scholarly journals Real and Pseudoaccommodation in Accommodative Lenses

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Ioannis G. Pallikaris ◽  
Georgios A. Kontadakis ◽  
Dimitra M. Portaliou
Keyword(s):  
Ray Tracing ◽  
Ultrasound Imaging ◽  
Intraocular Lens ◽  
Refractive Error ◽  
Pupil Size ◽  
Crystalline Lens ◽  
Complex Phenomenon ◽  
Near Vision ◽  
Pharmacological Stimulation ◽  
Visual Results

In the attempt to manage presbyopia, different intraocular lens designs have been proposed such as monofocal IOLs with monovision or multifocal IOLs. Even though the lenses mentioned offer satisfactory visual results, contemporary ophthalmology has not completely answered the presbyopic dilemma by simulating the accommodative properties of the crystalline lens itself. Accommodative IOLs were designed to fill this gap and provide satisfactory vision for all distances by restoring some degree of “pseudoaccommodation.” Pseudo accommodative capability can be linked to monofocal IOL’s as well but the results are not satisfactory enough to fully support unaided near vision. Pseudoaccommodation is a complex phenomenon that can be attributed to several static (i.e., pupil size, against-the-rule cylindrical refractive error, multifocality of the cornea) and dynamic (i.e., anterior movement of the implant itself) factors. Objective measurement of the accommodative capability offered by the accommodative IOLs is extremely difficult to obtain, and different methods such as autorefractometers, retinoscopy, and ultrasound imaging during accommodative effort, ray tracing, or pharmacological stimulation have been developed but the results are sometimes inconsistent. Despite the difficulties in measuring accommodation, accommodative IOLs represent the future in the attempt to successfully “cure” presbyopia.

scholarly journals The simply modified intrascleral fixation using round flange (SMURF) technique for intrascleral intraocular lens fixation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Soa Kim ◽  
Jee Taek Kim
Keyword(s):  
Intraocular Lens ◽  
Invasive Procedure ◽  
Crystalline Lens ◽  
Early Postoperative Period ◽  
Cystoid Macular Oedema ◽  
Modified Technique ◽  
Intraocular Pressure Elevation ◽  
Wound Leakage ◽  
Iol Dislocation

AbstractWe describe a simply modified intrascleral fixation using round flange (SMURF) technique and report the clinical outcomes of the surgery. Forty-one eyes of 41 consecutive patients, with intraocular lens (IOL) dislocation, crystalline lens subluxation, and zonular weakness, who underwent surgery using the SMURF technique were included. The modified technique included the use of a conventional 27-gauge needle, a non-bent needle, oblique sclerotomy, direct threading of the leading haptic, and simple placement of the following haptic. IOLs were successfully placed and showed good centring. There were no cases of wound leakage or hypotony during the early postoperative period. Postoperative complications included vitreous haemorrhage in one eye (2.4%), intraocular pressure elevation in one eye (2.4%), and iris capture in six eyes (14.6%). There were no cases of postoperative retinal detachment, cystoid macular oedema, endophthalmitis, or IOL dislocation during the follow-up period. We proposed a few modifications in the intrascleral flanged technique for IOL fixation. The modified technique is a simple, easy, and minimally invasive procedure for successful IOL intrascleral fixation.

Anterior Movement of the Crystalline Lens in the Process of Accommodation in Children

2007 ◽  
Vol 17 (4) ◽  
pp. 515-520 ◽  
Author(s):  
B.J. Kaluzny
Keyword(s):  
Refractive Error ◽  
Axial Length ◽  
Crystalline Lens ◽  
Posterior Pole ◽  
Anterior Pole ◽  
Forward Movement ◽  
Ophthalmic Examination ◽  
Lens Thickness ◽  
Lens Position ◽  
Refractive Status

Purpose To investigate changes of crystalline lens position during accommodation in children with emmetropia, myopia, and hyperopia. Methods A total of 188 children (372 eyes) from 4 to 19 years old (mean age 11.3±4.43) with cycloplegic refractive error within a range +9.00 D to −9.00 D were enrolled. After a general ophthalmic examination, ultrasound biometry was performed, with the eye at a maximal accommodative effort. Cycloplegia was induced by triple installation of 1% tropicamide drops and 30 minutes later the biometric examination was repeated. Results In emmetropic eyes in the process of accommodation, the anterior pole of the crystalline lens moved forward by 0.144±0.14 mm (p ≤ 0.001); the position of the posterior pole did not change. In myopic eyes, the anterior pole moved forward by 0.071±0.13 mm (p≤0.001) and the posterior pole moved backward by 0.039±0.10 mm (p=0.003). In hyperopic eyes, the whole lens translocated anteriorly: anterior pole moved forward by 0.242±0.16 mm (p≤ 0.001) and posterior pole moved forward by 0.036±0.09 mm (p≤0.001). Differences among emmetropia, myopia, and hyperopia were statistically significant. Forward movement of the posterior pole correlated with a low axial length of the eye, and also with plus refractive error and with a smaller accommodative increase of lens thickness. Conclusions In children, accommodative changes of the crystalline lens position depend on refractive status.

