scholarly journals Phacoemulsification and calculation of intraocular lenses in patients given keratorefractive surgery. Part 2

2022 ◽  
Vol 14 (4) ◽  
pp. 118-125
Author(s):  
I. E. Ioshin
Keyword(s):  
Anterior Segment ◽  
Optical Power ◽  
Intraocular Lenses ◽  
Radius Of Curvature ◽  
Thin Lens ◽  
Main Technique ◽  
Iol Calculation ◽  
Hyperopic Shift ◽  
Keratorefractive Surgery ◽  
Master Device

Effective rehabilitation of patients with cataracts who underwent keratorefractive surgeries requires that the optical power of the IOL be calculated correctly to avoid hyperopic error. The purpose of the 2nd part of the research (for the 1st part, see ROJ, 2021; 14 (2): 55–58) is to present the results of cataract phacoemulsification in patients subjected to keratorefractive surgery based on the author’s algorithm for calculating the optical power of the IOL. Material and methods. The algorithm used optical biometry with an IOL-Master device. The main technique of improving the accuracy of IOL calculation after keratorefractive operations has been to introduce amendments to standard IOL calculation formulas. This work proposes an alternative, which consists in using the Hoffer Q formula, as it is more consistent with changes in the anterior segment of the myopic eye after keratorefractive surgery than other basic. The main distinguishing feature of the Hoffer Q formula is that the corneal refraction is not converted into the radius of curvature but is applied directly as the optical power of a “thin lens”. Results. The empirical customized correction was +1.0 D with regard to the estimated planned postoperative refraction (for patients with initial myopia from -3 to -9 D). The use of the “thin lens” principle made it possible to extrapolate this formula and apply it after LASIK surgery and after radial keratotomy. Conclusion. The proposed technique of IOL calculation was implemented for cataract phacoemulsification in over 200 patients who underwent keratorefractive surgeries. No cases of hyperopic shift of postoperative refraction were noted. The deviation from the planned myopic refraction did not exceed 1.0 D.

scholarly journals Phacoemulsification and calculation of intraocular lenses in patients given keratorefractive surgery. Part 1

2021 ◽  
Vol 14 (2) ◽  
pp. 55-58
Author(s):  
I. E. Ioshin
Keyword(s):  
Postoperative Period ◽  
Outer Part ◽  
Optical Power ◽  
Intraocular Lenses ◽  
Subconjunctival Injection ◽  
Initial State ◽  
Surgical Technology ◽  
Keratorefractive Surgery ◽  
Surgical Tactics ◽  
Fast Adaptation

Rationale.Qualitative rehabilitation of patients with cataracts who had keratorefractive surgeries depends on phacoemulsification technology and correctly calculated optical power of the IOL. Purpose: present the author’s own approaches to the development of surgical tactics for treating patients with cataracts who underwent keratorefractive surgeries. Material and methods. The complicated character of cataract surgery performed after LASIK — deterioration of visualization due to the presence of an optical ablation zone and a transition zone (6–7 mm) — is successfully compensated by instillations of a dispersed viscoelastic (methylcellulose) onto the surface of the cornea. Another factor is the deepening of the anterior chamber in high myopia, which is uncomfortable for manipulation and may require a lowerlevel of irrigation (up to 60 mm Hg). The technology of surgery performed after radial keratotomy (RK) requires utmost attention to the prevention of surgical astigmatism that could emerge due to biomechanical instability of the cornea. To ensure such prevention, paracentesis is performed outside the zone of keratotomy scars, the main 2.2 mm incision is made after capsulorhexis in the sclerolimbal zone, and at theend of the operation, a subconjunctival injection is performed in the conjunctival zone of the knife keratom entrance for the tamponade ofthe outer part of the incision without suturing. These techniques made it possible to successfully perform more than 200 operations and achieve a favorable course of the postoperative period from the first day. Fast adaptation of the incision (1–2 days), uncomplicated course of the postoperative period and the absence of induced astigmatism are important advantages of this technology. Conclusion. The choice of surgical technology, taking into account the initial state of the eye after LASIK and RK surgeries, is an important task. Yet the main problem with which the doctor is faced after keratorefractive surgery is the difficulty of calculating the optical power of the IOL which must take into account the special needs of the patient with a particular refractive history, which will be reported in part 2 of the article.

