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PubMed2002

[Miyake-Apple video analysis of movement patterns of an accommodative intraocular lens implant].

BACKGROUND: The potentially accommodative intraocular lens (IOL) is a new development in IOL design METHODS: We evaluated the new Humanoptics 1CU accommodative IOL in a laboratory study with human post mortem autopsy eyes. Using the Miyake-Apple posterior view video technique, the movement pattern of the IOL was tested and observed from the posterior perspective. RESULTS. A circular bend at the level of the ciliary body applied slight circular force onto the sclera allowing the relaxation of the zonules. The shift of focus was demonstrated by using a reading target. In addition, viscoelastic was injected into the vitreous resulting in the same anterior movement of the IOL optic. CONCLUSIONS: The 1CU Humanoptics accommodative IOL showed potential accommodative behaviour in the laboratory. The accommodative (respectively pseudoaccommodative) effect was based on the anterior shift principle with anterior movement of the IOL-optic in the state of relaxing zonules. Whether this reflects the clinical situation, especially to this extent, must be further evaluated.

Accommodation, Ocular↗
PubMed2002

[Validity of anterior chamber depth measurements for the evaluation of accommodation after implantation of an accommodative Humanoptics 1CU intraocular lens].

BACKGROUND: Changes in the anterior chamber depth (ACD) after pilocarpin application are generally regarded as reflecting an accommodative effect of accommodative intraocular lenses (IOLs) METHODS: We implanted Humanoptics 1CU accommodative IOLs into 25 eyes of 20 patients aged 53.2+/-14.7 years (range: 30-83 years). In seven of these patients, we were able to measure anterior chamber depth changes after the application of pilocarpine (2%) eye drops 3 months postoperatively using a Zeiss IOLMaster, an Orbscan II topography system, as well as by ultrasound biomicroscopy (20 MHz-US-head). RESULTS: Uncorrected near acuity was on average 0.4+/-0.23 (0.1-0.8) and uncorrected distance acuity was 0.76+/-0.23 (0.3-1). Before pilocarpine, ACD was 3.19+/-2.11 mm (IOL-Master), 3.35+/-2.22 mm (Orbscan II) and 3.35+/-2.21 mm (US-biomicroscopy) ( P=0.96). After pilocarpine, ACD was 2.61+/-1.71 mm (IOL-Master), 2.63+/-1.78 mm (Orbscan II) and 3.15+/-2.08 mm (US-biomicroscopy) ( P=0.002). The average individual ACD change before/after pilocarpine was 0.83+/-0.25 mm with the IOL-Master, 1.04+/-0.39 mm with the Orbscan II System and 0.28+/-0.14 with US-biomicroscopy ( P=0.0004). DISCUSSION: The 1CU Humanoptics accommodative IOL presented with potential accommodative capabilities in clinical evaluation. Drug induced accommodation by pilocarpine does not reflect real accommodative effects. The differences in ACD measurements between three different methods were statistically significant. Evaluation methods for accommodative IOLs should be carefully analysed and further development of objective means for evaluation is needed.

Accommodation, Ocular↗
PubMed2002

[Two years experience with the new accommodative 1 CU intraocular lens].

After marked improvement of optical rehabilitation of cataract patients during the last decades due to small incision surgery and foldable intraocular lenses (IOL), presbyopia is now one of the great unsolved questions in ophthalmology. During recent years a new accommodative IOL, the 1CU lens, has been developed based on the concepts of K.D. Hanna and on finite element computer simulation models. The 1CU IOL is designed to transform contracting forces of the ciliary muscle into anterior movement of the IOL optic (optic-shift concept). After the first implantation of a 1CU IOL in Erlangen in June 2000, we have now successfully implanted the 1CU IOL in over 90 patients. Our experiences and the results of several clinical studies indicate good and safe implantability, good centration, no IOL-specific complications, and good distance visual acuity. In comparison to control groups with conventional IOL, patients with the 1CU enjoyed significantly better distance-corrected near visual acuity, a larger accommodative range, and increased anterior and posterior axial movement of the lens optic after medical stimulation or inhibition of the ciliary muscle. We interpret our results as confirmation of the optic-shift concept of the 1CU IOL. Overall, the concept of accommodative IOL appears attractive and may have a great potential in the future. Additional studies including randomized blind multicenter evaluation of the 1CU IOL are necessary to further evaluate long-term and accommodative results.

Accommodation, Ocular↗
PubMed2003

[Impairment of safety in navigation caused by alcohol: impact on visual function].

