Comparative analysis of visual outcomes following small-incision lenticule extraction with or without cyclotorsion compensation in eyes with high astigmatism: Contralateral eye study

Purpose: To compare the visual outcomes in patients undergoing small?incision lenticule extraction (SMILE) for correction of myopic astigmatism (??1.50 D) with or without manual cyclotorsion compensation. Methods: A prospective, double?blinded, randomized, contralateral study was conducted in the refractive services of a tertiary eye care center. Eligible patients with bilateral high myopic astigmatism (?1.5 D) and intraoperative cyclotorsion (?5°) undergoing SMILE between June 2018 and May 2019 were included. Cyclotorsion compensation was performed using triple centration method before femtosecond laser delivery. Uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively) measurement, manifest refraction, slit?lamp biomicroscopy, and corneal tomography were performed preoperatively and at 1 and 3 months’ postoperative visit. Astigmatic outcomes were analyzed using Alpins criteria. Results: A total of 30 patients (60 eyes) were included in this study. The patients underwent bilateral SMILE surgery, with manual cyclotorsion compensation in one eye (CC group, n = 30 eyes) and no cyclotorsion compensation in the other eye (NCC group, n = 30 eyes). Preoperative astigmatism and intraoperative cyclotorsion were ?2.0 D and 7.03° ± 1.06° (CC) and ?1.75 D and 7.24° ± 0.98° (NCC) (P = 0.472 and 0.240, respectively). No significant differences were noted in mean refractive spherical equivalent (MRSE), UDVA, CDVA, and refractive error between the two groups at 3 months’ postoperative visit. Astigmatic outcomes measured using Alpins criteria demonstrated no significant difference between the two cohorts. Conclusion: The cyclotorsion compensation technique provided no additional advantage in terms of astigmatic outcomes or postoperative visual quality, in eyes with high preoperative astigmatism and intraoperative cyclotorsion.

Meta-analysis of the efficacy of small incision lenticule extraction for astigmatism correction after cyclotorsion compensation / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To compare the efficacy of and without small incision lenticule extraction(SMILE)with cyclotorsion compensation for astigmatism correction.METHODS: PubMed, Web of Science, EMBASE, Cochrane and CNKI, VIP, CBM, and Wan Fang Data were searched for clinically controlled studies from January 2010 to August 2022, including an experimental group with cyclotorsion compensation during SMILE and a control group without cyclotorsion compensation during SMILE. After literature screening, quality evaluation, and data extraction by two researchers independently, the Meta-analysis of uncorrected distance visual acuity(UDVA), residual astigmatism, vector analysis indicators for measuring the astigmatism correction including absolute value of angle of error(|AE|)and magnitude error(ME), and post-operative total higher order aberrations, spherical aberration and coma was carried out with Stata 16.0 software.RESULTS: Seven studies with a total of 846 eyes(442 in the experimental group, 404 in the control group)were finally included. The Meta-analysis showed that there were significant differences in the percentage of eyes with residual astigmatism ≥1.00D(OR=0.17, 95%CI: 0.06～0.49, P<0.01), |AE|(WMD=-1.56, 95%CI: -2.68～-0.45, P<0.01), the coma(WMD=0.06, 95%CI: -0.08～-0.04, P<0.01), and the total higher order aberrations(WMD=-0.04, 95%CI: -0.06～-0.02, P<0.01). However, there were no differences in the postoperative UDVA(WMD=0.00, 95%CI: -0.02～0.01, P=0.54), residual astigmatism(WMD=0.08, 95%CI: -0.02～0.18, P=0.10), ME(WMD=-0.01, 95%CI: -0.14～0.12, P=0.85), and the spherical aberration(WMD=0.03, 95%CI: -0.07～0.13, P=0.52).CONCLUSION: Cyclotorsion compensation in SMILE can reduce the angular error caused by eye rotation during astigmatism correction. It also decreases postoperative residual astigmatism. Overall, the SMILE with cyclotorsion compensation is superior in clinical efficacy of the precise correction of astigmatism.

