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Purpose: To evaluate the accuracy of nine formulas to calculate the power of a new extended depth-of-focus intraocular lens (EDOF IOL), the AcrySof IQ Vivity (Alcon Laboratories, Inc), using measurements from two optical biometers, the IOLMaster 700 (Carl Zeiss Meditec AG) and Anterion (Heidelberg Engineering GmbH). Methods: After constant optimization, the accuracy of these formulas was analyzed in 101 eyes: Barrett Universal II, EVO 2.0, Haigis, Hoffer Q, Holladay 1, Kane, Olsen, RBF 3.0, and SRK/T. Both standard and total keratometry from the IOLMaster 700 and standard keratometry from the Anterion were used for each formula. Results: Constant optimization provided slightly different values for the A-constant, which ranged between 118.99 and 119.16, depending on the formula and the optical biometer. According to the heteroscedastic test, within each keratometry modality the standard deviation of the SRK/T was significantly higher compared to that of the Holladay 1, Kane, Olsen, and RBF 3.0 formulas. The SRK/T formula provided less accurate results also when the absolute prediction errors were compared by Friedman test. According to McNemar's test with Holm corrections, statistically significant differences were found within each keratometry modality between the percentage of eyes with a prediction error within ±0.25 diopters obtained with the Olsen formula compared to the Holladay 1 and Hoffer Q formulas. Conclusions: Constant optimization remains a mandatory step to achieve the best outcomes with the new EDOF IOL: the same constant should not be used for all formulas and for both optical biometers. Different statistical tests revealed that older IOL formulas have lower accuracy compared to newer formulas. [ J Refract Surg . 2023;39(3):158–164.]

To report the results of intraocular lens (IOL) power calculation by ray tracing in eyes with previous myopic excimer laser surgery.G.B. Bietti Foundation I.R.C.C.S., Rome, Italy.Retrospective interventional case series.A series of consecutive patients undergoing phacoemulsification and IOL implantation after myopic excimer laser was investigated. IOL power was calculated using ray-tracing software available on the anterior segment optical coherence tomographer MS-39. Axial length (AL) was measured by optical biometry, and 4 values were investigated: (1) that from the printout, (2) the modified Wang/Koch formula, and (3) the polynomial equation for the Holladay 1 and (4) for the Holladay 2 formulas. The mean prediction error (PE), median absolute error (MedAE), and percentage of eyes with a PE within ±0.50 diopters (D) were reported.The study enrolled 39 eyes. Entering the original AL into ray tracing led to a mean hyperopic PE (+0.56 ±0.54 D), whereas with the Wang/Koch formula, a mean myopic PE (-0.41 ±0.53 D) was obtained. The Holladay 1 and 2 polynomial equations lead to the lowest PEs (-0.10 ±0.49 D and +0.08 ±0.49 D, respectively), lowest MedAE (0.37 D and 0.25 D), and highest percentages of eyes with a PE within ±0.50 D (71.79% and 76.92%). Calculations based on the Holladay 2 polynomial equation showed a statistically significant difference compared with other methods used (including Barrett-True K formula), with the only exception of the Holladay 1 polynomial equation.IOL power was accurately calculated by ray tracing with adjusted AL according to the Holladay 2 polynomial equation.

PurposeTo compare axial length (AL) measurements in long eyes by two swept-source optical coherence tomography (SS-OCT) biometers, one based on the group refractive index (IOLMaster 700, Zeiss) and the other based on sum of segments (Argos, Movu), and compare these measurements to previously published methods to optimize AL.SettingI.R.C.C.S. - G.B. Bietti Foundation, Rome, ItalyDesignProspective case seriesMethodsAL was measured with both optical biometers in myopic patients (AL > 24.00 mm) and compared to the values obtained with Wang-Koch adjustment, polynomial equations for the Holladay 1 and 2 formulas and Cooke modified AL (CMAL).ResultsIn 102 eyes of 55 subjects, a statistically significant difference (p

Background: this retrospective study aimed to analyze the results of the combination of the Haigis formula and Total Keratometry (TK) to calculate the IOL power in eyes with previous corneal refractive surgery. Methods: The TK value provided by the IOL Master 700 (Carl Zeiss Meditec) was introduced into the Haigis formula; the mean prediction error (PE), mean absolute error (MAE), median absolute error (MedAE) and percentage of eyes with a PE within ±0.25 D, ±0.5 D, ±0.75 D and ±1.00 D were calculated. Results: Ninety-three eyes of 93 patients with previous laser refractive surgery were evaluated. Two groups were defined: Group A included 51 previously myopic eyes, Group B included 42 previously hyperopic eyes. The mean PE in Group A was +0.09 ±0.44 D and 76.47% of eyes had a PE within ±0.50 D. In Group B the mean PE was -0.15 ±0.46 D and 66.67% of eyes had a PE within ±0.50 D. Discussion: The Haigis formula combined with TK is one of the most accurate available methods for IOL power calculation in eyes with prior myopic and hyperopic corneal refractive surgery. In such eyes the results are similar to or better than those reported in previous studies.

Purpose. To evaluate the morphological features and density of corneal subbasal plexus (SBP) using in vivo corneal confocal microscopy (IVCCM) in patients affected by Fuchs’ endothelial corneal dystrophy (FECD) six months after Descemet membrane endothelial keratoplasty (DMEK) and Descemet-stripping automated endothelial keratoplasty (DSAEK). Methods. We included patients affected by FECD, requiring corneal endothelial surgery due to corneal oedema occurred from 3 to 6 months. 7 eyes underwent DMEK and 7 eyes DSAEK. All patients performed IVCCM preoperative and in six months postoperative. We analyzed SBP parameters, using CS4 Nerves Tracking Tool, and we studied the differences between the two endothelial keratoplasties. Results. Comparing the eyes treated with DMEK with those treated with DSAEK, preoperative corneal thickness, corrected distance visual acuity (CDVA), and age were similar in both groups. SBP was not detectable at preoperative IVCCM in any eye. Postoperatively, the nerve fibers length, the nerve fibers density, the tortuosity, and the number of fibers and of branching did not differ in the eyes that underwent DMEK compared to DSAEK. The corneal beadings density was higher after DMEK than DSAEK, and this difference was statistically significant ( P = 0.004). The type of endothelial keratoplasty was not associated with the presence or absence of postoperative corneal SBP (Pearson’ chi-square, 0.755). Conclusions. Postoperative corneal reinnervation should be easily and noninvasively studied using IVCCM. Morphological postoperative features of SBP did not differ between two different types of endothelial keratoplasty, DMEK and DSAEK, despite the different sizes of the corneal incision. The lower beading density in the DSAEK group should be the consequence of a different distribution of mitochondria along the nerve fibers, as expression of a supposed higher metabolic distress in the DSAEK group.