scholarly journals Intraocular lens power calculation for plus and minus lenses in high myopia using partial coherence interferometry

2021 ◽  
Author(s):  
Matthias Fuest ◽  
Niklas Plange ◽  
David Kuerten ◽  
Hannah Schellhase ◽  
Babac A. E. Mazinani ◽  
...  
Keyword(s):  
Axial Length ◽  
Absolute Error ◽  
Intraocular Lenses ◽  
Partial Coherence ◽  
Power Calculation ◽  
Partial Coherence Interferometry ◽  
Intraocular Lens Power Calculation ◽  
Hyperopic Shift ◽  
Lens Power ◽  
Lens Power Calculation

Abstract Purpose We assessed the accuracy of lens power calculation in highly myopic patients implanting plus and minus intraocular lenses (IOL). Methods We included 58 consecutive, myopic eyes with an axial length (AL) > 26.0 mm, undergoing phacoemulsification and IOL implantation following biometry using the IOLMaster 500. For lens power calculation, the Haigis formula was used in all cases. For comparison, refraction was back-calculated using the Barrett Universal II (Barrett), Holladay I, Hill-RBF (RBF) and SRK/T formulae. Results The mean axial length was 30.17 ± 2.67 mm. Barrett (80%), Haigis (87%) and RBF (82%) showed comparable numbers of IOLs within 1 diopter (D) of target refraction. Visual acuity (BSCVA) improved (p < 0.001) from 0.60 ± 0.35 to 0.29 ± 0.29 logMAR (> 28-days postsurgery). The median absolute error (MedAE) of Barrett 0.49 D, Haigis 0.38, RBF 0.44 and SRK/T 0.44 did not differ. The MedAE of Haigis was significantly smaller than Holladay (0.75 D; p = 0.01). All median postoperative refractive errors (MedRE) differed significantly with the exception of Haigis to SRK/T (p = 0.6): Barrett − 0.33 D, Haigis 0.25, Holladay 0.63, RBF 0.04 and SRK/T 0.13. Barrett, Haigis, Holladay and RBF showed a tendency for higher MedAEs in their minus compared to plus IOLs, which only reached significance for SRK/T (p = 0.001). Barrett (p < 0.001) and RBF (p = 0.04) showed myopic, SRK/T (p = 002) a hyperopic shift in their minus IOLs. Conclusions In highly myopic patients, the accuracies of Barrett, Haigis and RBF were comparable with a tendency for higher MedAEs in minus IOLs. Barrett and RBF showed myopic, SRK/T a hyperopic shift in their minus IOLs.

Use of various keratometry data (ring and zone) in trifocal IOL calculation

2021 ◽  
pp. 53-56
Author(s):  
A.D. Loginova ◽  
◽  
S.V. Shukhaev ◽  
S.S. Kudlakhmedov ◽  
E.V. Boiko ◽  
...  
Keyword(s):  
Power Distribution ◽  
Optical Power ◽  
Iol Implantation ◽  
Universal Formula ◽  
Significant Difference ◽  
Trifocal Iol ◽  
Iol Calculation ◽  
Km Value ◽  
Tomographic Data ◽  
Corneal Refractive Power

