Intraocular Lens Alignment Research Articles

In vivo Assessment of Higher-Order Aberrations after Acrysof Toric Intraocular Lens Implantation: A Comparative Study

To compare higher-order aberrations (HOAs) and optical quality in eyes implanted with AcrySof SN60TT toric intraocular lens (IOL) or with non-toric AcrySof SN60AT IOL (Alcon Laboratories, Inc., Fort Worth, TX). This was a prospective, consecutive, nonrandomized, interventional, comparative study. One hundred eyes with cataract in 56 patients were included (SN60TT group, n=50; SN60AT group, n=50). Patients underwent phacoemulsification through a 2.2-mm temporal corneal incision. Postoperative HOAs, point spread function (PSF) and modulation transfer function (MTF), residual objective refractive astigmatism, and IOL alignment were evaluated using Optical Path Difference (OPD)-Scan II (Nidek, Gamagori, Japan). A novel technique to calculate IOL axis alignment was introduced. One year postoperatively, no statistical difference in corneal, intraocular, and total HOAs, Strehl ratio, and MTF based on HOAs was found between groups. Toric IOL patients had a net residual refractive astigmatism (M) of 0.44 D±0.47; the difference between expected and obtained astigmatism (M) was 0.043 D (p=0.16). Toric IOL axis misalignment was 2.65±2.39 degrees and no correlation with HOAs was found. AcrySof SN60TT determines HOAs comparable to the non-toric version providing a good optical quality, and predictably corrects corneal cylinder with a stable postoperative alignment. The OPD-Scan II might be regarded as a fast and reliable method of toric IOL analysis.

Visual function and patient experience after bilateral implantation of toric intraocular lenses

To evaluate the efficacy, stability, predictability, and patient-reported outcomes of bilateral toric intraocular lens (IOL) implantation in cases of cataract with preexisting astigmatism. Fourteen universities, hospitals, or private practices, Canada. Patients with cataracts and corneal astigmatism from 1.00 to 2.50 diopters (D) were included in a prospective study of bilateral AcrySof toric IOL implantation. Binocular uncorrected distance visual acuity (UDVA), manifest refraction, and IOL rotational stability were assessed 1 day and 1, 3, and 6 months postoperatively. Patients completed a questionnaire that assessed spectacle independence, visual disturbances, and satisfaction with vision (1 = completely unsatisfied; 10 = completely satisfied) preoperatively and 3 and 6 months postoperatively. The study included 117 patients (234 eyes). The binocular UDVA was 20/40 or better in 99% of patients and 20/20 or better in 63% of patients. The mean residual refractive astigmatism was 0.4 D +/- 0.4 (SD). The spherical equivalent was within +/-0.5 D of target in 77% of eyes. At last observation, IOL alignment was within +/-5 degrees in 91% of eyes and within +/-10 degrees in 99%. Sixty-nine percent of patients reported never using distance spectacles. The frequency and severity of halos and glare were significantly reduced from preoperatively to postoperatively. Satisfaction with vision was rated 7 or higher by 94% of patients. Bilateral implantation of toric IOLs yielded excellent and stable visual outcomes that patients rated as highly satisfactory. No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Detection of Toric intraocular lens misalignment by digital photograph

Background Toric intraocular lens (Toric IOL) is a well accepted method of correct of corneal astigmatism.Axial misalignment,including the error of intraocular lens alignment during surgery and rotation of Toric IOL,is the main barrier to the precise alignment of Toric intraocular lenses.Therefore,the angle of axial misalignment is a main index to evaluate the effectiveness of Toric IOL implantation.Objective The present study is to describe a method of precisely detecting Toric IOL misalignment using postoperative digital photograph.Methods A measuring template (polar coordinates) was constructed using Adobe Photoshop software.Minimum graduate to detect the Toric axis was 1° (maximum error 0.5°).The clinical data of 24 eyes undergone Toric IOL implantation was retrospectively analyzed.Corneal astigmatism was detected by rotating Scheimpflug camera (Pentacam) or slit scan (Orbscan).Digital retro illumination picture was photographed after mydriasis.The picture was analyzed by our derived template.The steepest corneal axis and the axis of Toric IOL were then determined.The misalignment of Toric IOL was determined as the angle between the steepest corneal axis and the axis of Toric IOL.Misalignment of Toric IOL and its distribution were analyzed by statistical means.Results A method using polar coordinates and digital photo to precisely detect Toric IOL misalignment was derived.Mean Toric IOL misalignment was 10.93±6.90 degrees (0-24 degrees) in the 24 cases.The axial misalignment in all of cases were within 25 degrees,including clockwise in 14 eyes(58.33%),anticlockwise in 10 eyes (41.67%).In this study,the misalignment angle of 4 eyes were within 5 degrees;11 eyes were 5 to 10 degrees;1 eye was 10 to 15 degrees;6 eyes were 15 to 20 degrees;2 eyes were 20 to 25 degrees.Conclusion The method is feasible to the direction of Toric IOL misalignment in clinic. Key words: digital photograph analysis; Toric intraocular lens; misalignment; corneal astigmatism