PURPOSE: To assess the accuracy of different corneal powers for intraocular (IOL) power calculation in combined Descemet membrane endothelial keratoplasty (DMEK) and cataract surgery and investigate whether preoperative parameters correlate to the prediction error (PE). METHODS: This prospective case series involved patients with Fuchs endothelial dystrophy receiving combined DMEK and cataract surgery. Preoperatively, patients underwent optical biometry and anterior segment OCT (AS-OCT). AS-OCT measurements were repeated 6 months postoperatively, when final refraction was assessed. The PE was calculated using the preoperative average keratometry (K ave ) measured by the optical biometer and User Group for Laser Interference Biometry (ULIB) constants. It was also calculated, after constant optimization, using the preoperative K ave from both devices and the total corneal power (TCP) measured by AS-OCT, as well as the postoperative K ave and TCP measured by AS-OCT. RESULTS: ULIB constants resulted in the highest hyperopic PE ( P < .0001). Constant optimization improved the results, because the PE was zeroed out and the absolute PEs decreased. No significant difference was found among the Barrett Universal II, Emmetropia Verifying Optical 2.0, Haigis, Hoffer Q, Holladay 1, Kane, and SRK/T formulas. Further improvement was achieved with the postoperative K ave and TCP, although the accuracy remained moderate. The PE based on preoperative corneal measurements was correlated to the amount of corneal flattening; the latter could be predicted by multiple linear regression accounting for anterior and posterior corneal radii ( P = .0002) and was correlated to the preoperative anterior/posterior ratio. CONCLUSIONS: Constant optimization is beneficial for combined DMEK and phacoemulsification. Predicting postoperative corneal flattening may improve the results of IOL power accuracy. [ J Refract Surg . 2022;38(7):435–442.]

Purpose To evaluate the accuracy of the measurements provided by a Scheimpflug camera combined with partial coherence interferometry for intraocular lens (IOL) power calculation. Setting I.R.C.C.S - G.B. Bietti Foundation, Rome, Italy. Design Prospective case series. Methods Consecutive patients scheduled for cataract surgery were enrolled. Preoperative biometry was carried out with a Pentacam AXL (Oculus). All patients received the same IOL (AcrySof SN60WF; Alcon). Measurements were entered into the following formulas: Barrett Universal II, Emmetropia Verifying Optical (EVO) 2.0, Haigis, Hoffer Q, Holladay 1, Holladay 2 with axial length adjustment, Kane, Ladas Super Formula (LSF) 2.0, Naeser 2, Pearl-DGS, SRK/T, T2, and VRF. When refraction was measured at 1 month postoperatively, the mean prediction error (PE), the median absolute error (MedAE), and the percentage of eyes with a PE within ±0.25, ±0.50, and ±1.00 diopter (D) were calculated after constant optimization. Results Ninety-one eyes of 91 patients were analyzed. Comparison of the mean PE and MedAE did not reveal any statistically significant difference. However, the Pearl DGS formula achieved the lowest MedAE (0.19 D) followed by the LSF 2.0 (0.22). Twelve of the 13 formulas obtained a PE within ±0.50 D in at least 80% of eyes (range 80% - 87%) and 7 of them in at least 85%. Twelve formulas yielded a PE within ±0.25 D in at least 50% of eyes (range 51% - 64%). Conclusions All the investigated formulas performed well using the Pentacam AXL measurements. The newest Pearl DGS formula version and LSF 2.0 showed promising results.

OBJECTIVES: We aimed (1) to assess the repeatability of Total Keratometry (TK) and standard keratometry (K) measurements, as provided by the IOLMaster 700 (Carl Zeiss Meditec), and (2) to compare the corneal astigmatism measured by TK to the total corneal astigmatism (TCA) measured by a Scheimpflug camera (Pentacam AXL, Oculus). METHODS: Two groups of patients were prospectively enrolled: Group A included previously unoperated eyes undergoing cataract surgery, and Group B eyes with previous myopic corneal excimer laser surgery. TK and K were measured three times by the same examiner. Repeatability was assessed based on the within-subject standard deviation (S(w)), test–retest variability, coefficient of variation and intraclass correlation coefficient (ICC). In Group A, TCA was measured once and compared to TK astigmatism. Vector analysis was performed according to Næser. RESULTS: In Group A (69 eyes) the mean K and TK were, respectively, 43.14 ± 1.37 D and 43.18 ± 1.37 D. In Group B (51 eyes) the mean K and TK were, respectively, 40.14 ± 2.20 D and 39.71 ± 2.35 D. The repeatability of the average K and TK was high (S(w) 0.9. For most measurements the variance of K and TK did not show any statistically significant difference either within groups or between groups. Vectors KP(45) were significantly different between TK astigmatism and TCA. CONCLUSIONS: TK measurements offer high repeatability in unoperated and post-excimer laser surgery eyes. TK astigmatism and TCA measurements could not be considered interchangeable.

