Toric lens implantation in cataract surgery: Automated versus manual horizontal axis marking, analysis of 50 cases

Insights into the rotational stability of toric intraocular lens implantation: diagnostic approaches, influencing factors and intervention strategies

Toric intraocular lenses (IOLs) have been developed to enhance visual acuity impaired by cataracts and correct corneal astigmatism. However, residual astigmatism caused by postoperative rotation of the toric IOL is an important factor affecting visual quality after implantation. To decrease the rotation of the toric IOL, significant advancements have been made in understanding the characteristics of toric IOL rotation, the factors influencing its postoperative rotation, as well as the development of various measurement techniques and interventions to address this issue. It has been established that factors such as the patient's preoperative refractive status, biological parameters, surgical techniques, postoperative care, and long-term management significantly impact the rotational stability of the toric IOL. Clinicians should adopt a personalized approach that considers these factors to minimize the risk of toric IOL rotation and ensure optimal outcomes for each patient. This article reviews the influence of various factors on toric IOL rotational stability. It discusses new challenges that may be encountered to reduce and intervene with rotation after toric IOL implantation in the foreseeable future.

Time Savings Using a Digital Workflow versus a Conventional for Intraocular Lens Implantation in a Corporate Chain Hospital Setting

Purpose

To evaluate and compare the digital cataract workflow with the existing conventional workflow in terms of time savings for overall diagnostic procedures from preoperative measurements, data transfer, intraocular lens (IOL) power calculation, and axis marking for cataract surgery in a corporate hospital chain setting.

Patients and Methods

This prospective non-clinical study assessed the mean procedural times for preoperative assessments, calculation of IOL power, data transfer to operating devices, and total surgery for both digital and existing conventional workflows.

Results

Overall, 430 workflows (digital cataract workflow: 227; existing conventional workflow: 203) were included for time measurements. The digital cataract workflow resulted in shorter mean (± standard deviation [SD]) preoperative assessments with lesser variability among individual assessments than the existing workflow (14.15 ± 1.86 vs 21.41 ± 1.18 min, respectively); with a time saving of 35%. Similarly, the mean (± SD) time required for the subsequent assessment steps such as IOL calculation (2.19 ± 1.23 vs 3.17± 2.29 min; 30%), data transfer (0 vs 1.33 ± 0.25 min; 100%), IOL axis marking and alignment (0 vs 3.07 ± 0.53 min; 100%) were shorter with digital cataract workflow versus existing conventional cataract workflow. Briefly, the overall mean time from preoperative assessments to final surgery was 16.48 min with digital cataract workflow and 30.58 min with existing conventional workflow; resulting in a time saving of 46%.

Conclusion

The Zeiss digital cataract workflow demonstrated greater time savings at each step of the cataract surgery workflow compared to the existing conventional workflow. In addition, digitalization can lead to a more streamlined cataract surgery workflow that is more convenient and cost-effective than the existing conventional practices in a corporate chain hospital setting.

Comparison of INTEGRA and the Manual Method to Determine the Axis for Intraocular Lens Implantation-A Case Series of 60 Eyes

(1) Background: To compare the results of a new intraoperative contactless device (INTEGRA Optomed, Poland) with the result of a manual method for determining the axis for toric intraocular lens implantation. (2) Material and Methods: This retrospective observational study included 60 eyes of 40 patients (17 men, 23 women) who had toric intraocular lenses implanted. A video recording of each surgery that used the INTEGRA system was made for the analysis. Two researchers then independently assessed the location of the implant axes determined with both digital and manual slit-lamp methods, and compared the results between methods. (3) Results: The implantation axes suggested through the manual and INTEGRA methods were similar. The median axis disparities were 0.0 degrees for both groups. The standard deviation was 0.63 and 0.75 for researcher 1 and 2, respectively. The dominant value was 0.0 in both groups. The INTEGRA axis designation was statistically significantly different from the manual method for researcher 1 (p < 0.05), but it was statistically insignificant for researcher 2 (p = 0.79). (4) Conclusions: The INTEGRA system is a digital ink-free device for image tracking scleral vessels. It was helpful for determining the implantation axis in a precise manner, and the measurements were comparable with those obtained through a manual technique.

