Evaluation of 4 corneal astigmatic marking methods

The comparison of white-to-white via triple person-times caliper measuring and machine-measuring in V4c implantable collamer lens implantation

This study aimed to compare the differences and characteristics of white-to-white (WTW) values obtained before V4c implantation using triple person-times caliper, IOL-Master 700, Pentacam HR, and UBM, and to assess their correlation with vaulting. A total of 930 myopia patients (1842 eyes) who were interested in undergoing ICL surgery were assessed before the procedure using various instruments. The WTW measurements were obtained using a triple person-times caliper, Pentacam HR, and IOL-Master 700, whereas the angle-to-angle (ATA) measurements were obtained using UBM. The size of the ICL was subsequently calculated using triple person-times caliper measurements. The vault of the ICL was assessed using Pentacam HR three months after the surgery. The WTW was determined to be 11.30 ± 0.29 mm, 11.43 ± 0.29 mm, and11.86 ± 0.38 mm, respectively, using the triple person-times caliper, Pentacam HR, and IOL-Master 700. The measurement of ATA was 11.57 ± 0.51 mm, as done by UBM. The ICL vault was measured to be 400.97 ± 198.46 µm when examined with Pentacam HR three monthsafter the procedure. The linear regression analyses of ICL size and WTW of triple person-times caliper, ICL vault and WTW were (R = 0.703, p < 0.001; R = 0.0969, p < 0.001) respectively. The highest correlation was found between IOL-Master and Pentacam HR (r = 0.766, p = 0.000). The lowest correlation was found between UBM and Pentacam HR (r = 0.358, p = 0.002). Bland-Altman analysis showed that the 95% limits of agreement (LoA) were the triple person-times caliper and Pentacam HR (- 0.573, 0.298) and the triple person-times caliper and UBM (- 1.15, - 0.605). This indicated a strong agreement between the triple person-times caliper and Pentacam HR and a lack of agreement between the triple person-times caliper and UBM. Triple person-times caliper measurements offer excellent maneuverability, practicality, and reliable outcomes for determining ICL vaults. Measurements obtained using the triple-person caliper were less differece than those obtained using the Pentacam HR.

Comparison of toric intraocular lens alignment between femtosecond laser-assisted capsular marking and digital marking

PURPOSE

To compare the accuracy of toric intraocular lens (IOL) alignment between femtosecond laser-assisted capsular marking and digital marking.

SETTING

Ruhr University Eye Clinic, Bochum, Germany.

DESIGN

Prospective clinical trial.

METHODS

In this study, 28 eyes of 23 patients, who underwent femtosecond laser-assisted cataract surgery with implantation of a toric IOL, were included. Intraoperatively, both femtosecond laser-assisted capsular marking and digital marking were applied simultaneously and compared in every case. The toric IOL was aligned to the capsular markings. Postoperatively, the axis of the capsular markings and toric IOL alignment was examined. Visual acuity and refractive outcomes were evaluated.

RESULTS

Both alignment methods were performed without intraoperative complications in all cases. 25 eyes were included in the final analysis. Misalignment was significantly lower with femtosecond laser-assisted capsular marking than with digital marking (1.71 ± 1.25 degrees vs 2.64 ± 1.70 degrees, P = .016). Deviation from the target axis of the toric IOL was 1.62 ± 1.24 degrees 4 to 6 weeks postoperatively. Postoperative uncorrected distance visual acuity was 0.14 ± 0.13 logMAR, and residual astigmatism was 0.3 ± 0.23 diopter (D) with an astigmatism ≤0.5 D in 93% of eyes.

CONCLUSIONS

Both methods showed excellent results for the alignment of toric IOLs. However, femtosecond laser-assisted capsular marking was significantly more precise than digital marking and showed good refractive results. In addition, capsular marking offers the possibility to avoid parallax error and evaluating postoperative IOL rotation.

Comparison of Visual and Refractive Outcome between Two Methods of Corneal Marking for Toric Implantable Collamer Lenses (TICL) in Phakic Eyes

PURPOSE

To compare the efficacy of digital-assisted reference marking for toric implantable collamer lenses (Callisto Eye System) with manual marking technique using a slit lamp markeur.

METHODS

This study included patients that underwent implantation of a toric implantable collamer lens (EVO Visian toric ICL, Staar Surgical). Patients were included if they had a myopia above -3 diopters (D) and regular corneal astigmatism of 0.75 diopters or higher. Between both groups a 1:2 matching regarding similar preoperative level of myopia and astigmatism was performed. Visual and refractive outcomes were evaluated. Vector analysis was performed to evaluate total astigmatic changes.

RESULTS

This study comprised 57 eyes of 57 patients with 19 eyes in the digital group and 38 eyes in the manual marking group. Postoperatively there were no statistically significant differences between both groups in UDVA (p = 0.467), spherical equivalent (SE) (p = 0.864), sphere (p = 0.761) and cylinder (p = 0.878). Vector analysis showed a slightly more accurate postoperative refractive astigmatism in the manual group (0.26 D at 107° ± 0.50 D) compared to the digital marking group (0.31 D at 107° ± 0.45 D), nevertheless with no statistically significant differences between both groups.

CONCLUSIONS

A digital tracking approach for toric ICL alignment was an efficient and safe method for toric marking with similar results regarding visual and refractive outcomes compared to a conventional corneal marking method. Nevertheless, image-guided surgery helped to streamline the workflow in refractive ICL surgery.

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.

Deviation from the planned axis of three toric intraocular lenses

In this study, we retrospectively evaluated the deviation from the planned axis of 3 Toric intraocular lenses (TIOL). Included in the study 190 eyes, operated by two surgeons using two different manual marking techniques. The patients were implanted with either AcrySof IQ Toric SN6AT (Alcon) (n = 90), POD FT (PhysIOL) (n = 50), or TECNIS Symfony Toric (J&J) (n = 50). At least 1 month postoperatively, the IOL was photographed, and the axis was measured using a designed software. The difference between the planned and actual axis was defined as axis deviation. The effect of IOL type, astigmatism direction, and marking techniques on the average degree and direction of the IOL deviation were evaluated and compared. There was no significant difference in the average deviation between the IOLs (TECNIS Symfony: 4.03° ± 4.34, POD FT: 3.52° ± 3.38, and SN6AT: 4.24° ± 4.10), and its direction (55.8%, 39.0%, and 56.6% clockwise (CW) deviation, respectively). With the rule, astigmatism had significantly more CW deviation compared with against the rule and oblique astigmatism (64.3%, 43.8%, and 41.7%, respectively, P = 0.027), but the average deviation was similar. The marking techniques did not influence the degree or direction of the deviation.