To evaluate the repeatability of the measurements provided by a new optical biometer (EyeStar 900) based on swept-source optical coherence tomography (SS-OCT) and their agreement with the measurements given by 2 validated biometers based on the same technology, the IOLMaster 700 and Argos.IRCCS G.B. Bietti Foundation, Rome, Italy.Prospective evaluation of diagnostic test.In a series of unoperated eyes, 3 consecutive scans were acquired with the EyeStar 900, and 1 with the IOLMaster 700 and the Argos. The following biometry parameters were analyzed: axial length (AL), keratometry (K), corneal astigmatism, central corneal thickness, corneal diameter (CD), anterior chamber depth (ACD), lens thickness (LT), and lens tilting. Repeatability was assessed using test-retest variability, the coefficient of variation (CoV), and the intraclass correlation coefficient (ICC); agreement was based on the 95% limits of agreement.56 eyes of 56 patients were analyzed. High repeatability was achieved for all measured parameters, as the CoV was1% in most cases and ICC was0.95 for all parameters. Good to high agreement was found among the measurements of the 3 optical biometers, although some statistically significant differences were detected between the EyeStar 900 and Argos (mean K, ACD, LT, and CD were higher with the Argos). The Argos measured a shorter AL in eyes25 mm.The new generation SS-OCT EyeStar 900 optical biometer produces highly repeatable measurements that are in good agreement with those provided by 2 previously validated instruments.

AimsTo assess the repeatability and reproducibility of the ocular measurements obtained with the Suoer SW-9000 μm Plus, a new fully automatic biometer based on optical low coherence reflectometry (OLCR) biometer, and to compare them to those obtained by a swept-source optical coherence tomography (SS-OCT)-based biometer.MethodsThis prospective study consisted of 115 eyes of 115 healthy subjects. The measurements were taken by the two optical biometers in random order. The measured parameters were axial length (AL), central corneal thickness (CCT), aqueous depth (AQD), anterior chamber depth (ACD), mean keratometry (Km), lens thickness (LT) and corneal diameter (CD). To evaluate the intraobserver repeatability and interobserver reproducibility, the within-subject SD, test–retest variability, coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were adopted. The Bland-Altman plot was drawn to assess the agreement.ResultsThe repeatability and reproducibility of all parameters for the new device were excellent (ICC>0.960 and CoVConclusionsThe new Suoer SW-9000 μm Plus biometer showed excellent repeatability and reproducibility. All the parameters obtained by this biometer were similar to those measured by SS-OCT-based biometer.

To compare phakic intraocular lens size calculations based on corneal diameter (CD) measurements by 3 instruments.G.B. Bietti Foundation I.R.C.C.S., Rome, Italy.Retrospective interventional case series.Preoperatively, CD was measured with the Aladdin, IOLMaster 700, and Pentacam AXL Wave. The simulated ICL size was computed by entering CD measurements into the manufacturer's calculator. Postoperatively, vaulting was measured by anterior segment optical coherence tomography. The optimal ICL size (OIS) was calculated and compared with the commercially available OIS (CAOIS).54 eyes (29 patients) with the implantable collamer lens (ICL) were enrolled. The mean CD was 12.02 ± 0.36 mm with the Aladdin, 12.35 ± 0.39 mm with the IOLMaster 700, and 12.22 ± 0.41 mm with the Pentacam AXL Wave ( Pamp;lt; .0001), with the closest agreement between the Pentacam AXL Wave and IOLMaster 700 (95% limits of agreement: -0.43 to +0.17 mm). Vaulting (mean: 558 ± 261 μm) was within 251 and 1000 μm in 49 eyes (83.3%). The mean difference between the simulated ICL size and OIS ranged between -0.11 ± 0.35 mm and 0.10 ± 0.30 mm ( Pamp;lt; .0001), with no statistically significant difference between the IOLMaster 700 and Pentacam AXL Wave. The simulated ICL size was equal to CAOIS in 38 eyes (70.37%) with the Aladdin, 37 eyes (68.52%) with the IOLMaster 700, and 39 eyes (72.22%) with the Pentacam AXL Wave, without any statistically significant difference.CD measurements by the 3 devices lead to similar percentages of eyes with an ICL size equal to the OIS. Agreement is closer between the IOLMaster 700 and Pentacam AXL Wave.

PURPOSE: To compare the accuracy of Total Keratometry (TK) and standard keratometry (K) with the IOLMaster 700 (Carl Zeiss Meditec) in evaluating the corneal refractive change in eyes with previous myopic femtosecond laser–assisted LASIK (FS-LASIK). METHODS: A series of consecutive patients who had undergone myopic FS-LASIK was prospectively enrolled. The refractive change in spherical equivalent (ΔSE) was defined as the difference between the preoperative target correction entered into the laser software and the postoperative cycloplegic refraction. The difference between the postoperative and the preoperative K (ΔK) and the difference between the postoperative and the preoperative TK (ΔTK) were compared to the ΔSE. Only the right eye of each patient was selected for the statistical analysis. RESULTS: Twenty-five eyes of 25 patients were enrolled. The mean ΔSE was −4.41 ± 1.68 diopters (D). The mean ΔK (−3.82 ± 1.60 D) revealed a statistically significant underestimation of the laser-induced refractive change ( P < .0001), whereas the mean ΔTK (−4.36 ± 1.78 D) did not show any significant difference ( P = .45). The difference between ΔK and ΔTK was statistically significant ( P < .0001). Linear regression between the laser-induced refractive change and the individual difference between the postoperative K and TK disclosed a statistically significant relationship ( r = −0.6930, r 2 = 0.4803, P < .0001), thus revealing that higher refractive corrections increase the difference between the postoperative values of K and TK. CONCLUSIONS: TK does not underestimate the laser-induced corneal changes and can be considered a reliable option for intraocular lens power calculation after myopic excimer laser surgery. [ J Refract Surg . 2021;37(12):848–852.]