Comparing IOLM700 TK, Berdahl and Hardten astigmatism fix calculator and Barrett Rx formula in managing residual astigmatism due to toric intraocular lens misalignment

Purpose:

To compare the accuracy in astigmatism reduction by using IOLM 700 steep total keratometry (TK) axis, Berdahl and Hardten astigmatism fix, and Barrett Rx formula following misaligned toric intraocular lens (IOL).

Methods:

Ten patients with residual refractive astigmatism due to misalignment following toric IOL implantation were included in this retrospective study. They were analyzed at days 4, 7/8, and 10/11 following primary cataract surgery on the platform of Berdahl and Hardten astigmatism fix, Barrett Rx formula, and IOLM 700 to determine the optimum axis of repositioning, and underwent IOL realignment on the steep TK axis of IOLM 700 assisted by the Callisto eye. The final outcome parameters were subjective refraction and orientation of toric IOL assessed 22 ± 1 days following repositioning surgery. These parameters were fed in the Barrett Rx formula and its vector analysis graph was utilized to determine the predicted ideal axis with the least residual astigmatism and the estimated residual astigmatism if the toric IOL was realigned according to the axis suggested by Berdahl and Hardten astigmatism fix and Barrett Rx formula.

Results:

Realigning the toric IOL on IOLM 700 steep TK axis along with the Callisto eye reduces the residual refractive astigmatism significantly (P = 0.003) from 2.00 ± 0.78 D to 0.18 ± 0.12 D (90.5 ± 7.6%) in comparison to the estimated 0.57 ± 0.31 D (68.4 ± 21.9%) by Berdahl and Hardten astigmatism fix and 0.61 ± 0.33 D (66.4 ± 23.5%) by Barrett Rx formula.

Conclusion:

Realigning the misaligned toric IOL on the IOLM 700 steep TK axis gives a better reduction in the residual refractive astigmatism in comparison to Berdahl and Hardten astigmatism fix and Barrett Rx formula.

Should Artificial Tears Be Used During the Preoperative Assessment of Toric IOLs Before Age-Related Cataract Surgery? The TORIDE Study

PURPOSE

To assess the impact of the use of artificial tears during the preoperative work-up performed before age-related cataract surgery, when a toric intraocular lens (IOL) was indicated.

METHODS

This was a monocentric prospective study assessing 73 eyes of 51 patients, included consecutively after a preoperative work-up performed without artificial tears (no artificial tears group), when a toric IOL was indicated. Each included patient underwent a second series of examinations: biometry using the IOLMaster 700 (Carl Zeiss Meditec AG) and topography using the OPD-Scan II (Nidek), 1 minute after artificial tears instillation (artificial tears group; hyaluronate de sodium 0.15%, threalose 3% [Théalose; Théa]). Changes in anterior corneal astigmatism and subsequent changes in toric IOL calculation were analyzed. The error in predicted residual astigmatism was calculated.

RESULTS

Anterior corneal astigmatism and total corneal astigmatism measured with the IOLMaster 700 were significantly modified when artificial tears were instilled before the examinations (1.51 ± 0.57 diopters [D], range: 0.75 to -3.55 vs 1.42 ± 0.63 D, range: 0.42 to 3.35 D; P = .043 and 1.59 ± 0.54 D, range: 0.87 to 3.48 vs 1.51 ± 0.59 D, range: 0.56 to 3.27 D, P = .038, respectively). This modification led to a change in IOL cylinder calculation in 43.8% of cases and to a change in implantation axis greater than 10° in 17.7% of cases. These changes were significantly greater in patients with a breakup time (BUT) less than 5 seconds (57.5% and 27.8%, with P = .009 and .029, respectively). In the subgroup of patients with a BUT of less than 5 seconds, the mean absolute error in predicted astigmatism was significantly lower after artificial tears instillation (0.48 ± 0.50 D, range: 0.00 to 2.79 vs 0.37 ± 0.25 D, range: 0.00 to 1.10 D, P = .048).

CONCLUSIONS

Dry eye significantly impacted toric IOL calculations and should be taken into account during the preoperative assessments. Using artificial tears reduced the number of refractive errors. [J Refract Surg. 2021;37(11):759-766.].

