Refraction and defocus curves in eyes with monofocal and multifocal intraocular lenses

Several clinical techniques have been described to evaluate visual performance and optical quality with intraocular lenses (IOL). However, subjective refraction remains one of the most important methods for assessing post-surgery results, taking decisions about retreatments, advanced spectacle prescription and the refinement of the constant for the formula used in the IOL power calculation. Beyond clinical refraction, defocus curve measurement has been described as a complementary tool for assessing visual performance and taking clinical decisions. However, to date, there are no clinical guidelines or evidence-based protocols published in the scientific literature recommended for pseudophakic patients implanted with either monofocal or multifocal IOLs. This narrative review highlights the importance of clinical refraction in pseudophakic eyes, its utility in the decision of different types of IOL implantation, and describes a clinical refraction protocol for eyes implanted with monofocal and multifocal IOLs. (AU)

The Current Burden and Future Solutions for Preoperative Cataract-Refractive Evaluation Diagnostic Devices: A Modified Delphi Study.

Purpose: To obtain consensus on the key areas of burden associated with existing devices and to understand the requirements for a comprehensive next-generation diagnostic device to be able to solve current challenges and provide more accurate prediction of intraocular lens (IOL) power and presbyopia correction IOL success. Patients and Methods: Thirteen expert refractive cataract surgeons including three steering committee (SC) members constituted the voting panel. Three rounds of voting included a Round 1 structured electronic questionnaire, Round 2 virtual face-to-face meeting, and Round 3 electronic questionnaire to obtain consensus on topics related to current limitations and future solutions for preoperative cataract-refractive diagnostic devices. Results: Forty statements reached consensus including current limitations (n = 17) and potential solutions (n = 23) associated with preoperative diagnostic devices. Consistent with existing evidence, the panel reported unmet needs in measurement accuracy and validation, IOL power prediction, workflow, training, and surgical planning. A device that facilitates more accurate corneal measurement, effective IOL power prediction formulas for atypical eyes, simplified staff training, and improved decision-making process for surgeons regarding IOL selection is expected to help alleviate current burdens. Conclusion: Using a modified Delphi process, consensus was achieved on key unmet needs of existing preoperative diagnostic devices and requirements for a comprehensive next-generation device to provide better objective and subjective outcomes for surgeons, technicians, and patients.

Ray tracing optimization: a new method for intraocular lens power calculation in regular and irregular corneas.

To develop a novel algorithm based on ray tracing, simulated visual performance and through-focus optimization for an accurate intraocular lens (IOL) power calculation. Custom-developed algorithms for ray tracing optimization (RTO) were used to combine the natural corneal higher-order aberrations (HOAs) with multiple sphero-cylindrical corrections in 210 higher order statistical eye models for developing keratoconus. The magnitude of defocus and astigmatism producing the maximum Visual Strehl was considered as the optimal sphero-cylindrical target for IOL power calculation. Corneal astigmatism and the RMS HOAs ranged from - 0.64 ± 0.35D and 0.10 ± 0.04 µm (0-months) to - 3.15 ± 1.38D and 0.82 ± 0.47 µm (120-months). Defocus and astigmatism target was close to neutral for eyes with low amount of HOAs (0 and 12-months), where 91.66% of eyes agreed within ± 0.50D in IOL power calculation (RTO vs. SRK/T). However, corneas with higher amounts of HOAs presented greater visual improvement with an optimized target. In these eyes (24- to 120-months), only 18.05% of eyes agreed within ± 0.50D (RTO vs. SRK/T). The power difference exceeded 3D in 42.2% while the cylinder required adjustments larger than 3D in 18.4% of the cases. Certain amounts of lower and HOAs may interact favourably to improve visual performance, shifting therefore the refractive target for IOL power calculation.

Refraction and defocus curves in eyes with monofocal and multifocal intraocular lenses.

Several clinical techniques have been described to evaluate visual performance and optical quality with intraocular lenses (IOL). However, subjective refraction remains one of the most important methods for assessing post-surgery results, taking decisions about retreatments, advanced spectacle prescription and the refinement of the constant for the formula used in the IOL power calculation. Beyond clinical refraction, defocus curve measurement has been described as a complementary tool for assessing visual performance and taking clinical decisions. However, to date, there are no clinical guidelines or evidence-based protocols published in the scientific literature recommended for pseudophakic patients implanted with either monofocal or multifocal IOLs. This narrative review highlights the importance of clinical refraction in pseudophakic eyes, its utility in the decision of different types of IOL implantation, and describes a clinical refraction protocol for eyes implanted with monofocal and multifocal IOLs.

Corneal diameter measurements by 3 optical biometers and their effect on phakic intraocular lens sizing.

PURPOSE: To compare phakic intraocular lens size calculations based on corneal diameter (CD) measurements by 3 instruments. SETTING: G.B. Bietti Foundation I.R.C.C.S., Rome, Italy. DESIGN: Retrospective interventional case series. METHODS: 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). RESULTS: 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 ( P < .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 ( P < .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. CONCLUSIONS: 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.

Traumatic cataract in a young patient with myopia.