The purpose was to define a normative database for a grating test for contrast sensitivity, based on a chart monitor with high-definition liquid crystal display, and validate its measurements by assessing their repeatability and determining responsiveness to cataract surgery. Three samples were analyzed: (1) healthy volunteers to assess the repeatability of measurements, (2) healthy subjects to develop the normative database, (3) patients undergoing cataract surgery. All subjects were tested with the grating contrast sensitivity test (Vision Chart, CSO) at 1.5, 3, 6, 12 and 18 cycles per degree. The instrument software progressively reduces the contrast of the gratings according to the Quick Estimate by Sequential Testing (QUEST) procedure. In the subjects of the first sample, three consecutive measurements were taken and repeatability was assessed on the basis of the intra-session test-retest variability and the coefficient of variation. The test offered high repeatability, with test-retest variability ranging between 0.05 and 0.23 Log CS and the coefficient of variation between 0.61 and 4.21%. Normative data did not show a normal distribution. The highest median values were observed at 1.5, 3 and 6 cycles per degree frequencies. At these frequencies a ceiling effect was evident. In cataract patients, postoperative values showed an improvement at all spatial frequencies. In conclusion, the new contrast sensitivity test provides repeatable measurements that can be used for clinical purposes. In patients with healthy eyes and good vision, attention has to be paid to the ceiling effect.

Purpose: To evaluate the 2-year clinical outcomes of corneal crosslinking (CXL) using transepithelial iontophoresis CXL (T-ionto CXL) in comparison with standard CXL for the treatment of progressive keratoconus. Setting: Single-site study. Design: Randomized controlled clinical trial with identifier code NCT02117999. Methods: The eyes of the participants were randomized to have either T-ionto CXL and/or standard CXL. Assessments of uncorrected (UDVA) and corrected (CDVA) distance visual acuities (logarithm of the minimum angle of resolution [logMAR]), manifest refraction spherical equivalent, maximum simulated keratometry (K) (diopters [D]), corneal higher-order aberrations (HOAs), central corneal thickness (CCT), and endothelial cell density (ECD) were performed at 3 days, 7 days, and 1, 3, 6, 12, and 24 months postoperatively. Results: The study comprised 34 eyes (25 patients). There were 22 eyes in the T-ionto CXL group and 12 eyes in the standard CXL group. Two years after T-ionto CXL and standard CXL, the mean maximum K flattened by -1.05 ± 1.20 D (P = .07) (20 eyes) and -1.51 ± .89 D (P < .001) (11 eyes), respectively. Two study cases (10%) and no control showed maximum K steepening of more than 1.0 D at 24 months postoperatively. The mean change in CDVA was -0.08 ± 0.15 logMAR (P = .04) and -0.02 ± 0.06 logMAR (P = .34) after T-ionto CXL and standard CXL, respectively. A significant average decrease in the myopic defocus (+0.81 D; P < .05) was found in both groups. No significant differences in the outcome measures between treatments were found at 24 months. The corneal HOAs, CCT, and ECD values did not change significantly in any group at 2 years postoperatively. Conclusions: Clinically significant topographic, visual, and refractive improvements were found 2 years after T-ionto CXL; standard CXL showed more significant corneal apex flattening than the transepithelial iontophoresis protocol.

Purpose: To study the features of corneal confocal microscopy of eyes with Fuchs’ endothelial corneal dystrophy (FECD) after successful Descemet stripping automated endothelial keratoplasty (DSAEK) versus Descemet membrane endothelial keratoplasty (DMEK). Methods: Thirty-two eyes affected by FECD with corneal oedema requiring a corneal graft were treated with DSAEK (15 eyes) or DMEK (17 eyes). All patients underwent in vivo corneal confocal microscopy (IVCCM) at 6 months postoperatively. We evaluated preoperative and postoperative corrected distance visual acuity (CDVA) and the correlation with IVCCM characteristics. Results: Using IVCCM, Z-scan curve analysis showed similar subepithelial reflectivity peaks between the two groups (DSAEK 1256 SU ± 514 vs DMEK 1118 SU ± 408, p = 0.411), while the interface reflectivity was significantly higher in the DMEK group (1511 SU ± 357) than in the DSAEK group (1029 SU ± 413, p = 0.002). Conclusion: Comparing the corneal confocal microscopic characteristics after DMEK with those after DSAEK and their correlation with visual outcome at 6 months, we hypothesized that the presence of a third reflectivity peak in the Z-scan curves of DSAEK patients could justify the poorer visual outcome with this endothelial surgery than with DMEK.

We assess repeatability of automatic measurements of a new anterior segment optical coherence tomographer and biometer (ANTERION) and their agreement with those provided by an anterior segment-optical coherence tomography device combined with Placido-disk corneal topography (MS-39) and a validated optical biometer (IOLMaster 500). A consecutive series of patients underwent three measurements with ANTERION and one with MS-39. A subgroup of patients underwent biometry also with IOLMaster 500. Repeatability was assessed by means of within-subject standard deviation, coefficient of variation (COV), and intraclass correlation coefficient (ICC). Agreement was investigated with the 95% limits of agreement. Paired t-test and Wilcoxon matched-pairs test were performed to compare the measurements of the different devices. Repeatability of ANTERION measurements was high, with ICC > 0.98 for all parameters except astigmatism (0.963); all parameters apart from those related to astigmatism revealed a COV

Background: Cataract surgery is the most common operation performed worldwide. A fixed topical corticosteroid-antibiotic combination is usually prescribed in clinical practice for 2 or more weeks to treat post surgical inflammation and prevent infection. However, this protracted schedule may increase the incidence of corticosteroid-related adverse events and notably promote antibiotic resistance. Methods: This International, multicentre, randomized, blinded-assessor, parallel-group clinical study evaluated the non-inferiority of 1-week levofloxacin/dexamethasone eye drops, followed by 1-week dexamethasone alone, vs. 2-week gold-standard tobramycin/dexamethasone (one drop QID for all schedules) to prevent and treat ocular inflammation and prevent infection after uncomplicated cataract surgery. Non-inferiority was defined as the lower limit of the 95% confidence interval (CI) around a treatment difference >–10%. The study randomized 808 patients enrolled in 53 centres (Italy, Germany, Spain and Russia). The primary endpoint was the proportion of patients without anterior chamber inflammation on day 15 defined as the end of treatment. Endophthalmitis was the key secondary endpoint. This study is registered with EudraCT code: 2018-000286-36. Results: After the end of treatment, 95.2% of the patients in the test arm vs. 94.9% of the control arm had no signs of inflammation in the anterior chamber (difference between proportions of patients = 0.028; 95% CI: −0.0275/0.0331). No case of endophthalmitis was reported. No statistically significant difference was evident in any of the other secondary endpoints. Both treatments were well tolerated. Conclusions: Non-inferiority of the new short pharmacological strategy was proven. One week of levofloxacin/dexamethasone prevents infection, ensures complete control of inflammation in almost all patients and may contain antibiotic resistance.

