Optimizing the intraocular lens formula constant according to intraocular lens diameter

AIM: To determine whether the different diameters of a specific intraocular lens (IOL) have significantly different optimized SRK/T A constants and whether these new A constants can improve refractive outcomes. METHODS: Data were collected prospectively from Jan. 2011 to Dec. 2012 on all patients undergoing routine cataract surgery at a district general hospital in the UK. Patients were divided into three groups according to the size of the Akreos AO MI60 IOL used. A constants for the SRK/T formula were optimized according to the size of the IOL. These optimized A constants were then used to select future refractive outcomes. RESULTS: A total of 2398 cataract operations were performed during the study period of which 1131 met the inclusion criteria. The three optimized A constants for the different sized IOLs were 118.98, 119.13, 119.32. The difference between them was highly significant (P≤0.0001). Two optimized A constants for three sizes of IOL led to an improvement in refractive outcomes (from 93.4% to 94.6% of refractive outcomes within 1.00 D of predicted spherical equivalent). The optimized A constant for the largest IOL was based on a small number of cases and was not used. CONCLUSION: Optimizing the A constant for the three distinct sizes of the Bausch & Lomb Akreos MI60 lens lead to three significantly different A constants. In our practice, using two different optimized A constants for three different sized IOLs give the least refractive error, however, using three optimized A constants may give better results with a larger dataset.

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Refractive outcomes following cataract surgery in patients who have had myopic laser vision correction

BMJ Open Ophthalmology ◽

10.1136/bmjophth-2018-000242 ◽

2019 ◽

Vol 4 (1) ◽

pp. e000242 ◽

Cited By ~ 1

Author(s):

Chung Shen Chean ◽

Boon Kang Aw Yong ◽

Samuel Comely ◽

Deena Maleedy ◽

Stephen Kaye ◽

...

Keyword(s):

Cataract Surgery ◽

Refractive Error ◽

Control Group ◽

Prediction Errors ◽

Spherical Equivalent ◽

Refractive Outcomes ◽

Vision Correction ◽

Laser Vision ◽

The Mean ◽

The Difference

ObjectivePrediction errors are increased among patients presenting for cataract surgery post laser vision correction (LVC) as biometric relationships are altered. We investigated the prediction errors of five formulae among these patients.Methods and analysisThe intended refractive error was calculated as a sphero-cylinder and as a spherical equivalent for analysis. For determining the difference between the intended and postoperative refractive error, data were transformed into components of Long's formalism, before changing into sphero-cylinder notation. These differences in refractive errors were compared between the five formulae and to that of a control group using a Kruskal-Wallis test. An F-test was used to compare the variances of the difference distributions.Results22 eyes post LVC and 19 control eyes were included for analysis. Comparing both groups, there were significant differences in the postoperative refractive error (p=0.038). The differences between the intended and postoperative refractive error were greater in post LVC eyes than control eyes (p=0.012), irrespective of the calculation method for the intended refractive error (p<0.01). The mean difference between the intended and postoperative refractive error was relatively small, but its variance was significantly greater among post LVC eyes than control eyes (p<0.01). Among post LVC eyes, there were no significant differences between the mean intended target refraction and between the intended and postoperative refractive error using five biometry formulae (p=0.76).ConclusionBiometry calculations were less precise for patients who had LVC than patients without LVC. No particular biometry formula appears to be superior among patients post LVC.

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Lenstar LS 900 versus Pentacam-AXL: analysis of refractive outcomes and predicted refraction

Scientific Reports ◽

10.1038/s41598-021-81146-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Henrique Aragão Arruda ◽

Joana M. Pereira ◽

Arminda Neves ◽

Maria João Vieira ◽

Joana Martins ◽

...

Keyword(s):