A 36-year-old man was referred to our clinic because of traumatic cataract in his right eye, which had developed after being hit in the eye with a badminton shuttle as a child. He noticed that his vision in his right eye was gradually becoming worse. His refraction, corrected with spectacles, was -4.25 -2.00 × 115 in his right eye and -5.50 -1.50 × 57 in his left eye, with a corrected distance visual acuity of 20/32 and 20/20, respectively. Because of allergies, the patient never tolerated contact lens wear for more than 2 hours. On a slitlamp examination, we confirmed anterior subcapsular star-like cataract without any signs of zonulolysis. Optical biometry showed an axial length of 25.73 mm and 26.66 mm and an anterior chamber depth of 3.70 mm and 3.78 mm in the right and left eyes. Keratometric astigmatism measured by optical biometry was 1.56 diopters (D) at 30 degrees and 1.12 D at 138 degrees for the right and left eyes, and Scheimpflug tomography showed 1.1 D of regular astigmatism at 33 degrees in the right eye, and 0.9 D of regular astigmatism at 130 degrees in the left eye. The patient is a professional photographer and asked for a treatment that would still allow him to be able to perform his job: he wants to read all the buttons on the camera up close and focus on the scenery in the distance. What is your advice on this challenging case?

Performance and Safety of the Extended Depth of Focus Implantable Collamer® Lens (EDOF ICL) in Phakic Subjects with Presbyopia.

PURPOSE: To evaluate the performance and safety of the Extended Depth of Focus Implantable Collamer® Lens (EDOF ICL) for improvement of uncorrected near, intermediate and distance visual acuity in phakic subjects with myopia and presbyopia. DESIGN: Prospective multicenter study. METHODS: Presbyopic subjects who required an EDOF ICL in the range of -0.50 D to -18.00 D, exhibited ≤ 0.75 D refractive astigmatism and required from +1.00 to +2.50 D reading add were implanted bilaterally. Assessments at 6 months included uncorrected near, intermediate and distance visual acuities, defocus curves, contrast sensitivity, responses to the National Eye Institute Refractive Error Quality of Life Questionnaire and a Task Assessment Questionnaire. RESULTS: A total of 34 subjects completed the study. Investigators targeted emmetropia in all eyes. Mean binocular uncorrected near, intermediate and distance visual acuities measured logMAR -0.01 ± 0.05 (20/20), -0.02 ± 0.08 (20/19) and 0.07 ± 0.10 (20/23), respectively. Mean monocular uncorrected near, intermediate and distance visual acuities measured logMAR 0.068 ± 0.09 (20/23), 0.062 ± 0.10 (20/23) and 0.16 ± 0.12 (20/29). There were no clinically or statistically significant differences in contrast sensitivity between baseline and 6 months under any testing conditions. Subjects reported significant improvements in measures of vision-related quality of life and ability to perform tasks at all distances without glasses or contact lenses. Overall, satisfaction with the EDOF ICL was high: postoperatively, 91.2% of subjects were satisfied with their vision. CONCLUSION: This multicenter, prospective clinical investigation demonstrated the ability of the EDOF ICL to correct myopia and presbyopia, resulting in improvement of uncorrected near, intermediate and distance visual acuity without compromising the quality of vision. The EDOF ICL allowed subjects to perform tasks of daily living without glasses or contact lenses. Subjects reported significant improvements in quality of life with high levels of spectacle independence and satisfaction.

Accuracy of a New Swept-Source Optical Coherence Tomography Biometer for IOL Power Calculation and Comparison to IOLMaster.

PURPOSE: To investigate the accuracy of the measurements provided by a new optical biometer (OA-2000, Tomey Corporation, Nagoya, Japan) for calculating the intraocular lens (IOL) power and to compare the refractive outcomes to those obtained with the IOLMaster 500 (Carl Zeiss Meditec, Jena, Germany). METHODS: In this interventional multicenter study, consecutive patients having cataract surgery were enrolled. Only the IOL model used in the largest sample of patients was selected and the eyes implanted with that IOL were subsequently analyzed. The OA-2000, an optical biometer based on swept-source optical coherence tomography (SS-OCT), was used to measure axial length and corneal power in all eyes. IOL power was calculated with the Hoffer Q, Holladay 1, and SRK/T formulas. In a subsample of eyes, the IOL power was also calculated with measurements obtained by partial coherence interferometry (IOLMaster 500). The median absolute error and percentage of eyes with a prediction error of ±0.50 diopters (D) or less were calculated. RESULTS: Two hundred forty-nine eyes were analyzed. Using SS-OCT, the median absolute error ranged between 0.33 (Holladay 1) and 0.35 (SRK/T) D. The rate of eyes with a prediction error of ±0.50 D or less ranged between 71.5% (Hoffer Q) and 67.1% (SRK/T). In the subsample of 87 eyes with measurements by both devices, the median absolute error was lower with the OA-2000 (Hoffer Q: P = .0377; Holladay 1: P = .0191; SRK/T: P = .0087). CONCLUSIONS: The SS-OCT-based optical biometer investigated in the current study provides accurate measurements for IOL power calculation and seems to offer more predictable refractive results compared to the partial coherence interferometry IOLMaster. [J Refract Surg. 2017;33(10):690-695.].