Background/aims To compare the accuracy of 13 formulas for intraocular lens (IOL) power calculation in cataract surgery. Methods In this retrospective interventional case series, optical biometry measurements were entered into these formulas: Barrett Universal II (BUII) with and without anterior chamber depth (ACD) as a predictor, EVO 2.0 with and without ACD as a predictor, Haigis, Hoffer Q, Holladay 1, Holladay 2AL, Kane, Næser 2, Pearl-DGS, RBF 2.0, SRK/T, T2 and VRF. The mean prediction error (PE), median absolute error (MedAE), mean absolute error and percentage of eyes with a PE within ±0.25, ±0.50, ±0.75 and ±1.00 diopters (D) were calculated. Results Two hundred consecutive eyes were enrolled. With all formulas, the mean PE was zero. The BUII with no ACD had the lowest standard deviation (±0.343 D), followed by the T2 (0.347 D), Kane (0.348 D), EVO 2.0 with no ACD (0.348 D) and BUII with ACD (0.353 D) formulas. The difference among the MedAEs of all formulas was statistically significant (p Conclusion All investigated formulas achieved good results; there was a tendency towards better outcomes with newer formulas. Traditional formulas can still be considered an accurate option.

PURPOSE: Given that a previous study found that corneal asphericity influences the refractive outcome of intraocular lens (IOL) power calculation by means of thin-lens formulas in eyes with spherical IOLs, the authors aimed to verify whether such influence can also be observed in eyes with aspherical IOLs. METHODS: In this retrospective comparative case series, IOL power was calculated with the Haigis, Hoffer Q, Holladay 1, and SRK/T formulas in two groups of eyes undergoing phacoemulsification and implantation of an aspherical IOL (Acrysof SN60WF; Alcon Laboratories, Inc., Fort Worth, TX). For each formula, the refractive prediction error was calculated once the constants had been optimized. Biometric data were obtained by partial coherence interferometry in one group and immersion ultrasound biometry and corneal topography in the other. Corneal asphericity was assessed by two different corneal topographers in the optical biometry group (Magellan; Nidek, Gamagori, Japan) and ultrasound biometry group (Keratron, Optikon 2000 Spa, Rome, Italy). RESULTS: The mean Q-value was −0.12 ± 0.08 in the optical biometry group (n = 51) and −0.22 ± 0.14 in the ultrasound biometry group (n = 79). In both groups, linear regression disclosed a statistically significant correlation between the Q-value and the prediction error (the only exception being the SRK/T formula). More negative Q-values were correlated to a positive prediction error, indicating a myopic outcome for prolate corneas. However, the correlation coefficients were lower than those previously reported for spherical IOLs. CONCLUSIONS: Corneal asphericity also influences the refractive outcomes of IOL power calculation by thinlens formulas when aspherical IOLs are implanted, although this influence is exerted to a lesser degree compared to spherical IOLs. [ J Refract Surg. 2017;33(7):476–481.]

To analyze the results of intraocular lens (IOL) power calculation using measurements by a swept-source optical coherence tomography (SS-OCT) optical biometer.IRCCS G.B. Bietti Foundation, Rome, Italy.Evaluation of a diagnostic test instrument.Preoperative measurements by the OA-2000 (Tomey Inc.) were taken in a consecutive series of patients undergoing cataract surgery with one IOL model (AcrySof SN60WF; Alcon Laboratories, Inc.). Measurements were entered into the following formulas: Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Hoffer Q, Holladay 1, Holladay 2, Holladay 2 with axial length adjustment, Kane, Olsen, Panacea, SRK/T, T2, and VRF. When refraction was measured at 1 month postoperatively, the mean arithmetic prediction error, the median absolute error (MedAE), and the percentage of eyes with a error of ±0.50 D or less were calculated after constant optimization.We enrolled 150 eyes. All formulas yielded excellent outcomes. The MedAE ranged between 0.200 D and 0.259 D, with a statistically significant difference among formulas (P = .0004). The lowest MedAE values were obtained with the Barrett, EVO, Kane, Olsenstandalone, Radial Basis Function (RBF), and T2 formulas. The percentage of eyes with a prediction error of ±0.50 D or less ranged between 80.00% and 90.67%, with a statistically significant difference (P.0001). The Barrett, EVO, Holladay 2 with axial length adjustment, Kane, RBF, and T2 achieved the highest percentages (≥88%).Measurements provided by the SS-OCT optical biometer enable accurate IOL power calculation because all formulas yielded a prediction error within 0.50 D in at least 80% of eyes.

Corneal tomography is an important tool to identify and follow up eyes with keratoconus. Our study evaluate the repeatability of the automatic measurements provided in keratoconic eyes by a new anterior-segment optical coherence tomographer (AS-OCT) combined with Placido-disk topography (MS-39, CSO) and assess their agreement with the corresponding measurements taken with a rotating Scheimpflug camera combined with Placido-disk topography (Sirius, CSO). Mean simulated keratometry, posterior and total corneal power, total corneal astigmatism, corneal asphericity, thinnest corneal thickness, epithelial thickness, corneal diameter, and aqueous depth were evaluated. Repeatability was assessed using test–retest variability, the coefficient of variation, and the intraclass correlation coefficient; agreement was assessed by the 95% limits of agreement. Good repeatability was achieved for most parameters. Moderate repeatability was found for total corneal astigmatism measurements. The repeatability of mean simulated keratometry and total corneal power measurements worsened with more severe stages of keratoconus with a statistically significant relationship between the individual coefficient of variation and corneal power values. Agreement with the Scheimpflug camera was moderate for aqueous depth and thinnest corneal thickness and poor for most other measured parameters. The good repeatability of automatic measurements suggests the new AS-OCT device to be a viable option in clinical practice of eyes with keratoconus.

