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PubMed2006

Pseudophakic accommodation and pseudoaccommodation under physiological conditions measured with partial coherence interferometry.

PURPOSE: To distinguish pseudophakic accommodation from pseudoaccommodation by measuring the physiologically and pharmacologically induced anterior chamber depth (ACD) shifts. SETTING: Department of Ophthalmology, University of Debrecen, Debrecen, Hungary. METHODS: This study comprised 100 pseudophakic eyes of 79 patients. Forty patients (Group 1) received the AcrySof MA60AC intraocular lens (IOL) (Alcon Laboratories), 50 patients (Group 2) received the SA60AT IOL (Alcon Laboratories), and 10 patients (Group 3) received the apodized diffractive SA60D3 ReSTOR IOL. Visual function was evaluated a mean of 10.2 months +/- 9.2 (SD) postoperatively, and the total pseudoaccommodative amplitude was determined with a defocusing technique. To distinguish pseudophakic accommodation from pseudoaccommodation, ACD measurements were performed using partial coherence interferometry during distance fixation and physiologic accommodation after pharmacologic relaxation of the ciliary muscle. RESULTS: Best corrected distance and near visual acuities were similar in the 3 groups (P = .75 and P = .08, respectively). Distance corrected near visual acuity was significantly better in Group 3 (P < .001), with all eyes achieving J1 or better. Three percent in Group 1 and 8% in Group 2 achieved J1 or better. Subjective accommodation was similar in Groups 1 and 2 (-0.82 +/- 0.18 diopter [D] and -1.00 +/- 0.35 D, respectively; P = .3). Group 3 had an accommodation curve with 2 peaks. Intraocular lens movement differences between the groups were not significant (physiologic stimulus: P = .07; cyclopentolate: P = .46), and significant ACD shifts from baseline were not detected (physiologic stimulus: P = .14; cyclopentolate: P = .10). CONCLUSIONS: Pseudoaccommodative amplitude of the investigated monofocal IOLs was independent of IOL movement. Anterior shift did not affect good near visual acuity with the AcrySof ReSTOR IOL.

Accommodation, Ocular↗
PubMed2006

Analysis of patients with good uncorrected distance and near vision after monofocal intraocular lens implantation.

PURPOSE: To analyze factors contributing to uncorrected visual acuity of at least 6/12 for distance and at least J4 for near (pseudoaccommodation) after monofocal intraocular lens (IOL) implantation. SETTING: Iladevi Cataract and IOL Research Center, Ahmedabad, India. METHODS: In a case-controlled study of 30 eyes (30 patients) that had phacoemulsification, those with pseudoaccommodation were assigned to cases and 30 eyes (30 patients) without pseudoaccommodation were designated as controls. Controls were matched by identical best corrected visual acuity, age, and postoperative duration. Subjective refraction was done with retinoscopy. Factors analyzed included corneal astigmatism, pupil size, axial IOL movement, amplitude of accommodation, axial length (AL), and age. Corneal astigmatism was noted on topography and interpreted as against the rule (ATR) (180 +/- 15 degrees), with the rule (WTR) (90 +/- 15 degrees), and oblique (OB) (45/135 +/- 30 degrees). Pupil size was noted on topographic display and AL and anterior chamber depth (ACD) on immersion A-scan. The axial IOL movement was calculated as the difference in ACD after instillation of cyclopentolate 1% (Cyclopent) and subsequently pilocarpine nitrate 2% (Carpinol) at separate visits, and amplitude of accommodation was measured with static and dynamic retinoscopy. Multivariate logistic regression and odds ratio with 95% confidence intervals were determined. RESULTS: Mean spherical equivalent was -0.45 +/- 0.63 diopter (D) in cases and -0.35 +/- 0.83 D (P = .61) in controls. Multivariate logistic regression in cases versus controls: corneal astigmatism (ATR versus WTR and OB collectively): 10.19 [1.8,57.44], P = .009; pupil size: 0.45 [0.07,2.71], P = .38; axial IOL movement: 1.39 [0.51,0.77], P = .514; amplitude of accommodation: 2.95 [0.93,9.3], P = .065; AL: 0.55 [0.29,1.02], P = .058; and age: 0.98 [0.5,1.95], P = .963. CONCLUSION: The study suggests a significant role of ATR corneal astigmatism in good uncorrected distance and near vision after monofocal IOL implantation.

