12 year results of a prospective trial comparing poly(methyl methacrylate) and poly(hydroxyethyl methacrylate) intraocular lenses

Softec HD hydrophilic acrylic intraocular lens: biocompatibility and precision

Intraocular lens development is driven by higher patient expectations for ideal visual outcomes. The recently US Food and Drug Administration-approved Softec HD^™ lens is an aspheric, hydrophilic acrylic intraocular lens (IOL). The hydrophilic design of the lens is optimized to address dysphotopsia while maintaining biocompatibility, optical clarity, resistance to damage, and resistance to biocontamination. Aspheric lenses decrease postoperative spherical aberration. The addition of the Softec lens provides clinicians with another option for IOL placement; however, randomized comparative studies of this lens to others already on the market remain to be completed.

Osmotic cavitation of elastomeric intraocular lenses

In recent years, traditional rigid materials have been replaced with softer elastomers in intraocular lenses to minimize the size of the required surgical incision, thereby reducing patient recuperation time. However, water-filled cavities that may impact visual acuity are found in many of these new implants. We demonstrate that the cavitation observed in vivo can occur due to an osmotic pressure difference between the aqueous solution within the cavity and the external media in which the lens is immersed. By reducing the osmolarity of the external solution from 300 to 0mM, we observe an increase in cavity volume of almost a factor of 30. Further, we have developed a model for cavity growth assuming the controlling factor is diffusion of hydrophilic molecules from the polymer matrix into the cavity. We find that the experimental observations are consistent with the model and suggest that oligomeric species generated during polymerization are responsible for the observed cavitation.

Recurrent occlusion of laser iridotomy sites after posterior chamber phakic IOL implantation

We report a case of recurrent occlusion of laser iridotomy (LI) sites after a Visian ICL (Implantable contact lens version 4, Staar Surgical AG, Nidau, Switzerland) implantation. A 45-year-old woman had bilateral ICL implantation after placement of two peripheral LI sites in each eye to prevent pupillary block. At one month after the operation, severe narrowing or occlusion of four LI sites occurred. After this, although she received four additional LIs at postoperative months 1, 6, 9 and 10 in both eyes, the narrowing or occlusion recurred. Mild chronic anterior chamber inflammation was observed intermittently throughout the follow-up period. We performed clear lens extraction in both eyes (at postoperative month 11 in the left eye and month 26 in the right eye) due to recurrent occlusion of the LI sites and excess trabecular meshwork pigment deposition presumably caused by the four repeated LIs. Recurrent obstruction of LI sites can occur after ICL implantation. These problems were unresolvable despite four repeated laser iridotomies. The risks associated with anterior uveitis must be considered when planning an ICL implantation.

Rate of posterior capsule opacification in eyes with the Akreos intraocular lens

PURPOSE

To determine the rate of posterior capsule opacification (PCO) in eyes with an Akreos Adapt or Akreos Fit intraocular lens (IOL) (Bausch & Lomb) over a minimum follow-up of 18 months.

SETTING

Department of Ophthalmology, Worthing and Southlands Hospital NHS Trust, Worthing, United Kingdom.

METHOD

This was a retrospective analysis of 102 patients who had uneventful phacoemulsification with implantation of an Akreos Adapt IOL or Akreos Fit IOL from September 2001 to May 2004. Patients from a single surgeon's operating list were recruited into the study. Exclusion criteria included posterior subcapsular cataract, history of uveitis, diabetic retinopathy, glaucoma, and age-related macular degeneration. The protocol included the determination of logMAR best corrected visual acuity (BCVA) and PCO scoring using the Evaluation of Posterior Capsular Opacification System (EPCO 2000) by digital photography of the posterior capsule. The number of patients having a neodymium:YAG (Nd:YAG) capsulotomy was also recorded.

RESULTS

The mean follow-up was 30 months +/- 10.3 (SD). The mean BCVA was 20/32 (0.2 logMAR). The mean EPCO score at the central 6.0 mm of the posterior capsule was 0.39 +/- 0.53 and at the central 3.0 mm, 0.18 +/- 0.40. The Nd:YAG capsulotomy rate was 8.8%.