scholarly journals Pupil dynamics after in-the-bag versus anterior and retropupillary iris-fixated intraocular lens implantation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yanxiu Sun ◽  
Maximilian Hammer ◽  
Timur M. Yildirim ◽  
Ramin Khoramnia ◽  
Gerd U. Auffarth
Keyword(s):  
Intraocular Lens ◽  
Pupil Size ◽  
Surgical Techniques ◽  
Case Series ◽  
Case Series Study ◽  
Pupil Motility ◽  
Series Study ◽  
Iol Fixation ◽  
Iol Dislocation ◽  
Iris Claw

AbstractAn Intraocular Lens (IOL) fixated on the iris either anteriorly, as a phakic IOL, or posteriorly, as an aphakic IOL, can influence pupil motility. In this interventional case series study, we evaluated pupil size under different levels of illumination (scotopic = 0.04 lx, low-mesopic = 0.4 lx and high-mesopic = 4 lx) for anterior iris-claw IOL fixation for correcting myopia or hyperopia (IFPH), retropupillary iris-claw IOL fixation to correct aphakia or as treatment for late in-the-bag IOL dislocation/subluxation (IFRP), and capsular-fixation IOL in-the-bag implantation (IB). Pupil size was measured preoperatively for the IFPH- and IB-group as well as 6 months after surgery for all groups. We analyzed a total of 70 eyes: 22 eyes of 11 patients with phakic IOLs, 22 eyes of 20 patients in the IFRP group and 26 eyes of 13 patients in the IB group. Both IFPH and IB showed a smaller postoperative scotopic pupil size, compared with the preoperative values. When compared to postoperative values of IB and IFPH, IFRP showed a significantly smaller postoperative scotopic pupil size (IFPH: 5.89 ± 0.83 mm, IFRP: 4.37 ± 0.83 mm, IB: 5.34 ± 0.98 mm, p < 0.001) while no differences were seen at high-mesopic lighting. Neither of the surgical techniques seems to impair the constriction of the pupil.

scholarly journals Post Cataract Surgery Refractive Error in Myopic Patients Using SRK/T Versus Holladay 1 Formula for IOL Power Calculation

2019 ◽  
Vol 34 (2) ◽  
Author(s):  
Sidra Anwar, Atif Mansoor Ahmad, Irum Abbas, Zyeima Arif
Keyword(s):  
Intraocular Lens ◽  
Refractive Error ◽  
Axial Length ◽  
Power Calculation ◽  
Mean Error ◽  
Iol Power Calculation ◽  
Group A ◽  
Iol Power ◽  
The Mean ◽  
Group B

Purpose: To compare post-operative mean refractive error with SandersRetzlaff-Kraff/theoretical (SRK-T) and Holladay 1 formulae for intraocular lens (IOL) power calculation in cataract patients with longer axial lengths. Study Design: Randomized controlled trial. Place and Duration of Study: Department of Ophthalmology, Shaikh Zayed Hospital Lahore from 01 January 2017 01 January, 2018. Material and Methods: A total of 80 patients were selected from Ophthalmology Outdoor of Shaikh Zayed Hospital Lahore. The patients were randomly divided into two groups of 40 each by lottery method. IOL power calculation was done in group A using SRK-T formula and in group B using Holladay1 formula after keratomery and A-scan. All patients underwent phacoemulsification with foldable lens implantation. Post-operative refractive error was measured after one month and mean error was calculated and compared between the two groups. Results: Eighty cases were included in the study with a mean age of 55.8 ± 6.2 years. The mean axial length was 25.63 ± 0.78mm, and the mean keratometric power was 43.68 ± 1.1 D. The mean post-operative refractive error in group A (SRK/T) was +0.36D ± 0.33D and in group B (Holladay 1) it was +0.68 ± 0.43. The Mean Error in group A was +0.37D ± 0.31D as compared to +0.69D ± 0.44D in group B. Conclusion: SRK/T formula is superior to Holladay 1 formula for cases having longer axial lengths. Key words: Phacoemulsification, intraocular lens power, longer axial length, biometry.