Purpose To investigate agreement between rotating Scheimpflug camera (Pentacam HR, Oculus) and rotating Scheimpflug camera combined with Placido disc corneal topography (Sirius, CSO) in measuring total corneal astigmatism (TCA). Methods In this observational study, all patients undergoing cataract surgery with preoperative measurement of TCA by both devices and a validated corneal topographer (Keratron, Optikon 2000) were retrospectively evaluated. Astigmatism analysis was performed with and without vector analysis separately in eyes with with-the-rule, against-the-rule, and oblique astigmatism. Vector analysis was performed using the Naeser polar system. Results In 130 eyes of 130 subjects, nonvectorial analysis revealed that the mean TCA values obtained with the Sirius were higher than the corresponding values given by the Pentacam HR in all subgroups, although the difference was statistically significant only in eyes with against-the-rule astigmatism (P = 0.0009). This finding was confirmed by vector analysis. A TCA magnitude difference greater than 0.5 diopters was observed in 20.8% of cases, and a TCA axis difference greater than 10 degrees was observed in 45.4% of cases. Axis differences dropped to 18.5% when only eyes with astigmatism >0.75 diopters were analyzed and 3 measurements were averaged. The mean difference in the meridional and torsional power of TCA was close to zero in all subgroups, but with relatively large standard deviations (approximately 0.5 D). Conclusions Agreement between both devices in measuring TCA is only moderate with respect to both magnitude and axis orientation.

PURPOSE: To investigate whether the Estimated Pre-Refractive SimK accurately predicts the preoperative corneal power (K) in eyes with previous myopic femtosecond laser-assisted LASIK (FS-LASIK) and whether a better prediction can be developed. METHODS: Preoperatively and 3 months after FS-LASIK, patients underwent anterior segment imaging with the Pentacam HR rotating Scheimpflug camera (Oculus Optikgeräte, Wetzlar, Germany). Posterior and anterior corneal curvature and power and asphericity (Q-value at 8 mm) were recorded. Multiple linear regression was used to assess the relationship among variables. RESULTS: One hundred four eyes of 104 patients were enrolled. The Estimated Pre-Refractive SimK (43.19 ± 1.63 diopters [D]) was lower ( P = .0014) than the mean preoperative K (43.44 ± 1.49 D). The difference was within ±0.50 and ±1.00 D in 53.8% and 86.5% of eyes, respectively. Multiple linear regression detected a statistically significant relationship ( r 2 = 0.8497, P < .0001) among the investigated parameters: preoperative anterior corneal radius = 1.156 + 1.012 * postoperative posterior corneal radius – 0.3800 * postoperative Q-value. When this equation was used to predict the preoperative K, the difference between the actual preoperative K and the predicted value (43.41 ± 1.38 D) was not statistically significant. The rate of eyes with a difference between the predicted and actual preoperative K within ±0.50 and ±1.00 D increased to 61.5% and 93.3%, respectively. CONCLUSIONS: The corneal power before FS-LASIK can be accurately predicted from the postoperative corneal measurements of a rotating Scheimpflug camera. The multiple regression formula described may be more accurate than the Estimated Pre-Refractive SimK available on the Pentacam. [ J Refract Surg. 2016;32(5):332–336.]

Purpose To validate the accuracy of the SToP formula for calculating the intraocular lens (IOL) power from measurements obtained with a rotating Scheimpflug camera (Pentacam) in eyes with previous myopic excimer laser surgery. Setting IRCCS - Fondazione Bietti, Rome, Italy. Design Retrospective case series. Methods Corneal curvature measurements were taken in eyes that had cataract surgery after myopic excimer laser surgery. Values from both versions of the SToP calculator (based, respectively, on the Holladay 1 and the SRK/T formulas) were compared with historical (Masket and Savini) and no-history methods (Barrett True-K, BESSt formula, equivalent K-readings, Triple-S, and Shammas). Results Fifty eyes of 50 patients with historical data were analyzed. The SToP formula based on the SRK/T achieved the lowest median absolute error (MedAE) (0.31 diopters [D]) and a higher percentage of eyes (62%) with a prediction error in refraction within ±0.5 D. Excellent outcomes were also achieved with the Masket method, the BESSt formula, the Savini method, and the Triple-S method, which led to similar MedAEs (from 0.31 to 0.37 D) and an even higher percentage of eyes with a prediction error within ±0.5 D (from 64% to 76%). The SToP formula based on the Holladay 1 was slightly less accurate. Conclusions Several methods based on Scheimpflug camera measurements were used to successfully calculate the IOL power in eyes with previous myopic excimer laser surgery. The SToP formula based on the SRK/T was one of the best choices.

Purpose. The purpose of our study is to describe the in vivo corneal confocal microscopy characteristics of subbasal nerve plexus in a highly selected population of patients affected by type 1 diabetes mellitus (T1DM) without any microvascular diabetes complications.Methods. We included 19 T1DM patients without diabetic peripheral neuropathy, diabetic autonomic neuropathy, diabetic retinopathy, and microalbuminuria. All patients underwent in vivo corneal confocal microscopy and blood analysis to determine subbasal nerve plexus parameters and their correlation with clinical data. We compared the results with 19 healthy controls.Results. The T1DM group showed a significant decrease of the nerve fiber length (P=0.032), the nerve fiber length density (P=0.034), the number of fibers (P=0.005), and the number of branchings (P=0.028), compared to healthy subjects. The nerve fiber length, nerve fiber length density, and number of fibers were directly related to the age at onset of diabetes and inversely to the duration of DM. BMI (body mass index) was highly related to the nerve fiber length (r = −0.6,P=0.007), to the nerve fiber length density (r = −0.6,P=0.007), and to the number of fibers (r = −0.587,P=0.008). No significant correlations were found between the corneal parameters and HbA1c.Conclusions. Early subclinical fiber corneal variation could be easily detected using in vivo corneal confocal microscopy, even in type 1 diabetes without any microvascular diabetes complications, including diabetic peripheral neuropathy, diabetic autonomic neuropathy, diabetic retinopathy, and microalbuminuria.

