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Biometry in cataract surgery
摘要： Purpose of review To review the literature in 2017 and 2018 pertaining to biometry for cataract surgery and report pertinent findings. Recent findings New devices using swept-source ocular coherence tomography can measure axial length in dense cataracts more frequently than common biometers. Computer-assisted registration may be superior to intraoperative aberrometry for toric intraocular lens (IOL) placement. Soft contact lenses may not require removal as long before biometry as previously thought. The Barrett Universal II IOL formula has been found to perform well at all axial lengths. Summary New swept-source ocular coherence tomography biometers are more frequently successful at measuring axial length in dense cataracts which promises to improve refractive outcomes. Accuracy in toric IOL placement is likely to increase with improved devices. It may not be necessary to have patients remove soft contact lens any more than 2 days prior to biometry. The Barrett Universal II IOL formula may be used confidently for most eyes. Advancements acknowledged, purchasing new equipment will not be necessary for all surgeons.
关键词： swept-source ocular coherence tomography,toric,cataract,biometry
更新于2025-09-23 15:23:52
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Rotational Stability and Patient Satisfaction after Implantation of a New Toric IOL
摘要： Purpose: To evaluate rotational stability, astigmatism correction, visual outcomes, and patient satisfaction after implantation of the toric intraocular lens (IOL) Torica-aA following cataract extraction over a 6-month follow-up period. Methods: This prospective observational study enrolled 40 eyes of 26 patients presenting with preexisting corneal astigmatism of 1.00 to 2.60 D. The rotational stability of the IOL was evaluated using retroillumination photographs taken within 24 hours after surgery and 1 week and 6 months postoperatively. Other main study outcomes were assessed 6 months postoperatively and included uncorrected and distance-corrected visual acuities, astigmatism correction, and patient satisfaction. Results: Six months postoperatively, mean absolute IOL rotation was 1.99 ± 1.88° (range 0.10-7.40°) and secondary repositioning was not required. The IOL rotation was <3° in 85% of eyes, ≤5° in 94% of eyes, and <8° in 100% of eyes. Mean residual refractive cylinder was -0.57 ± 0.34 D. The magnitude of the J0 vector was significantly decreased postoperatively (p<0.0001). The mean J45 vector was close to zero preoperatively and postoperatively (p = 0.27). Mean monocular uncorrected distance visual acuity (UDVA) was 0.09 ± 0.12 logMAR and 97% of eyes achieved UDVA of 20/40 or better including 66% of eyes having 20/25 or better. The good UDVA resulted in high levels of spectacle independence and patient satisfaction. conclusions: Implantation of the Torica-aA IOL was safe and effective in reducing low to moderate preexisting corneal astigmatism and provided good rotational stability and refractive outcomes, which led to a high degree of patient satisfaction.
关键词： Hydrophilic acrylic,Astigmatism,Intraocular lens,Toric IOL,Cataract,Rotational stability
更新于2025-09-23 15:21:21
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Fewer-axis grinding methodology with simultaneously guaranteeing surface accuracy and grinding force for large optical SiC mirror
摘要： This paper presents a grinding force control strategy with simultaneously guaranteeing surface accuracy for large optical SiC mirror. A fewer-axis grinder with toric wheel is used to ensure the high stiffness during the grinding process. According to the geometric properties of the contact area at the grinding point between the grinding wheel and the workpiece, the relationship between the grinding force, the feed rate, and grinding depth is derived. Furthermore, the dynamic grinding process model is established by considering the deformation of grinding machine and contour deviation of toric wheel. The contour deviation of toric wheel is also identified by the Fourier transform and analysis of the high frequency fluctuation of grinding force. Based on the grinding principle of toric wheel and the above grinding process model, the force-controlled trajectory planning method for toric grinding is introduced. To ensure the workpiece surface accuracy and decrease the subsurface damage simultaneously, the force-controlled method by adjusting the feed rate and keeping the grinding depth unchanged is proposed. The strategy is successfully validated by grinding experiments of SiC mirror on a high-precision fewer-axis grinding machine.