BACKGROUND: So far in Germany, no legally binding standards for blood alcohol concentration exist that prove an impairment of navigability. The aim of our interdisciplinary project was to obtain data in order to identify critical blood alcohol limits. In this context the visual system seems to be of decisive importance. MATERIALS AND METHODS: 21 professional skippers underwent realistic navigational demands soberly and alcoholized in a sea traffic simulator. The following parameters were considered: visual acuity, stereopsis, color vision, and accommodation. RESULTS: Under the influence of alcohol (average blood alcohol concentration: 1.08 per thousand ) each skipper considered himself to be completely capable of navigating. While simulations were running, all of the skippers made nautical mistakes or underestimated dangerous situations. Severe impairment in visual acuity or binocular function were not observed. Accommodation decreased by an average of 18% ( p=0.0001). In the test of color vision skippers made more mistakes ( p=0.017) and the time needed for this test was prolonged ( p=0.004). CONCLUSIONS: Changes in visual function as well as vegetative and psychological reactions could be the cause of mistakes and alcohol should therefore be regarded as a severe risk factor for security in sea navigation.

Accidents↗
PubMed2002

[Dynamic aberrometry during accommodation of phakic eyes and eyes with potentially accommodative intraocular lenses].

Since the introduction of potentially accommodative intraocular lenses (IOLs), it was hard to perform an objective evaluation of the accommodative amplitude in pseudophakic eyes. Laser interferometric measurements were performed to evaluate anterior chamber depth changes, which provides information on the functionality of potentially accommodative IOLs. By means of wavefront analysis, the dynamic behaviour of potentially accommodative IOLs can be determined. All measurements in this study were performed using a Hartmann-Shack aberrometer at a frequency of 7 Hz. Six to 8 weeks after implantation of potentially accommodative IOLs (CrystaLens AT-45, C&C Vision, 1CU, Humanoptics), 43 eyes were investigated using this dynamic wavefront analysis. Patients focussed at a distance target for 10 s, followed by focussing at a near target for 10 s and then again at a distance target for a further 10 s. During these 30 s, a total of 200 single measurements were performed. The same measurements were also conducted in healthy eyes of young persons as well as in eyes after implantation of standard IOLs for comparative purposes. The dynamic course of changes in low-order aberrations (defocus, astigmatism) as well as high-order (e.g., fourth-order spherical aberration) were analysed. Dynamic wavefront analysis allowed objective and observer-independent measurement of changes in accommodation in phakic and pseudophakic eyes. Dynamic aberrometry is capable of objectively quantifying the effect of any surgical option for the treatment of presbyopia. We recommend use of this technology in addition to the common psychophysical examinations to attain objective information on the efficacy of the treatment modality used.

Accommodation, Ocular↗
PubMed2003

[Nd-YAG laser iridotomy in pigment dispersion syndrome and pigment dispersion glaucoma].

Pigment dispersion syndrome is characterized by iris transillumination defects, Krukenberg spindels, and dense trabecular pigmentation. Additional features are bilaterality, myopia, concavity of the peripheral iris, a higher incidence in men than in woman,and young age of onset. A mechanism of reverse pupillary block causes iridozonular friction. Laser iridotomy is recommended as treatment to prevent further pigment dispersion and pigmentary glaucoma.

Accommodation, Ocular↗
PubMed2004

[Dissociated near reflex and accommodative convergence excess].

We report on an 8-year-old boy whose near reflex could be elicited exclusively when the left eye was fixing (LF) but not when the right eye was fixing (RF). With RE +1.25/-1.25/169 degrees and LE +1.0/-0.75/24 degrees, the visual acuity was 1.0 OU at 5 m and RE 0.5, LE 1.0 at 0.3 m improving to 1.0 OU by a near addition of 3.0 D. Stereopsis was 100 degrees (Titmus test). The prism and cover test revealed an esophoria of 4 degrees at 5 m. At 3 m there was an esophoria of 6 degrees (RF) and an esotropia of 28 degrees (LF), compensating to an esophoria of 3 degrees (RF/LF) with a near addition of 3.0 D. Accommodation and the pupillary near reaction (OU) were hardly elicitable during RF. During LF, retinoscopy revealed an accommodation of 8 D (OU) and the pupils constricted normally. Correction by bifocal glasses yielded orthotropia with random dot stereopsis at near.

Accommodation, Ocular↗
PubMed2005

[Three-dimensional ultrasound biomicroscopic examinations for haptic differentiation of potentially accommodative intraocular lenses].

