Long-term prevention of capsular opacification after lens-refilling surgery in a rabbit model.

Purpose: To reduce capsular opacification by a peri-surgical treatment of the lens capsule with drugs in an in vivo rabbit model. Lens-refilling surgery is a potential therapeutic intervention to treat patients with a cataract lens. The lens material is replaced with an injectable (bio)polymer that retains the natural mechanical and optical lens properties, therewith allowing accommodation.

Prevention of capsule opacification after accommodating lens refilling: pilot study of strategies evaluated in a monkey model.

Purpose: To test 2 strategies to prevent capsule opacification after accommodating lens refilling in a rhesus monkey model.

Setting: Animal laboratory and laboratory of European university medical centers.

Design: Experimental study.

Rostock Glare Perimeter: a distinctive method for quantification of glare.

Purpose: Disability glare induced by headlights of oncoming cars has been associated with reduced quality of vision. This study aimed at developing the Rostock Glare Perimeter to quantify dysphotopsia effects under simulated realistic conditions.

Methods: Sixty phakic subjects of different ages were dazzled by a bright light source centered at a projection screen 3.

Prevention of capsular opacification after accommodative lens refilling surgery in rabbits.

Silicone gel-like polymers have been proposed to replace the cataractous lens and therewith restore both vision and accommodation. Lens replacement is associated with opacification of the capsular bag due to the lens epithelial cell response. In this study, the in vivo effectiveness of a 5 min treatment with actinomycin D and/or cycloheximid to prevent the development of capsular opacification after filling the capsular bag with a silicone polymer as an accommodating lens was studied.

In vivo 7.1 T magnetic resonance imaging to assess the lens geometry in rabbit eyes 3 years after lens-refilling surgery.

Purpose: To evaluate the utility of high-resolution magnetic resonance imaging (MRI) in assessing the normal and refilled lens geometry in rabbits after lens-refilling surgery.

Setting: University of Rostock, Rostock, Germany.

Design: Experimental study.

Drug-induced secondary cataract prevention: experimental ex vivo and in vivo results with disulfiram, methotrexate and actinomycin D.

Background/aims: A clinical approach to prevent secondary cataract after lens implantation involves the intraocular application of pharmacological agents. The goals of our study were to develop an ex vivo model to test the drug effectiveness for lens epithelial cell ablation from the basal membrane and to verify the data in rabbit intraocular lens implantation experiments.

Methods: Human capsular rhexis specimens were incubated with drugs and the residual cells were differentiated by use of the Live-Dead assay and quantified by staining with Hoechst dye.

7.1 T MRI to assess the anterior segment of the eye.

Purpose: Visualization of the anterior segment and biometric evaluation of the entire crystalline lens pose significant challenges for imaging techniques because of tissue-induced distortion artifacts. The present study was conducted to demonstrate the advantages of high-resolution magnetic resonance imaging (micro-MRI) for visualizing the anterior segment.

Methods: High-resolution MR ocular images were acquired on an ultra-high-field MR unit using a two-channel coil with four coil elements and T(2)-weighted turbo spin echo sequences ex vivo in pig, rabbit, monkey, and human donor eyes and in vivo in rabbits.

Relationship between contrast sensitivity and spherical aberration: comparison of 7 contrast sensitivity tests with natural and artificial pupils in healthy eyes.

Purpose: To find a contrast sensitivity test that can be used clinically to evaluate interventions aimed at minimizing spherical aberration and determine the circumstances under which these tests should be performed.

Setting: Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands.

Methods: Contrast sensitivity tests were performed using 2 experimental designs.

Development of a ciliary muscle-driven accommodating intraocular lens.

Purpose: To develop a ciliary muscle-driven accommodating intraocular lens (IOL) that has a large and predictable range of variable power as a step toward spectacle independence.

Setting: Department of Physics and Medical Technology, VU University Medical Center, Amsterdam, The Netherlands.

Methods: A concept IOL that has a rotating focus mechanism and a mechanical frame that can operate within the range of ciliary muscle contraction of a typical 60-year-old human eye was designed.

Visualization of the retinal image in an eye model with spherical and aspheric, diffractive, and refractive multifocal intraocular lenses.