Toric intraocular lenses: Expanding indications and preoperative and surgical considerations to improve outcomes

Since the introduction of the first toric intraocular lens (IOLs) in the early 1990s, these lenses have become the preferred choice for surgeons across the globe to correct corneal astigmatism during cataract surgery. These lenses allow patients to enjoy distortion-free distance vision with excellent outcomes. They also have their own set of challenges. Inappropriate keratometry measurement, underestimating the posterior corneal astigmatism, intraoperative IOL misalignment, postoperative rotation of these lenses, and IOL decentration after YAG-laser capsulotomy may result in residual cylindrical errors and poor uncorrected visual acuity resulting in patient dissatisfaction. This review provides a broad overview of a few important considerations, which include appropriate patient selection, precise biometry, understanding the design and science behind these lenses, knowledge of intraoperative surgical technique with emphasis on how to achieve proper alignment manually and with image-recognition devices, and successful management of postoperative complications.

Sources of Error in Toric Intraocular Lens Power Calculation

PURPOSE

To evaluate the influencing factors on remaining astigmatism after implanting a toric intraocular lens (IOL) during cataract surgery.

METHODS

This retrospective study included parameters that were considered to have an influence on toric IOL power calculation. Therefore, data from the literature and the authors' own data were used. This included axial eye length, anterior chamber depth, central corneal thickness, corneal radii (anterior and posterior), diurnal changes of the cornea, inter-device differences, rotational misalignment of the IOL, tilt and decentration of the IOL, pupil size, angle kappa, and surgically induced astigmatism. Ray-tracing and Gaussian error propagation analysis was performed to quantify the sources of error.

RESULTS

In total, 4,949 eyes (4,365 eyes of 42 studies and 584 eyes of retrospectively analyzed study data) were included in the study and the difference vector between aimed and calculated remaining astigmatism was 0.81 diopters (D). The main source of error was the preoperative measurement of the cornea (27%), followed by IOL misalignment (14.4%) and IOL tilt (11.3%). Other factors, such as angle kappa (10.9%), pupil size (8.1%), surgically induced astigmatism (7.8%), anterior chamber depth (7.5%), axial eye length (7.5%), and decentration (5.6%), also contributed to the refractive astigmatic error.

CONCLUSIONS

The main source of error in toric IOL power calculation is the preoperative corneal measurement followed by IOL misalignment and tilt. [J Refract Surg. 2020;36(10):646-652.].

Comparison of Toric Intraocular Lens Alignment Between Femtosecond Laser-Assisted Capsular Marking and Manual Corneal Marking

PURPOSE

To compare toric intraocular lens (IOL) alignment between femtosecond laser-assisted capsular marking and manual corneal marking.

METHODS

This study prospectively included 72 consecutive eyes (from 72 patients) with cataract and anterior corneal astigmatism of 1.00 diopter (D) or greater that underwent femtosecond laser-assisted cataract surgery with implantation of a toric IOL. These eyes were randomly categorized into two groups based on the IOL alignment method. The femtosecond laser capsular marking group included 36 eyes with capsular markers using the latest femtosecond laser platform. The manual marking group included 36 eyes with manual corneal markers. The preservation of the markers was assessed. Visual acuity and refractive outcomes, as well as deviation from the target axis, were evaluated.

RESULTS

In the femtosecond laser capsular marking group, all capsular markers were retained for at least 3 months. In the manual marking group, 22.2% of the corneal markers disappeared within 1 month and all markers disappeared within 3 months. At 1 month postoperatively, the mean magnitudes of refractive astigmatism were -0.41 ± 0.26 and -0.45 ± 0.31 D (P = .81), and the uncorrected distance visual acuities were 0.07 ± 0.06 and 0.07 ± 0.05 logMAR (P = .56) in the femtosecond laser capsular marking and manual marking groups, respectively. The misalignment of the toric IOL within 1 hour postoperatively was 1.5° ± 1.4° in the femtosecond laser capsular marking group and 4.4° ± 2.1° in the manual marking group (P < .01). The deviation from the target axis of implantation was 1.6° ± 1.3° in the femtosecond laser capsular group and 4.8° ± 2.5° in the manual marking group (P < .01) at 1 month postoperatively.

CONCLUSIONS

IOL misalignment was significantly lower in the femtosecond laser-assisted capsular marking group than in the manual corneal marking group. In addition, the long-term preservation of the capsular marker is helpful in evaluating the rotation of the toric IOL. [J Refract Surg. 2020;36(8):536-542.].

Comparison of Preoperative Measurements with Intraoperative Aberrometry in Predicting Need for Correction in Eyes with Low Astigmatism Undergoing Cataract Surgery

Purpose

To determine whether intraoperative aberrometry during cataract surgery measures higher levels of absolute astigmatism than preoperative biometry readings and which method yields a lower, final level of astigmatism if the two do not agree.

Patients and Methods

Retrospective record review of all patients who underwent uncomplicated cataract surgery from February 2015 to May 2019 with planned intraoperative aberrometry. Data analysis included preoperative keratometry, total astigmatism as measured by intraoperative aberrometry, intraocular lens model and power used, and postoperative manifest refraction ≥1 month after surgery. The primary outcome measure was the proportion of patients requiring astigmatism correction (≥0.5 D) when measured by preoperative keratometry vs intraoperative aberrometry. Secondary outcomes included postoperative residual astigmatism, where adjusted preoperative astigmatism fell below the 0.5 D threshold for treatment but the intraoperative measurement was ≥0.5 D or ≥1.0 D.

Results

A total of 451 patient records were evaluated. Intraoperative aberrometry measured statistically higher levels of mean astigmatism than keratometry (0.86 D vs 0.79 D, respectively; P < 0.0001) and significantly greater astigmatism among patients with 0.5–1.5 D of adjusted preoperative astigmatism (P < 0.0001). Significantly more patients qualified for with-the-rule astigmatism correction when measured by intraoperative aberrometry (n=339; 75%) than by preoperative keratometry alone (n=314; 70%); P < 0.03. This difference did not hold for against-the-rule or oblique astigmatism. For patients whose preoperative biometry astigmatism differed from intraoperative biometry, final postoperative astigmatism was lower when corrected if the adjusted preoperative and intraoperative measurements had a vector difference of <0.5 D, but there was no additional benefit in final astigmatism reduction when the vector difference was ≥0.5 D.

Conclusion

Using intraoperative biometry readings can produce lower postoperative astigmatism than using preoperative biometry readings, but caution should be used when interpreting intraoperative readings that disagree with preoperative measurements with a vector magnitude of >0.5 D.

Evaluation of Scheimpflug imaging system as an added tool in improving the accuracy of reference marking (as compared to the slit lamp marking system) for toric intraocular lens implantation

Purpose:

To assess the role of Scheimpflug imaging in improving the accuracy of reference marking for toric IOL implantation.