关键词： Grinding process model,Toric wheel,Force control,Contour deviation
更新于2025-09-10 09:29:36
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Trial-based cost-effectiveness analysis of toric versus monofocal intraocular lenses in cataract patients with bilateral corneal astigmatism in the Netherlands
摘要： To evaluate the cost-effectiveness of toric versus monofocal intraocular lens (IOL) implantation in cataract patients with bilateral corneal astigmatism. Setting: Two ophthalmology clinics in the Netherlands. Design: Prospective cost-effectiveness analysis. Methods: Resource-use data were collected over a 6-month postoperative period. Consecutive patients with bilateral age-related cataract and 1.25 diopters or more of corneal astigmatism were included in the economic evaluation. Patients were randomized to phacoemulsification with bilateral toric or monofocal IOL implantation. All relevant resources were included in the cost analysis. The base-case analysis was performed from a societal perspective based on quality-adjusted life years (QALYs). The main outcome was the incremental cost-effectiveness ratio. Results: The analysis comprised 77 consecutive patients (33 toric IOL; 44 monofocal IOL). Societal costs were higher in the toric IOL group (V3203 [$3864]) than in the monofocal IOL group (V2796 [US$3373]). QALYs were slightly lower in the toric IOL group (0.30 versus 0.31; P Z .75). Toric IOLs were therefore inferior to monofocal IOLs from a cost-effectiveness perspective. The cost-effectiveness probability ranged from 1% to 15%, assuming a ceiling ratio for the incremental cost-effectiveness ratio of V2500 to V20 000 per QALY. Conclusions: From a societal perspective, bilateral toric IOL implantation in cataract patients with corneal astigmatism was not cost-effective compared with monofocal IOL implantation. Copayment by patients should therefore be considered.
关键词： monofocal intraocular lens,corneal astigmatism,cost-effectiveness,toric intraocular lens,cataract
更新于2025-09-10 09:29:36
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Comparison between Toric and Non-Toric Intraocular Lenses in Patients with Corneal Astigmatism: A One-Year Multicenter Study
摘要： Objective: To compare the clinical results obtained with a toric intraocular lens (IOL) and non-toric IOL in eyes with corneal astigmatism. Methods: This multicenter retrospective study included eyes with corneal astigmatism ranging from 0.75 diopter (D) to 3.00 D that were implanted with a toric IOL and a non-toric IOL. Non-toric IOLs were implanted before toric IOLs were approved, and the eyes were divided into three groups (T3, T4, or T5) depending on the preoperative degree of corneal astigmatism. Residual refractive cylinder, uncorrected distance visual acuity (UDVA), and contrast sensitivity were compared more than 1 year after implantation. Results: The toric group included 149 eyes (mean patient age, 73.7 ± 7.9 years standard deviation, SD) and the non-toric group included 121 eyes (mean patient age, 76.2 ± 5.9 years). One year postoperatively, the respective residual refractive cylinder values and ± SD of the toric/non-toric groups were -0.61 ± 0.43/-1.45 ± 0.98 D (all eyes), -0.58 ± 0.42/-1.14 ± 0.70 D (T3), -0.59 ± 0.42/-1.63 ± 0.99 D (T4), and -0.67 ± 0.47/-2.18 ± 1.27 D (T5). The respective logarithm of the minimum angle of resolution UDVA values was 0.00 ± 0.12/0.16 ± 0.20 (all eyes), 0.00 ± 0.11/0.13 ± 0.18 (T3), 0.00 ± 0.13/0.25 ± 0.23 (T4), and 0.00 ± 0.11/0.17 ± 0.16 (T5). The toric group had better cylinder and UDVA outcome values; the difference between the groups reached significance (p<0.0001). In the toric group, the IOL rotation after implantation was 4.3 ± 4.0 degrees. Conclusion: Toric IOLs reduced the residual refractive cylinder in cases with corneal astigmatism between 0.75 and 3.00 D, and this effect was similar among different toric models. Toric IOLs are useful to improve the UDVA after cataract surgery.
关键词： Uncorrected visual acuity,Cataract surgery,Contrast sensitivity,Toric intraocular lens,Corneal astigmatism
更新于2025-09-04 15:30:14