Purpose: To present a method that visually demonstrates how spherical, aspheric, diffractive, and refractive multifocal intraocular lenses (IOLs) process light received from the cornea.

Methods: Monochromatic green light was projected through an Average Cornea Eye (ACE) Model with a cornea in front of the IOL. The model simulates a human cornea with average spherical aberration and visualizes the converging bundle of light leaving the IOL.

Changes in spherical aberration after lens refilling with a silicone oil.

Purpose: It may be possible to restore accommodation to presbyopic human eyes by refilling the lens capsular bag with a soft polymer. In the present study, optical changes were measured that occurred in a pig eye model after the refilling of the capsular bag.

Methods: The optical power and spherical aberration in 10 isolated pig lenses were measured under different conditions.

Development of an accommodating intra-ocular lens--in vitro prevention of re-growth of pig and rabbit lens capsule epithelial cells.

Cataract surgery is routinely performed to replace the clouded lens by a rigid polymeric intra-ocular lens unable to accommodate. By implanting a silicone gel into an intact capsular bag the accommodating properties of the natural lens can be maintained or enhanced. The implantation success of accommodating lenses is hampered by the occurrence of capsular opacification (PCO) due to lens epithelial cell (LEC) growth.

Accommodative lens refilling in rhesus monkeys.

Purpose: Accommodation can be restored to presbyopic human eyes by refilling the capsular bag with a soft polymer. This study was conducted to test whether accommodation, measurable as changes in optical refraction, can be restored with a newly developed refilling polymer in a rhesus monkey model. A specific intra- and postoperative treatment protocol was used to minimize postoperative inflammation and to delay capsular opacification.

Artificial crystalline lens.

If presbyopia is caused by hardening of the crystalline lens, replacing it with a material with mechanical properties similar to the young crystalline lens should restore accommodative ability. Such a silicone material has been developed. Refilling the capsular bag with this material results in 3 to 5 D of accommodation in primates in response to pilocarpine.

Comparison of the accommodation theories of Coleman and of Helmholtz by finite element simulations.

Purpose: The accommodation process of the human eye is still a controversial subject. Coleman assumes that the lens, together with the zonula fibers, forms a diaphragm which is held in a catenary shape due to the pressure difference between the aqueous and vitreous body of the lens. The aim of the paper is to compare the results of two simulations (according to the Helmholtz and to the Coleman theories) with ultrasonographic data.

Relation between injected volume and optical parameters in refilled isolated porcine lenses.

Purpose: This study was performed to elucidate the correlation between added lens refill material and enhanced lens power as well as the correlation between lens refilling volume and accommodative amplitude as determined by equatorial stretching of ex vivo refilled pigs' lenses.

Methods: Nine porcine lenses were refilled with increasing amounts of silicone oil. After each refill step, the lens power, the lens power change, and the lens thickness were measured both in the relaxed state and with a 3-mm larger ciliary body diameter.

Effect of infusion bottle height on lens power after lens refilling with and without a plug.

Purpose: To evaluate the influence of intraoperative infusion bottle height on the power of refilled pig lenses.

Setting: Research Laboratory, Pharmacia Intraocular Lens Manufacturing Plant, Groningen, The Netherlands.

Methods: This study comprised 2 groups of pig eyes.

Polymer refilling of presbyopic human lenses in vitro restores the ability to undergo accommodative changes.

Purpose: Because presbyopia is thought to be accompanied by increased lens sclerosis this study was conducted to investigate whether refilling the capsule of the presbyopic human lens with a soft polymer would restore the ability of the lens to undergo accommodative changes.

Methods: Accommodative forces were applied to natural and refilled lenses by circumferential stretching through the ciliary body and zonular complex. Nine natural lenses and 10 refilled lenses from donors ranging in age from 17 to 60 years were studied.

Monitoring accommodative ciliary muscle function using three-dimensional ultrasound.

Background: Our objective was to develop a three-dimensional high-resolution ultrasonic imaging technique to be utilized for in-vivo characterization of the ciliary body and the posterior iris. The benefit of this imaging in enhancing the quantification of the configurational changes in the ciliary body during accommodation is demonstrated.

Methods: Sequential ultrasound biomicroscopic images of the ciliary body region were obtained with a computer-controlled scanning device designed for use with a standard ultrasound biomicroscope for 3D imaging.