Refractive Error ◽

Prediction Error ◽

Mean Absolute Error ◽

Absolute Error ◽

Spherical Equivalent ◽

Refractive Outcomes ◽

Iol Calculation ◽

Median Absolute Error ◽

The Difference ◽

Mean Prediction Error

AbstractAnalysis of refractive outcomes, using biometry data collected with a new biometer (Pentacam-AXL, OCULUS, Germany) and a reference biometer (Lenstar LS 900, HAAG-STREIT AG, Switzerland), in order to assess differences in the predicted and actual refraction using different formulas. Prospective, institutional study, in which intraocular lens (IOL) calculation was performed using the Haigis, SRK/T and Hoffer Q formulas with the two systems in patients undergoing cataract surgery between November 2016 and August 2017. Four to 6 weeks after surgery, the spherical equivalent (SE) was derived from objective refraction. Mean prediction error (PE), mean absolute error (MAE) and the median absolute error (MedAE) were calculated. The percentage of eyes within ± 0.25, ± 0.50, ± 1.00, and ± 2.00 D of MAE was determined. 104 eyes from 76 patients, 35 males (46.1%), underwent uneventful phacoemulsification with IOL implantation. Mean SE after surgery was − 0.29 ± 0.46 D. Mean prediction error (PE) using the SRK/T, Haigis and Hoffer Q formulas with the Lenstar was significantly different (p > 0.0001) from PE calculated with the Pentacam in all three formulas. Percentage of eyes within ± 0.25 D MAE were larger with the Lenstar device, using all three formulas. The difference between the actual refractive error and the predicted refractive error is consistently lower when using Lenstar. The Pentacam-AXL user should be alert to the critical necessity of constant optimization in order to obtain optimal refractive results.

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Outcomes of refractive error correction in pseudophakic patients using a sulcus piggyback intraocular lens

European Journal of Ophthalmology ◽

10.1177/1120672120903560 ◽

2020 ◽

pp. 112067212090356

Author(s):

Eliya Levinger ◽

Michael Mimouni ◽

Yaron Finkelman ◽

Yossi Yatziv ◽

Jonathan Shahar ◽

...

Keyword(s):

Visual Acuity ◽

Cataract Surgery ◽

Intraocular Lens ◽

Refractive Error ◽

Spherical Equivalent ◽

Distance Visual Acuity ◽

Refractive Outcomes ◽

Uncorrected Distance Visual Acuity ◽

Corrected Distance Visual Acuity

Purpose: The purpose of this study was to assess the results of a sulcus intraocular lens (Sulcoflex) for pseudophakic refractive errors following phacoemulsification cataract surgery. Methods: This retrospective clinical observational cohort study included consecutive eyes in which a Sulcoflex was implanted. Uncorrected distance visual acuity and corrected distance visual acuity as well as refractive outcomes were assessed. The minimum follow-up time required for inclusion was 3 months. Results: In total, 15 eyes ( n = 15) were evaluated. The mean follow-up was 14 months (range: 3–18 months). The Sulcoflex aspheric (653L) was implanted in 13 eyes and the Sulcoflex toric (653T) in two eyes. The preoperative mean logMAR (Snellen) uncorrected distance visual acuity and corrected distance visual acuity were 0.88 (20/150) and 0.27 (20/40), respectively. The postoperative mean logMAR (Snellen) corrected distance visual acuity was 0.15 (20/30). The preoperative mean spherical equivalent was −0.22 ± 5.95 D and the postoperative mean spherical equivalent was −1.59 ± 1.45 D. There was a significant and strong correlation ( r = 0.64, p < 0.001) between the attempted and the achieved spherical equivalent. Conclusion: The Sulcoflex is a safe and viable option for patients with residual refractive error following cataract surgery.

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Myopia progression from wearing first glasses to adult age: the DREAM Study

British Journal of Ophthalmology ◽

10.1136/bjophthalmol-2020-316234 ◽

2021 ◽

pp. bjophthalmol-2020-316234

Author(s):

Jan Roelof Polling ◽

Caroline Klaver ◽

Jan Willem Tideman

Keyword(s):

Retrospective Study ◽

The Netherlands ◽

Refractive Error ◽

High Myopia ◽

Prognostic Indicator ◽

Treatment Intensity ◽

Spherical Equivalent ◽

Inclusion Criteria ◽

Myopia Progression ◽

Adult Age

PurposeData on myopia progression during its entire course are scarce. The aim of this study is to investigate myopia progression in Europeans as a function of age and degree of myopia from first prescription to final refractive error.MethodsThe Drentse Refractive Error and Myopia Study assessed data from a branch of opticians in the Netherlands from 1985 onwards in a retrospective study. First pair of glasses prescribed was defined as a spherical equivalent of refraction (SER) ≤−0.5 D to ≥−3.0 D. Subjects with prescriptions at an interval of at least 1 year were included in the analysis.ResultsA total of 2555 persons (57.3% female) met the inclusion criteria. Those with first prescription before the age of 10 years showed the strongest progression (−0.50 D; IQR: −0.75 to −0.19) and a significantly (p<0.001) more negative median final SER (−4.48 D; IQR: −5.37 to −3.42). All children who developed SER ≤−3 D at 10 years were highly myopic (SER ≤−6D) as adults, children who had SER between −1.5 D and −3 D at 10 years had 46.0% risk of high myopia, and children with SER between −0.5 D and −1.5 D had 32.6% risk of high myopia. Myopia progression diminished with age; all refractive categories stabilised after age 15 years except for SER ≤−5 D who progressed up to −0.25 D annually until age 21 years.ConclusionOur trajectories of the natural course of myopia progression may serve as a guide for myopia management in European children. SER at 10 years is an important prognostic indicator and will help determine treatment intensity.