Impact of measured total keratometry versus anterior keratometry on the refractive outcomes of the AT TORBI 709-MP toric intraocular lens

PURPOSE

The aim of this study was to compare the visual and refractive outcomes of total keratometry (TK) versus anterior keratometry (AK) measurements of the IOLMaster 700® (Carl Zeiss Meditec AG, Jena, Germany) in surgery for age-related cataract with preexisting corneal astigmatism.

METHODS

Monocentric retrospective comparative study. The IOLMaster 700® biometer was used in the 2 groups: in AK mode (AK group) and in TK mode (TK group), for toric IOL (AT TORBI 709 MP) calculation with ZCALC®, Zeiss toric IOL calculator. A 2:1 matching was made between the AK and TK groups. Uncorrected distance visual acuity (UDVA), the correction index and the error in predicted residual astigmatism were analyzed 1 month postoperatively using the vector analysis by the Alpins method.

RESULTS

The whole cohort included 405 eyes distributed as follows after 2:1 matching: 158 eyes in the AK group and 79 eyes in the TK group. The mean UDVA was similar in both groups (0.07 ± 0.10 LogMAR; p = 0.587). No significant difference in mean absolute error in predicted residual astigmatism (0.37 ± 0.33 D versus 0.35 ± 0.26 D; p = 0.545) and in mean centroid error in predicted residual astigmatism (0.19 ± 0.49 at 3° and 0.06 ± 0.46 at 0°; p = 0.008 and 0.161 respectively for the x- and y-components) was found between the AK and TK groups.

CONCLUSION

TK of the IOLMaster 700® gives excellent refractive and visual outcomes, comparable to those obtained in AK mode, without showing its superiority for corneas with regular astigmatism.

Effect of femtosecond laser-assisted steepest-meridian clear corneal incisions on preexisting corneal regular astigmatism at the time of cataract surgery

AIM

To investigate the clinical efficacy and safety of femtosecond laser-assisted steepest-meridian clear corneal incisions for correcting preexisting corneal astigmatism performed at the time of cataract surgery.

METHODS

This prospective case series study comprised consecutive age-related cataract patients with corneal regular astigmatism (range: +0.75 to +2.50 D) who had femtosecond laser-assisted steepest-meridian clear corneal incisions (single or paired). Corneal astigmatism was performed with the Pentacam preoperatively and 3mo postoperatively. Total corneal astigmatism and steepest-meridian measured in the 3-mm central zone were used to guide the location, size and number of clear corneal incision. The vector analysis of astigmatic change was performed using the Alpins method.

RESULTS

Totally 138 eyes of 138 patients were included. The mean preoperative corneal astigmatism was 1.31±0.41 D, and was significantly reduced to 0.69±0.34 D (equivalent to difference vector) after surgery (P<0.01). The surgically-induced astigmatism was 1.02±0.54 D. The correction index (ratio of target induced astigmatism and surgically-induced astigmatism: 0.72±0.36) as well as the magnitude of error (difference between surgically-induced astigmatism and target induced astigmatism: -0.29±0.51) represented a slight under correction. For angle of error, the arithmetic mean was 1.11±13.70, indicating no significant systematic alignment errors.

CONCLUSION

Femtosecond-assisted steepest-meridian clear corneal incision is a fast, customizable, adjustable, precise, and safe technique for the reduction of low to moderate corneal astigmatism during cataract surgery.

Comparison of the Orientation of the Corneal Steep Meridian Determined by Image-Guided System and Manual Method in the Same Eye

Purpose

To evaluate the difference between the preoperative marking methods for toric intraocular lens (IOL) implantations using an image-guided system (IGS) and the manual marking method in the same eye.

Patients and Methods

In this retrospective case series, 82 patients (101 eyes) who underwent cataract surgery using both manual and IGS (VERION, Alcon  Laboratories) marking were enrolled. First, preoperative reference marks were placed at 6 o’clock and 3 or 9 o’clock position under slit-lamp biomicroscope in the outpatient department using the manual method. Using the reference unit of IGS, the ocular surface data were captured and overlaid. The difference was then measured (preoperative axis misalignment). In the operating room, the orientation of the steep meridian of the manual method was determined based on this reference mark under the surgical microscope. Just before surgery, the digital degree gauge of IGS was overlaid on the ocular surface, and the difference was then measured (total axis misalignment). We calculated the intraoperative axis misalignment by subtracting preoperative axis misalignment from the total axis misalignment.