Assessment of toric intraocular lens alignment by a refractive power/corneal analyzer system and slitlamp observation

To assess the validity of an internal optical path difference map of a refractive power/corneal analyzer system in determining the alignment of toric intraocular lenses (IOLs). Private practices, Spring Hill, Brisbane, and Chermside, Australia. This retrospective study comprised patients with more than 1.5 diopters of preexisting corneal astigmatism who had phacoemulsification and AcrySof toric IOL implantation. Preoperatively, the surgical eye was marked at the slitlamp microscope using a 4-point technique. The desired IOL orientation was marked with a Mendez marker based on the steep corneal axis. The toric IOL axis was measured 3 weeks postoperatively by rotating the slitlamp beam to align with the IOL axis indicator marks and using the Internal OPD Map on the Nidek OPD-Scan system. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, residual refractive sphere, and residual keratometric and refractive cylinders were also measured at 3 weeks. Postoperatively, the mean UDVA was 0.17 logMAR +/- 0.18 (SD) and the mean CDVA, -0.01 +/- 0.12 logMAR; 88.2% of eyes had a UDVA of 0.3 or better, and no eye lost lines of visual acuity. There was an 82.33% reduction in defocus equivalent and a 64.62% reduction in refractive cylinder. The mean IOL misalignment measured by slitlamp was 2.55 +/- 2.76 degrees and by the internal map, 2.65 +/- 1.98 degrees. The correlation between the 2 methods was highly significant (r = 0.99, P<.001). Both refractive power/corneal analyzer system and slitlamp observation were reliable and predictable methods of assessing IOL alignment. The 4-point preoperative marking technique yielded clinically acceptable, accurate toric IOL alignment.

Digital overlay technique for documenting toric intraocular lens axis orientation

Purpose To describe a digital overlay technique for documenting toric intraocular lens (IOL) axis alignment. Setting Jules Stein Eye Institute and the Department of Ophthalmology, University of California at Los Angeles School of Medicine, Los Angeles, California, USA. Methods Digital overlay imaging was used to evaluate the alignment of Staar toric IOLs in 4 eyes of 3 patients who had regular corneal astigmatism at the time of cataract surgery. Lens axes were determined by computerized analysis of digitally scanned retroillumination photographs. A stock digital image of a Staar AA4203TF toric IOL was superimposed on corneal topography images to document IOL alignment with the steep corneal meridian. Results Digital overlay images demonstrated that 3 IOLs in the sample group were within 5 degrees and 1 was within 20 degrees of the intended axis at the time of the final postoperative examination. Slitlamp lens axis estimations were 3 to 18 degrees different from that determined by this technique. Conclusion Digital overlay imaging of correctly oriented toric IOLs on computerized corneal topography maps represents an intuitive, accurate, and visually appealing method of documenting toric IOL axis alignment.

The society of thoracic surgeons database: A progress report

To assess the validity of an internal optical path difference map of a refractive power/corneal analyzer system in determining the alignment of toric intraocular lenses (IOLs).Private practices, Spring Hill, Brisbane, and Chermside, Australia.This retrospective study comprised patients with more than 1.5 diopters of preexisting corneal astigmatism who had phacoemulsification and AcrySof toric IOL implantation. Preoperatively, the surgical eye was marked at the slitlamp microscope using a 4-point technique. The desired IOL orientation was marked with a Mendez marker based on the steep corneal axis. The toric IOL axis was measured 3 weeks postoperatively by rotating the slitlamp beam to align with the IOL axis indicator marks and using the Internal OPD Map on the Nidek OPD-Scan system. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, residual refractive sphere, and residual keratometric and refractive cylinders were also measured at 3 weeks.Postoperatively, the mean UDVA was 0.17 logMAR ± 0.18 (SD) and the mean CDVA, −0.01 ± 0.12 logMAR; 88.2% of eyes had a UDVA of 0.3 or better, and no eye lost lines of visual acuity. There was an 82.33% reduction in defocus equivalent and a 64.62% reduction in refractive cylinder. The mean IOL misalignment measured by slitlamp was 2.55 ± 2.76 degrees and by the internal map, 2.65 ± 1.98 degrees. The correlation between the 2 methods was highly significant (r = 0.99, P<.001).Both refractive power/corneal analyzer system and slitlamp observation were reliable and predictable methods of assessing IOL alignment. The 4-point preoperative marking technique yielded clinically acceptable, accurate toric IOL alignment.No author has a financial or proprietary interest in any material or method mentioned.