Correlation between refractive state, corneal thickness, and keratometry in ametropic patients

Purpose: To analyze the correlation between age, gender, refractive error, keratometry, and corneal thickness in a large group of subjects. Methods: This study is a retrospective analysis of patients who underwent refractive surgery between January 2000 and February 2015 at Care Vision Refractive Clinic, Tel Aviv, Israel. Patient demographics, subjective refraction, pachymetry, and average keratometry were collected. Results: Overall, 51,113 eyes of patients averaging 28.8 ± 9.3 years of which 53.9% were males were included. Average keratometry, spherical equivalent and cylindrical error differed significantly between male and female subjects (p < 0.001), while pachymetry did not (p = 0.332). In myopic eyes, correlations between age, pachymetry, average keratometry, spherical equivalent, and cylindrical error were all statistically significant except for the correlation between age and either pachymetry (p = 0.462) or spherical equivalent (p = 0.016). All correlations found were negligible or small (|r|= 0.003 to 0.141). In hyperopic eyes, correlations between age, pachymetry, average keratometry, spherical equivalent, and cylindrical error were all statistically significant except for the correlation between average keratometry and either pachymetry or cylindrical error (p = 0.344 or p = 0.274, respectively). All correlations found were negligible or small, except for a moderate correlation found between age and cylindrical error (r = 0.365). Conclusion: Refractive state, pachymetry, and keratometry of refractive surgery candidates are mostly weakly correlated.

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Comparison of Intraocular Pressure before and after Laser In Situ Keratomileusis Refractive Surgery Measured with Perkins Tonometry, Noncontact Tonometry, and Transpalpebral Tonometry

Journal of Ophthalmology ◽

10.1155/2015/683895 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Isabel Cacho ◽

Juan Sanchez-Naves ◽

Laura Batres ◽

Jesús Pintor ◽

Gonzalo Carracedo

Keyword(s):

Intraocular Pressure ◽

Refractive Surgery ◽

Corneal Thickness ◽

Laser In Situ Keratomileusis ◽

Spherical Equivalent ◽

Transpalpebral Tonometry ◽

Spherical Equivalent Refraction ◽

Before And After ◽

Noncontact Tonometry

Purpose. To compare the intraocular pressure (IOP) before and after Laser In Situ Keratomileusis (LASIK), measured by Diaton, Perkins, and noncontact air pulse tonometers.Methods. Fifty-seven patients with a mean age of 34.88 were scheduled for myopia LASIK treatment. Spherical equivalent refraction (SER), corneal curvature (K), and central corneal thickness (CCT) and superior corneal thickness (SCT) were obtained before and after LASIK surgery. IOP values before and after surgery were measured using Diaton, Perkins, and noncontact air pulse tonometers.Results. The IOP values before and after LASIK surgery using Perkins tonometer and air tonometers were statistically significant (p<0.05). However, no significant differences were found (p>0.05) for IOP values measured with Diaton tonometer. CCT decreases significantly after surgery (p<0.05) but no statistical differences were found in SCT (p=0.08). Correlations between pre- and postsurgery were found for all tonometers used, withp=0.001andr=0.434for the air pulse tonometer,p=0.008andr=0.355for Perkins, andp<0.001andr=0.637for Diaton.Conclusion. Transpalpebral tonometry may be useful for measuring postsurgery IOP after myopic LASIK ablation because this technique is not influenced by the treatment.

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Comparison between OrbscanIIz, Pentacam, Ultrasound Pachymetry (Tomey SP-100) at Different Stages of Keratoconus

Ophthalmology Research An International Journal ◽

10.9734/or/2020/v13i230163 ◽

2020 ◽

pp. 7-33

Author(s):

E. Pateras ◽

Ch. Koufala

Keyword(s):