Results

Mean absolute preoperative, intraoperative, and total axis misalignment values were 3.87±3.95 degrees, 5.46±4.42 degrees, and 4.98±4.49 degrees, respectively. In preoperative, intraoperative, and total misalignment, the ratios of 10 degrees or greater were 10 (14.7%), 12 (17.6%), and 20 (19.8%) eyes, respectively.

Conclusion

The manual method that determines the fixed position of the toric intraocular lens (IOL) may cause large misalignment compared with the IGS, suggesting that using manual method could sometimes result in a large misalignment of toric IOL implantation.

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Comparative meta-analysis of toric intraocular lens alignment accuracy in cataract patients: Image-guided system versus manual marking

This meta-analysis studied toric intraocular lens (IOL) alignment accuracy using image-guided and manual marking methods by comparing the axis misalignment of toric IOLs, percentage of eyes with toric IOL axis misalignment within ±5 degrees, postoperative astigmatism, difference vector, and postoperative uncorrected distance visual acuity. The methodological quality was assessed using the modified Quality Assessment of Diagnostic Accuracy Studies-2 tool. Continuous variables were analyzed using weighted mean differences, and dichotomous variables were compared using the odds ratio. Five studies comprising a total of 257 eyes were analyzed. For heterogeneity, neither sensitivity analysis nor the Egger test detected statistical findings. The image-guided marking group had smaller toric IOL axis misalignment (P < .00001), less postoperative astigmatism (P = .003), and a smaller difference vector (P < .00001) than the manual marking group. The overall evidence from the studies indicates that image-guided marking is better than manual marking, resulting in less axis misalignment, a smaller difference vector, and less postoperative astigmatism.

Rotational slit-beam marking: an advanced manual corneal astigmatic marking method for toric intraocular lens implantation

PURPOSE

To evaluate the accuracy of an advanced manual corneal astigmatic marking method for toric intraocular lens (IOL) implantation.

METHODS

From 52 patients, 52 eyes with cataracts and corneal astigmatism were included. The target axis of the toric IOL was marked with the new manual marking method preoperatively and with the Zeiss CALLISTO Eye image-guided system intraoperatively. For the manual method, a slit-lamp with a minimum rotation angle of 5 degrees was used and rotated to the meridian of the toric IOL and incision axes. The relative rotational and vertical deviation of the IOL and incision axes were measured using the digital marker as a reference.

RESULTS

There was no significant difference between the manually marked IOL axis (100.9° ± 65.62°) and the digital mark (100.8° ± 65.76°; P = 0.771). The absolute values of the relative rotational and vertical deviations of the manually marked IOL axis were small, at 2.03° ± 1.44° and 0.46 ± 0.43 mm, respectively. There was no significant difference between the manually marked corneal incision and the digital meridian (P = 0.179). Then, patients were classified into three groups based on the type of astigmatism they had. There was no significant difference in mean absolute deviation among the groups (P = 0.112). The manual incision mark had a relative rotational deviation of 1.65° ± 1.44°. The vertical misalignment of the manually marked incision axis was 0.27 ± 0.30 mm.

CONCLUSION

Rotational slit-beam marking could be an effective and convenient marking method for toric IOL implantation. This method could be a potential alternative in underdeveloped areas where digital image-guided systems are not available.

Evaluation of axis alignment and refractive results of toric phakic IOL using image-guided system

AIM

To evaluate accuracy of axis alignment and refractive results of toric phakic intraocular lens (IOL) implantation using a digital imaging system.

METHODS

This retrospective study investigated toric implantable collamer lens (ICL) implantation in 30 eyes of 21 patients with myopic astigmatism more than 2.0 D guided with digital imaging system. Data were collected during the first week after phakic IOL implantation.

RESULTS

Thirty eyes of 21 patients were included in our study. Patients includes 9 males and 12 females. The mean age of the patients was 26.5±7.1 (range 21-44)y. The mean preoperative manifest astigmatism was 3.2±1.7 (range from 2.25 to 4.75) D. The mean postoperative uncorrected distance visual acuity (UCDVA) were 0.07±0.07 (range from 0.1 to 0.0) logMAR. The mean postoperative residual refractive cylinder was 0.25±0.29 (range 0-0.75) D. Eyes with postoperative residual refractive cylinder of 0.5 D or less represented 80% (24 eyes). The mean postoperative toric IOL misalignment measured by the OPD scan III was 1.9°±1.45° (range from 0 to 5°).