Effects of postural changes in eye cyclotorsion and pupil centroid shifts on corneal refractive surgery / 中华实验眼科杂志

The main purpose of corneal refractive surgery is not only to improve vision, but also to improve visual quality, which is a higher level of visual ability except vision.At present, most corneal refractive surgeries take the pupil center as the center of examination and treatment, since changes in body position may result in pupil centroid shifts and eye cyclotorsion and postoperative visual quality can be affected by undercorrected astigmatism, induced astigmatism and increased high order aberration that results from eccentric cutting occurring during corneal refractive surgery.The measurement of centroid shifts and eyeball rotation that can be attributed to the change of body position guiding the design of surgery is of great significance to enhance the accuracy of pupil center positioning, improve the safety of surgery and promote the postoperative visual quality.In this article, the relevant literature on the measurement methods of the pupil centroid shifts and ocular cyclotorsion, pupil centroid shifts and ocular cyclotorsion measured by iris recognition technology in response to changes in body position, and the effects of posture-related pupil centroid shifts and ocular cyclotorsion during refractive surgery on postoperative visual quality (postoperative astigmatism, aberration, and modulation transfer function) were reviewed.

Comparison of torsional amplitudes between emmetropes and myopes using after-image slides

Purpose: To describe the influence of corrected refractive error on measured torsional fusional amplitudes (TA) by comparing the TA between emmetropes and spectacle corrected myopes, using the after-image slides of the synoptophore, as targets. Methods: Fifty emmetropes (Group I) and 50 myopes (Group II) with best-corrected acuity of 6/6 in each eye were included in the study. Near point of convergence (NPC), near point of accommodation (NPA), and horizontal fusional amplitudes (HFA) were assessed in all the subjects. After-image slides, both horizontally aligned, were used as targets (without the bright flashes). One of the slides was rotated inwards, till cyclo-diplopia was reported by the subject; the procedure was repeated with the slide rotated outwards. The sum of the two readings was taken as TA. NPC, NPA, HFA, and TA were analyzed. Results: There was no significant difference in the NPC, NPA, and HFA between the two groups. The emmetropic subjects had significantly better torsional amplitude (8.4 ± 1.4 degrees) compared to myopes (7.7 ± 1.5 degrees, P = 0.03). We postulate that this difference may be due to perceived image minification, which brings the edges of retinal image of the targets closer to the fovea, thus rendering the myopes lesser tolerant to cyclodiplopia than emmetropes. Conclusion: Refractive error, corrected with spectacles, influences the measured TA. Myopic subjects have lesser torsional fusional amplitude than emmetropes.

Analysis of the direction and degree of static cyclotorsion component and dynamic cyclotorsion component in corneal refractive surgery / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To analyze the direction and degree of static cyclotorsion component (SCC) and dynamic cyclotorsion component (DCC) in corneal refractive surgery. METHODS:Retrospective analysis. Totally 130 patients (260 eyes) with corneal refractive surgery in our hospital, according to the operation method were divided into femtosecond laser - assisted laser in situ keratomileusis (FS-LASIK) group and T-photorefractive keratectomy (T-PRK) group, the differences of the parameters of the two groups were compared; the differences of SCC success rate, SCC, DCC, and the eyeball rotation direction were compared between the two groups; correlation analysis on SCC, DCC and the parameters of postoperative patients were performed. RESULTS: High order aberrations and spherical aberration in the T-PRK group after operation was higher than those of FS - LASIK group, and the difference was statistically significant (P0. 05); DCC in T-PRK group (2. 86o±1. 14o) was higher than that of FS-LASIK group ( 2. 17o ± 1. 09o), and the difference was statistically significant (P0. 05). The SCC of subjects in operation was positively correlated with UCVA, BCVA, spherical equivalent refraction and high order aberrations ( P CONCLUSION: The success rate of SCC in T - PRK surgery is higher than that in LASIK, DCC in T - PRK surgery is higher than that in LASIK, and accurate measurement of SCC and DCC can be effective to compensate for it.

