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Zhang G, Jiang J, Wei Q, Qu C. Effects of accommodation on geometrical parameters of human lens: A systematic review and meta-analysis. Heliyon 2024; 10:e29298. [PMID: 38681553 PMCID: PMC11053204 DOI: 10.1016/j.heliyon.2024.e29298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 03/29/2024] [Accepted: 04/04/2024] [Indexed: 05/01/2024] Open
Abstract
Purpose To investigate the effects of accommodation on the geometrical parameters of human lens. Methods Eight databases from inception to November 2023 were used for the literature search: CNKI, CBM, VIP, Wan-Fang, PubMed, Web of Science, EMBASE, and the Cochrane Library. The Methodological Index for Non-randomized Studies was used to assess the risk of bias. The PRISMA were followed and the following outcomes were taken into consideration: lens diameter (LD), lens thickness (LT), anterior curvature radius (ACR), posterior curvature radius (PCR), lens center position (LCP), and total cross-sectional area (TCSA). This systematic review was registered on an international platform for registered systematic reviews and meta-analysis (INPLASY202260085). Results A total of 19 studies were included. LT increased by 0.04 mm/D (18 studies; 95% confidence interval [CI], 0.03-0.06; I2 = 96.6%; P < 0.001). At the same time, LD, ACR, and PCR decreased by 0.06 mm/D (6 studies; 95%CI, -0.07-0.05; I2 = 50.1%; P < 0.001), 0.53 mm/D (8 studies; 95%CI, -0.64-0.41; I2 = 96.5%; P < 0.001), and 0.14 mm/D (9 studies; 95%CI, -0.19-0.09; I2 = 94.7%; P < 0.001) during accommodation, respectively. Moreover, LCP shifted forward by 0.01 mm/D (3 studies; 95%CI, -0.02-0.00; I2 = 0.0%; P < 0.001), and TCSA by 0.58 mm2/D (2 studies; 95%CI, 0.41-1.57; I2 = 97.0%; P = 0.457) during accommodation. Conclusions Changes in LT, LD, ACR, PCR and LCP supported Helmholtz's theory. Different apparatuses or measurement methods influenced the measurement of lens geometrical parameters.
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Affiliation(s)
- Guanghong Zhang
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- School of Medicine, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- Sichuan Key Laboratory for Disease Gene Study, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, No. 32 of the West 2nd Section of First Ring Road, Chengdu 610072, China
| | - Jun Jiang
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- School of Medicine, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- Sichuan Key Laboratory for Disease Gene Study, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, No. 32 of the West 2nd Section of First Ring Road, Chengdu 610072, China
| | - Qian Wei
- Southwest Medical University, No. 319, Section 3, Zhongshan Road, Luzhou 646000, China
| | - Chao Qu
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- School of Medicine, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN 611731, China
- Sichuan Key Laboratory for Disease Gene Study, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, No. 32 of the West 2nd Section of First Ring Road, Chengdu 610072, China
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Zhang G, Wei Q, Lu L, Lin AL, Qu C. The evolution of mechanism of accommodation and a novel hypothesis. Graefes Arch Clin Exp Ophthalmol 2023; 261:3083-3095. [PMID: 37103620 DOI: 10.1007/s00417-023-06045-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 01/06/2023] [Accepted: 03/24/2023] [Indexed: 04/28/2023] Open
Abstract
Myopia and presbyopia are two major optometry problems facing the whole society. The mechanism of accommodation is strongly related to the treatments of myopia and presbyopia. However, the key mechanism of accommodation has puzzled us for over 400 years and is still not clear at present, leading to the stagnation of prevention and treatment of myopia and presbyopia. With the continued development of experimental technologies and equipment, the approaches to elucidate accommodation's intricacies have become more methodological and sophisticated. Fortunately, some significant progress has been made. This article is to review the evolution of the mechanism of accommodation. Helmholtz proposed a classical theory of "zonules relax during accommodation." In contrast, Schachar put forward a theory of "zonules taut during accommodation." Those hypotheses are relatively complete, but either do not fully explain everything about the accommodation mechanism or lack sufficient experimental and clinical evidence to support them. Then, some contentious issues are discussed in detail to find the truth. Finally, we proposed our hypothesis about accommodation based on the anatomy of the accommodative apparatus.
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Affiliation(s)
- Guanghong Zhang
- School of Medicine, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN611731, China
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN611731, China
- Sichuan Key Laboratory for Disease Gene Study, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, No. 32 of the West 2nd Section of First Ring Road, Chengdu, 610072, China
| | - Qian Wei
- Southwest Medical University, No. 319, Section 3, Zhongshan Road, Luzhou, 646000, China
| | - Lei Lu
- School and Hospital of Stomatology, Wenzhou Medical University, Xueyuan West Road, Wenzhou, Zhejiang, 325027, China.
| | - Andy L Lin
- Department of Internal Medicine, UC Irvine Medical Center, 333 City Blvd. West, Suite 400, Orange, CA, 92868-3298, USA.
| | - Chao Qu
- School of Medicine, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN611731, China.
- Department of Ophthalmology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, No. 2006, Xiyuan Ave West Hi-Tech Zone, Chengdu, CN611731, China.
- Sichuan Key Laboratory for Disease Gene Study, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, No. 32 of the West 2nd Section of First Ring Road, Chengdu, 610072, China.