CONCLUSIONS

All patients had stable visual acuity with low rates of PCO 2.5 years after surgery. The PCO rate with the Akreos IOL was similar to that with other acrylic IOLs reported in the literature.

Iris and trabecular meshwork pigment changes after posterior chamber phakic intraocular lens implantation

PURPOSE

To evaluate the changes in laser iridotomies, intraocular pressure (IOP), angle structures, and pupil diameter after implantable contact lens (ICL) (Version 4 Staar Surgical) implantation in myopic Asian eyes.

SETTING

Department of Ophthalmology, Chung-Ang University Yongsan Hospital, Seoul, Korea.

METHODS

The ICL was implanted in 81 eyes of 43 patients with spherical equivalent greater than -6.00 diopters. Gonioscopy examination was performed 1 day after laser iridotomy and 6 and 12 months after ICL implantation. The changes in laser iridotomy sites, IOP, and pupil diameter were also evaluated.

RESULTS

Ten eyes (12.3%) had occlusion or narrowing of the laser iridotomy sites. The angle width was more than 30 degrees in all cases preoperatively but narrowed to less than 20 degrees in 16 eyes (19.8%) 6 months postoperatively. The mean pigment, measured by the semiquantitative method (grade 0 to 4), was 2.03 in the inferior angle, 0.18 in the nasal angle, 0.12 in the temporal angle, and 0.00 in the superior angle 12 months postoperatively. The pigment in all quadrants increased temporally as a result of the laser iridotomy or iris rubbing by the ICL; however, the pigments absorbed gradually and decreased to values before laser iridotomy 12 months postoperatively. There was a temporary increase in IOP from the instillation of steroid eyedrops 1 week and 1 month postoperatively; IOP returned to the preoperative level and remained there 12 months postoperatively. There was a significant decrease in pupil diameter 1 and 3 months postoperatively; the diameter returned to the preoperative size at 6 and 12 months. Pigment dispersion syndrome and pigmentary glaucoma were not seen.

CONCLUSION

Implantation of the ICL narrowed the angle width but did not increase trabecular pigmentation compared with values after laser iridotomy, indicating ICL implantation is safe regardless of the pigmentary changes in the trabecular meshwork.

Functionalized chitosan/NIPAM (HEMA) hybrid polymer networks as inserts for ocular drug delivery: Synthesis,in vitro assessment, andin vivo evaluation

A series of hybrid polymeric hydrogels, prepared by the reaction of acrylic acid-functionalized chitosan with either N-isopropylacrylamide or 2-hydroxyethyl methacrylate monomers, were synthesized, pressed into minitablets, and investigated for their ability to act as controlled release vehicles for ophthalmic drug delivery. For comparison, interpolymeric complex analogues synthesized using the same monomers and pure, unfunctionalized chitosan were examined by means of an identical characterization protocol. The effects of network structure and composition upon the swelling properties, adhesion behavior, and drug release characteristics were investigated. Comparative in vitro studies employing chloramphenicol, atropine, norfloxacin, or pilocarpine informed the selection of drug-specific carrier compositions for the controlled delivery of these compounds. In addition, in vivo (rabbit model) experiments involving the delivery of pilocarpine indicated that chitosan-based hybrid polymer networks containing 2-hydroxyethyl methacrylate are useful carriers for the delivery of this therapeutic agent.

Retrospective evaluation of intraocular lenses in adults younger than 60 years

Data from the U.S. Food and Drug Administration, the American Academy of Ophthalmology's National Eyecare Outcomes Network, and Storm Eye Institute databases were analyzed for short- and long-term safety and efficacy outcomes of intraocular lens (IOL) implantation in adults younger than 60 years and 60 years and older. Statistical analyses for significance were performed where appropriate. A comprehensive literature review was conducted to identify safety and efficacy outcomes and their relationship to patient age at the time of implantation. Analyses established that the performance of IOLs in adults younger than 60 years was comparable to that in adults older than 60 years and supported the use of IOLs in the younger adult population.