Methods:

In this prospective, randomized, clinical trial all patients with cataract and pre-existing significant regular corneal astigmatism, who required implantation of a toric IOL were included in the study, and patients with any ocular pathology or abnormality were excluded. Patients were divided into two groups: For one group of patients, Group I (GI), reference marking was finalized using slit lamp only, and for the second group, Group II (GII), after slit lamp marking, the reference marks were checked using Goniometer of Scheimpflug imaging. The primary outcome was to determine the axis of toric intraocular lens (IOL) postoperatively (within 1 hour) and compare it with the desired axis of placement.

Results:

We found a statistically significant difference in the two groups (P < 0.001) suggesting Group II (4 step technique) is better than Group I (3 step technique).

Conclusion:

Scheimpflug imaging, an extra step preoperatively, is an effective measure to reduce errors in reference marking and thereby improving the refractive outcome of toric intraocular lens.

Time-efficiency assessment of guided toric IOL cataract surgery: a pilot study

PURPOSE

To compare the time spent on toric intraocular lens (IOL) implantation during cataract surgery using a manual-marking versus a digital image-guided system (the Verion) for toric IOL alignment.

SETTINGS

All procedures were performed at the Instituto Oftalmológico Quirónsalud ophthalmology clinic (A Coruña, Spain).

DESIGN

We designed an experimental and longitudinal (1-month follow-up) study.

METHODS

A total of 98 eyes of 65 participants (68.2 ± 12.2 years) were divided into two groups: 49 eyes operated with toric IOL alignment using a manual-marking technique (manual group) and another 49 eyes operated using image-guided marking (Verion group). The primary variable for comparison between both groups was cataract surgery time. Other outcomes such as toric IOL misalignment, spherical equivalent (SE), astigmatism, uncorrected distance visual acuity (UDVA), and corrected distance visual acuity (CDVA) were also measured.

RESULTS

The total cataract surgery time was 2:09 minutes shorter (p  < 0.001) with the Verion system (12:12 ± 2:20) compared to the surgical procedure performed using manual marking (15:27 ± 3:04). One month after surgery, there were no statistical differences in terms of toric IOL misalignment between the Verion (3.38° ± 2.95°) and the manual group (4.66° ± 3.95°). No statistical differences were observed between groups for refractive and visual outcomes either (p ≥ 0.05).

CONCLUSIONS

The cataract surgery time was reduced when the procedure was assisted using the Verion system to align the IOL compared to manual marking, maintaining the same efficacy in terms of toric IOL misalignment, residual refraction, and visual acuity.

Femtosecond laser-assisted arcuate keratotomy at the time of cataract surgery for the management of preexisting astigmatism

PURPOSE

To evaluate the outcomes of femtosecond laser-assisted arcuate keratotomy combined with cataract surgery in eyes with low-to-moderate corneal astigmatism.

SETTING

Eyes of York Private Practice Ophthalmology Clinic, York, Pennsylvania, USA.

DESIGN

Retrospective case series.

METHODS

This retrospective analysis included case records of patients with preexisting corneal astigmatism ranging from 0.5 to 2.0 diopter (D). Study parameters included corneal astigmatism, refractive astigmatism, and uncorrected (UDVA) and corrected (CDVA) distance visual acuities. The results, which were analyzed at 3 months postoperatively, included frequency distribution histograms, vector analysis, and single-angle polar plots.

RESULTS

The study comprised case records of 189 eyes of 143 patients (56 men and 87 women). The postoperative refractive astigmatism was reduced significantly compared with preoperative corneal astigmatism to 0.14 D ± 0.23 (SD) from 0.92 ± 0.34 D (P < .001). One hundred eighty-one eyes (95.8%) demonstrated postoperative refractive astigmatism of 0.5 D or less. The mean surgically induced change along the preoperative steep axis was -0.59 ± 0.56 D, and the change along the orthogonal axis was 0.01 ± 0.35 D. Postoperatively, 171 eyes (90.5%) had astigmatism angle of error of 15 degrees or less. The postoperative mean UDVA and CDVA were 0.09 ± 0.16 logarithm of the minimum angle of resolution (logMAR) and 0.02 ± 0.05 logMAR, respectively. One hundred seventy eyes (90%) had a postoperative UDVA of 20/30 or better. The results demonstrated stability at 12 months postoperatively. No intraoperative or postoperative arcuate keratotomy-related events were observed.

CONCLUSION

The results suggest that femtosecond laser-assisted arcuate keratotomy represents a safe and effective method for astigmatism correction at the time of cataract surgery with demonstrated stability of correction for at least 1 year postoperatively.

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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Femtosecond laser-assisted refractive capsulorhexis - Precise capsulotomy with accurate toric intraocular lens alignment

Femtosecond laser-assisted cataract surgery with refractive capsulorhexis and toric intraocular lens (IOL) implantation was performed in 14 eyes with senile cataract and a preexisting regular corneal astigmatism of 1.5 D or more. Intraoperatively, the accuracy of the capsular rim marks was confirmed using the digital overlay of CALLISTO Eye and Z Align (Carl Zeiss Meditec, Germany). Postoperatively, the mean deviation from target axis of implantation was 2.07° ± 1.49°. Refractive capsulorhexis combines the advantages of a femtosecond laser capsulotomy with a one-step visual guide for intraoperative toric IOL alignment as well as postoperative assessment of rotational stability.

Long-term Vector Outcomes of SMILE in Correcting Moderate to High With-the-Rule Astigmatism Under Astigmatism Axis Marked Condition

PURPOSE

To evaluate the vector outcomes of small incision lenticule extraction (SMILE) in correcting moderate to high myopic astigmatism under astigmatic axis marked condition.

METHODS

In a prospective, longitudinal, interventional study, 71 eyes (71 patients) that had with-the-rule preoperative cylinder refraction exceeding 1.50 diopters (D) were corrected with the VisuMax femtosecond laser (Carl Zeiss Meditec AG) at Zhongshan Ophthalmic Center. Refractive outcomes and astigmatic vector were evaluated preoperatively and at 1, 3, 6, and 30 months postoperatively.

RESULTS

At 30 months postoperatively, the efficacy and safety indexes were 1.04 ± 0.18 and 1.15 ± 0.17, respectively. The magnitude of the surgically induced astigmatism (SIA) (2.13 ± 0.71 D at 1 month [P_1m-pre = .018], 2.12 ± 0.72 D at 3 months [P_3m-pre = .006], 2.13 ± 0.69 D at 6 months [P_6m-pre = .010], and 2.19 ± 0.72 D at 30 months [P_30m-pre < .001]) was slightly higher than that of the target induced astigmatism (TIA) (2.07 ± 0.69 D). Only the y-coordinate of the SIA vector had a significant overcorrection compared to that of the TIA vector (P_1m-pre = .033, P_3m-pre = .011, P_6m-pre = .012, P_30m-pre < .001). The corrected index (CI = |SIA|/|TIA|) varied from 1.03 ± 0.07 at 1 month to 1.06 ± 0.10 at 30 months, which was higher when correcting moderate astigmatism than when correcting high astigmatism (P = .041) at 30 months postoperatively.