Accommodation, Ocular↗
PubMed2006

Correction of high myopia with the PRL phakic intraocular lens.

PURPOSE: To assess the predictability, efficacy, safety, and complications of the PRL (CIBA Vision) phakic intraocular lens (pIOL) in the correction of high myopia. SETTING: Clínica Oftalmológica Pasteur, Santiago, Chile. METHODS: This prospective study comprised 53 eyes of 39 patients who received a PRL pIOL. The spherical equivalent (SE), uncorrected visual acuity (UCVA), efficacy index (postoperative UCVA/preoperative best spectacle-corrected visual acuity [BSCVA]), safety index (BSCVA/preoperative BSCVA), intraocular pressure (IOP), iridocorneal angle, and distance between the crystalline lens and PRL were prospectively assessed during the follow-up period. RESULTS: The mean patient age was 39 years. The mean power of the implanted pIOL was -12.73 diopters (D) +/- 2.87 (SD) (range -20.00 to -7.00 D), for a preoperative SE of -17.27 +/- 4.58 D (range -31.50 to -8.75 D). The mean preoperative BSCVA was 0.50 +/- 0.70 (logMAR equivalent), and the mean follow-up was 8 +/- 9.4 months. The mean postoperative SE was -0.23 +/- 1.05 D; 71.2% of eyes were within +/-1.00 D. Sixty percent of patients had UCVA of 20/40 or better, and 88.2% of patients had BSCVA of 20/40 or better. Ninety-two percent maintained or gained 1 or more lines of BSCVA; 5.7% lost more than 1 line. There was no significant change in IOP (P = .40), and the mean distance between the crystalline lens and pIOL was 370 microm (ultrasound) and 604 microm (optical coherence tomography). Late complications included 1 case each of retinal detachment and lens subluxation. CONCLUSIONS: Although PRL implantation in high myopia was predictable and effective, retinal detachment and IOL subluxations occurred. Other posterior chamber pIOLs should be used until the complications associated with the PRL pIOL are resolved.

Accommodation, Ocular↗
PubMed2006

Magnetic resonance imaging of aging, accommodating, phakic, and pseudophakic ciliary muscle diameters.

PURPOSE: To quantify in vivo accommodative changes in the aging human ciliary muscle diameter in phakic and pseudophakic eyes. SETTING: Department of Surgery/Bioengineering, UMDNJ-Robert Wood Johnson Medical School, Piscataway, and the Institute of Ophthalmology and Visual Science UMDNJ-New Jersey Medical School, Newark, New Jersey, USA. METHODS: Images were acquired from 48 eyes of 40 people between the ages of 22 and 91 years, 1 eye of 32 phakic volunteers and both eyes of 8 patients who had monocular implantation of a single-piece AcrySof intraocular lens (IOL) (Alcon Laboratories). Images were acquired during physiological accommodation and with accommodation at rest, and the diameter of the ciliary muscle ring was measured. RESULTS: Results show the ciliary muscle remains active throughout life. The accommodative change in its diameter (mean 0.64 mm) (P<.00001) was undiminished by age or IOL implantation. Preliminary data showed that the accommodative decrease in muscle diameter in phakic and pseudophakic eyes was statistically identical. The phakic eyes had a marked decrease in ciliary muscle diameter with advancing age for both accommodative states (P<.000001 and P<.000001), which did not appear to be altered by IOL implantation. The lens equator was constant with age in the unaccommodated human eye, resulting in decreased circumlental space with advancing age in the phakic eyes. CONCLUSION: Although the undiminished ability of the ciliary muscle to decrease its diameter with accommodation can be relied on in strategies for presbyopia correction, even in advanced presbyopia, the decreasing circumlental space and its potential effects on zonular tension must also be considered.

Accommodation, Ocular↗
PubMed2006

Secondary diffractive bifocal piggyback intraocular lens implantation.