Purpose. To compare the results of trifocal IOL calculation using various corneal tomographic data (ring and zone). Methods. This retrospective study involved 46 patients (46 eyes), underwent cataract surgery with trifocal IOL implantation (AcrySof IQ PanOptix). The calculation was performed using Tomey OA-2000 according to 2 formulas (Barrett II Universal, Olsen). Keratometry values included Km (the average of two main meridians of a cornea) provided by Pentacam HR Power Distribution Apex map, which describes total corneal refractive power (TCRP) with diameter of 3.0, 4.0 and 5.0 mm on a ring and zone. Mean (MAE) and median (MedAE) predicted postoperative refraction errors were assessed after surgery. Results. Mean Km value on 3 mm zone and ring was: 42.75±1,46 D and 42,91±1,43 D, respectively (p<0,0001). Mean Km on 4 mm zone and ring was: 42.6±1.5 D and 43.3 ± 1.5 D, respectively (p <0.005). Mean Km value on 5 mm zone and ring was: 43,09±1,5 D and 43,55±1,48 D, respectively (p<0,0001). Calculations using the Barrett II Universal formula revealed significant difference between MAE and MedAE of the predicted postoperative refraction on 5mm zone and ring (p=0.045). When using the Olsen formula in the calculations, significant difference was revealed using the Km data with a diameter of 3 mm and 5 mm (p=0.001 и p=0.009, respectively). The calculation on 3 mm ring was more accurate than for 3 mm zone. With a 5 mm diameter, the calculation is more accurate according to the zone data. Conclusion. Mean Km value on Power Distribution Apex map according to ring is significantly greater then according to zone. 1) The calculation of the trifocal IOL based on the TCRP zone data is reliably more accurate than the ring data according to both formulas (Barrett II Universal and Olsen) with a diameter of 5 mm. 2) According to the Olsen formula with a diameter of 3 mm, the calculation of the optical power of trifocal IOL based on TCRP ring data is more accurate. Key words: IOL calculation, Trifocal IOL, corneal topography

Intraocular lenses optic power calculation with seven formulas in short eyes

2021 ◽  
pp. 57-61
Author(s):  
K.B. Pershin ◽  
◽  
N.F. Pashinova ◽  
I.A. Likh ◽  
А.Y. Tsygankov ◽  
...  
Keyword(s):  
Axial Length ◽  
Mean Absolute Error ◽  
Optical Power ◽  
Absolute Error ◽  
Intraocular Lenses ◽  
Power Calculation ◽  
Retrospective Comparison ◽  
Monofocal Iol ◽  
The Mean ◽  
Axial Eye Length

Purpose. The choice of the optimal formula for calculating the IOL optical power in patients with an axial eye length of less than 20 mm. Material and methods. A total of 78 patients (118 eyes) were included in the prospective study. 1st group included 30 patients (52 eyes) with short eyes (average axial eye length of 19.60±0.42 (18.54–20.0) mm), 2nd group consisted of 48 patients (66 eyes) with a axial length 22.75±0.46 (22.0–23.77) mm. Various monofocal IOL models were used. The average follow-up period was 13 months. IOL optical power was calculated using the SRK/T formula, retrospective comparison – according to the formulas Hoffer-Q, Holladay II, Olsen, Haigis, Barrett Universal II and Kane. Results. In 1st group, the mean absolute error was determined for the formulas Haigis, Olsen, Barrett Universal II, Kane, SRK/T, Holladay II and Hoffer-Q (0.85, 0.78, 0.21, 0.17, 0.79, 0.73, 0.19 respectively). When comparing the formulas, significant differences were found for the formulas Hoffer-Q, Barrett Universal II and Kane in comparison with the formulas Haigis, Olsen, SRK/T and Holladay II (p<0.05) in all cases, respectively. In 2nd group, the mean absolute error was determined for the formulas Haigis, Olsen, Barrett Universal II, Kane, SRK/T, Holladay II and Hoffer-Q (0.15, 0.16, 0.23, 0.10, 0.19, 0.23, 0,29 respectively). In 2nd group, there were no significant differences between the studied formulas (p>0.05). Conclusion. This paper presents an analysis of data on the effectiveness of seven formulas for calculating the IOL optical power in short (less than 20 mm) eyes in comparison with the normal axial length. The advantage of the Hoffer-Q, Barrett Universal II and Kane formulas over Haigis, Holladay II, Olsen, and SRK/T is shown. Key words: cataract, hypermetropia, short eyes, calculation of the IOL optical power.

