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Optics and refractive errors
Published in Mostafa Khalil, Omar Kouli, The Duke Elder Exam of Ophthalmology, 2019
Nemat Ahmed, Omar Kouli, Mostafa Khalil, Obaid Kousha
Transposition of prescription lenses/glasses refers to converting a minus cylindrical lens to a plus cylindrical lens and vice versa. This method, however, does not change the optical properties. This method is frequently used in toric lens prescriptions.
Contact lenses
Published in Pablo Artal, Handbook of Visual Optics, 2017
Ultimately, correction of the measured population average value for spherical aberration with contact lenses provides the potential to improve visual performance to varying degrees under low-light, large-pupil conditions in a relatively large portion of the population. Additional degrees of freedom in the ability to refine this correction will increase both the magnitude of the visual improvement and the number of patients experiencing the benefit. However, other significant low- and high-order aberrations coexist with spherical aberration in the eye that cannot easily be corrected with an aspheric or aspheric toric lens as well as those generated by the decentration of the contact lens relative to the center of the pupil, and the correction of these aberrations needs to be addressed if the optical performance of the eye is to reach its maximum potential.
Utilization of Crowdfunding for Cataract and LASIK Procedures
Published in Seminars in Ophthalmology, 2022
Sachi A. Patil, Amanda Luu, Daniel G. Vail, Arjun Watane, Russell Levine, Brian Hafler, Ravi Parikh
For outpatient procedures, out-of-pocket costs have been increasing, even for those who are privately insured. It has been reported that increasing costs for outpatient elective surgery have risen largely from facility fees and out of pocket expenses.16 For cataract surgery, the introduction of specialized technology including multifocal, toric lenses, and femtosecond laser-assisted cataract surgery, offers new methods of restorative surgery which are not covered by insurance beyond standard phacoemulsification with a monofocal lens. The results are mixed regarding the efficacy of each of these innovations. Indeed, laser assisted cataract surgery has not been demonstrated to be particularly cost-effective when compared to other developments in ophthalmic surgery, including standard phacoemulsification.10 Multifocal IOLs may lead to patient dissatisfaction secondary to photopic phenomena, glare, and lower contrast sensitivity.17 Studies on outcomes after toric lens implantation demonstrate mixed results, as they have been shown to reduce spectacle dependency but uncorrected vision was worse in some toric implanted eyes.18
Corneal surgically induced astigmatism in resident surgeons
Published in Baylor University Medical Center Proceedings, 2022
Timothy Sipos, Kendall Bicknell
As cataract surgery has become technologically more advanced, the correction of astigmatism has become ever more important. Factors influencing the correction of astigmatism include but are not limited to SIA, preoperative keratometry measurements, lens rotation, and the accepted range of manufacturer error of intraocular lenses. As beginning surgeons learn the intricacies of operating and wound creation, it is expected that there is less reproducibility in clear corneal incisions than that of experienced surgeons. As reported by Abulafia et al, the centroid value of 0.1D should be used instead of the traditional mean SIA of 0.35D.7 Significant ocular surface disease may result in >0.5D refractive surprise in up to 10% of patients.9 Toric IOLs may rotate after implantation, with most rotating <5° postoperatively.10 With every degree of rotation displaced, the toric lens loses 3.3% of its astigmatism-correcting power.11 Manufacturer lens errors may also provide a source of unexpected refractive outcomes. According to the international standard, spherical power may range 0.4D for lenses with power between 15 and 25D.12
Comparison of Wash-out Properties after Use of the Vital Dye Trypan Blue in the Form of an Ophthalmic Dye and Bound in a Sodium Hyaluronate by Raman Spectroscopy
Published in Current Eye Research, 2021
Andreas F. Borkenstein, Eva-Maria Borkenstein, Johannes Rattenberger, Harald Fitzek, Achim Langenbucher
In addition to the effectiveness of the surgical workflow, Pe-Ha-Blue®PLUS may increase the safety of dye-supported eye surgeries. The safe and complete removal of a potentially toxic and carcinogenic substance from the eye is essential. As the concentration of TB in Pe-Ha-Blue®PLUS is lower and the dye is bound in the matrix of the OVD, there is a certain additional safety aspect. Further studies regarding a possible protective effect on the macula as well as investigation on the protective effect for toric lens rotation or refractive stability and postoperative intraocular pressure behavior are necessary to address these issues. Clinical results have shown in a previous study on additional safety benefits in a variety of surgical situations.6 Although this in vitro study is an experimental setup, the findings may support clinical observations. For example, it has been observed in everyday clinical practice that blue OVD (PeHaBlue Plus) can be removed from the anterior chamber more easily and faster using iris hooks or Malyugin rings. The same arrangement with the trypan blue (standard) results in some bluish remnants (like clouds or swaths) on the ring.