PURPOSE: To assess the efficacy and safety of implanting a bifocal diffractive intraocular lens (IOL) using the piggyback technique to provide pseudoaccommodation. SETTING: Instituto Oftalmológico Fernández-Vega, Oviedo, Spain. METHODS: This prospective noncomparative case series included 6 pseudophakic emmetropic patients who had a monofocal IOL implanted in the capsular bag. All eyes had secondary piggyback Acri. Twin bifocal diffractive IOL (Acri.Tec) implantation in the ciliary sulcus to provide pseudoaccommodation. Contralateral implantation of 1 Acri. Twin near-weighted 733D IOL in the nondominant eye and 1 Acri. Twin distance-weighted 737D IOL in the dominant eye was performed. Monocular and binocular best distance-corrected visual acuity and distance-corrected near visual acuity were evaluated 6 months after surgery. RESULTS: The mean binocular best distance-corrected visual acuity and distance-corrected near visual acuity were -0.080 +/- 0.056 logMAR and -0.016 +/- 0.037 logMAR, respectively. There were no statistically significant differences in binocular best distance-corrected acuity after the piggyback IOL implantation (P>.01). The differences between monocular and binocular visual acuity were the result of the distance- and near-weighted light distribution of the Acri. Twin IOLs. All IOLs were well centered with no tilt. Two eyes had pupillary capture of the optic. CONCLUSIONS: The Acri. Twin bifocal diffractive IOL implanted in the ciliary sulcus using the piggyback technique provided pseudoaccommodation in emmetropic pseudophakic eyes. Binocular implantation of these IOLs should be performed considering the differences in light distribution of the distance-weighted IOL and the near-weighted IOL models.

Accommodation, Ocular↗
PubMed2007

Synchrony dual-optic accommodating intraocular lens. Part 2: pilot clinical evaluation.

PURPOSE: To evaluate the clinical outcomes of an accommodating dual-optic intraocular lens (IOL). SETTING: Private practice and university centers. METHODS: A prospective noncomparative case series with retrospective control comprised 21 patients (26 eyes) scheduled for small-incision extracapsular cataract extraction by phacoemulsification with implantation of the Synchrony dual-optic accommodating IOL (Visiogen) (accommodating IOL group) and 10 patients who had small-incision extracapsular phacoemulsification with implantation of a monofocal, single-optic IOL at least 6 months previously (control group). Patients were examined 1, 3, 6, and 12 months after surgery. Defocus curves in the accommodating IOL group were compared with those in the control group. The main outcome measures were postoperative distance uncorrected and best corrected visual acuity; near uncorrected, distance corrected, and near corrected visual acuity; and accommodative range based on defocus curves. RESULTS: Twenty-four eyes were available at the 6-month follow-up visit. All eyes had best corrected distance visual acuity of 20/40 or better, and 19 eyes (79%) had an uncorrected distance visual acuity of 20/40 or better. Uncorrected near visual acuity was 20/40 or better in all eyes. With distance correction, 23 eyes (96%) had an acuity of 20/40 or better at near. Defocus curve analysis suggested a mean accommodative range of 3.22 diopters (D) +/- 0.88 (SD) (range 1.00 to 5.00 D) in the accommodating IOL group and 1.65 +/- 0.58 D in the control group (range 1.00 to 2.50 D) (P<.05). CONCLUSION: The Synchrony dual-optic IOL shows promise as an option to provide accommodative function in pseudophakic patients.

Accommodation, Ocular↗
PubMed2007

Synchrony dual-optic accommodating intraocular lens. Part 1: optical and biomechanical principles and design considerations.

PURPOSE: To describe a dual-optic accommodating intraocular lens (IOL) based on theoretical considerations. SETTING: University and independent research group. METHODS: Ray-tracing analysis using optical modeling software (ZEMAXTM, Focus Software Inc., Tucson, Ariz) in a theoretical model eye was used to analyze lens configurations to optimize the accommodative and magnification effects of axial lens displacement. Finite-element modelling using a commercially available PC-based software package (COSMOS DesignSTAR) was applied to design the biomechanical parameters of the inter-optic articulations and optics. RESULTS: Ray-tracing analysis indicated that a dual-optic design with a high plus-powered front optic coupled to a minus posterior optic produced greater change in conjugation power of the eye compared to a single-optic intraocular lens and that magnification effects were unlikely to account for improved near vision. Finite-element modelling indicated that the 2 optics can be linked by spring-loaded haptics that allow anterior and posterior axial displacement of the front optic in response to changes in ciliary body tone and capsular tension. CONCLUSION: A dual-optic design linked by spring haptics increases the accommodative effect of axial optic displacement with minimal magnification effect and has promise for improving the performance of accommodative intraocular lenses.