Anterior segment parameters: Comparison of 1-piece and 3-piece acrylic foldable intraocular lenses

2010 ◽  
Vol 36 (10) ◽  
pp. 1650-1655 ◽  
Author(s):  
Mahmoud Jabbarvand Behrouz ◽  
Ahmad Kheirkhah ◽  
Hesam Hashemian ◽  
Rahman Nazari
Keyword(s):  
Anterior Segment ◽  
Intraocular Lenses ◽  
Anterior Segment Parameters

scholarly journals Explantation of domestic models of posterior chamber phakic intraocular lenses in the development of subcapsular cataract in higly myopic patients: clinical features

2021 ◽  
Vol 14 (1) ◽  
pp. 61-64
Author(s):  
G. V. Sorokoletov ◽  
E. R. Tumanyan ◽  
A. N. Bessarabov ◽  
M. A. Soboleva
Keyword(s):  
Young Patients ◽  
Optical Power ◽  
Functional Results ◽  
Intraocular Lenses ◽  
Posterior Chamber ◽  
Corneal Incision ◽  
Irrigation Solution ◽  
Phakic Intraocular Lenses ◽  
Surgical Tactics

To date, the operation of choice in young patients with high myopia, is the implantation of posterior chamber phakic intraocular lenses (PIOL), provided that there are contraindications to keratorefractive interventions, However, in the late postoperative period, cataracts may occur, which requires the development of surgical tactics for lens explantation with simultaneous phacoemulsification of cataract (FEC) implementation.The purpose is to develop and analyze a method for removing a PIOL through a 2 mm corneal incision in subcapsular cataract cases.Material and methods. Posterior chamber domestic models of PIOL type RSK-1(3) and RSK-3 in 22 patients (37 eyes), implanted in the S.N. FEDOROV “EYE MICROSURGERY” clinic in 1994 – 2001 had to be removed due to the development of secondary cataracts. PIOL stayed in the eye 2 to 26 years (averagely 14.30 ± 1.30 yrs). In all cases, the P IOL was removed followed by FEC with implantation of a posterior chamber IOL. The optical power of the IOL was calculated mainly in such a way that the residual myopic refraction was 2.0–3.0 D.Results. The intraoperative condition of the anterior chamber was stable, the volume of irrigation fluid consumed was within 90–120 ml. No complications were detected in the early and late postoperative periods. The results of dynamic ophthalmological follow up of patients showed that visual acuity without correction and with correction after surgery averaged 0.2 ± 0.1 and 0.60 ± 0.15, respectively.Conclusion. The proposed method of explantation of domestic lenses of S.N. FEDOROV NMRC MNTK “EYE MICROSURGERY” shows that it enables a safe, simple removal of PIOL in the event of secondary subcapsular cataract, which allows achieving high clinical and functional results without overspending the irrigation solution.

scholarly journals The Effects of Different Shapes of Capsulorrhexis on Postoperative Refractive Outcomes and Effective Position of the Intraocular Lens in Cataract Surgery

2018 ◽  
Author(s):  
Shixu Li ◽  
Yiping Hu ◽  
Ran Guo ◽  
Yushuang Shao ◽  
Jiangyue Zhao ◽  
...  
Keyword(s):  
Cataract Surgery ◽  
Intraocular Lens ◽  
Anterior Segment ◽  
The Other ◽  
Intraocular Lenses ◽  
Vertical Diameter ◽  
Refractive Outcomes ◽  
Age Related ◽  
Horizontal Diameter ◽  
Different Shapes