CONCLUSIONS

SMILE had long-term safety, efficacy, predictability, and stability when correcting moderate to high myopic astigmatism under astigmatism axis marked condition. Meanwhile, a cylinder overcorrection was observed due to the overcorrection of y-coordinate astigmatic power, which implied that the vector adjustment of the cylinder refraction nomogram should be considered. [J Refract Surg. 2020;36(9):585-591.].

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.

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.

Intraoperative capsular marking for toric intraocular lens placement

Preoperatively, the surgeon instills two drops of 0.5% proparacaine and then marks the 0° and 180° points at the limbus using a Gentian violet marker and 26G needle edge. Intraoperatively, after phacoemulsification and irrigation and aspiration of the cortex are complete, the surgeon inspects the previously marked 0°–180° points on the limbus. In case the steeper astigmatic meridian needs to be marked, a Mendez Ring is used and the meridian is marked using a Gentian violet marker and 26G needle edge. The desired markings (2 mm in length only) on the anterior lens capsule can be made using 26G needle bent at the bevel or using micro-vitreoretinal scissors. The toric intraocular lens (IOL) is then rotated in the bag in the desired meridian (customized-toric IOL in 0°–180° meridian and noncustomized toric IOL in steeper marked meridian), viscoelastic substance is aspirated and corneal wounds are hydrated.

Image-guided system versus manual marking for toric intraocular lens alignment in cataract surgery

PURPOSE

To compare the accuracy of toric intraocular lens (IOL) alignment using the Verion Image-Guided System versus a conventional manual ink-marking procedure.

SETTING

University Eye Clinic Maastricht, Maastricht, the Netherlands.

DESIGN

Prospective randomized clinical trial.

METHODS

Eyes with regular corneal astigmatism of at least 1.25 diopters (D) that required cataract surgery and toric IOL implantation (Acrysof SN6AT3-T9) were randomly assigned to the image-guided group or the manual-marking group. The primary outcome was the alignment of the toric IOL based on preoperative images and images taken immediately after surgery. Secondary outcome measures were residual astigmatism, uncorrected distance visual acuity (UDVA), and complications.

RESULTS

The study enrolled 36 eyes (24 patients). The mean toric IOL misalignment was significantly less in the image-guided group than in the manual group 1 hour (1.3 degrees ± 1.6 [SD] versus 2.8 ± 1.8 degrees; P = .02) and 3 months (1.7 ± 1.5 degrees versus 3.1 ± 2.1 degrees; P < .05) postoperatively. The mean residual refractive cylinder was -0.36 ± 0.32 D and -0.47 ± 0.28 D in the image-guided group and manual group, respectively (P > .05). The mean UDVA was 0.03 ± 0.10 logarithm of minimum angle of resolution (logMAR) and 0.04 ± 0.09 logMAR, respectively (both P > .05). No intraoperative complications occurred during any surgery.

CONCLUSION

The IOL misalignment was significantly less with digital marking than with manual marking; this did not result in a better UDVA or lower residual refractive astigmatism.

Cyclorotation during femtosecond laser-assisted cataract surgery measured using iris registration

PURPOSE

To assess ocular cyclorotation of eyes having femtosecond laser-assisted cataract surgery using iris registration.

SETTING

Eye Institute of West Florida, Largo, Florida, USA.

DESIGN

Retrospective cases series.

METHODS

Charts of patients who had femtosecond laser-assisted cataract surgery with preoperative and intraoperative iris registration in 1 or 2 eyes between November 2015 and March 2016 were reviewed. Cyclorotation was assessed via iris-registration acquired preoperatively using the Cassini topographer (patient in upright position) and intraoperatively using the iris registration option of the Lensar laser system (patient in supine position) acquired immediately before the laser treatment.

RESULTS

The study comprised 241 patients (337 eyes). The mean age of the 107 men and 134 women was 68.0 years ± 9.0 (SD) (range 37 to 90 years). The mean absolute value of cyclorotation was 5.81 ± 4.20 degrees (range 0 to 17 degrees), which was statistically significant when comparing the preoperative axis with the intraoperative axis deviation (P < .0001). Overall, incyclorotation (67.4%) was more common than excyclorotation (30.9%). In patients having bilateral femtosecond laser-assisted cataract surgery, bilateral incyclorotation (47.37%) was the most common occurrence.

CONCLUSIONS

During femtosecond laser-assisted cataract surgery, clinically significant cyclotorsion that might influence astigmatism correction outcomes can occur in patients having cataract extraction. Iris registration was useful in accounting for cyclorotation during this procedure when corneal or intraocular lens-based forms of astigmatic corrections will be used.

Toric IOL positioning with a no-touch head-up display axis alignment

PURPOSE

To compare a new no-touch alignment technique for toric intraocular lenses (IOL) with the conventional technique that uses a manual pendulum.

METHODS

In this retrospective case-control study, patients who underwent toric IOL implantation using two different alignment techniques (digital Callisto^® system vs. manual-pendulum-based marking) were compared in a vector analysis using the Alpins method and an analysis of variance regarding corrected and uncorrected visual acuity and the deviation of the achieved IOL axis from the targeted axis.

RESULTS

Sixty-one eyes were included into analysis. Thirty-six of these surgeries were performed via the Callisto^® system and 25 eyes via pendulum-based corneal markings. Median IOL axis misalignment was 3° in both groups. Median uncorrected distance visual acuity was 0.097 logMAR versus 0.200. Median best-corrected visual acuity was 0.000 logMAR versus 0.097. All these data were below the range of statistical significance (p > 0.05). Vector analysis showed no significant difference for TIA [median of 3.14 diopters (D) vs. 2.73 D], SIA (median of 3.82 D vs. 3.79 D), DV (1.18 D vs. 1.08 D), and CI (1.23 vs. 1.29). Median angle of error was 1.96° versus - 0.44° (p > 0.05).

CONCLUSIONS

We found no significant difference in the refractive results, the IOL positioning, and the best-corrected and uncorrected distance visual acuity between the two compared methods. Nevertheless, the Callisto^® IOL alignment system delivers a standardized and easy-to-use technology. In particular, less-experienced surgeons might benefit from this marking technique.