CONCLUSION

Image guided system allows accurate alignment of toric ICL. This is associated with good postoperative visual acuity and low residual refractive astigmatism which correlates with the precision of toric phakic IOL alignment.

Effect of corneal marking features on toric intraocular lens alignment

PURPOSE

The purpose of this study was to investigate the relation of the corneal ink mark size, shape, and location with the corneal perimeter in terms of the corresponding corneal axis.

MATERIAL AND METHODS

This study was designed both prospective experimental and literature search. Contact lenses were used to demonstrate the spreading effect of the surgical ink mark. Open-access published corneal images with corneal ink marks were reviewed. Mark size and perimeter of both contact lenses and corneal images were performed in Image J software.

RESULTS

Twenty contact lenses and 15 corneal images with 32 corneal marks, which were obtained from the literature, were included in the study. Mean degree corresponding to the ink size for the group 1 was 8.3° ± 1.2° (range 5.5-10.3), for group 2 was 11° ± 1.1° (range 8-12), for group 3 was 4.2° ± 0.7° (range 3.2-5.5), for group 4 was 4.2° ± 0.7° (range 3.2-5.5), and for group 5 was 6.3° ± 2.5° (range 2-11.5).

DISCUSSION

Theoretically, it is wise to target further located ink mark from central cornea based on the 360/2π × (r2 - r1)/(r1 × r2) × M formula. It has been experimentally shown that the smaller corneal perimeter and closer mark to the central cornea may lead the more significant deviation from the targeted axis. Preoperative manual corneal marking may be more responsible for residual astigmatism than it is thought.

Accuracy of the refractive prediction determined by intraocular lens power calculation formulas in high myopia

Purpose:

Our study was conducted to evaluate and compare the accuracy of the refractive prediction determined by the calculation formulas for different intraocular lens (IOL) powers for high myopia.

Methods:

This study reviewed 217 eyes from 135 patients who had received cataract aspiration treatment and IOL implantation. The refractive mean numerical error (MNE) and mean absolute error (MAE) of the IOL power calculation formulas (SRK/T, Haigis, Holladay, Hoffer Q, and Barrett Universal II) were examined and compared. The MNE and MAE at different axial lengths (AL) were compared, and the percentage of every refractive error absolute value for each formula was calculated at ±0.25D, ±0.50D, ±1.00D, and ±2.00D.

Results:

In all, 98 patients were recruited into this study and 98 eyes of them were analyzed. We found that Barrett Universal II formula had the lowest MNE and MAE, SRK/T and Haigis formulas arrived at similar MNE and MAE, and the MNE and MAE calculated by Holladay and Hoffer Q formula were the highest. Barrett Universal II formulas have the lowest MAE among different AL patients, whereas it reached the highest percentage of refractive error absolute value within 0.5D in this study. The MAE of each formula is positively correlated with AL.

Conclusion:

Barrett Universal II formula rendered the lowest predictive error compared with SRK/T, Haigis, Holladay, and Hoffer Q formulas. Thus, Barrett Universal II formula may be regarded as a more reliable formula for high myopia.

Image-guided lens extraction surgery: a systematic review

A systematic review of the recent literature regarding the current image-guided systems used for cataract surgery or refractive lens exchange was performed based on the PubMed and Google Scholar databases in March 2018. Literature review returned 21 eligible studies. These studies compared image-guided systems with other keratometric devices regarding their accuracy, repeatability and reproducibility in measurement of keratometric values, astigmatism magnitude and axis, as well as in IOL power calculation. Additionally, the image-guided systems were compared with conventional manual ink-marking techniques for the alignment of toric IOLs. In conclusion, image-guided systems seem to be an accurate and reliable technology with measurements of high repeatability and reproducibility regarding the keratometry and IOL power calculation, but not yet interchangeable with the current established and validated keratometric devices. However, they are superior over the conventional manual ink-marking techniques for toric IOL alignment.