Accommodation, Ocular↗
PubMed2006

Age-related changes of vergence under natural viewing conditions.

Vergence eye movements were recorded with the scleral search-coil system in 32 healthy subjects (ages 19-73 years) to characterize the age-related effects on the dynamic parameters of vergence responses to step (transient components) and ramp or sinusoidal targets (sustained components) under natural viewing conditions. Transient vergence showed an age-related increase in latency and decreases in peak velocity and acceleration in the binocular stimulus condition but not in accommodative vergence. Sustained vergence showed no age-related effect in the binocular condition, but there was an age-related decrease in accommodative vergence steady-state velocity and an increase in latency. Age-related changes of the transient and sustained components were very similar to those reported for saccades and smooth pursuit; they thus might support a distinction between a sustained and transient vergence system. Furthermore, such age-related effects have to be taken into account when assessing eye movement disorders in neurodegenerative and cerebrovascular diseases.

Accommodation, Ocular↗
PubMed2006

Multifocal intraocular lenses.

This article reviews clinical and optical data for three unique lens designs: the ReSTOR diffractive intraocular lens (IOL), the Vision Membrane, and the ReZOOM refractive multifocal IOL.

Accommodation, Ocular↗
PubMed2006

Accommodation: mechanism and measurement.

A clear understanding of the anatomy of accommodative structures, the mechanism of accommodation, and the causes of presbyopia is necessary to understand whether accommodation may be restored to the presbyopic eye. Not withstanding the significant challenges that are faced owing to age-related changes in the eye, theoretically, it may be possible to restore accommodation to a presbyopic eye with an artificial accommodative intraocular lens.

Accommodation, Ocular↗
PubMed2006

The NuLens accommodating intraocular lens.

The NuLens intraocular lens (IOL) uses a new optomechanical concept to generate a wide range of dioptric power from minimal movements of the ciliary apparatus during accommodative effort. Basic study of the concept of optomechanics in the primate eye led to successful construction and implantation of functioning IOL prototypes.

Accommodation, Ocular↗
PubMed2006

Single optic accommodative intraocular lenses.

Currently, two single optic accommodative intraocular lenses are available for implantation. Both designs rely on the interaction of the ciliary muscle with the zonule and capsule to induce axial movement of the optic. This article reviews the historical development, laboratory data, and clinical findings relating to these interesting devices.

Accommodation, Ocular↗
PubMed2006

A light adjustable lens with injectable optics.

The light adjustable lens (LAL) is an innovative intraocular lens optic composed of partially polymerized macromers with an appropriately bonded photosensitizer. The injectable technology and multifocality associated with the LAL can produce precise refractive correction and, it is hoped, the type of accommodative range that is taken for granted during youth. Combining these technologies with a lens material that behaves like the crystalline lens of 25-year-old could precisely return near and distance vision to older adults.

Accommodation, Ocular↗
PubMed2006

Sarfarazi dual optic accommodative intraocular lens.

The Sarfarazi accommodative intraocular lens, currently in clinical studies, is a single continuous silicon accommodative lens with dual optics and three haptics that mimic the action of the natural lens by using the contraction and relaxation of ciliary muscles. The lenses have been implanted in the eyes of patients. There have been no surgical or patient complications related to the lens, and its safety has been clearly demonstrated. Patient acceptance of the lens is excellent. Clinical enrollment will continue to expand.

Accommodation, Ocular↗
PubMed2006

Keratorefractive approaches to achieving pseudoaccommodation.

Although presbyopia is ostensibly an age-related disease of the lens, ciliary body, and zonular apparatus, surgeons have nonetheless persevered in their attempts to create a solution to the problem of diminished near vision by performing keratorefractive procedures. This article discusses two approaches of varying technological sophistication, beginning with surgically induced astigmatism and continuing through enhanced monovision. Sometimes simple solutions are the best, and the technological innovation in cataract and refractive surgery has met with unrivalled success in the last three decades.

Accommodation, Ocular↗