Stability and visual outcomes yielded by three intraocular trifocal lenses with same optical zone design but differing material or toricity

2018 ◽  
Vol 29 (4) ◽  
pp. 417-425 ◽  
Author(s):  
Francisco Poyales ◽  
Nuria Garzón ◽  
Daniel Pizarro ◽  
Santiago Cobreces ◽  
Adolfo Hernández
Keyword(s):  
Intraocular Lens ◽  
Intraocular Lenses ◽  
Rotational Stability ◽  
Slit Lamp ◽  
Spherical Lens ◽  
Visual Outcomes ◽  
Loop Design ◽  
Optical Zone ◽  
Processing Techniques ◽  
Visual Results

Purpose: To compare rotational stability, centration and visual outcomes provided by three trifocal lens models that have the same optical zone design but different material, composition, and/or toricity. Methods: The study included 78 patients with symmetric bilateral intraocular lens implantation. The lenses under evaluation were trifocal intraocular lenses made of hydrophilic acrylic material: a spherical lens 26% hydrophilic acrylic (POD FineVision), a similar lens but having a toric design (POD Toric FineVision), and a trifocal lens 25% hydrophilic acrylic material (FineVision/MicroF). Moreover, the lenses share the same optical zone design. The lenses’ rotational stability and centration were measured by means of the PIOLET software, which relies on recording and image processing techniques to determine lens rotation and centration based on slit-lamp images. We also assessed patients’ visual quality by means of 25, 40, and 80 cm VA tests. Results: The best centration results were achieved with the POD Toric FineVision model, although the differences were not statistically significant. As for lens rotation, it was below 5° in all cases under study. Regarding VA, all subjects attained at least 0.3 logMAR for far distance uncorrected VA, at 80 cm VA was about 0.2 logMAR, at 40 cm it was above 0.15 logMAR, and at 25 cm it was about 0.3 logMAR for both lens types. Conclusion: All three intraocular lens models yield excellent visual results at far, near as well as intermediate distances. The POD FineVision and POD Toric FineVision models, with double C-loop design, yielded the best results centration-wise and rotation-wise. Differences had no clinical relevance.

scholarly journals Clinical outcomes with a diffractive trifocal intraocular lens

2018 ◽  
Vol 28 (4) ◽  
pp. 419-424 ◽  
Author(s):  
Jorge L Alió ◽  
Ana B Plaza-Puche ◽  
Jorge L Alió del Barrio ◽  
Pedro Amat-Peral ◽  
Vicente Ortuño ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Contrast Sensitivity ◽  
Intraocular Lens ◽  
Case Series ◽  
Optical Quality ◽  
Near Vision ◽  
Case Series Study ◽  
Defocus Curve ◽  
Near Visual Acuity

Purpose: To evaluate clinical and visual outcomes, quality of near vision, and intraocular optical quality of patients bilaterally implanted with a trifocal PanOptix intraocular lens. Methods: In this prospective consecutive case-series study, 52 eyes of 26 bilateral patients (mean age, 60.2 ± 7.4 years) were implanted with the AcrySof IQ Panoptix intraocular lens. Visual acuity, defocus curve, contrast sensitivity (Pelli-Robson test), near activity visual questionnaire, and internal aberrations with Osiris were evaluated. A prototype light-distortion analyzer was used to quantify the postoperative light-distortion indices. The follow-up was 6 months after surgery. Results: Uncorrected, corrected distance, and uncorrected near visual acuities improved with the surgery (p ≤ 0.02). Distance corrected near visual acuity was 0.13 ± 0.10, 0.13 ± 0.13, and 0.13 ± 0.08 at 1, 3, and 6 months after surgery, respectively (p = 0.82). Distance corrected intermediate visual acuities were 0.09 ± 0.13, 0.13 ± 0.15, and 0.12 ± 0.12 at 1, 3, and 6 months, postoperatively. Binocular contrast sensitivity was 1.86 ± 0.15 Log Units. Defocus curve provided a visual acuity equal or better to 0.30 LogMAR between defocus levels of +0.50 to −3.00 D. The near activity visual questionnaire scores improved significantly with the surgery (p < 0.01). Conclusion: The AcrySof IQ Panoptix intraocular lens is able to restore visual function with an acceptable intermediate and near vision after cataract surgery with good contrast sensitivity and an improvement in the near activity visual questionnaire.

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