The Effect of Texture Floor Profile on the Lubricant Film Thickness in a Textured Hard-On-Soft Bearing With Relevance to Prosthetic Hip Implants.

Polyethylene wear debris limits the longevity of prosthetic hip implants. We design a pattern of axisymmetric texture features to increase hydrodynamic pressure and lubricant film thickness and, thus, reduce solid-on-solid contact, friction, and wear in hard-on-soft prosthetic hip implant bearings. Specifically, we study the effect of the texture floor profile on the lubricant film thickness using a soft elastohydrodynamic lubrication model. We compute the optimum texture parameters that maximize the lubricant film thickness for different texture floor profiles, as a function of bearing operating conditions. Flat texture floor profiles create thicker lubricant films than sloped or curved texture floor profiles for their respective optimum texture design parameters. We find that the texture feature volume is the most important parameter in terms of maximizing the lubricant film thickness, because a linear relationship exists between the texture feature volume with optimum texture parameters and the corresponding optimum lubricant film thickness, independent of the texture floor profile.

Surface Texturing of Prosthetic Hip Implant Bearing Surfaces: A Review.

More than 300,000 total hip replacement surgeries are performed in the United States each year to treat degenerative joint diseases that cause pain and disability. The statistical survivorship of these implants declines significantly after 15-25 years of use because wear debris causes inflammation, osteolysis, and mechanical instability of the implant. This limited longevity has unacceptable consequences, such as revision surgery to replace a worn implant, or surgery postponement, which leaves the patient in pain. Innovations such as highly cross-linked polyethylene and new materials and coatings for the femoral head have reduced wear significantly, but longevity remains an imminent problem. Another method to reduce wear is to add a patterned microtexture composed of micro-sized texture features to the smooth bearing surfaces. We critically review the literature on textured orthopedic biomaterial surfaces in the context of prosthetic hip implants. We discuss the different functions of texture features by highlighting experimental and simulated results documented by research groups active in this area. We also discuss and compare different manufacturing techniques to create texture features on orthopedic biomaterial surfaces and emphasize the key difficulties that must be overcome to produce textured prosthetic hip implants.

Maximizing the Lubricant Film Thickness Between a Rigid Microtextured and a Smooth Deformable Surface in Relative Motion, Using a Soft Elasto-Hydrodynamic Lubrication Model.

We design a pattern of microtexture features to increase hydrodynamic pressure and lubricant film thickness in a hard-on-soft bearing. We use a soft elastohydrodynamic lubrication model to evaluate the effect of microtexture design parameters and bearing operating conditions on the resulting lubricant film thickness and find that the maximum lubricant film thickness occurs with a texture density between 10% and 40% and texture aspect ratio between 1% and 14%, depending on the bearing load and operating conditions. We show that these results are similar to those of hydrodynamic textured bearing problems because the lubricant film thickness is almost independent of the stiffness of the bearing surfaces in full-film lubrication.

Dysfunctional tear syndrome: dry eye disease and associated tear film disorders - new strategies for diagnosis and treatment.

Dysfunctional tear syndrome (DTS) is a common and complex condition affecting the ocular surface. The health and normal functioning of the ocular surface is dependent on a stable and sufficient tear film. Clinician awareness of conditions affecting the ocular surface has increased in recent years because of expanded research and the publication of diagnosis and treatment guidelines pertaining to disorders resulting in DTS, including the Delphi panel treatment recommendations for DTS (2006), the International Dry Eye Workshop (DEWS) (2007), the Meibomian Gland Dysfunction (MGD) Workshop (2011), and the updated Preferred Practice Pattern guidelines from the American Academy of Ophthalmology pertaining to dry eye and blepharitis (2013). Since the publication of the existing guidelines, new diagnostic techniques and treatment options that provide an opportunity for better management of patients have become available. Clinicians are now able to access a wealth of information that can help them obtain a differential diagnosis and treatment approach for patients presenting with DTS. This review provides a practical and directed approach to the diagnosis and treatment of patients with DTS, emphasizing treatment that is tailored to the specific disease subtype as well as the severity of the condition.