Correlation Coefficient ◽

Study Design ◽

Refractive Surgery ◽

Corneal Thickness ◽

Cross Linking ◽

Moderate Correlation ◽

Measurement Systems ◽

Ultrasound Pachymetry ◽

Collagen Cross Linking ◽

Corneal Collagen

Aims: To compare results of OrbscanIIz and Pentacam and Ultrasound pachymetry at different stages of keratoconus on corneal thickness. Sample and Study Design: 94 keratoconic patients participated in the study, of which 52 were men and 42 women. Keratoconus patients were measured with OrbscanIIz, Pentacam and Ultrasound pachymetry in pre-operation examinations for corneal collagen cross-linking. The patients belong to different keratoconus stages. Place and Duration of Study: University of West Attica Dept Biomedical Sciensce Course Optics & Optometry in collaboration with Athens “Ophthalmologico” Clinic during the period between October 2017 to January 2019. Methodology: Corneal Pachymetry maps correlation of three types of corneal pachymeters OrbscanIIz, Pentacam and Ultrasound pachymetry (Tomey SP-100 Pachymeter). The measurements of the thinnest point of the cornea from each patient were collected at different stages of keratoconus and compared. Results: A sample of 188 eyes were measured at different stages of keratoconus and compared for the thinnest corneal thickness with three different measurement systems, OrbscanIIz ,Pentacam and Ultrasound pachymetry. At sublinical stage Orbscan-Pentacam had Correlation coefficient r=0,7971, Orbscan-Ultrasound r=0,7483 and Pentacam-Ultrasound r=0,9442. At 1st stage Orbscan-Pentacam had Correlation coefficient r=0,8913, Orbscan-Ultrasound r=0,8151 and Pentacam-Ultrasound r=0,8151. At 2nd stage Orbscan-Pentacam had Correlation coefficient r=0,9339, Orbscan-Ultrasound r=0,8819 and Pentacam-Ultrasound r=0,9633. For 3rd stage Orbscan-Pentacam had Correlation coefficient r=0,8317, Orbscan-Ultrasound r=0,8457 and Pentacam-Ultrasound r=0,9633. For 4th stage Orbscan-Pentacam had Correlation coefficient r=-0,4655, Orbscan-Ultrasound r=0,3089 and Pentacam-Ultrasound r=0,9633. In Iatrogenic keratoectasiaafter refractive surgery Orbscan-Pentacam had Correlation coefficient r=0,9327, Orbscan-Ultrasound r=0,3089 and Pentacam-Ultrasound r=0,9859. Conclusion: Statistical differences between OrbscanIIz, Pentacam and Ultrasound pachymetry were found for corneal thickness in all stages of keratoconus for the thinnest point measured. Orbscan-Pentacam have statistical significant differences but weak to moderate correlation. Orbscan-Ultasound have also statistical significant differences their correlation is very weak, while Pentacam-Ultrasound have statistical significant differences smaller as the previous but their correlation is very strong at all stages of keratoconus.

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The Effect of Astigmatism Axis on Visual Acuity

European Journal of Ophthalmology ◽

10.5301/ejo.5000890 ◽

2016 ◽

Vol 27 (3) ◽

pp. 308-311 ◽

Cited By ~ 3

Author(s):

Michael Mimouni ◽

Achia Nemet ◽

Russell Pokroy ◽

Tzahi Sela ◽

Gur Munzer ◽

...

Keyword(s):

Visual Acuity ◽

Refractive Surgery ◽

Laser In Situ Keratomileusis ◽

Stepwise Multiple Regression ◽

Spherical Equivalent ◽

Tel Aviv ◽

Uncorrected Distance Visual Acuity ◽

Laser Refractive Surgery ◽

Better Than

Purpose To evaluate the effect of astigmatism axis on uncorrected distance visual acuity (UDVA) in emmetropic eyes that underwent laser refractive surgery. Methods This retrospective study included patients who underwent laser in situ keratomileusis or photorefractive keratectomy between January 2000 and December 2015 at the Care-Vision Laser Centers, Tel Aviv, Israel. Eyes with a 3-month postoperative spherical equivalent between -0.5 D and 0.5 D were included in this study. Eyes with ocular comorbidities and planned ametropia were excluded. Study eyes were divided into 3 groups according to the steep astigmatic axis: with the rule (WTR) (60-120), oblique (31-59 or 121-149), and against the rule (ATR) (0-30 or 150-180). The UDVA of these 3 groups was compared. The oblique group was divided into oblique ATR and oblique WTR, which were compared with each other. Results A total of 17,416 consecutive eyes of 8,708 patients were studied. The WTR eyes (n = 10,651) had significantly better UDVA (logMAR 0.01 ± 0.08) than the oblique (n = 3,141, logMAR 0.02 ± 0.09) and ATR eyes (n = 3,624, logMAR 0.02 ± 0.10) (p<0.001). The oblique WTR group had significantly better UDVA than the oblique ATR group (p<0.001). The UDVA of the oblique and ATR groups was similar. Stepwise multiple regression analysis showed that the group accounted for 15% of the UDVA variance (p = 0.04). Conclusions The astigmatic axis has a small but significant effect on UDVA in emmetropic eyes; WTR was better than oblique and ATR astigmatism. Therefore, when correcting astigmatism, it may be preferable to err towards WTR astigmatism.

