Measurement of change in angle kappa and its correlation with ocular biometric parameters pre- and post-phacoemulsification

Purpose: Angle kappa has been considered to play a role in causing glare and haloes despite accurate centration during implantation of multifocal intraocular lenses following phacoemulsification. There is a lack of substantial data regarding whether angle kappa is a constant entity or changes following ocular surgical procedures. To answer this question, in this prospective observational study, we measured change in angle kappa following phacoemulsification, and studied the ocular biometric parameters correlating with this change. Methods: Angle kappa was measured objectively using synoptophore. Ocular Biometric parameters (Anterior Chamber Depth, Corneal White?to?White measurement, Lens Thickness, and Axial Length) using LenStar LS 900 Haag Streit Anterior Segment imaging system. outcome measures were a quantitative change in angle kappa from the preoperative value by one degree or more and observation of correlation between change in angle kappa and ocular biometric parameters. The Wilcoxin Signed Rank Test was used to determine the difference between pre?operative and post?operative measurements for angle kappa. A p?value of less than 0.05 was considered statistically significant. Pearson's correlation coefficient was employed to find the relationship between preoperative ocular biometric parameters and a change in angle kappa. A linear regression model was used to derive an equation considering corneal white?to?white measurement as the predictor and change in angle kappa as the outcome measure. Results: A significant change in angle kappa was recorded, and a significant correlation was found with corneal white to white measurements. This change could be predicted preoperatively, for a known corneal white to white measurement using the standard equation y=mx+c. Conclusion: This study explains the possible cause of dissatisfaction among seemingly ideal patients who undergo multifocal IOL implantation and the potential for better decision? making during patient selection for multifocal IOL implantation.

Clinical application and research progress of angle Kappa in ophthalmic surgery / 国际眼科杂志(Guoji Yanke Zazhi)

The human eye has various axes and angles, of which the angle Kappa is an important indicator of the centrality of the human eye and is widely used in ophthalmic surgery. Proper preoperative evaluation and application of the angle Kappa facilitated the achievement of optimal postoperative visual quality. Chord mu is a new term that has emerged recently to better express the angle Kappa. The two concepts are not well understood clinically, limiting their usefulness. Therefore, to better understand the angle Kappa and chord mu, the definitions and connections between them are presented separately in this paper. Meanwhile, the application of angle Kappa in strabismus surgery was summarized, the method for compensating large angle Kappa in corneal refractive surgery and the clinical significance of angle Kappa in predicting postoperative centrality of multifocal intraocular lens(MIOL)in phacoemulsification combined with MIOL implantation were discussed, with a view to providing references for clinical work.

Comparative study of angle Kappa and angle Alpha measured with three instruments before age-related cataract surgery / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To compare the consistency of angle Kappa and angle Alpha in age-related cataract eyes with three different instruments. <p>METHODS: Prospective study. Totally 60 eyes of 30 patients with age-related cataract from December 1 to December 30, 2020 were collected. After adapting to 10min in the darkroom before operation, the angle Kappa and angle Alpha were measured with iTrace, Lenstar 900 and IOL Master 700 biometric instruments, respectively. The difference and consistency of the three instruments were analyzed.<p>RESULTS: The results of angle Kappa measurement of iTrace, Lenstar 900 and IOL Master 700 were 0.25±0.13, 0.19±0.11, 0.21±0.11mm(F=1.903, P=0.155). The results of angle Alpha measurement of the three instruments were 0.31±0.11, 0.36±0.16, 0.36±0.14mm(F=2.999, P=0.052). The proportion of angle Kappa of the three instruments greater than 0.5mm is 3%, 2% and 2%, and the proportion of angle Alpha greater than 0.5mm is 5%, 15% and 22%. The distribution of angle Kappa and angle Alpha is mainly in the temporal side of both eyes. Compared with the angle Kappa distribution of both eyes, the temporal distribution ratio of angle Alpha is higher, and the distribution of angle Alpha measured by iTrace is closer than that of Lenstar 900 and IOL Master 700 along the horizontal line. There was a positive correlation between angle Alpha and angle Kappa measured by each instrument(r=0.2941, 0.4082, 0.5137; P=0.0226, P=0.0012, P<0.0001). The consistency of angle Kappa measurement results of three kinds of instruments was good, while that of angle Alpha measurement results was poor.<p>CONCLUSION: When making the decision of multifocal intraocular lens implantation before cataract surgery, the consistency of angle Alpha measured by Lenstar 900, IOL Master 700 and iTrace is poor, so it is necessary to compare and refer to the results of various instruments in clinical application. When the data of angle Alpha could not be obtained before cataract surgery, the angle Kappa measured with the three instruments could provide useful information for multifocal IOL implantation decision.