Abstract Background：To evaluate the effects of anterior capsular opening size on deviation from predicted refraction and the effective position of intraocular lens (ELP) in cataract surgery. Methods：Eighty patients (80 eyes) with simple age-related cataracts were treated from May 2018 to September 2018 at the Fourth Affiliated Hospital of China Medical University. The patients were divided into 2 groups : 40 eyes were implanted with the C-loop haptic intraocular lens (AMO Tecnis ZCB00) while the other 40 eyes were implanted with the plate haptic intraocular lens (CT ASPHINA 509M). Follow-up visits were conducted postoperatively at 1 week, 1 month, and 3 months during which patients underwent refraction and data collection after pupil dilation that included anterior segment photography and Scheimpflug imaging by Pentacam. The area, horizontal and vertical diameter of the capsulorrhexis, circularity, decentration, and package were analysed using the image analysis software Image-Pro-Plus 6.0 that evaluated the relationship between the different shapes of capsulorrhexis with deviation from predicted refraction and ELP in cataract surgery. Results: Deviation from predicted refraction and all of the parameters of capsulorrhexis were not correlative in the 509M IOL group, however, in the Tecnis IOL group, while the deviation from predicted refraction and all of the capsulorrhexis parameters were not correlative at 1 week, the deviation from predicted refraction did correlate with capsulorrhexis area,horizontal diameter at 1 month (P=0.029, P=0.048), and the capsulorrhexis area ,vertical diameter at 3 months (P=0.03, P=0.017).The ELP correlated with package in both groups postoperatively (r>0, P<0.05), but there is no other capsulorrhexis parameters correlate with ELP in the 509M IOL group (all P>0.05). For the Tecnis IOL group, the ELP and capsulorrhexis area were correlated at 1 week and 1 month, while the ELP and horizontal diameter, the ELP and vertical diameter were correlated at 1 week , but did not correlate with the other capsulorrhexis parameters in the Tecnis IOL group (all P>0.05). Conclusions: The shape of the capsulorrhexis has an effect on postoperative refractive outcomes and the effective position of intraocular lens in cataract surgery, and plate haptic intraocular lenses have better refractive stability than C-loop haptic intraocular lenses.（ChiCTR-TRC-1800015638）

scholarly journals THE DYNAMICS OF THE LENGTH OF THE ANTERIOR-POSTERIOR EYE AXIS FOLLOWING THE EXTRACTION OF UNILATERAL CONGENITAL CATARACTS WITH THE IMPLANTATION OF INTRAOCULAR LENSES IN THE CHILDREN DURING THE FIRST YEAR OF LIFE

2017 ◽  
Vol 12 (1) ◽  
pp. 6-10
Author(s):  
L. A Katargina ◽  
T. B Kruglova ◽  
N. S Egiyan ◽  
O. B Trifonova
Keyword(s):  
Surgical Treatment ◽  
Pediatric Population ◽  
Optical Power ◽  
Intraocular Lenses ◽  
First Year ◽  
Congenital Cataracts ◽  
Before And After ◽  
First Year Of Life ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

Introduction. Unilateral congenital cataracts in the children account for up to 16.0% of the total number of congenital cataracts diagnosed among the pediatric population. Aphakia is considered to be the most physiological method for the surgical treatment and correction of unilateral congenital cataracts in the combination with the implantation of intraocular lenses. The optical power of the lenses is calculated based on the results of evaluation of the dynamics of the length of the anterior-posterior eye axis in individual patients. Aim. The objective of the present study was to analyze the dynamics of the length of the anterior-posterior axis of the eyes in the children presenting with pseudophakia following the extraction of unilateral congenital cataract. Materials and methods. The study included a total of 77 children with unilateral congenital cataracts examined before and after the surgical treatment. Phacoaspiration in the combination with the implantation of intraocular lenses was performed in the patients at the age varying from 3 to 11 months. The infants underwent the ultrasound biometric study and the evaluation of the dynamics of the length of the anterior-posterior axis in the affected eye in comparison with that in the contralateral eye before they reached the age of 7 years. Results. The results of this study give evidence of marked variability of the dynamics of the length of the anterior-posterior axis of the eyes following the early surgical treatment of the children presenting with unilateral congenital cataracts. Conclusion. The differences in the tendency toward the change in the length of the anterior-posterior axis of the eyes following the surgical treatment of unilateral congenital cataracts in the children during the first year of life suggest the necessity of further in-depth investigations and the need for the regular follow-up of such patients for the purpose of choosing the proper approach to the correction of the refraction error and ametropia.

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