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Reversal of Myopic Correction for Patients Intolerant to LASIK

Journal of Ophthalmology ◽

10.1155/2021/7113676 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Amr A. Gab-Alla

Keyword(s):

Refractive Surgery ◽

Average Duration ◽

Corneal Thickness ◽

Case Series ◽

Spherical Equivalent ◽

Efficacy And Safety ◽

Effective Option ◽

Optical Zone ◽

The Mean ◽

One Year

Purpose. To evaluate the outcome of the reversal of myopia correction in patients intolerant to LASIK. Methods. This study is a retrospective and case series of patients who decided to reverse their previous myopic LASIK correction between July 2012 and July 2020. It was conducted at a private refractive surgery centre, Ismailia, Egypt. The patients were followed up after reversal treatment for one year. Primary LASIK and reversal treatment were performed by a 500 kHz Amaris excimer laser platform. The main outcomes included refractive predictability, stability, efficacy, and safety and any reported complications. Results. This study included 48 eyes of 24 patients (6 male and 18 female patients). The average duration between the primary LASIK surgery and reversal treatment was 3.20 ± 0.30 months (range 3 to 4 months). Reversal treatment was bilateral in all patients. The mean age of the patients was 38 ± 1.9 years (range 37 to 45 yrs). After reversal, the mean postreversal cycloplegic refraction spherical equivalent was −1.82 ± 0.34 D (range −1.50 to −3.00 D). The mean ablation depth was 34.10 ± 7.36 μm (range 20 to 46 μm), and the mean of the central corneal thickness 12 months after reversal treatment was 510.2 ± 14.4 μm (range 515 to 487 μm). The mean keratometric reading was 42.6 ± 1.6 (range 42.5 to 44.8). The mean of CDVA was 0.2 ± 0.03 log MAR (range −0.10 to 0.4 log MAR). The mean optical zone of reversal treatment was 6.1 ± 0.3 mm (range 5.9 to 6.2 mm). UDVA was 0.4 log MAR in 87.5% of the patients, 0.5 log MAR in 8.3% of the patients, and 0.6 log MAR in 4.2% of the patients. CDVA remained unchanged in 83.3% of patients; 2.1% of the patients gained one line of CDVA (Snellen); 8.3% of the patients lost one line of CDVA; 6.3% of the patients lost two lines of CDVA. No cases of corneal ectasia were recorded. The only postoperative complications were flap microfolds in 3 eyes (6.25%). Conclusion. In conclusion, this study demonstrates that reversal of myopic LASIK treatment is a safe, stable, and effective option for intolerant patients.

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Relationship between minimum corneal thickness and refractive state, keratometry, age, sex, and left or right eye in refractive surgery candidates

Journal of Cataract & Refractive Surgery ◽

10.1016/j.jcrs.2011.06.033 ◽

2011 ◽

Vol 37 (12) ◽

pp. 2175-2180 ◽

Cited By ~ 12

Author(s):

Stephan J. Linke ◽

Johannes Steinberg ◽

Mau-Thek Eddy ◽

Gisbert Richard ◽

Toam Katz

Keyword(s):

Refractive Surgery ◽

Corneal Thickness ◽

Refractive State

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New avenues of preoperative evaluation before corneal refractive surgery during the COVID-19 pandemic

Clinical ophthalmology ◽

10.32364/2311-7729-2021-21-2-72-77 ◽

2021 ◽

Vol 21 (2) ◽

pp. 72-77

Author(s):

S.N. Sakhnov ◽

◽

O.A. Klokova ◽

A.V. Piskunov ◽

R.O. Damashauskas ◽

...