Influencing factors for eye cyclotorsion and pupil centroid shift during LASIK / 眼科

Objective To investigate the influencing factors for eye cyclotorsion and pupil centroid shift during LASIK.Design Non-controlled retrospective case series.Participant 131 patients (262 eyes) with myopia received bilateral LASIK.Methods Eye cy- clotorsion and pupil centroid shift were measured with Custom Vue~(TM) software during operation and compared with age,gender,right or left eye,flap-making method,spherical equivalent (SE),pupil diameter before and during operation.Main Outcome Measures The de- gree of eye cyclotorsion and distance of pupil centroid shift during LASIK.Results The mean eye cyclotorsion during LASIK was 3.07??2.07?(0?-8.6?).The mean pupil centroid shift was 0.33?0.14 mm (0.04-0.51 mm).The eye cyclotorsion was relevant to preoperative pupil size,difference of pupil size before and during operation,and preoperative SE (r=0.188,0.156,0.130,all P7.0 mm was higher than that of with pupil diameter≤7.0mm (3.35??2.17?,2.71??1.89?,P=-0.014).Pupil centroid shift was higher in fight eyes than that in left eyes (0.39?0.12 mm,0.28?0.13 mm,P=0.000).Conclu- sion Eye cyclotorsion and pupil centroid shift during LASIK can be measured with Custom Vue~(TM) system.The eye cyclotorsion may be influenced by the preoperative pupil size.The pupil centroid during LASIK was more significant in the right eyes than in the left eyes.

Position-induced Cyclotorsion under Monocular Fixation

PURPOSE: To determine whether cyclotorsion occurs when a patient moves from the seating to supine position fixating with one eye. METHODS: The axis of astigmatism was measured with the handheld automated refractometer (Retinomax K-plus, Nikon, Japan) in 33 eyes having more than -1.0D cylinder in seated and supine positions under monocular fixation. RESULTS: There was a cyclotorsional deviation in 30 eyes (90.90%). Excyclotorsion was shown in 22 eyes (66.67%) and incyclotorsion in 8 (24.24%). Seventeen eyes (51.50%) had a torsional deviation less than 4 degrees, 5 eyes (15.15%) from 5 to 6 degrees, 7 eyes (21.21%) from 7 to 14 degrees and one eye greater than 15 degrees. CONCLUSIONS: Positionally induced cyclotorsion occurs under fixation with one eye simulating refractive surgery. Surgeons should therefore make an effort to align the wavefront measurement to the ablation onto the cornea.

The Range of Ocular Torsion in Mass Screening

PURPOSE: To determine the range of cyclotorsion in the mass screening of patients by studying the spatial relationship between the optic disc and the fovea. METHODS: We examined the horizontal and vertical distances from the center of the optic disc to the fovea using the fundus photographs of 249 subjects (498 eyes) without a past history of strabismus through mass screening and then calculated the optic disc-foveal angle. We studied the differences in all the measured parameters between the right and left eyes and between men and women. RESULTS: The horizontal distance from the center of the optic disc to the fovea was 2.59+/-0.26 DD (disc diameter) in the right eye and 2.58+/-0.27 DD in the left eye. The mean horizontal distance was 2.59+/-0.26 DD. The vertical distance from the center of the optic disc to the fovea was 0.28+/-0.14 DD in the right eye and 0.30+/-0.13 DD in the left eye. The mean vertical distance was 0.29+/-0.14 DD. The calculated disc-foveal angle was 6.26+/-2.98 degrees in the right eye and 6.69+/-2.84 degrees in the left eye (mean, 6.50+/-2.92 degrees). There were no significant differences between the right and left eyes or between males and females. The 95% range of the location of the fovea was from 0.01 DD to 0.57 DD inferior to the optic disc center. CONCLUSIONS: We concluded that the clinical location of the fovea, as measured in the mass screening, extends from the center of the optic disc to the lower edge of the optic disc.