The Vivity Extended Range of Vision IOL vs the PanOptix Trifocal, ReStor 2.5 Active Focus and ReStor 3.0 Multifocal Lenses: A Comparison of Patient Satisfaction, Visual Disturbances, and Spectacle Independence.

PURPOSE: To compare patient-reported outcomes (PROs) after intraocular lens (IOL) implantation with the AcrySof IQ Vivity IOL or Vivity Toric IOL to those achieved with other multifocal IOLs. PATIENTS AND METHODS: Prospective, open-label, multicenter analysis of PROs, including spectacle independence, dysphotopsia, and overall satisfaction among patients who underwent cataract surgery at least 1 month previously with bilateral Vivity or Vivity Toric lenses (n=60). Results were compared to outcomes from two similar prospective studies of bilateral AcrySof IQ PanOptix or PanOptix Toric trifocal IOLs (n = 59), blended AcrySof ReSTOR 2.5/3.0 IOLs (n=72) or bilateral ReSTOR ActiveFocus 2.5 D IOLs with a mini-monovision target [n = 95]). RESULTS: Patients in the Vivity cohort were significantly less likely to notice glare and halo in dim light (85% "none" or "just a little") compared to PanOptix (69%, p<0.03), 2.5 mini-monovision (75%, p< 0.05) or 2.5/3.0 (71%, p< 0.05) patients. Complete spectacle independence for all visual activities combined (never need glasses) with Vivity was comparable to the mini-monovision and 2.5/3.0 groups (33%, 36%, and 31%, respectively) but significantly lower than in the PanOptix cohort (83%, p < 0.0001). Satisfaction was high across all groups. There were no statistically significant differences in best-corrected visual acuity, and no new safety concerns were reported. CONCLUSION: The AcrySof IQ Vivity extended depth of focus IOL offers an expanded range of vision and better spectacle independence than has typically been achieved with traditional monofocal IOLs, with high rates of satisfaction and a favorable dysphotopsia profile compared to diffractive multifocal IOLs.

The PanOptix Trifocal IOL vs the ReSTOR 2.5 Active Focus and ReSTOR 3.0-Add Multifocal Lenses: A Study of Patient Satisfaction, Visual Disturbances, and Uncorrected Visual Performance.

PURPOSE: To compare spectacle independence, patient-reported outcomes (PROs), and dysphotopsia after multifocal intraocular lens (IOL) implantation with the AcrySof PanOptix trifocal or the ReSTOR +2.5/3.0 D or ReSTOR +2.5 D mini-monovision multifocal IOL. PATIENTS AND METHODS: Prospective, open-label, multicenter analysis of PROs, spectacle independence, and satisfaction among patients undergoing cataract surgery who had been implanted at least 1 month previously with AcrySof IQ PanOptix or PanOptix Toric trifocal (n = 59) IOLs bilaterally. Results were compared to outcomes from a similar study with the AcrySof ReSTOR 2.5/3.0 or the ReSTOR ActiveFocus 2.5 mini-monovision lens [n = 191]). RESULTS: Spectacle independence was significantly higher in the PanOptix cohort, with 83% of patients "never" needing glasses for any activity versus 36% in the ReSTOR 2.5 mini-monovision and 34% in the ReSTOR 2.5/3.0 cohorts. No significant differences in patient satisfaction rates were reported between the three cohorts. Glare and halo were rated "extremely" noticeable more with the PanOptix (10%) than with the ReSTOR 2.5 mini-monovision (1%) or ReSTOR 2.5/3.0 (3%). BCVA differences were not statistically significant, and no new safety concerns were reported. CONCLUSION: The AcrySof PanOptix trifocal provides significantly greater spectacle independence across all measured activities than the AcrySof ReSTOR multifocal IOLs.

