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Durkee H, Ruggeri M, Rohman L, Williams S, Ho A, Parel JM, Manns F. Dynamic refraction and anterior segment OCT biometry during accommodation. BIOMEDICAL OPTICS EXPRESS 2024; 15:2876-2889. [PMID: 38855690 PMCID: PMC11161352 DOI: 10.1364/boe.512193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 03/26/2024] [Accepted: 03/27/2024] [Indexed: 06/11/2024]
Abstract
Accommodation is the process by which the eye changes focus. These changes are the result of changes to the shape of the crystalline lens. Few prior studies have quantified the relation between lens shape and ocular accommodation, primarily at discrete static accommodation states. We present an instrument that enables measurements of the relation between changes in lens shape and changes in optical power continuously during accommodation. The system combines an autorefractor to measure ocular power, a visual fixation target to stimulate accommodation, and an optical coherence tomography (OCT) system to image the anterior segment and measure ocular distances. Measurements of ocular dimensions and refraction acquired dynamically on three human subjects are presented. The individual accommodative responses are analyzed to correlate the ocular power changes with changes in ocular dimensions.
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Affiliation(s)
- Heather Durkee
- Ophthalmic Biophysics Center, Department of
Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10 Ave, Miami, Florida 33136, USA
- Department of Biomedical Engineering, University of Miami College of Engineering, 1251 Memorial Drive, Coral Gables, Florida 33146, USA
| | - Marco Ruggeri
- Ophthalmic Biophysics Center, Department of
Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10 Ave, Miami, Florida 33136, USA
- Department of Biomedical Engineering, University of Miami College of Engineering, 1251 Memorial Drive, Coral Gables, Florida 33146, USA
| | - Leana Rohman
- Ophthalmic Biophysics Center, Department of
Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10 Ave, Miami, Florida 33136, USA
- Department of Biomedical Engineering, University of Miami College of Engineering, 1251 Memorial Drive, Coral Gables, Florida 33146, USA
| | - Siobhan Williams
- Ophthalmic Biophysics Center, Department of
Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10 Ave, Miami, Florida 33136, USA
- Department of Biomedical Engineering, University of Miami College of Engineering, 1251 Memorial Drive, Coral Gables, Florida 33146, USA
| | - Arthur Ho
- Ophthalmic Biophysics Center, Department of
Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10 Ave, Miami, Florida 33136, USA
- Department of Biomedical Engineering, University of Miami College of Engineering, 1251 Memorial Drive, Coral Gables, Florida 33146, USA
- Brien Holden Vision Institute Limited, Sydney, NSW, Australia
- School of Optometry and Vision Science, University of New South Wales, NSW 2052, Sydney, Australia
| | - Jean-Marie Parel
- Ophthalmic Biophysics Center, Department of
Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10 Ave, Miami, Florida 33136, USA
- Department of Biomedical Engineering, University of Miami College of Engineering, 1251 Memorial Drive, Coral Gables, Florida 33146, USA
- Brien Holden Vision Institute Limited, Sydney, NSW, Australia
| | - Fabrice Manns
- Ophthalmic Biophysics Center, Department of
Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, 1638 NW 10 Ave, Miami, Florida 33136, USA
- Department of Biomedical Engineering, University of Miami College of Engineering, 1251 Memorial Drive, Coral Gables, Florida 33146, USA
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Sheppard AL, Bashir A, Wolffsohn JS, Davies LN. Accommodating intraocular lenses: a review of design concepts, usage and assessment methods. Clin Exp Optom 2021; 93:441-52. [DOI: 10.1111/j.1444-0938.2010.00532.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
| | - Abar Bashir
- Aston University, Birmingham, United Kingdom
E‐mail:
| | | | - Leon N Davies
- Aston University, Birmingham, United Kingdom
E‐mail:
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Martin H, Guthoff R, Schmitz KP. The influence of injection volume and capsular bag contraction on the refractive power of polymer refilled lenses - a finite element modelling simulation study. Acta Ophthalmol 2011; 89:579-84. [PMID: 20064123 DOI: 10.1111/j.1755-3768.2009.01709.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE Polymer injection into the capsular bag after phakoemulsification is an interesting and promising approach to lens surgery. Safe clinical application of this technique will require an appropriate estimate of the effect of implantation variables on the lens power. This article details the results of finite element investigations into the effects of the injected polymer volume and capsular bag contraction on the resultant lens power and accommodation amplitude. METHODS An axisymmetric finite element model was created from literature sources. Polymer injection and the capsular contraction were simulated, and their effect on the lens power was calculated. RESULTS AND CONCLUSION The simulations show that overfilling during polymer injection leads to a refractive power increase of the lens. Capsular bag contraction also results in a power increase. The calculated accommodative amplitude of the lens is minimally affected by capsular bag contraction but decreases significantly with increased capsular bag stiffness as a result of fibrosis.