Purpose To assess the outcomes of implantation of a single-piece toric intraocular lens (IOL) with 4 fenestrated haptics. Setting IRCCS Fondazione Bietti, Rome, Italy. Design Prospective case series. Methods All patients who had implantation of the Mini Toric Ready IOL were consecutively enrolled. Intraoperatively, the IOL was aligned using an automated system. Follow-up visits were performed at 1 day, 1 week, and 1, 3, and 6 months. At each visit, retroillumination pictures were taken to assess IOL orientation; visual acuity and refraction were also measured. Results The final analysis comprised 63 eyes (63 patients). From the first to the last follow-up, the mean arithmetic rotation was −0.2 degrees ± 3.5 (SD) (range −13 to +10 degrees) and the mean absolute rotation was 1.6 ± 3.1 degrees. Intraocular lens rotation from the first to the last examination was within 5 degrees in 92.1% of eyes and on consecutive visits, within 5 degrees in 98.4% or more of eyes. By 6 months, 10 IOLs (15.9%) had rotated clockwise and 10 counterclockwise. Linear regression did not show a statistically significant relationship between rotational stability and the axis of placement with any preoperative parameter (eg, axial length). The mean magnitude of preexisting corneal astigmatism was 1.9 ± 0.7 diopters (D) (range 0.76 to 3.72 D). At the last follow-up, the mean magnitude of refractive astigmatism was 0.5 ± 0.4 D (range 0.0 to 1.5 D); the difference was statistically significant (P Conclusion The toric IOL showed good rotational stability and is an option for correcting corneal astigmatism at the time of cataract surgery.

Purpose To assess the refractive accuracy of different formulas for intraocular lens (IOL) power calculation in eyes with keratoconus. Setting IRCCS Fondazione Bietti, Rome, Italy. Design Multicenter retrospective interventional study. Methods A consecutive series of eyes with keratoconus that had cataract surgery were evaluated. Keratometry, anterior chamber depth, and axial length were measured preoperatively with optical biometry; IOL power was calculated with the Barrett Universal II, Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. Subjective refraction was assessed at 1 month. The mean prediction error (PE), median absolute error (MedAE) and percentage of eyes with a PE within ±0.50 diopters (D), ±0.75 D, and ±1.00 D were calculated. Results The final spherical equivalent was −0.52 D ±1.61 (SD). In the whole sample (41 eyes), the mean PE was positive (hyperopic surprise) with all formulas; the lowest PE (0.91 D) and MedAE (0.62 D) were obtained with the SRK/T formula. In stage I eyes (n = 21), the MedAE ranged between 0.43 and 0.91 D; the SRK/T formula achieved the lowest MedAE and the highest rate of eyes with a PE within ±0.50 (61.9%). In stage II eyes (n = 13), the MedAE ranged between 0.75 D and 1.50 D; the SRK/T formula achieved the lowest MedAE and the highest rate of eyes with a PE within ±0.50 (30.8%). In stage III eyes (n = 7), the MedAE was higher than 2.50 D with all formulas. Conclusions In keratoconus eyes, all formulas led to a hyperopic refractive outcome. The SRK/T was the most accurate formula. The results were worse in advanced stages of the disease.

Purpose. To investigate the effectiveness of toric intraocular lenses (IOLs) for treating corneal astigmatism in patients with cataract and previous deep anterior lamellar keratoplasty (DALK). Setting. San Giovanni-Addolorata Hospital, Rome, Italy. Design. Prospective interventional case series. Methods. Patients undergoing cataract surgery after DALK for keratoconus were enrolled. Total corneal astigmatism (TCA) was assessed by a rotating Scheimpflug camera combined with Placido-disk corneal topography (Sirius; CSO, Firenze, Italy). A customized toric IOL (FIL 611 T, Soleko, Rome, Italy) was implanted in all eyes. One year postoperatively, refraction was measured, the IOL position was recorded, and vectorial and nonvectorial analyses were performed to evaluate the correction of astigmatism. Results. Ten eyes of 10 patients were analyzed. The mean preoperative TCA magnitude was 4.92 ± 1.99 diopters (D), and the mean cylinder of the IOL was 6.18 ± 2.44. After surgery, the difference between the planned axis of orientation of the IOL and the observed axis was ≤10° in all eyes. The mean surgically induced corneal astigmatism was 0.35 D at 20°. The mean postoperative refractive astigmatism power was 1.13 ± 0.94 D; with respect to preoperative TCA, the reduction was statistically significant (p<0.0001). The mean change in astigmatism power was 3.80 ± 1.60 D, corresponding to a correction of 77% of preoperative TCA power. Nine eyes out of 10 had a postoperative refractive astigmatism power ≤ 2D. Conclusions. Toric IOLs can effectively correct corneal astigmatism in eyes with previous DALK. The predictability of cylinder correction is partially lowered by the variability of the surgically induced changes of TCA. This trial is registered with NCT03398109.

To compare lens thickness measurements provided by immersion ultrasound (US) biometry and optical biometry.IRCCS-Fondazione Bietti, Rome, Italy.Evaluation of diagnostic technology.Immersion US biometry and optical biometry were performed in a consecutive series of eyes having cataract surgery. Three optical biometers (OA-2000, Aladdin, and Galilei G6) were used. To assess how the differences in lens thickness measurements influenced intraocular lens (IOL) power calculation, the lens thickness values were entered into the Olsen formula.Eighty-eight eyes were analyzed. Ultrasound immersion biometry yielded significantly higher lens thickness values than all of the optical biometers (P .0001). The mean difference ranged between 0.29 mm and 0.43 mm. Although the differences between the 3 optical biometers were smaller, they were still statistically significant (P .001). With respect to the immersion US biometry, lens thickness measurements using the optical biometric measurements would have resulted in the selection of a lower IOL power in between 43.2% and 62.5% of eyes, depending on the optical biometer. Comparison of the measurements of the 3 optical biometers showed that a different IOL power would have been selected in between 9.1% and 19.3% of eyes.Lens thickness measurements by immersion US biometry and optical biometry cannot be considered interchangeable. Minor, but still significant, differences between the 3 optical biometers tested were also found.