Application of Itrace visual function analyzer in the evaluation of regional refractive multifocal intraocular lens / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To evaluate the centration of the SBL-3 multifocal intraocular lens, the size of the distant and near power zone in the pupil area and the area of the visual axis using Itrace visual function analyzer. <p>METHODS: Retrospective case study. From January 2018 to January 2019, 51 eyes of 36 patients underwent phacoemulsification cataract combined with regional refraction multifocal intraocular lens implantation at Beijing Aier-Intech Eye Hospital were enrolled. The centration, visual axis, angle α, angle Kappa and the orientation of the intraocular lens measured by Itrace were used to calculate the position of the visual axis in the intraocular lens and the changes in the proportions of the distant and near power zones in the pupil area. <p>RESULTS: The centration(R)of intraocular lens is 0.217±0.09mm. The distribution of the visual axis in the intraocular lens is 0.217±0.09mm. The visual axis is evenly distributed in the distant and near power zones. There was no statistical significance between the two groups with postoperative visual acuity ≥0.8 and <0.8(<i>P</i>>0.05). The size of the angle Kappa is 0.187±0.079mm. The displacement of angle Kappa on the y-axis is 0.10±0.06mm. There was no statistical significance between the changes in the pupil size of distant and near power zones in the pupil area caused by the deviation of the pupil and the postoperative visual acuity ≥0.8 and <0.8(<i>P</i>>0.05). <p>CONCLUSION: The intraocular lens centration and axial data measured by the Itrace visual function analyzer can be used to estimate the area where the visual axis is located and the size of the distant and near power zones in the pupil area, thereby assisting in evaluating the postoperative visual quality of the regional refraction multifocal intraocular lens implanted after cataract surgery.

Changes of angle Kappa and corneal morphology changes in myopic patients after Sub / 中南大学学报(医学版)

OBJECTIVES@#To investigate angle Kappa and diopter distribution in myopic patients and the changes of angle Kappa and corneal morphology after Sub-Bowman-Keratomileusis (SBK), and to analyze the effects of the surgery on corneal morphologic changes and the patients' near fixation characteristics.@*METHODS@#The clinical data of 134 myopic patients (268 eyes) undergoing SBK from August 2015 to August 2016 were retrospectively analyzed. Angle Kappa, corneal curvature in the central corneal region of 3 mm, and post-corneal Diff value were measured by Orbscan IIz Corneal Topography System before operation, 1 month and 6 months after operation. According to the values of angle Kappa before SBK, the patients were divided into 2 groups: the large K group (angle Kappa≥5°, 71 eyes) and the small K group (angle Kappa<5°, 197 eyes). Correlation analysis of the factors influencing angle Kappa at 6 months after operation was performed.@*RESULTS@#In the large K group, angle Kappa was (5.67±0.65)°, spherical equivalent was (-4.84±2.32) D, and angle Kappa was decreased after operation (both @*CONCLUSIONS@#The angle Kappa is decreased in low-moderate myopia patients with large angle Kappa, while is increased in high myopia patients with small angle Kappa after SBK. Myopia patients after SBK will look for the new balance of the binocular accommodation and vergence function for improving the comfort in the near-work situations.