PURPOSE: The principal ability of potentially accommodative IOLs is based on an axial shift of the IOL optics induced by the ciliary body action in interaction with a reversible change in haptic angulation. The aim of this study was to investigate the accommodative performance of this new IOL generation. METHOD: The authors have designed a test device to study IOL performance experimentally. These results were extrapolated to the in vivo situation in patients with accommodative implants. RESULTS: The 3D high-resolution presentation of the anterior segment of the eye allows a separation of the IOL haptic elements. In vitro and in the selected in vivo cases a change in haptic angulation <10 degrees in combination with a maximal IOL shift of 0.5 mm was found. CONCLUSIONS: The simulation model used in combination with 3D ultrasound biomicroscopy provides information about the potential of accommodative IOL designs. Conclusions corresponding to changes in haptic angulation during accommodation can be drawn and applied to the in vivo situation.

Accommodation, Ocular↗
PubMed2006

[Accommodation ability under the aspect of refractive, demographic, and biometric parameters].

PURPOSE: The aim of this study was to evaluate the accommodation ability in healthy phakic eyes in relation to refraction and biometric parameters in order to get comparable results for patients with the accommodative 1 CU posterior chamber lens. METHODS: The study included 120 normal eyes of 120 patients (77 males, 43 females, mean age: 40+/-18, range: 11-70 years). The inclusion criteria were spherical equivalent for distance refraction <2 D, astigmatism <1.5 D, and a best-corrected visual acuity > or =0.8. Exclusion criteria were diabetes, glaucoma, cataract, traumas, or previous surgery. Subjects were divided into six age groups at increments of 10 years. Each group consisted of 20 subjects. Measurements included subjective and objective refraction (D), the accommodation ability (D) assessed with an accommodometer, and biometric parameters using the IOLMaster. In addition, the relation of anterior chamber depth and length of the eye was calculated for analyzing the relationship of anterior eye segment and accommodation. RESULTS: The spherical equivalent for distance refraction was 0.04+/-0.6 D with a range of -1.5 to 2.0 D. There was no sex-related significant difference of accommodation range. The accommodation range (D) decreased significantly with increasing age (p<0.0001, r=-0.895). The highest decrease could be found between the ages of 30 and 50 years. In subsequent years, the decline in accommodation ability was comparatively less. In association with the anterior chamber depth and the relation of anterior chamber depth and length of the eye, the accommodation ability fell with increasing age (p<0.001). The length of the eye did not correlate with the accommodation ability (p=0.8). CONCLUSION: There is a strong relationship between accommodation ability and age. Accommodation ability decreases strongly from the 3rd to the 5th decade; after that the loss of accommodation ability is relatively lower. The increase in lens thickness during the life span can implicate a correlation between the change of anterior chamber depth in relation to the length of the eye and a decrease of accommodation ability. Our results confirm Duane's hypothesis of accommodation and age.

Accommodation, Ocular↗
PubMed2006

[Presbyopia treatment using a femtosecond laser].

Presbyopia is by far the most common refractive error worldwide, with no permanent therapeutic option available. All efforts to restore accommodation by the use of surgery have not led to a generally accepted therapy. However, there is evidence from an animal model that the use of a femtosecond (fs) laser might influence the modulus of elasticity in the lens. Fs-laser impulses can create intralenticular disruption in animal eyes as well as human cadaver lenses and improve elasticity. The concept of treating presbyopia with fs-laser requires a new, complex theory combining the optical and the mechanical aspects of accommodation in the eye. Diagnostic tools for measuring optical change in power and geometrical modification as the eye views from far to near are needed to obtain objective clinical data. A non-invasive treatment of presbyopia to restore accommodation might be possible in the future.

Accommodation, Ocular↗
PubMed2000

[Motor and sensory responses in fusion of vertical disparities in different convergence places].

UNLABELLED: To study motor and sensory responses in vertical fusion at different angles of horizontal vergence in normal humans. METHODS: The study included 12 normal subjects. A cross (+) extending 3.4 degrees x3.2 degrees was presented dichoptically. Vertical disparity was introduced by changing the vertical position of the cross in front of one eye. The disparity was incremented by 0.08 degrees every 8 s. Distance viewing was tested with 1 degrees of convergence demand, near vision with 6-15 degrees convergence demand. Eye movements were recorded using three-axis search coils. RESULTS: Vertical fusion capability was larger at near vision than at distance in 9 of 12 subjects. For the entire group, total vertical fusion capability (motor plus sensory response) differed between distance (mean 1.68 degrees ) and near (mean 2.39 degrees ). The motor component differed significantly between distance (mean 1.42 degrees ) and near (mean 2.13 degrees ). No difference in the sensory component was seen between distance (mean 0.26 degrees ) and near (mean 0.27 degrees ). CONCLUSIONS: Vertical fusion capability increases with convergence. This increase is mainly due to an increase of the motor response.