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Sulcoflex Piggyback Intraocular Lens Implantation For Correction Of Refractive Errors Following Cataract Surgery

Canadian Journal of Optometry ◽

10.15353/cjo.78.469 ◽

2016 ◽

Vol 78 (2) ◽

pp. 20

Author(s):

Mona Purba ◽

Cynthia Mardinger ◽

Abby Hibma ◽

Howard V Gimbel

Keyword(s):

Intraocular Lens ◽

Refractive Error ◽

Chart Review ◽

Retrospective Chart Review ◽

Refractive Errors ◽

Refractive Outcomes ◽

Lens Implantation ◽

The Mean ◽

Target Refraction ◽

Piggyback Iol

Purpose: To investigate the visual and refractive outcomes following implantation of a Sulcoflex intraocular lens (IOL) to correct pseudophakic refractive error. Methods: This retrospective chart review included 14 pseudophakic eyes of 13 patients who underwent implantation of a Sulcoflex IOL. The Sulcoflex IOL is a piggyback IOL technique where a secondary, supplementary lens is implanted in the ciliary sulcus. Results: Eleven eyes (78.6%) had a postoperative SE within 0.50 D of the targeted SE. Preoperative UDVA was 20/30 in 4 eyes (28.6%), and 20/40 or worse in 10 eyes (71.4%). Postoperative UDVA was 20/30 or better in all eyes, where half (50.0%) of eyes were 20/20 or better. The mean preoperative logMAR (0.50 ± 0.33) significantly improved to 0.06 ± 0.09, p<.01. There were no complications. Conclusions. The significant improvement in UDVA and the precision in reaching the target refraction suggest that the Sulcoflex is a viable and successful treatment option for pseudophakic refractive error.

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Visual and Refractive Outcomes of Cataract Surgeries Performed in One Year in a Private Practice Setting: Review of 2714 Procedures

Journal of Ophthalmology ◽

10.1155/2020/2421816 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9

Author(s):

Laureano A. Rementería-Capelo ◽

Jorge L. García-Pérez ◽

Juan Gros-Otero ◽

Aida Morán ◽

José M. Sánchez-Pina ◽

...

Keyword(s):

Cataract Surgery ◽

Private Practice ◽

Outcome Data ◽

Practice Setting ◽

Spherical Equivalent ◽

Refractive Outcomes ◽

Preoperative Information ◽

The Difference ◽

One Year ◽

Spectrum Of Patients

Introduction. Currently available outcome data for cataract surgery include mostly patients from public health systems. The purpose of this study was to report the visual and refractive outcomes of cataract procedures performed during one year in a private practice center, which may include a different spectrum of patients. Methods. Our center’s database was used to identify all isolated cataract procedures performed during 2017. The electronic records were reviewed to collect the preoperative information, presence of intra- or postsurgical complications, and visual and refractive outcomes one month after surgery. Results. In 2017, 2714 eyes of 1543 patients underwent cataract surgery in our center. Mean patient age was 70.42 years. 775 eyes (28.55%) had prior ophthalmic pathologies, and 113 eyes (4.16%) had undergone previous surgical procedures. Surgical complications developed in 35 eyes (1.29%), including 9 posterior capsule tears (0.33%) and 3 cases of dropped lens fragments (0.11%). A toric or multifocal intraocular lens was implanted in 45.6% of eyes. As regards postoperative complications, 59 eyes (2.17%) required a return to the operating theater, including 29 eyes (1.07%) requiring reinterventions due to an unexpected refractive result. There were no cases of endophthalmitis. Mean LogMAR-corrected distance visual acuity (CDVA) improved from 0.25 (SD 0.34) preoperatively to 0.04 (SD 0.17) postoperatively; 86.5% of eyes achieved a CDVA ≤0.0, with 97.5% achieving ≤0.3. In 86.4% of eyes, the difference between target and residual spherical equivalent difference was of 0.50 D or lower; 88% of eyes had a spherical equivalent ±0.50 D. Conclusions. The visual and refractive outcomes of cataract surgery in a private practice setting were excellent, well over the benchmarks set by the ESCRS. The safety profile was also within expected standards. This study provides information for ophthalmologists in private practice on expected outcomes.