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Affiliation(s)
- Heiner Martin
- Institute for Biomedical Engineering, University of Rostock, Rostock, Germany.
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Bharadwaj SR, Wang J, Candy TR. Pupil responses to near visual demand during human visual development. J Vis 2011; 11:6. [PMID: 21482712 DOI: 10.1167/11.4.6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Pupil responses of adults to near visual demands are well characterized but those of typically developing infants and children are not. This study determined the following pupil characteristics of infants, children and adults using a PowerRefractor (25 Hz): i) binocular and monocular responses to a cartoon movie that ramped between 80 and 33 cm (20 infants, 20 2-4-yr-olds and 20 adults participated) ii) binocular and monocular response threshold for 0.1 Hz sinusoidal stimuli of 0.25 D, 0.5 D or 0.75 D amplitude (33 infants and 8 adults participated) iii) steady-state stability of pupil responses at 80 cms (8 infants and 8 adults participated). The change in pupil diameter with viewing distance (Δpd) was significantly smaller in infants and 2-4-yr-olds than in adults (p < 0.001) and significantly smaller under monocular than binocular conditions (p<0.001). The 0.75 D sinusoidal stimulus elicited a significant binocular pupillary response in infants and a significant binocular and monocular pupillary response in adults. Steady-state pupillary fluctuations were similar in infants and adults (p = 0.25). The results suggest that the contribution of pupil size to changes in retinal image quality when tracking slow moving objects may be smaller during development than in adulthood. Smaller monocular Δpd reflects the importance of binocular cues in driving near-pupillary responses.
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Affiliation(s)
- Shrikant R Bharadwaj
- Hyderabad Eye Research Foundation, Bausch and Lomb School of Optometry, L V Prasad Eye Institute, Hyderabad, Andhra Pradesh, India.
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Pedrigi RM, Humphrey JD. Computational model of evolving lens capsule biomechanics following cataract-like surgery. Ann Biomed Eng 2010; 39:537-48. [PMID: 20665113 DOI: 10.1007/s10439-010-0133-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 07/14/2010] [Indexed: 10/19/2022]
Abstract
Cataract surgery is an invasive procedure whereby lens fibers are removed through a permanent central hole, or capsulorhexis, in the surrounding lens capsule and replaced with an artificial intraocular lens (IOL). Remnant lens epithelial cells subsequently transdifferentiate to a more contractile and synthetic wound-healing phenotype, which causes significant structural and mechanical adaptations of the residual lens capsule. The goal of this study is to present a computational model capable of capturing salient features of the biomechanical evolution of the lens capsule following cataract-like surgery. The model is shown to predict marked long-term increases in thickness and stiffness of the lens capsule nearest the edge of the capsulorhexis comparable to reported measurements. Such models represent a first step toward understanding better the long-term interactions between the residual lens capsule and implanted IOL, thus initiating a new paradigm for the design of improved IOLs, including those having an accommodative feature.
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Affiliation(s)
- R M Pedrigi
- Department of Bioengineering, Royal School of Mines, Imperial College London, London, SW7 2AZ, UK.
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Candy TR, Bharadwaj SR. The stability of steady state accommodation in human infants. J Vis 2007; 7:4.1-16. [PMID: 17997659 DOI: 10.1167/7.11.4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Accepted: 06/01/2007] [Indexed: 11/24/2022] Open
Abstract
Retinal image quality in infants is largely determined by the accuracy and the stability of their accommodative responses. Although the accuracy of infants' accommodation has been investigated previously, little is known about the stability of their responses. We performed two experiments that characterized the stability of infants' steady state accommodation. Analyses were performed in the time domain (root mean square [RMS] deviation) and in the frequency domain (spectral analysis). In Experiment 1, accommodation responses were recorded for a period of 3 s from the left eye of four groups of infants (8-10, 11-13, 14-19, and 20-30 weeks of age) and eight prepresbyopic adults while they focused on a small toy placed at a dioptric viewing distance of 1.0 D (at 1 m). In Experiment 2, accommodation responses were recorded for a period of 14 s from the left eye of a group of 8- to 12-week-old infants and six prepresbyopic adults while they focused on a cartoon image placed at three different dioptric viewing distances (1.25, 2.0, and 3.0 D). The data, collected using a photorefractor sampling at 25 Hz, showed two important characteristics. First, the RMS deviations and the power were quantitatively similar across different infant age groups, and they were significantly larger in infants than in adults. Second, the overall and relative power also increased with the dioptric viewing distance both in infants and adults. At all three dioptric viewing distances, the measures of power were larger in infants than in adults. These data demonstrate that infants' accommodative responses contain instabilities that are qualitatively very similar to those observed in adults. However, the larger RMS deviations suggest that infants are likely to experience larger fluctuations in retinal image quality than adults.
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Affiliation(s)
- T Rowan Candy
- Indiana University School of Optometry, Bloomington, IN 47405, USA.
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