Effects of Cyclotorsion Orientation and Magnitude in Eyes with Compound Myopic Astigmatism on the Compensation Capacity of WaveLight EX500 Photorefractive Keratectomy

Purpose

To investigate the clinical effects of different orientation and magnitude of cyclotorsion on the compensation capacity of the WaveLight EX500 photorefractive keratectomy (PRK) platform.

Methods

This retrospective study comprised 400 eyes of 200 patients who underwent bilateral simultaneous PRK due to compound myopic astigmatism. The subjects were separated according to the orientation of cyclotorsion into incyclotorsion and excyclotorsion groups, and by the magnitude of cyclotorsion into group 1 (0.50 to 2.50 degrees), group 2 (3.00 to 5.00 degrees), group 3 (5.50 to 7.50 degrees), and group 4 (8.00 to 9.50 degrees).

Results

The mean magnitude of cyclotorsion was 3.50 ± 2.4 degrees (0.50 to 9.50 degrees) in the incyclotorsion group and 3.32 ± 2.3 degrees (0.50 to 9.50 degrees) in the excyclotorsion group (p = 0.617). The postoperative refractive outcomes of the incyclotorsion and excyclotorsion groups were similar (p > 0.05 for all). The postoperative mean cylindrical refractive error was −0.32 ± 0.3 diopters (D, −1.25 to 0.00 D) in group 1, −0.47 ± 0.2 D (−2.00 to 0.00 D) in group 2, −0.62 ± 0.2 D (−1.00 to −0.25 D) in group 3, and −0.91 ± 0.2 D (−1.50 to −0.50 D) in group 4 (p < 0.001). Preoperative cylindrical refractive error was positively correlated with magnitude of cyclotorsion (r = 0.125 and p = 0.013), which was also positively correlated with postoperative cylindrical refractive error (r = 0.600 and p < 0.001).

Conclusions

Incyclotorsion and excyclotorsion can be equally compensable in the WaveLight EX500 PRK platform for compound myopic astigmatism. A value of ≤2.50 degrees cyclotorsion magnitude was observed to be more compensable than higher degrees of cyclotorsion magnitude. Preoperative high astigmatism was associated with high cyclotorsion magnitude, which was also associated with a high degree of postoperative astigmatism.

Accuracy of toric intraocular lens implantation using automated vs manual marking

BACKGROUND

Accurate alignment of toric intraocular lens (TIOL) to steep corneal astigmatic axis is important to achieve effective postoperative results. The authors compare the accuracy of astigmatism correction using automated and manual marking in TIOL implantation during cataract surgery.

METHODS

One hundred thirty-two eyes with nuclear density from Grade 2 to 4 were randomly subdivided into 2 groups (automated and manual marking). All patients underwent manual marking and the steep axis was compared to SensoMotoric Instruments (SMI). After phacoemulsification, 62 patients underwent toric IOL implantation using the SMI and 70 patients underwent toric IOL implantation using manual marking. Intraoperative measurement was the steep axis difference. Clinical measurements included preoperative and postoperative best corrected visual acuity (BCVA), and TIOL axis.

RESULTS

The intraoperative steep axis difference between SMI and manual marking was 7.86 ± 6.4 degrees. The difference between the preoperative steep axis and the postoperative TIOL axis using SMI (3.63 ± 1.12 degrees) was significantly lower than that using manual marking (8.29 ± 2.23 degrees) (P < 0.05).

CONCLUSIONS

The steep axis measurements may be different when using SMI vs. manual marking. The SMI is more accurate than manual marking for TIOL implantation during cataract surgery.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN12294725 , Retrospectively registered, on 20 July 2018.

Evaluation of an intraoperative toric intraocular lens alignment system using an image-guided system

PURPOSE

To evaluate an intraoperative toric intraocular lens (IOL) alignment system using a dedicated operating microscope with an image-guided system without preoperative corneal marking.

SETTING

Vienna Institute for Research in Ocular Surgery, Department of Ophthalmology, Hanusch Hospital, Vienna, Austria.

DESIGN

Prospective case series.

METHODS

In this prospective study, a new operating microscope system was used for cataract surgery (toric IOL alignment system of the OPMI Lumera 700 microscope and CALLISTO eye software). This system allows toric IOL alignment by matching limbal vessels from a preoperative photograph with the live image of the microscope. The preoperative photograph was taken with IOLMaster 500, which included a "Reference Image Attachment" system (red-free image), and this was used to track and follow the eye during surgery. After surgery, rotational alignment was assessed and compared with the preoperative axis calculation. At 1 hour postoperatively, a retroilluminaton photograph was taken, and then rotational alignment was compared with the preoperative axis calculation to see the rotational stability.

RESULTS

Fifty eyes of 50 patients were included. The feasibility of the intraoperative marking was high. Deviation between the postoperative (at the end of surgery in the operating room) and aimed IOL axes was 0.52 degrees ± 0.56 (SD). The deviation between 1 hour postoperatively and the aimed IOL axes was 5.10 ± 4.45 degrees.

CONCLUSION

Intraoperative toric IOL alignment using an image-guided system was an accurate and fast procedure resulting in precise toric IOL alignment, and the system simplified the positioning of toric IOLs. There was a slight rotation of IOLs shortly after surgery (within the first hour).

Novel method for preventing cyclorotation in Ziemer Femto LDV Z8 femtosecond laser-assisted cataract surgery with Verion image-guided system

Purpose

To investigate the feasibility of a new method involving the use of the Verion image-guided system in preventing cyclorotation during femtosecond laser-assisted cataract surgery (FLACS).

Patients

Our preliminary data included details of 24 consecutive patients. All patients underwent cataract surgery at Universal Eye Center, Zhong-Li, Taiwan, between December 2016 and January 2017.

Methods

We developed a technique to use the Verion image-guided system in FLACS and evaluated whether this new technique is compatible with Femto LDV Z8. The Verion image-guided system was used to prevent misalignments. The only additional step in this technique is using a marking tool to place ink on the corneal limbus (at 3 and 9 o’clock positions) guided by the Verion digital marker system. Remaining procedures could be performed using the touchscreen of Femto LDV Z8 to calibrate the horizontal reference axis.

Results

This study included 24 patients who underwent cataract surgery. The technique used could effectively neutralize misalignments at an average of 8.08° and 2.66° in clockwise and counterclockwise directions, respectively.

Conclusion

This technique combines the advantages of iris fingerprinting technology and mobile features of Femto LDV Z8, has fewer transfer steps, improves centration of the eyes, and, most importantly, can prevent misalignments through cyclotorsion or docking procedures. Furthermore, this method can improve the accuracy of arcuate incisions and toric intraocular lens alignment in astigmatism correction.

