started with toric IOLs. December 21, 2020. Accessed February 21, 2024.
  8. Rombold F, Niederdellmann C, Pariti R, Khayat B. Time savings using a digital workflow versus a conventional for intraocular lens implantation in a corporate chain hospital setting. Clin Ophthalmol. 2024;18:113-119.
  9. Varsits RM, Hirnschall N, Döller B, Findl O. Evaluation of an intraoperative toric intraocular lens alignment system using an image-guided system. J Cataract Refract Surg. 2019;45(9):1234-1238.

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The statements of the authors reflect only their personal opinions and experiences and do not necessarily reflect the opinion of any institution with whom they are affiliated with. The authors alone are responsible for the content of their experience reported and any potential resulting infringements. Carl Zeiss Meditec AG and its affiliates do not have clinical evidence supporting the opinions and statements of the authors nor accept any responsibility or liability of the authors’ content.
The authors Wolfgang Mayer and Nino Hirnschall have a contractual or other financial relationship with Carl Zeiss Meditec AG and its affiliates.

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