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PERBANDINGAN BESARAN SFERIKAL EKUIVALEN BERDASARKAN METODE PENGUKURAN VISUS SUBJEKTIF DAN OBJEKTIF PENDERITA AMETROPIA PADA MAHASISWA FAKULTAS KEDOKTERAN UNIVERSITAS SAM RATULANGI

Jurnal e-Biomedik ◽

10.35790/ebm.2.1.2014.3585 ◽

2014 ◽

Vol 2 (1) ◽

Author(s):

Rezky Palangi ◽

Fransisca Lintong ◽

Maya Moningka Moningka

Keyword(s):

Visual Acuity ◽

Refractive Error ◽

Medical Personnel ◽

Spherical Equivalent ◽

Cross Sectional ◽

Analytical Research ◽

The Difference ◽

Cross Sectional Design ◽

The Right ◽

Objective Visual Acuity

Abstract: Ametropia or refractive error of the eye is the case almost every time we encounter in our environment and increasing steadily each year. One of the factors why refractive error often are not fully corrected due to the difference in the value of spherical and cylindrical or spherical equivalent between the examination of subjective and objective visual acuity. This study aims to determine the difference of the results of subjective and objective visual acuity at patiens ametropia. Analytical research methods with cross sectional design. The subjects were taken from a population that is 40 people. Selected subjects who met the inclusion criteria ; suffering that can be in a correction of ametropia with refractive lenses, suffer ametropia in one eye or both and are willing to be examined. The results obtained are very significant differences in spherical equivalent subjective and objective examination of patients with abnormalities of refraction of-0.8D on the right and left eye of the subject. With more negative value of objective examination. By doing so required a certain effort of medical personnel to maximize the refractive examinations on patients in order to minimize the error correction of ametropia. Conclusion: There is differences in spherical equivalent subjective and objective examination. Keywords: spherical equivalent, subjective vision, objective vision Abstrak: Ametropia atau kelainan refraksi mata merupakan kasus yang hampir setiap saat kita jumpai di lingkungan sekitar kita dan meningkat terus setiap tahunnya. Salah satu faktor mengapa kelainan refraksi sering dikoreksi secara tidak penuh akibat perbedaan nilai sferis dan silinder ataupun sferikal ekuivalen antara hasil pemeriksaan visus subjektif dan objektif. Penelitian ini bertujuan untuk mengetahui perbedaan dari hasil pemeriksaan visus subjektif dan objektif pada penderita ametropia. Metode penelitian analitik dengan desain potong lintang. Subyek diambil dari populasi yang ada sejumlah 40 orang. Subyek dipilih yang memenuhi kriteria inklusi, yaitu; menderita ametropia yang dapat di koreksi dengan lensa bias, menderita ametropia pada salah satu mata atau keduanya dan bersedia untuk diperiksa. Hasil yang didapatkan perbedaan sferikal ekuivalen sangat bermakna pada pemeriksaan subjektif dan objektif penderita kelainan refraksi sebesar -0.8D pada mata kanan dan kiri subyek. Dengan nilai pemeriksaan objektif lebih negatif. Dengan begitu diperlukan upaya tertentu dari tenaga medis untuk memaksimalkan pemeriksaan kelainan refraksi pada penderita ametropia agar meminimalkan kesalahan koreksi. Simpulan: terdapat perbandingan besaran sferikal ekuivalen antara pemeriksaan visus subjektif dan objektif. Kata kunci: Sferikal Ekuivalen, visus subjektif, visus objektif

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Comparison of 6.0 mm versus 6.5 mm Optical Zone on Visual Outcomes after LASIK

Journal of Clinical Medicine ◽

10.3390/jcm10173776 ◽

2021 ◽

Vol 10 (17) ◽

pp. 3776

Author(s):

Majid Moshirfar ◽

Rachel Huynh ◽

Nour Bundogji ◽

Alyson N. Tukan ◽

Thomas M. Sant ◽

...

Keyword(s):

Visual Acuity ◽

Laser System ◽

Spherical Equivalent ◽

Distance Visual Acuity ◽

Visual Outcomes ◽

Refractive Outcomes ◽

Uncorrected Distance Visual Acuity ◽

Corrected Distance Visual Acuity ◽

Optical Zone ◽

The Difference

Previous studies have demonstrated safety and efficacy using 6.0 and 6.5 mm optical zones in the WaveLight EX500 Excimer Laser System but have not evaluated if differing optical zone sizes influence refractive outcomes. This study examines visual outcomes between two study populations undergoing LASIK with either a 6.0 mm (1332 patients) or 6.5 mm (1332 patients) optical zone. Outcomes were further stratified by severity of myopia (low, moderate, and high) and astigmatism (low and high). Patients were matched by age and preoperative manifest sphere and cylinder. Postoperative measurements were then compared. The 6.5 mm group demonstrated better postoperative manifest refractive spherical equivalent (MRSE), manifest sphere, and absolute value of the difference in actual and target spherical equivalent refraction (|∆ SEQ|), within the total population, moderate myopia, and low astigmatism groups, but this did not lead to improved postoperative uncorrected distance visual acuity (UDVA) or best corrected distance visual acuity (CDVA). Though astigmatic correction and postoperative angle of error were similar between optical zone sizes, they were significantly worse with high myopia. Overall, this study demonstrates differences in visual outcomes between the 6.0 and 6.5 mm optical zone sizes that may warrant consideration; however, essentially, the results are comparable between them.