Consensus on the management of astigmatism in cataract surgery

This project was aimed at achieving consensus on the management of astigmatism during cataract surgery by ophthalmologists from Latin America using modified Delphi technique. Relevant peer-reviewed literature was identified, and 21 clinical research questions associated with the definition, classification, measurement, and treatment of astigmatism during cataract surgery were formulated. Twenty participants were divided into seven groups, and each group was assigned three questions to which they had to respond in written form, after thoroughly reviewing the literature. The assigned questions with corresponding responses by each group were discussed with other participants in round 4 – presentation of findings. The consensus was achieved if approval was obtained from at least 80% of participants. The present paper provides several agreements and recommendations for management of astigmatism during cataract surgery, which could potentially minimize the variability in practice patterns and help ophthalmologists adopt optimal practices for cataract patients with astigmatism and improve patient satisfaction.

Preoperative Prediction of the Optimal Toric Intraocular Lens Alignment Meridian

PURPOSE

To determine whether any of three keratometry devices is superior to the others in predicting the ideal toric intraocular lens (IOL) alignment meridian.

METHODS

A retrospective review was performed to identify patients who underwent cataract phacoemulsification with toric IOL implantation from November 2014 to November 2016 at a single academic institution. For each patient, corneal measurements were performed with an optical low-coherence reflectometer/autokeratometer (OLCR), a dual Scheimpflug/Placido analyzer, and a color light-emitting diode (LED) topographer. Postoperatively, the ideal toric IOL alignment meridian that would have resulted in the least amount of residual astigmatism was determined using the online Berdhal & Hardten Toric Results Analyzer (BHTRA). To determine the prediction error, this ideal alignment meridian was compared to the corneal meridian with the highest refractive power, as provided by the three devices.

RESULTS

Fifty-six eyes of 56 patients were included in the study. The mean absolute errors in the toric IOL alignment meridians of the color LED topographer, dual Scheimpflug/Placido analyzer, and OLCR were 5.2° ± 5.2°, 7.6° ± 5.7°, and 5.4° ± 5.1°, respectively. There was no significant difference in the ability of each device to predict the ideal alignment meridian as determined by the BHTRA.

CONCLUSIONS

The color LED topographer, dual Scheimpflug/Placido analyzer, and OLCR may all be used to preoperatively determine the best alignment meridian for toric IOL placement. Surgeons should use their best judgment in determining which device to use in preoperative planning for individual patients. [J Refract Surg. 2018;34(8):515-520.].

Rotational Stability of Monofocal and Trifocal Intraocular Toric Lenses With Identical Design and Material but Different Surface Treatment

PURPOSE

To compare the rotational stability, total misalignment, and visual and refractive outcomes achieved with a trifocal toric versus a monofocal toric intraocular lens (IOL).

METHODS

In this prospective, interventional case series, eyes of patients consecutively scheduled for cataract surgery who had clinically relevant astigmatism were implanted with a FineVision Pod FT trifocal toric IOL or an Ankoris monofocal toric IOL (both PhysIOL SA, Liège, Belgium). Certain comorbidities, such as pseudoexfoliation syndrome, were allowed. IOL rotation and total misalignment were analyzed 15 minutes, 1 day, 1 week, 6 weeks, 6 months, and 1 year postoperatively.

RESULTS

Seventy-one eyes of 53 patients were assessed: 37 eyes were implanted with the trifocal IOL and 34 eyes with the monofocal IOL. More IOL rotation occurred in the monofocal group compared to the trifocal group (mean 4.23° ± 4.64° vs 2.55° ± 2.62°; P = .043, 12 months). Mean total misalignment was higher in the monofocal group (6.67° ± 6.59° at 12 months vs 3.79° ± 3.59° in the trifocal group) (P = .017). Postoperatively, more eyes achieved a refractive cylinder of 0.50 diopters or below in the trifocal group (65% at 12 months) than in the monofocal group, even in the monofocal subgroup analysis that excluded keratoconic eyes (42% at 12 months; P = .009).

CONCLUSIONS

The monofocal and trifocal toric IOLs both appear to effectively reduce refractive astigmatism and provide good visual acuity in astigmatic patients having cataract surgery. The trifocal toric IOL offers better rotational stability than the monofocal IOL, probably due to the higher frictional coefficient of its surface. [J Refract Surg. 2018;34(2):84-91.].

[Refractive outcomes and precision in toric intraocular lens alignment using an automated alignment system]

PURPOSE

To compare precision in toric intraocular lens (TIOL) alignment and refractive outcomes between an intraoperative automated digital marker system and the conventional manual-ink marking.

MATERIALS AND METHODS

Prospective single center study including consecutive patients undergoing uneventful cataract surgery with corneal astigmatism greater than 1 diopter. Total corneal astigmatism was measured using a placido-dual Scheimpflug system (GalileiG4^®, Ziemer). Acrysof^® SN6AT (Alcon) TIOL's were implanted, and patients were divided into 2 groups, the digital group (Verion^®, Alcon) and the ink-marking group (Pendular marker, AMO). Mean error in TIOL axis, visual acuity and residual astigmatism were analyzed at 3 days, one month and 6 months after surgery.

RESULTS

In total, 45 eyes of 30 patients were included (n=25 digital group, n=20 ink-marking group). The mean preoperative total corneal astigmatism was 1.71±0.53 diopters. At one month, there was a significantly lower mean average error in TIOL axis in the digital group compared to the ink-marking group (2.6±2.3° and 6.4±2.8° respectively, P=0.009). At 6months, these results remained statistically significant. Mean residual astigmatism was 0.7±0.4 diopters at one month, without significant difference between the two groups (P=0.9). The rate of misalignment less than or equal to 5° was 86 % (n=25) in the digital group and 63 % (n=20) in the ink-marking group (P=0.05).

CONCLUSION

Intraoperative digital marker system is associated with better TIOL alignment accuracy and better reproducibility than the manual ink-marking method.

Comparative evaluation of toric intraocular lens alignment and visual quality with image-guided surgery and conventional three-step manual marking

Purpose

To compare toric intraocular lens (IOL) alignment assisted by image-guided surgery or manual marking methods and its impact on visual quality.

Patients and methods

This prospective comparative study enrolled 80 eyes with cataract and astigmatism ≥1.5 D to undergo phacoemulsification with toric IOL alignment by manual marking method using bubble marker (group I, n=40) or Callisto eye and Z align (group II, n=40). Postoperatively, accuracy of alignment and visual quality was assessed with a ray tracing aberrometer. Primary outcome measure was deviation from the target axis of implantation. Secondary outcome measures were visual quality and acuity. Follow-up was performed on postoperative days (PODs) 1 and 30.