Dual versus single Scheimpflug camera for anterior segment analysis: Precision and agreement.

PURPOSE: To assess the repeatability, reproducibility, and agreement of the Pentacam HR single-camera and Galilei G2 dual-camera Scheimpflug devices in anterior segment analysis. SETTING: Begitek Clínica Oftalmológica, San Sebastián, Spain. DESIGN: Prospective randomized observational study. METHODS: Healthy young individuals had 3 consecutive tests by 2 examiners. Analyzed parameters were anterior and posterior cornea simulated keratometry (K), K flat, K steep, astigmatism magnitude and axis, J(0) and J(45) vectors, asphericity, total corneal higher-order wavefront aberrations (root mean square [RMS], coma, trefoil, spherical aberration), central cornea and thinnest-point thicknesses, and anterior chamber depth. Repeatability and reproducibility were evaluated by calculating the within-subject standard deviation (S(w)), some derived coefficients, and the intraclass correlation coefficient. Agreement was assessed with the Bland-Altman method. RESULTS: The single-camera device reproducibility (S(w)) was simulated K, 0.04 diopter (D); J(0), 0.03 D; J(45), 0.04 D; total power, 0.04 D; spherical aberration, 0.02 µm; higher-order aberrations (HOAs), 0.02 µm; central corneal thickness (CCT), 3.39 µm. The dual-camera device S(w) was simulated K, 0.07 D; J(0), 0.13 D; J(45), 0.04 D; total power, 0.08 D; spherical aberration, 0.02 µm; HOAs, 0.11 µm; CCT, 1.36 µm. Agreement was good for most parameters except total corneal power (mean difference 1.58 D ± 0.22 (SD) and HOA RMS (mean difference 0.48 ± 0.19 µm) (both P<.00). CONCLUSIONS: Repeatability and reproducibility were good for all parameters. The single-camera device was more precise for curvature, astigmatism, and corneal wavefront error measurements and the dual-camera device for pachymetry measurements. Agreement was good with some relevant exceptions. FINANCIAL DISCLOSURE: Dr. Aramberri is consultant to Costruzione Strumenti Oftalmici, Firenze, Italy. No other author has a financial or proprietary interest in any material or method mentioned.

Foldable toric intraocular lens for astigmatism correction in cataract patients.

PURPOSE: To evaluate the results of AcrySof toric intraocular lens (IOL) (Alcon) implantation to correct preexisting astigmatism in patients having cataract surgery. SETTING: Ophthalmology Service, Donostia Hospital, San Sebastián, Spain. METHODS: This prospective observational study included 30 eyes of 15 consecutive patients with more than 1.00 diopter (D) of preexisting corneal astigmatism having cataract surgery. Bilateral implantation of the AcrySof toric IOL was performed after phacoemulsification. The uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), residual refractive sphere, residual keratometric and refractive cylinders, and toric IOL axis were measured. RESULTS: The UCVA was 20/40 or better in 93.3% of eyes and 20/25 or better in 66.6%. All eyes achieved 20/25 or better BCVA. The mean refractive cylinder decreased significantly after surgery from -2.34 D +/- 1.28 (SD) to -0.72 +/- 0.43 D (P<.01). Vector analysis of attempted versus achieved correction showed that 100% of eyes were within +/-1.00 D and 80% and 93.9% were within +/-0.50 D for J(0) and J(45), respectively. The mean toric IOL axis rotation was 3.63 +/- 3.11 degrees, with rotation less than 10 degrees in 96.7% of eyes. CONCLUSIONS: The results indicate that phacoemulsification and posterior chamber AcrySof toric IOL implantation is an effective option to correct preexisting astigmatism in cataract surgery. The AcrySof toric IOL showed good rotational stability.

Intraocular lens power calculation after corneal refractive surgery: double-K method.

PURPOSE: To determine the accuracy of a method of calculating intraocular lens (IOL) power after corneal refractive surgery. SETTING: Department of Ophthalmology, Hospital de Gipuzkoa, San Sebastián, Spain. METHODS: The SRK/T formula was modified to use the pre refractive surgery K-value (Kpre) for the effective lens position (ELP) calculation and the post refractive surgery K-value (Kpost) for IOL power calculation by the vergence formula. The Kpre value was obtained by keratometry or topography and the Kpost, by the clinical history method. The formula was assessed in 9 cases of cataract surgery after laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) in which all relevant data were available. Refractive results of the standard SRK/T and the double-K SRK/T were compared statistically. RESULTS: The mean IOL power for emmetropia and the achieved refraction (mean spherical equivalent [SE]), respectively, were +17.85 diopters (D) +/- 3.43 (SD) and +1.82 +/- 0.73 with the standard SRK/T and +20.25 +/- 3.55 D and +0.13 +/- 0.62 D with the double-K SRK/T. No case in the standard SRK/T group and 6 cases (66.66%) in the double-K group achieved a +/-0.5 D SE. CONCLUSION: Double-K modification of the SRK/T formula improved the accuracy of IOL power calculation after LASIK and PRK.