Accommodation, Ocular↗
PubMed2000

[Analysis of the dynamics of the ciliary muscle during accommodation].

BACKGROUND: The magnitude of anterioaxial shift of the human ciliary muscle during accommodation and its ceasing of ciliary function with advanced age are still unknown. PATIENTS AND METHODS: A total 105 patients (aged 10-91 years) were examined by high-resolution ultrasound biomicroscopy during disaccommodation and voluntary accommodation. Accommodative changes in the total area of the ciliary muscle and in the outer contour were quantified with a specially developed software program for automatic contour determination. RESULTS: A significant anterior shift independent of age was observed in the total area of the ciliary muscle and defined points on the outer contour of the muscle in the range of 56-121 microns, while the inward displacement was less obvious. A decrease in the magnitude of configurational changes during accommodation was observed with age. CONCLUSION: The new software program could be useful in further investigations of the accommodative process and evaluation of the potential causes of presbyopia.

Accommodation, Ocular↗
PubMed2000

[Effect of dorzolamide on accommodation and pupillary reaction?].

PURPOSE: To test the effect of dorzolamide on accommodation or pupillary function. MATERIALS AND METHODS: This double-blind study examined 35 young subjects with normal ophthalmological findings. Before and after the application of two drops dorzolamide in one eye and placebo in the other eye the subjects were examined by pupillography, infrared video-retinoscopy, and subjective near-point determination. RESULTS: None of the parameters concerning accommodation or pupillary function differed significantly before and after application of the eye drops. CONCLUSION: Dorzolamide has no short-term effect on accommodation or pupillary function.

Accommodation, Ocular↗
PubMed2001

[History of the development of intraocular lenses].

Even though cataract surgery has been practiced for over 2000 years, modern cataract surgery started just some 50 years ago. with the first IOL implantation by Sir Harold Ridley. The development of intraocular lenses was accompanied by great successes and disasters. With the fast development of cataract surgical techniques over the past 15 years (ECCE, Phacoemulsification, Capsulorhexis) a successful marriage between IOL-developments and surgery was established. Indication profiles for cataract surgery and IOL implantation extended to more and more patient groups. At this time classical cataract surgery is further developing into refractive intraocular lens surgery to correct higher ametropia in clear lens or phakic eyes. This development was only possible because of the improvements of surgical techniques and implants in classical cataract surgery.

Accommodation, Ocular↗
PubMed2001

[Accommodative lens implant].

PROBLEM: To date, approaches to restore accommodation following cataract surgery have been based on the principle of a liquid or solid implant that moves within the capsular bag and thereby changes the optical characteristics of the eye. However, these implants have been associated with shrinking and fibrosis of the capsular bag, a problem that will not be solved in the foreseeable future. APPROACH: If accommodation is effected by shifting the whole capsule including its contents on the optical axis, capsular fibrosis will virtually no longer play a role. In order to execute this shift via the neuronal feedback mechanisms of the ciliary muscle in a controlled way, radial zonular forces or movements must be transformed into axial ones, which is possible by means of tiny permanent magnets. This paper describes the basic aspects of such an implant. The dependence of accommodation on all relevant parameters is quantified in a computer simulation. CONCLUSION: The implant described appears to be practicable with justifiable technical and surgical efforts.

Accommodation, Ocular↗
PubMed2003

Accommodation behaviour during prey capture in the Vietnamese leaf turtle ( Geoemyda spengleri).

Vietnamese leaf turtles ( Geoemyda spengleri) were tested for their ability to focus on prey objects at various distances. Accommodation was continuously measured by infrared photoretinoscopy. All animals investigated during this study showed a surprisingly high precision of accommodation over a range of over 30 D. Measured accommodation matched the target distance accurately for distances between 3 and 17 cm. The turtles switched between independent and coupled accommodation in the two eyes. Independent accommodation was observed when the turtles inspected their environment visually without a defined object of interest. Coupled accommodation was only observed during binocular prey fixation. When a turtle aimed at a target, the symmetrical focus of both eyes persisted even if vision was totally blocked in one eye or altered by ophthalmic lenses. This suggests that the eyes were linked by internal neuronal mechanisms. The pupil of the eye responded clearly to changes in ambient light intensity. A strong decrease in pupil size was also observed when the eye was focused on a close target. In this case, the constriction of the pupil probably aids in the deformation of the eye lens during near-accommodation.

Accommodation, Ocular↗