Patient-Reported Outcomes/Satisfaction and Spectacle Independence with Blended or Bilateral Multifocal Intraocular Lenses in Cataract Surgery.

PURPOSE: To compare patient-reported outcomes (PROs) and satisfaction results after multifocal intraocular lens (IOL) implantation in three groups: two receiving bilateral implantation of the same IOL and another undergoing blended vision with two different multifocal IOLs. PATIENTS AND METHODS: A questionnaire was administered to patients who had undergone uncomplicated cataract surgery and 2 months of follow-up: the first group underwent bilateral implantation with Alcon's AcrySof ReSTOR 3.0 lens ("3.0/3.0," n=78); the second group underwent implantation with the ReSTOR ActiveFocus 2.5 or the ReSTOR ActiveFocus 2.5 toric lens ("2.5 mini-monovision," n=102); and the third group underwent implantation with the ReSTOR 2.5 lens in the dominant eye and the ReSTOR 3.0 lens in the non-dominant eye ("2.5/3.0," n=89). RESULTS: Overall PROs and satisfaction was similar among the groups. Refractive outcomes and accuracy were similar among the groups, but the 2.5 mini-monovision group reported better intermediate vision. Refractive outcome differences were not meaningful among the groups and were not a differentiating factor in PROs. Substantially fewer patients in the 2.5 mini-monovision group noticed glare and halo compared with the 3.0/3.0 group (P<0.0001, chi-square test). No new safety concerns were reported. CONCLUSION: The 2.5 mini-monovision results in a higher percentage of patients being satisfied with intermediate vision than bilateral ReSTOR 3.0 or blended vision with ReSTOR 2.5/3.0 implants, but overall PRO differences were not statistically significant.

Phacoemulsification of the rock-hard dense nuclear cataract: Options and recommendations.

We describe the essential steps in the successful phacoemulsification of the rock-hard, dense cataract. Appropriate and directed preoperative history, physical examination, and diagnostics allow the surgeon to select the best incision, anesthesia, and intended surgical technique for a given dense nuclear challenge. Hard nucleus-specific approaches for hydrodissection, pupil management, and zonular protection then allow the surgeon to approach the rock-hard nucleus with maximum safety. Dense nuclear dismantling options are then discussed in detail along with fluidic and power modulation considerations. Various specific phacoemusification machine settings for rock-hard cataracts from the authors representing several different phaco systems are then presented. The combination of these steps and considerations allow a more successful dense cataract removal and potential restoration of vision for patients. This paper represents the collective experience and advice of the Challenging and Complex Cataract Surgery Subcommittee.

Cataract surgery in the small eye.

UNLABELLED: The surgical management of cataract in the small eye presents the ophthalmic surgeon with numerous challenges. An understanding of the anatomic classification in addition to a thorough preoperative assessment will help individualize each case and enable the surgeon to better prepare for the obstacles that might be encountered during surgery. Small eyes are especially challenging in terms of intraocular lens (IOL) calculations and possible current limitations of available IOL powers, which could necessitate alternative means of achieving emmetropia. Surgical strategies for minimizing complications and maximizing good outcomes can be developed from knowledge of the anatomic differences between various small-eye conditions and the pathologies that may be associated with each. A thorough understanding of the challenges inherent in these cases and the management of intraoperative and postoperative complications will ensure that surgeons approaching the correction of these eyes will achieve the best possible surgical results. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Management of the subluxated crystalline lens.

The surgical management of ectopia lentis presents the ophthalmic surgeon with numerous challenges and options. From the clinical evaluation to the surgical approach, ectopia lentis patients require additional methodologies, techniques, and devices to ensure the best possible outcome. The continued refinement of surgical techniques and adjunctive prosthetic devices has led to incremental improvements in the ability to achieve successful in-the-bag placement and centration of intraocular lenses while reducing complications. A thorough understanding of the challenges inherent in ectopia lentis cases and the management of intraoperative complications will ensure that surgeons approaching the correction of these eyes will achieve the best possible surgical results.