The Torsional Status of Normal Koreans

PURPOSE: We propose the criteria of cyclotorsion in patients of various torsional strabismus by describing the normal range of torsional state in normal Koreans. METHODS: Included were 296 eyes of 148 persons with no strabismus history and normal cyclofusion in Bagolini striated glass test from October 2003 to April 2004. Double Maddox rod test was done to detect subjective torsional state. Objective torsional state was obtained from fundus photography. Horizontal and vertical distance from the center of the optic nerve head to the fovea in fundus photographs was measured using computer program and the optic nerve head to foveal angle from horizontal line was calculated. RESULTS: By the fundus photograph, we determined the normal angle of the fovea from horizontal line crossing the center of the optic nerve head as 6.42 degrees and 0.30 disc diameter below the center of the optic nerve head. The mean difference in the height of the fovea was 0.16 disc diameter. In the double Maddox rod test, the mean angle of the right eye was -0.59 +/- 3.63 degree and that of the left eye was -0.99 +/- 3.91 degree. There was no specific relationship between the angle of double Maddox rod and the foveal angle measured from fundus photograph. CONCLUSIONS: In normal Koreans, the normal foveal angle from horizontal line is estimated to be 6~7 degrees with the normal range being about 0~13 degrees. That is very similar to the results of Bixenman and Von Noorden, reported in 1982.

Evaluation of the Ocular Cyclotorsion During Laser in Situ Keratomileusis

PURPOSE: To evaluate the presence, degree and direction of ocular cyclotorsion in eyes undergoing laser in situ keratomileusis (LASIK). METHODS: We measured the presence, degree and torsional direction of 161 eyes of 88 patients who underwent LASIK for myopic and hyperopic astigmatism with LADARVision 4000 excimer laser (Alcon Summit Autonomous). Preoperatively, each eye was marked at the 3, 9-o'clock conjunctival area with marking pen under the slit lamp observation with a horizontal beam while the patient was seated upright. After lifting of corneal flap and acquiring of LADARVision4000 auto-tracking system, the presence and torsional direction was confirmed on the computer monitor and the rotational deviation degree was measured from horizontal reference line by software program built in laser computer system before the laser exposure. RESULTS: There was a cyclotorsional deviation in 144 eyes (89%). The counter-clockwise rotation was shown in 99 eyes (69%) and clockwise rotation in 45 eyes (31%). Mean ocular torsional misalignment was 3.8 +/- 2.9 degrees (right eye; 4.7 +/- 2.9 degrees, left eye; 3.5 +/- 2.4 degrees). 85 eyes (53%) had a torsional deviation less than 4 degrees and 5 eyes (3%) had a deviation greater than 10 degrees. CONCLUSIONS: A misalignment of astigmatism axis caused by ocular cyclotorsion was known as a reason of astigmatism undercorrection during LASIK. Thus, preoperative marking on conjunctiva and cyclotorsional axis alignment before laser treatment may reduce the incomplete astigmatism correction in LASIK.

Digital Videographic Measurement of Cyclotorsional Angle in Normal Human Eye

The eyeball movement is classified into horizontal, vertical movement and cyclotorsion. The cyclotorsion has been known to be induced by two oblique and vertical rectus muscles. But there have been few precise methods for the measurement of cyclotorsion. So, we tried to find the precise method for the measurement of cyclotorsion with digital videographic method. Sixteen normal volunteers were included in this study, who had no eyeball movement disorders. For the measurement of cyclotorsion that followed by head tilt, the volunteers haed was tilted to fifteen, thirty, forty-five and sixty degree to the left and the partially compensated counter torsion was recorded with video camera. The movement was analyzed with digitally using IBM clone computer. The linear regression equation, between the head tilt and cyclotorsion was Y=2.019 X + 22.2280 (Y=head tilt, X=cyclotorsion) and coefficient of variation(%) was 0.88%. Therefore, our videographic method for the measurement of cyclotorsion was relatively precise and may be applied in the measurement of ocular torsion.

A New Computerized Cyclotorsion Test

Cyclotorsion is a well known feature of oblique muscle disorders in the eye, usually associated with vertical and/or horizontal strabismus. Its presence and amount of deviation are not easy to detect, therefore requiring more sensitive and accurate tests. But the present measuring devices such as the double Maddox rod test and Bagolini lens test, known to be the standard tests used for cyclodeviation in these days have some limitations. We developed a new computerized test for the measurement of cyclodeviation that remedies the weak points of the existing tests. The cyclotorsion at any eye position can be measured accurately. It is based on subjective response of the examinee. The examinee wears the red-green glasses and identifies when the two lines on the monitor are parellel while the examiner rotates the red or green line with keystroke of computer keyboard. It is possible to test the deviations in all directions. We hope this computerized application will be accepted widely as an useful subjective torsion test in near future.