Analysis of Positional Relationships of Various Centers in Cataract Surgery

PURPOSE: To analyze the positional relationships of various centers in patients undergoing femtosecond laser-assisted cataract surgery (FLACS). METHODS: The locations of the pupil center (PC), limbal center (LC) and lens center were analyzed in each patient using optical coherence tomography during FLACS in 35 eyes of 35 patients. Using the preoperative corneal aberrometry device, angle kappa and the location of the visual axis (VA) were calculated. After acquiring the relative horizontal and vertical coordinates of each center, the distance and location among each center were compared. The relative location and distance of each center were statistically evaluated. RESULTS: The distance from the PC to the lens center was 0.147 ± 0.103 mm, that from the LC to the lens center was 0.205 ± 0.104 mm, and that from the VA to the lens center was 0.296 ± 0.198 mm. The distance from the PC to the VA was 0.283 ± 0.161 mm, that from the LC to the VA was 0.362 ± 0.153 mm, and that from the lens center to the VA was 0.296 ± 0.198 mm. Among the various centers, the PC was the closest to the lens center, whereas the LC and VA were the farthest. Based on the location of the lens center, the PC, LC, and VA exhibited differences in the X and Y coordinate positions (vertical p = 0.004, horizontal p < 0.001). Among them, the LC was significantly inferior and temporal compared to the PC (vertical p = 0.026, horizontal p = 0.023). Based on the location of the VA, the respective locations of the PC, LC and lens center in two dimensions did not significantly differ (vertical p = 0.310, horizontal p = 0.926). CONCLUSIONS: This study demonstrated the positional and locational relationships between the centers regarding FLACS. The locations of the PC, LC, and VA were different from the lens center with the PC being the closest. Surgeons should be aware of these positional relationships, especially in FLACS.

Distribution of kappa angle measured by iTrace in a population of China / 眼科新进展

Objective To explore the distribution of the kappa angles in population of Tianjin,China and the differences in kappa angle measured by iTrace and Pentacam.Methods A retrospective research was conducted.The kappa angle of 4815 patients (4815 eyes) and kappa angle was measured and recorded through iTrace from June 2014 to December 2016 in Tianjin Medical University Eye hospital and meanwhile,the kappa angle of 10α1 eyes selected from the total sample was also measured with pencatam.Results The kappa angle was (0.47 ± 0.48) mm,and patients with kappa angle ＜ 0.50 mum accounted for 70.07％.There was no significant difference in kappa angle of different genders (P =0.090).Right eyes had larger kappa anger than left eyes,approaching significant difference (P =0.000).Kappa anger was slightly correlated with age (r =0.129,P ＜ 0.05).And kappa angle measured by iTrace was significantly smaller than that measured by Pentacam (P =0.000).Conclusion The kappa angle in the population is non-normal and most of them are less than 0.5 mm.There is significant difference between the kappa angle measured by iTrace and pentacam.

Research progress of angle Kappa in refractive surgery / 眼科新进展

It is great significant for angle Kappa in refractive surgery,and it has been a consensus to adjust angle Kappa,especially in the correction of hyperopia corneal refractive surgery.The population distribution of angle Kappa is influenced by race,age,gender,eye,refractive status,ocular biometry and different precision measuring instruments,and it may also vary with the change of position or pupil size and other factors.At present,fewer researches on visual quality and treatment have been conducted in femtoseeond laser and cataract phacoemulsification combined with multifocal intraocular lens implantation in eyes with large angle Kappa,so more large sample researches are needed to perform in order to provide evidences for clinicians.

Measurement of Angle Kappa Using Ultrasound Biomicroscopy and Corneal Topography

PURPOSE: To introduce a new convenient and accurate method to measure the angle kappa using ultrasound biomicroscopy (UBM) and corneal topography. METHODS: Data from 42 eyes (13 males and 29 females) were analyzed in this study. The angle kappa was measured using Orbscan II and calculated with UBM and corneal topography. The angle kappa of the dominant eye was compared with measurements by Orbscan II. RESULTS: The mean patient age was 36.4 ± 13.8 years. The average angle kappa measured by Orbscan II was 3.98°± 1.12°, while the average angle kappa calculated with UBM and corneal topography was 3.19°± 1.15°. The difference in angle kappa measured by the two methods was statistically significant (p < 0.001). The two methods showed good reliability (intraclass correlation coefficient, 0.671; p < 0.001). Bland-Altman plots were used to demonstrate the agreement between the two methods. CONCLUSIONS: We designed a new method using UBM and corneal topography to calculate the angle kappa. This method is convenient to use and allows for measurement of the angle kappa without an expensive device.