Results

Deviation from the target axis of implantation was significantly less in group II on PODs 1 and 30 (group I: 5.5°±3.3°, group II: 3.6°±2.6°; p=0.005). Postoperative refractive cylinder was −0.89±0.35 D in group I and −0.64±0.36 D in group II (p=0.003). Visual acuity was comparable between both the groups. Visual quality measured in terms of Strehl ratio (p<0.05) and modulation transfer function (MTF) (p<0.05) was significantly better in the image-guided surgery group. Significant negative correlation was observed between deviation from target axis and visual quality parameters (Strehl ratio and MTF) (p<0.05).

Conclusion

Image-guided surgery allows precise alignment of toric IOL without need for reference marking. It is associated with superior visual quality which correlates with the precision of IOL alignment.

Optimizing outcomes with toric intraocular lenses

Toric intraocular lenses (IOLs) are the procedure of choice to correct corneal astigmatism of 1 D or more in cases undergoing cataract surgery. Comprehensive literature search was performed in MEDLINE using “toric intraocular lenses,” “astigmatism,” and “cataract surgery” as keywords. The outcomes after toric IOL implantation are influenced by numerous factors, right from the preoperative case selection and investigations to accurate intraoperative alignment and postoperative care. Enhanced accuracy of keratometry estimation may be achieved by taking multiple measurements and employing at least two separate devices based on different principles. The importance of posterior corneal curvature is increasingly being recognized in various studies, and newer investigative modalities that account for both the anterior and posterior corneal power are becoming the standard of care. An ideal IOL power calculation formula should take into account the surgically induced astigmatism, the posterior corneal curvature as well as the effective lens position. Conventional manual marking has given way to image-guided systems and intraoperative aberrometry, which provide a mark-less IOL alignment and also aid in planning the incisions, capsulorhexis size, and optimal IOL centration. Postoperative toric IOL misalignment is the major factor responsible for suboptimal visual outcomes after toric IOL implantation. Realignment of the toric IOL is needed in 0.65%–3.3% cases, with more than 10° of rotation from the target axis. Newer toric IOLs have enhanced rotational stability and provide precise visual outcomes with minimal higher order aberrations.

Evaluation of a new electronic preoperative reference marker for toric intraocular lens implantation by two different methods of analysis: Adobe Photoshop versus iTrace

PURPOSE

The aim of this study is to compare two different methods of analysis of preoperative reference marking for toric intraocular lens (IOL) after marking with an electronic marker.

SETTING/VENUE

Cataract and IOL Implantation Service, Shroff Eye Centre, New Delhi, India.

PATIENTS AND METHODS

Fifty-two eyes of thirty patients planned for toric IOL implantation were included in the study. All patients had preoperative marking performed with an electronic preoperative two-step toric IOL reference marker (ASICO AE-2929). Reference marks were placed at 3-and 9-o'clock positions. Marks were analyzed with two systems. First, slit-lamp photographs taken and analyzed using Adobe Photoshop (version 7.0). Second, Tracey iTrace Visual Function Analyzer (version 5.1.1) was used for capturing corneal topograph examination and position of marks noted. Amount of alignment error was calculated.

RESULTS

Mean absolute rotation error was 2.38 ± 1.78° by Photoshop and 2.87 ± 2.03° by iTrace which was not statistically significant (P = 0.215). Nearly 72.7% of eyes by Photoshop and 61.4% by iTrace had rotation error ≤3° (P = 0.359); and 90.9% of eyes by Photoshop and 81.8% by iTrace had rotation error ≤5° (P = 0.344). No significant difference in absolute amount of rotation between eyes when analyzed by either method.

CONCLUSIONS

Difference in reference mark positions when analyzed by two systems suggests the presence of varying cyclotorsion at different points of time. Both analysis methods showed an approximately 3° of alignment error, which could contribute to 10% loss of astigmatic correction of toric IOL. This can be further compounded by intra-operative marking errors and final placement of IOL in the bag.

A comparison of three different corneal marking methods used to determine cyclotorsion in the horizontal meridian

During toric intraocular lens (IOL) implantation, surgeons must take particular care to ensure that inaccurate preoperative measurement and intraoperative misalignment do not cause unexpected postoperative residual astigmatism. This retrospective, comparative case series study aimed to analyze the rotational deviation, or cyclotorsion, of three corneal marking methods: VERION digital marker (VDM; reference), horizontal slit beam marking (HSBM), and subjective direct visual marking (SDVM) on the table (using a bevel knife tip). Subjects included 81 eyes of 61 patients (mean age: 65.70±13.14 years; range: 32–91 years) undergoing scheduled cataract surgery. A preoperative reference image was taken of each eye. Subsequently, a slit lamp with the light beam turned to the horizontal meridian was used to align the seated patient’s head, and two reference marks were placed at the 3- and 9-o’clock positions of the corneal limbus using a 27-gauge needle and marking pen (HSBM). Upon transfer to the surgical table, the VDM was used to display a real-time dial scale on the patient’s eye, with the entrance of the temporal clear corneal incision (CCI) at 0° (horizontal meridian). Simultaneously, a bevel knife tip was used to create a marker based on the surgeon’s visual determination of the temporal 0° point (SDVM). We used the VDM to quantitatively evaluate the accuracy of axis alignment via deviation from the horizontal reference meridian. Compared with the reference meridian, the SDVM (−3.46°±7.32°, range: −18° to 13°) exhibited greater average relative cyclotorsion versus the HSBM (0.41°±4.92°, range: −10° to 10°). Furthermore, the mean average misalignment was significantly less in the HSBM group versus the SDVM group (t=4.179, P<0.001). The VDM is likely a reliable marking method, similar to the HSBM. In contrast, the SDVM is not entirely reliable. The VDM usage may prevent inaccurate preoperative manual marking during toric IOL implantation.

Anterior stromal puncture with staining: A modified technique for preoperative reference corneal marking for toric lenses and its retrospective analyses

Introduction:

Toric intraocular lenses (IOLs) are an effective way of compensating preexisting corneal astigmatism during cataract surgery. To achieve success, it is imperative to align the toric IOLs in desired position and preoperative reference marking is one among the three important steps for accurate alignment. To make the marking procedure simpler and effective, we have modified the conventional three-step slit lamp-based technique.

Materials and Methods:

Patient is seated in front of the slit lamp and asked to keep the chin over chin rest. A 26-gauge bent needle with tip stained by sterile blue ink marker is used to make anterior stromal puncture (ASP) at the edges of horizontal 180° axis near the limbus.

Results:

A total of 58 eyes were retrospectively evaluated. Mean (+/-SD) IOL deviation on day 1 and day 30 was 5.7 ± 6.5° and 4.7 ± 5.6°, respectively. Median IOL misalignment on day 1 and day 30 was 3°. Redialing of IOL was required in 2 (3.4%) eyes only, all of which were performed within 1 week of surgery. In total, 2 (3.7%) eyes had a residual astigmatism of − 0.5 Dcyl and − 1.0 Dcyl, respectively.