PURPOSE: To investigate the changes in corneal backward light scattering, as measured by a rotating Scheimpflug camera with automated corneal densitometry software, in eyes treated with femtosecond laser-assisted LASIK (FS-LASIK). METHODS: The cornea was examined preoperatively and postoperatively at 1 day, 1 week, and 1, 3, and 6 months in 23 patients who underwent myopic FS-LASIK. Local analysis of corneal backscatter was performed on four concentric radial zones across a 12-mm diameter (0 to 2, 2 to 6, 6 to 10, and 10 to 12 mm) and at a different corneal depth (anterior 120 µ m, central and posterior 60 µ m). RESULTS: A statistically significant increase in corneal backward light scattering ( P < .0001) was detected within the central 10 mm of the anterior cornea. The increase in corneal densitometry was gradually reversed over 6 months. The difference compared to preoperative values was no longer statistically significant at 3 and 6 months after surgery in the central cornea, whereas it remained significant in the mid-peripheral annulus (ranging from 6 to 10 mm), where the flap edge was located. CONCLUSIONS: FS-LASIK is followed by an increase in corneal backward light scattering during the early postoperative period that returns to baseline by 3 months. Whereas the increase in corneal densitometry at the flap edge location can be related to a scarring reaction, the explanation for such an increase in the central anterior cornea remains speculative. [ J Refract Surg. 2016;32(1):20–25.]

Purpose To assess the accuracy of different methods to calculate the intraocular lens (IOL) power from measurements obtained with an optical biometer combined with a Placido disk–Scheimpflug tomographer (Galilei G6) in eyes that had previous myopic excimer laser surgery. Setting G.B. Bietti Foundation, Rome, Italy. Design Prospective case series. Methods When prerefractive surgery data were available, the following methods were evaluated: the Barrett True-K, total corneal power 1 (TCP 1) with double-K SRK/T, TCP with double-K Holladay 1, as well as the Masket and Savini methods. In all eyes, these “no-history” methods were studied: Barrett True-K No-History, TCP 1 using the American Society of Cataract and Refractive Surgery calculator, a ray-tracing program, and the Shammas No-History formula. Results In eyes with historical data (n = 15), the Masket method, Savini method, and TCP 1 with double-K SRK/T produced the highest percentage of cases with an absolute prediction error in refraction of 0.50 diopters (D) or less and the lowest median absolute error (0.32 D, 0.28 D, and 0.25 D, respectively). In the whole cohort (N = 22), the most accurate no-history method was paraxial ray tracing, which had the highest percentage of eyes with an absolute prediction error of 0.50 D or less and the lowest median absolute error of 0.31 D. Conclusion Different solutions can provide accurate IOL power calculations when using the measurements obtained with the optical biometer combined with a Placido–dual Scheimpflug tomographer.

To evaluate the results of intraocular lens (IOL) power calculation using different corneal power measurements provided by an optical biometer combined with a dual Scheimpflug analyzer and a Placido disk topographer (Galilei G6).G.B. Bietti Foundation, Rome, Italy, and Keio University Hospital, Tokyo, Japan.Evaluation of diagnostic technology.Consecutive patients having cataract surgery were enrolled. The IOL power was calculated with the Barrett Universal II, Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. Different options were used to calculate the corneal power: simulated keratometry (K) based on anterior corneal surface measurements only and total corneal power (TCP) based on ray tracing through both corneal surfaces. Three TCP measurements (TCP1, TCP2, and TCP-IOL) were evaluated.The study analyzed 118 eyes. The mean values of simulated K (43.74 diopters [D] ± 1.40 [SD]), TCP1 (43.13 ± 1.35 D), TCP2 (41.87 ± 1.30 D), and TCP-IOL (42.62 ± 1.35 D) were significantly different (P .0001). The best results were obtained using simulated K: the median absolute error ranged between 0.22 D and 0.29 D and the percentage of eyes with a prediction error of ±0.50 D or less, between 76.2% and 84.7%, depending on the formula. After constant optimization, the results using any TCP value and simulated K were similar with no statistically significant differences.Biometric measurements provided by the Scheimpflug-Placido optical biometer can be used to accurately calculate the IOL power. Simulated K and TCP led to similar outcomes after constant optimization.

Purpose To evaluate the repeatability of automatic measurements by a new anterior segment optical coherence tomographer (AS-OCT) combined with Placido topography and their agreement with those provided by 2 rotating Scheimpflug cameras. Setting G.B. Bietti Foundation IRCCS, Rome, Italy. Design Evaluation of a diagnostic test instrument. Methods Unoperated eyes and eyes with previous myopic excimer laser surgery were analyzed. Three consecutive scans were acquired with an AS-OCT device (MS-39) and 1 with 2 rotating Scheimpflug cameras (Pentacam HR and Sirius). The following parameters were evaluated: simulated keratometry, posterior and total corneal power, total corneal astigmatism, corneal asphericity, thinnest corneal thickness, central epithelial thickness, corneal diameter, and aqueous depth. Repeatability was assessed using test–retest variability, the coefficient of variation (CoV), and the intraclass correlation coefficient; agreement was assessed by the 95% limits of agreement. Results The study comprised 96 unoperated eyes and 43 eyes with previous myopic excimer laser surgery. High repeatability was achieved in both groups, as shown by a CoV less than 1.0% for most parameters. The repeatability of epithelial thickness was slightly lower than that of the whole corneal thickness, although the CoV was still good (1.87% in unoperated eyes; 3.28% in post-refractive surgery eyes). Moderate repeatability was found for total corneal astigmatism measurements, with a CoV greater than 20.0%. Agreement with Scheimpflug cameras was high for aqueous depth and thinnest corneal thickness and moderate for most other parameters. Conclusion The high repeatability of automatic measurements by the new AS-OCT device supports its use in clinical practice.