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Comparative Analysis of Refractive Result Predictability During Iridocapsular and Iridovitreal Fixation of Biplanar Intraocular Lens

Ophthalmology in Russia ◽

10.18008/1816-5095-2018-2-139-145 ◽

2018 ◽

Vol 15 (2) ◽

pp. 139-145

Author(s):

B. E. Malyugin ◽

E. N. Panteleev ◽

A. N. Bessarabov ◽

D. F. Pokrovskiy ◽

A. S. Semakina ◽

...

Keyword(s):

Comparative Analysis ◽

Intraocular Lens ◽

Mean Value ◽

Fixation Method ◽

Spherical Equivalent ◽

Mean Values ◽

Refractive Outcomes ◽

Significant Difference ◽

Iol Power ◽

Phacoemulsification Cataract Surgery

Purpose: to carry out a comparative analysis of refractive outcomes and features during preoperational calculation of the biplanar intraocular lens (IOL) with iridocapsular and iridovitreal fixation.Patients and methods. Study included the analysis IOL model RSP-3 implantation after phacoemulsification cataract surgery with subluxated lens grade 2. Analyzed 309 eyes of 304 patients with iridocapsular (n = 44) (ICF) and iridovitreal fixation (n = 265) (IVF). In both groups IOL power was calculated with use of A- constant (118.2) recommended by manufacturer. Mean period of examination was 6 months. To count optimized A-constant in both groups we used next data: IOL power and axial length before surgery, keratometry, spherical equivalent and IOL effective position during 6 months after surgery.Results. In group with ICF postoperative refraction was achieved ± 0,5 D in 10 cases (23%), in group IVF — in 29 cases (11%). Mean value of optimized A-constant for IOL model RSP-3 in groups with ICF and IVF were 117.2 ± 1.18 (114.0–120.8) and 116.9 ± 1,89 (109.6 до 123.6). There were no statistically significant difference between compared groups (p = 0.46).Conclusion. Use of A-constant recommended by manufacturer do not allow achieving target refraction in most cases. Mean values of biplanar IOL A-constant counted for ICF and IVF were 117,2 and 116,9 respectively, what should be taken into account during IOL power count, according to its fixation method.

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Comparison of Longitudinal Changes in Refractive Error of Hyperopic Children with or without Refractive Accommodative Esotropia

Diagnostics ◽

10.3390/diagnostics11091547 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1547

Author(s):

Ji Eun Song ◽

Hyo Ji Han ◽

Chul Young Choi ◽

Ramin Khoramnia ◽

Hae Ran Chang ◽

...

Keyword(s):

Refractive Error ◽

Control Group ◽

Spherical Equivalent ◽

Inclusion Criteria ◽

Initial Amount ◽

Longitudinal Changes ◽

Group Time ◽

Accommodative Esotropia ◽

Control Group Group

We investigated longitudinal changes in the spherical equivalent refractive error (SE) in hyperopic children with or without refractive accommodative esotropia (AccET). A total of 456 patients met the inclusion criteria: 190 (41.7%) in the hyperopic control group and 266 (58.3%) in the AccET group. All patients received at least 3 years of follow-up after spectacle prescription. Subgroups were divided according to age when spectacles were prescribed, presence of amblyopia, or initial SE. Longitudinal changes in SE in children with hyperopia showed a gradual decrease, although SE of younger children with AccET increased over the first 4 years and then decreased thereafter. SE in eye with higher SE was tended to decrease significantly in patient with Acc ET than hyperopic control group (group × time p = 0.015). Amblyopic eyes showed a greater decreased in SE compared with non-amblyopic eyes, but it was not statistically significant (p = 0.07). SE was significantly decreased in children with more hyperopia (≥ 3 D) compared with children with less hyperopia (<3 D) (p = 0.008). Emmetropization of hyperopia was faster in hyperopic patients without AccET and could be affected by the age of the initial spectacles prescription, initial amount of SE, or presence of amblyopia.

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