Conclusion:

ASP is an effective technique for reference marking, technically simpler and can be practiced by most of the surgeons. It avoids the necessity of high-end sophisticated machinery and gives a better platform for the reference corneal marking along with the benefit of reproducibility and simplicity.

Introduction of a Toric Intraocular Lens to a Non-Refractive Cataract Practice: Challenges and Outcomes

AIM

To identify challenges inherent in introducing a toric intraocular lens (IOL) to a non-refractive cataract practice, and evaluate residual astigmatism achieved and its impact on patient satisfaction.

METHODS

Following introduction of a toric IOL to a cataract practice with all procedures undertaken by a single, non-refractive, surgeon (SB), pre-operative, intra-operative and post-operative data was analysed. Attenuation of anticipated post-operative astigmatism was examined, and subjectively perceived visual functioning was assessed using validated questionnaires.

RESULTS

Median difference vector (DV, the induced astigmatic change [by magnitude and axis] that would enable the initial surgery to achieve intended target) was 0.93D; median anticipated DV with a non-toric IOL was 2.38D. One eye exhibited 0.75D residual astigmatism, compared to 3.8D anticipated residual astigmatism with a non-toric IOL. 100% of respondents reported satisfaction of ≥ 6/10, with 37.84% of respondents entirely satisfied (10/10). 17 patients (38.63%) reported no symptoms of dysphotopsia (dysphoptosia score 0/10), only 3 respondents (6.8%) reported a clinically meaningful level of dysphotopsia (≥ 4/10). Mean post-operative NEI VF-11 score was 0.54 (+/-0.83; scale 0 - 4).

CONCLUSION

Use of a toric IOL to manage astigmatism during cataract surgery results in less post-operative astigmatism than a non-toric IOL, resulting in avoidance of unacceptable post-operative astigmatism.

Comparison of two different methods of preoperative marking for toric intraocular lens implantation: bubble marker versus pendulum marker

AIM

To compare the accuracy of two different methods of preoperative marking for toric intraocular lens (IOL) implantation, bubble marker versus pendulum marker, as a means of establishing the reference point for the final alignment of the toric IOL to achieve an outcome as close as possible to emmetropia.

METHODS

Toric IOLs were implanted in 180 eyes of 110 patients. One group (55 patients) had preoperative marking of both eyes done with bubble marker (ASICO AE-2791TBL) and the other group (55 patients) with pendulum marker (Rumex(®)3-193). Reference marks were placed at 3-, 6-, and 9-o'clock positions on the limbus. Slit-lamp photographs were analyzed using Adobe Photoshop (version 7.0). Amount of alignment error (in degrees) induced in each group was measured.

RESULTS

Mean absolute rotation error in the preoperative marking in the horizontal axis was 2.42±1.71 in the bubble marker group and 2.83±2.31in the pendulum marker group (P=0.501). Sixty percent of the pendulum group and 70% of the bubble group had rotation error ≤3 (P=0.589), and 90% eyes of the pendulum group and 96.7% of the bubble group had rotation error ≤5 (P=0.612).

CONCLUSION

Both preoperative marking techniques result in approximately 3 of alignment error. Both marking techniques are simple, predictable, reproducible and easy to perform.

An easy and practical method for toric intraocular lens implantation: marking corneal astigmatic axis at slit-lamp

The objective of this study was to present a practical method of marking the corneal astigmatic axis for the patient sitting at the slit-lamp before toric intraocular lens (IOL) implantation. Eighteen eyes of 18 patients, who underwent uncomplicated phacoemulsification, with an implantation of Acrysof toric IOL were included. We marked the astigmatic axis while the patient sitting at the slit-lamp before surgery. The patient was asked to look at a distant target at head height with the fellow eye. Using the rotator switch, the slit light of the slit-lamp was just turned on to the steep astigmatic meridian in the orthograde position. Then, two tips of the astigmatic meridian were marked with a marking pen, where the slit light crossed at the limbus 180° away. Preoperative corneal and postoperative refractive astigmatism values were compared. Uncorrected and corrected postoperative visual acuities (UDVA and BCVA) and IOL rotations at early and late periods were noted. The mean age and mean follow-up were 63.6 ± 14.6 years and 9.4 ± 5.3 months (range 3-16 months), respectively. Mean postoperative UDVA and BCVA at Snellen chart were 0.62 ± 0.21 and 0.82 ± 0.13, respectively. Mean preoperative keratometric and mean postoperative refractive astigmatism values were 2.48 ± 0.87 D and 0.66 ± 0.48 D, respectively. Reduction of astigmatism was significant (p < 0.01). The mean rotation at 1 week and that at last follow-up were 2.1° ± 3.1° and 2.3° ± 3.0°, respectively. Marking corneal astigmatic axis at slit-lamp is a simple and effective method in toric intraocular lens implantation. Surgeon does not need additional instrument except a slit-lamp and a marking pen, and can complete the marking task in just one setting.

Intraocular lens alignment methods

PURPOSE OF REVIEW

This article reviews current concepts in intraocular lens alignment strategies to maximize intraocular lens (IOL) positioning.

RECENT FINDINGS

A variety of strategies has been developed to maximize toric IOL position, including preoperative calculators to determine the appropriate IOL power and orientation, intraoperative alignment devices, and postoperative software to determine if IOL rotation would be beneficial for refractive outcomes.

SUMMARY

The combination of using multiple toric IOL calculators and intraoperative alignment devices has improved toric IOL outcomes. The relationship of the posterior corneal power and its effect on outcomes remains to be fully elucidated. Postoperative IOL rotation may be necessary even when the IOL is aligned as planned because of surgically induced astigmatism.

Comparison of clinical outcomes among 3 marking methods for toric intraocular lens implantation

PURPOSE

To compare the clinical outcomes of 3 marking methods for toric intraocular lens (IOL) implantation in cataract patients.

METHODS

This study included 48 eyes of 48 cataract patients who underwent cataract surgery with toric IOL implantation. The rotational errors of 3 marking methods-the iris pattern marking method (iris pattern group), the pendulum marking method (pendulum group), and the 3-point marking method (3-point group)-were assessed.

RESULTS

The respective rotational errors were 4.0° ± 3.1° (mean ± SD), 5.3° ± 4.1°, and 7.3° ± 6.0°. The iris pattern group had significantly (P = 0.048) smaller rotational errors than did the 3-point group; no significant difference was found between the iris pattern and pendulum groups. However, the differences in postoperative uncorrected distance visual acuity and astigmatism did not reach significance among the 3 groups.

CONCLUSION

The refractive and visual results of toric IOL implantation using the 3-point marking method were comparable to the other methods evaluated in this study, although the accuracy of the axis alignment of the toric IOLs was significantly lower than that obtained with the iris pattern method.