Analysis of angle Kappa variation in corneal refractive surgery under light and dark conditions / 国际眼科杂志(Guoji Yanke Zazhi)

?AIM:To observe the values and changing rules of angle Kappa in corneal refractive surgery under light and dark conditions.?METHODS:Two hundred and thirty-four eyes of 118 patients for corneal refractive surgery were enrolled for this study.Pupil diameters and angle Kappa values under light and dark conditions were measured by Keratron Scout corneal topography.?RESULTS: There were significant differences in pupil diameters between light and dark conditions (P<0.01). More angle Kappa of both eyes distributed in the superior nasal quadrant under light conditions, and more angle Kappa distributed in the superior temporal quadrant under dark conditions.The differences of horizontal and vertical offsets of angle Kappa under two conditions were statistically significant (P<0.01).?CONCLUSION: The changes of pupil diameters in light and dark conditions could affect angle Kappa and then affect the accuracy of corneal refractive surgery centered on angle Kappa.

The Angle Kappa in Dominant and Non-Dominant Eye

PURPOSE: To evaluate differences between dominant and non-dominant eyes by analyzing angle kappa in dominant and non-dominant eyes. METHODS: Fifty-seven subjects who had best corrected visual acuity 20/20 in the better-seeing eye and no underlying ocular disease were recruited. Ocular dominance was determined using the hole-in-the-card test. Corneal topography, refractive error, intraocular pressure (IOP), and axial length were evaluated in both eyes. RESULTS: On corneal topography examination, the angle kappa and white-to-white measurements were significantly smaller in the dominant eye than the non-dominant eye (p = 0.013 and p = 0.045, respectively). However, no significant differences in sim K's' astigmatism (p = 0.210), central corneal thickness (p = 0.533), and anterior chamber depth (p = 0.216) were observed. In addition, cylindrical powers of the subjects measured by autorefraction (AR) were significantly lower in the dominant eye (p = 0.026); however no differences in spherical equivalent measured by AR (p = 0.061), IOP measured using pneumonic tonometer (p = 0.536), or axial length measured using laser biometry (p = 0.093) were observed. CONCLUSIONS: In this study, we found the angle kappa a new factor in determining the dominant and non-dominant eye. Difference in axial length and spherical equivalent between dominant and non-dominant eye may be associated with the difference in angle kappa.

Weight analysis of influencing factors of human angle Kappa / 中华实验眼科杂志

Background Angle Kappa is the angle between the pupillary axis and visual axis,and it is a major consideration in corneal refractive surgery and strabismic surgery.Researches showed that age and refractive status affect angle Kappa value,and additionally,the measuring results of angle Kappa are associated with instruments.Objective This study was to investigate and weight the influences of axial length,anterior chamber depth and corneal curvature to angle Kappa.Methods A cross-sectional study was designed.Fifty health volunteers were included from Dec 2009 to Aug 2010,with the age of 18-38 years and average diopter of-1.0 D and best corrected visual acuity of 1.0.The horizontal and vertical angle Kappa was binocular measured with a testing machine designed by laboratory of School of Optometry & Ophthalmology Wenzhou Medical University.IOLMaster was employed to measure the ocular axial length,anterior chamber depth and corneal curvature radius.A multiple linear regression model was established to analyze the influences of axial length,anterior chamber depth and corneal curvature radius to angle Kappa.Results An efficacious regression equation was established as Y =15.554-0.587X1+0.724X2+ 0.232X3 with the independent variables as axial length(X1),anterior chamber depth (X2),corneal curvature (X3) and dependent variable as horizontal angle Kappa (Y) (R =0.788,R2 =0.621,P =0.000).Horizontal angle Kappa showed a negative correlation with axial length (b1 =-0.587,β1 =-1.002,P =0.000) and a positive correlation with anterior chamber depth (b2 =0.724,β32 =0.296,P =0.030).No significant correlation was found between corneal curvature radius and horizontal angle Kappa (b3 =-0.232,β3 =-0.068,P=0.338).A new regression equation was Y =14.235-0.622X1 + 0.824X2 after removed the corneal curvature variable (R =0.786,R2=0.618,P =0.000),with a negative correlation between horizontal angle Kappa and axial length (b1 =-0.622,β1 =-1.062,P＜0.05) or positive correlation between horizontal angle Kappa and the anterior chamber depth (b2 =0.824,β2 =0.337,P＜0.05).In addition,a multiple linear regression equation among 3 independent variables and dependent variable of vertical angle Kappa was Y =0.492-0.020X1 +0.038X2 +0.089X3 (R =0.436,R2 =0.191,P =0.000).However,no significant correlations were seen between vertical angle Kappa and axial length,anterior chamber depth or corneal curvature radius (all at P ＞ 0.05).Conclusions Ocular axial length and anterior chamber depth have an obvious influence to horizontal but not vertical angle Kappa.Axial length appears to have more influence to horizontal angle Kappa than anterior chamber depth.