Keyword(s):

Refractive Surgery ◽

Preoperative Evaluation ◽

Corneal Thickness ◽

Diagnostic System ◽

Spherical Equivalent ◽

Mean Values ◽

Applanation Tonometer ◽

Corneal Refractive Surgery ◽

The Difference

Aim: to assess the reproducibility and comparability of measurements produced by Visionix VX130+ and their consistency with data produced by Topcon KR-800, NT-530P, Oculyzer, and RTVue-100. Patients and Methods: 124 patients (248 eyes) aged 18–45 years (mean age 25.24±7.5 years) were enrolled. Refractometry, IOP levels, and pachymetry measured by Visionix VX130+ system (LLC “Visionix Rus” — affiliated company of Luneau Technology Operations) were compared to the readings produced by Topcon KR-800 Auto Kerato-Refractometer (Topcon, Japan), Nidek NT-530P non-contact tonometer (Nidek, Japan), CT200 Goldman applanation tonometer (Reichert, USA), ALLEGRO Oculyzer (WaveLight AG, Germany), and RTVue-100 (Optovue, USA). Results: refractometry produced by Visionix VX130+ is highly reproducible and stable. Mean spread of spherical equivalent was 0.22±0.22 D and mean spread of cylindrical equivalent was 0.23±0.16 D. No significant differences were revealed between refractometry readings produced by Visionix VX130+ and Topcon KR-800 in patients with myopia (p>0.05). Both Visionix VX130+ and Nidek NT-530P (automated IOP measurements) produce two values, i.e., with and without corneal thickness. Our findings suggest that mean values are virtually similar in Visionix VX130+ group (p>0.05) while Nidek NT-530P produces significant differences (p<0.05). Mean central corneal thickness (CCT) measured by Visionix VX130+ was almost similar to CCT measured by Oculyzer (the difference was 3.8±2.23 μm, р>0.05) and greater than CCT measured by RTVue-100 (р<0.05). Conclusion: clinical trials comparing the readings produced by Visionix VX 130+ and other devices whose reliability was evidenced by long-term clinical experience have demonstrated that Visionix VX 130+ multifunctional diagnostic system is fully in line with the COVID-19 pandemic requirements. This device provides the measurements for performing safe and effective corneal refractive surgery for refractive errors. Keywords: corneal refractive procedure, pneumotonometry, aberrometry, corneal topography, pachymetry, cornea, intraocular pressure. For citation: Sakhnov S.N., Klokova O.A., Piskunov A.V. et al. New avenues of preoperative evaluation before corneal refractive surgery during the COVID-19 pandemic. Russian Journal of Clinical Ophthalmology. 2021;21(2):72–77. DOI: 10.32364/2311-7729-2021-21-2-72-77.

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Refraction in Preschool Children in Kazanlak, Bulgaria

Folia Medica ◽

10.3897/folmed.62.e47463 ◽

2020 ◽

Vol 62 (2) ◽

pp. 345-351

Author(s):

Kiril Slaveykov ◽

Kalina Trifonova

Keyword(s):

Preschool Children ◽

Refractive Error ◽

Axial Length ◽

Cross Sectional Study ◽

Spherical Equivalent ◽

Sectional Study ◽

Cross Sectional ◽

Refractive State ◽

Myopic Shift ◽

The City

Introduction: The refractive state of the eye changes as the eye’s axial length increases and the cornea and lens flatten. In general, eyes are hyperopic at birth, become slightly more hyperopic until the age of 7, which at this point we see a myopic shift toward plano until the eyes reach their adult dimensions, usually by about the age 16. Aim: To determine the prevalence of refractive error in preschool children aged 3 - 6 in the city of Kazanlak, Bulgaria. Materials and methods: A cross-sectional study was conducted in a kindergarten based school within the city of Kazanlak, Bulgaria. Out of 15 kindergarten schools, 10 chose to participate in the study. The children underwent non-mydriatic refraction screening using a Plus-Optix S12с mobile camera. Myopia, hyperopia and astigmatism were defined as being a spherical equivalent (SE) ≤ −0.50 D, SE ≥ +2.00 D and cylindrical diopters ≤ −1.00 D. Results: A total of 596 children were screened. Out of these 596 children; 526 were with ametropia (470 hypermetropia, 46 myopia) and 50 had astigmatism. Strabismus was found in 12 children, with a further 8 children suffering from amblyopia and finally 8 children were also found to be diagnosed with anisometropia. In 8 cases there were no results due to opacities or due to the small size of the pupil. Conclusion: The prevalence of refractive error in preschool children is similar to that found in other research in the field. While most cases fall into the category of emmetropia or mild hypermetropia, most of the children had never been to an ophthalmologist. A mandatory checkup should be issued for all children below the age of seven.

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Stabilization of refractive error and associated factors following small incision phacoemulsification cataract surgery

BMC Ophthalmology ◽

10.1186/s12886-021-02221-w ◽

2022 ◽

Vol 22 (1) ◽

Author(s):

Ammar M Khan ◽

Derek M. Waldner ◽

Micah Luong ◽

Emi Sanders ◽

Andrew C. S. Crichton ◽

...