Difference analysis of Orbscan Ⅱz corneal topography in anisometropic amblyopes:a contralateral eye study / 中华实验眼科杂志

Background The characteristics of anisometropic amblyopia in ocular morphology are becoming a hot topic in amblyopia field.And the interocular difference in corneal parameters of anisometropic amblyopia is to be understood here.Corneal topography is a non-invasive method for in vivo corneal examination and applied in our study.Objective This study was to investigate the interocular difference of corneal topography in anisometropic amblyopic patients Methods This was a serial cases observation.Thirty anisometropic amblyopes were selected in Center for Optometry and Visual Science,People's Hospital of Guangxi Zhuang Autonomous Region.The patients were divided into amblyopic eye group and fellow eye group based on the best corrected distance visual acuity.Corneal topography was examined with Orbscan Ⅱ z,and corneal morphological parameters such as Diff values of the anterior and posterior corneal surface,Sim K 's astigmatism,Kmax,angle kappa and central corneal thickness (CCT) were measured.The interocular differences in these parameters were evaluated by paired t test,and the correlations in these parameters between the amblyopic eyes and the fellow eyes were analyzed by Pearson linear correlation and simple regression analysis.Results The Diff values of the anterior corneal surface were (0.011±0.006)mm and (0.011±0.017)mm,and those in the posterior corneal surface were (0.031 ±0.012)mm and (0.026 ±0.008)mm in the amblyopic eye group and the fellow eye group,respectively.In addition,Sim K's astigmatism were (1.8± 1.1)D and (1.1 ±0.6) D,JCC were (77±80) °and (100±80) °,J0 values were (-0.17±0.72) D and (0.02±0.41) D,J45 values were (-0.16±0.79) D and (0.13 ±0.48) D,CCT values were (551 ±37) μm and (551 ±31) μm,angle kappa values were (6.4± 1.4) ° and (4.9 ± 1.2) ° in the amblyopic eye group and the fellow eye group,respectively.Significant differences were found in the Diff values of the anterior and posterior corneal surface,Sim K's astigmatism and angle kappa between the two groups (t=-3.041,P=0.005 ;t=-4.317,P=0.000 ;t=-4.571,P=0.000).Pearson's linear correlation test demonstrated significant interocular positive correlations in parameters such as the anterior corneal surface Diff values (r =0.444),J0 (r =0.383),posterior Diff values (r =0.600),and Sim K 's astigmatism (r =0.479),and CCT (r =0.948,P＜0.05).The linear regression equation between the two groups was Y =-0.005 +1.392X (R2 =0.197,F=6.858,P=0.014) in the Diff values in the anterior corneal surface,Y =-0.013+0.421X (R2=0.360,F=15.761,P=0.000) in the Diff values in the posterior corneal surface,Y =0.616+0.27X (R2=0.230,F=8.348,P=0.007) in the Sim K's astigmatism,Y=0.060+0.219X (R2 =0.147,F=4.814,P=0.037) in theJo and Y=i08.289+0.804X (R2 =0.899,F=250.293,P=0.000) in CCT.Conclusions Corneal morphological interocular differences exist significantly in anisometropic amblyopic patients.

Angle Kappa Measurement with Slit Lamp Biomicroscope

PURPOSE: There has been a difficulty in measuring angle kappa because special instrument was required. To measure the angle kappa conveniently, we designed a new method using slit lamp biomicroscope. METHODS: We measured the angle kappa in 124 eyes of 62 patients with newly designed method and compared the measurement by new method with those by T-shape ruler or the major amblyoscope. RESULTS: We found the average angle kappa was +3.12 degrees by slit lamp, +2.85 degrees by major amblyoscope and +3.04 degrees by T shape ruler method. There was no significant difference between slit lamp and either major amblyoscope method (p=0.48) or T shape ruler (p=0.18). CONCLUSIONS: The new method of measuring angle kappa using slit lamp biomicroscope seemed to be a convenient and relatively accurate method for measuring of angle kappa and appeared to be beneficial in measurement of ocular deviation.

Pseudoexotropia and Ectopic Macula

Ectopic macula is a condition in which the macula is displaced markedly from its normal position. It can be unilateral or bilateral, and the macula can be displaced in any direction, though it is displaced temporally in more than 90% cases. The occurrence of small variation of the position of the macula in relation to the pupillary axis of the eye is evidenced by the variability of the angle K. The most common cause of ectopic macula is probably retinopathy of prematurity and other causes are trauma, chorioretinitis, and angioma. The authors experienced six patients who had ectopic macula. They presented apparent exptropia on Hirschberg test, but no fixation movement on cover test. Fundus examination showed temporal displacement of macula and traction vessel. Pseudoexotropia result from positive angle kappa. It is dangerous to measure the deviation amount by only Hirschberg test or Krimsky test for the uncooperated young patients who have history of prematurity especially. We must check the fundus photographs. With regards to cosmetic surery, each case must be handled individually. Evaluation should include age, visual acuity, the status of binocular vision, and the angle of squint.

Comparison of Hirschberg Test with Prsim and Alternate Cover Test in Measuring the Ocular Deviation

Measurements of ocular deviation were obtained from 45 exotropes and 31 esotropes, using Hirschberg corneal reflex test, and prism and alternate cover test respectively. The mean angle of devation in exotropes was 27.42 +/- 8.60 delta by Hirschberg test, 27.80 +/- 8.11 delta by prism and alternate cover test. There was no significant difference between these two groups (p>0.05). The mean angle of deviation in esotropes was 28.55 +/- 12.92 delta by Hirschberg test, 31.58 +/- 13.08 delta by prism and alternate cover test. The difference between these two groups was significant (p<0.05). In patients whose angle kappa was zero and exotropes whose angle kappa was positive, there was no significant diHerence between the two tests. In esotropes whose angle kappa was positive, the mean angle of deviation was 29.74 +/- 15.59 delta by Hirschberg test, and 33.47 +/- 15.91 delta by prism and alternate cover test. The difference between the two groups was significant (p

Interrelationship between Refractive Error and Angle kappa

Distributions of angle kappa and of cycloplegic refraction and their association were studied. The subjects were 282 nonstrabismic Korean children, aged from 6 years to 11 years. who visited Ewha Women University Hospital from December 1990 to March 1991. The angle kappa was measured by major amblyoscope, and refraction was done under the cycloplegic state. The results were as follows: The frequency of angle kappa was positive. negative and 0 degree in decreasing order. The average values of refractive error and angle kappa were -1.03 +/- 2.20 degrees dipter and +1 34 +/- 1.33 degrees. The average values of angle kappa for hypermetropia, emmettopia and myopia were +2.52 +/- 0.81 degrees, +1.71 +/- 1.03 degrees and +0.90 +/- 1.37 degrees. And these values were significantly different from each other.