Keyword(s):

Visual Acuity ◽

Cataract Surgery ◽

Refractive Error ◽

Central Corneal Thickness ◽

Corneal Thickness ◽

Spherical Equivalent ◽

Small Incision ◽

Lens Position ◽

Phacoemulsification Cataract Surgery

Abstract Background Accumulating evidence suggests that refractive stabilization occurs rapidly following small incision cataract surgery. Nonetheless, many guidelines still suggest waiting four to 6 weeks before prescribing corrective lenses. This study was undertaken to supplement the existing literature regarding refractive stabilization, and evaluate multiple contributing factors that could dissuade clinicians from confidently correcting refractive error in the early post-operative course following routine cataract surgeries. Methods Adult patients undergoing phacoemulsification cataract surgery with uncomplicated surgeries and post-surgical courses at the Calgary Ophthalmology Centre (Calgary, Alberta, Canada) were included in this prospective observational case series. Exclusion criteria included known corneal dystrophies, infectious keratitis, complicated surgery or toric/multifocal IOLs. Data was collected at weekly intervals for a total of 6 weeks. Collected data included autorefraction, visual acuity, corneal pachymetry, and effective lens position. Results One hundred six eyes of 104 patients were included in this study. Post-operative sphere, cylinder and spherical equivalent were not significantly different at any post-operative week compared with week six, and 80–86% of patients were within 0.5D of last follow-up spherical equivalent at any week. The secondary outcomes of central corneal thickness, effective lens position and visual acuity did, however, exhibit significant differences between early post-operative weeks and last follow-up values. Conclusions These data suggest that refractive error can be effectively measured and corrected as early as one-week post-operatively in the majority of patients, though other measures of post-operative stability including central corneal thickness, effective lens position and visual acuity can require up to 4 weeks to stabilize. Thus a conservative and pragmatic approach may be to wait until 4 weeks post-operatively prior to obtaining refractive correction following uncomplicated phacoemulsification cataract surgery.

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Relationship between axial length, keratometry and central corneal thickness in patients with refractive errors at a teaching hospital in Southwest, Nigeria

International Journal of Advances in Medicine ◽

10.18203/2349-3933.ijam20214128 ◽

2021 ◽

Vol 8 (11) ◽

pp. 1657

Author(s):

Anthony O. Betiku ◽

Adeola O. Onakoya ◽

Olufisayo T. Aribaba ◽

Omodele O. Jagun

Keyword(s):

Teaching Hospital ◽

Refractive Error ◽

Axial Length ◽

Refractive Surgery ◽

Central Corneal Thickness ◽

Corneal Thickness ◽

University Teaching ◽

Refractive Errors ◽

Cross Sectional ◽

The Mean

Background: Aim of the study was to determine the relationship between axial length (AL), keratometry and central corneal thickness (CCT), and refractive errors in adult patients attending the Guinness eye centre (GEC), Lagos university teaching hospital (LUTH) Idi-Araba, Lagos.Methods: A descriptive cross-sectional study conducted among consecutive patients aged 16 years and above with refractive errors attending the GEC, LUTH. Ocular parameters measured included AL, anterior corneal curvature, CCT and refractive errors. AL and keratometry were measured with IOL master and CCT with ultrasonic A scan pachymeter. Refraction was done with auto-refractor-keratometer. Data analysis was done with statistical package for social science (SPSS) 20. Results: A total of 394 patients were studied, 157 males and 237 females. The age range was 16-65 years, mean -37.9±13.3 years and median -36.5 years. There were more myopic patients 215 (54.6%) than hyper-metropes 179 (45.4%). The mean AL was 23.9±1.1 mm and eyes with longer AL were more likely to be myopic (r=-0.676, p<0.001); to have flatter cornea (r=0.519, p<0.001) and thicker cornea (r=0.149, p=0.003). The mean CCT was 520.3±31.0 µm. There was a weak negative correlation between CCT and refractive error (r=-0.111, p=0.027).Conclusions: The mean CCT was lower than the mean CCT of other Nigerian studies. Hypermetropic patients were more likely to have thinner corneas. This may lead to underestimation of intraocular pressure (IOP) in these patients. Significant correlation was seen between AL and refractive error, CCT and keratometry. AL correlated with less spherical equivalent refractive error, flatter and thicker cornea. It is therefore important to measure the CCT of all patients going for refractive surgery to detect those at risk of developing corneal ectasia following refractive 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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