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Ting DSJ, Liu YC, Price ER, Swartz TS, Lwin NC, Hipsley A, Mehta JS. Improvement in Accommodation and Dynamic Range of Focus After Laser Scleral Microporation: A Potential Treatment for Presbyopia. Transl Vis Sci Technol 2022; 11:2. [DOI: 10.1167/tvst.11.12.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Affiliation(s)
- Darren S. J. Ting
- Academic Ophthalmology, School of Medicine, University of Nottingham, Nottingham, UK
- Department of Ophthalmology, Queen's Medical Centre, Nottingham, UK
- Singapore Eye Research Institute, Singapore
| | - Yu-Chi Liu
- Singapore Eye Research Institute, Singapore
- Singapore National Eye Centre, Singapore
- Duke–NUS Graduate Medical School, Singapore
| | | | | | | | | | - Jodhbir S. Mehta
- Singapore Eye Research Institute, Singapore
- Singapore National Eye Centre, Singapore
- Duke–NUS Graduate Medical School, Singapore
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Kyei S, Abowine JBV, Zaabaar E, Boadi-Kusi SB, Assiamah F, Abdul-Kabir M, Asiedu K. Age- and sex-related differences in the measures of anterior segment parameters in a myopic clinical sample using Pentacam Scheimpflug tomography. Int Ophthalmol 2022; 42:1573-1580. [PMID: 35083596 DOI: 10.1007/s10792-021-02192-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 12/17/2021] [Indexed: 10/19/2022]
Abstract
PURPOSE To assess age-and sex-related differences of anterior segment parameters in a myopic clinical sample. METHODS This clinic-based retrospective study involved eligible subjects grouped into myopia (i.e., low-to-moderate) and high myopia. Demographics and anterior segment parameters measures were recorded and analyzed. RESULTS Some 153 eligible eyes were analyzed-98 myopia and 55 high myopia-comprising 87 males and 66 females. The mean ages and ranges were 28.47 years (SD = 9.59 years), 8-50 years, and 27.82 years (SD = 9.69 years), 10-51 years, for the myopia and the high myopia groups, respectively. The means of the spherical equivalents were - 3.02 D (SD = 1.46 D, range: - 0.50 to - 5.85 D), for the myopia group and - 10.42 D (SD = 5.50 D, range: - 6.00 to - 21.86 D) for the high myopia group. No significant difference was found between degree of myopia and anterior segment measures. Males had larger anterior chamber volume (mean 175.71 ± 26.27, range: 124-225 mm3); (P = 0.007) and deeper anterior chamber depth (3.73 ± 0.27, range: 3.06-4.41 mm) (P = 0.017) than females in the myopia group. Females also had significantly steeper anterior corneal curvature, Km (ant.) but flatter posterior corneal curvature, Km (post.), (- 6.31 ± 0.25, range - 7.00 to - 5.90 D) in both the myopia group [Km (ant.): 44.06 D ± 1.33 D, range: 41.30-47.10; Km (post.): - 6.31 D ± 0.25 D, range: - 7.00 to - 5.90; P = 0.008, P = 0.002, respectively] and the high myopia group [Km (ant.): 43.79 D ± 0.33 D, range: 41.00-47.10; Km (post.): - 6.22 D ± 0.30 D, range: - 6.80 to - 5.60; P = 0.034, P = 0.049, respectively]. Age was not correlated with the anterior segment parameters in both degrees of myopia. CONCLUSION Sex has significant influence on the corneal curvature, anterior chamber volume and anterior chamber depth regardless of the degree of myopia.
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Affiliation(s)
- Samuel Kyei
- Department of Optometry and Vision Science, School of Allied Health Sciences, College of Health and Allied Sciences, University of Cape Coast, PMB, Cape Coast, Ghana.
| | | | - Ebenezer Zaabaar
- Department of Optometry and Vision Science, School of Allied Health Sciences, College of Health and Allied Sciences, University of Cape Coast, PMB, Cape Coast, Ghana
| | - Samuel Bert Boadi-Kusi
- Department of Optometry and Vision Science, School of Allied Health Sciences, College of Health and Allied Sciences, University of Cape Coast, PMB, Cape Coast, Ghana
| | - Frank Assiamah
- Eye Department, Korle-Bu Teaching Hospital, Accra, Ghana
| | - Mohammed Abdul-Kabir
- Department of Optometry and Visual Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Kofi Asiedu
- School of Optometry and Vision Science, Faculty of Medicine and Health, University of New South Wales, Sydney, Australia
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Choi KE, Anh VTQ, Yun C, Kim YJ, Jung H, Eom H, Shin D, Kim SW. Normative Data of Ocular Biometry, Optical Coherence Tomography, and Electrophysiology Conducted for Cynomolgus Macaque Monkeys. Transl Vis Sci Technol 2021; 10:14. [PMID: 34757392 PMCID: PMC8590181 DOI: 10.1167/tvst.10.13.14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Purpose To present normative data of optical coherence tomography (OCT) parameters, electrophysiological tests, and optical biometry conducted for cynomolgus monkeys. Methods Multimodal examinations were performed for 11 adult cynomolgus monkeys (Macaca fascicularis, weighing 2.6–7.5 kg, aged 45–99 months). A-scan biometry was performed to measure ocular biometry. OCT images were obtained at 30° and 55°. After the pupils were fully dilated, electroretinogram (ERG) and visual evoked potentials (VEP) were recorded with a commercial system using a contact lens electrode. Results All cynomolgus monkeys were males. The mean axial length was 17.92 ± 0.34 mm. The central total retinal layer (TRL) and subfoveal choroidal thicknesses were 286.27 ± 18.43 and 234.73 ± 53.93 µm, respectively. The TRL and nerve fiber layer thickness was greater in the nasal than in other quadrants in the Early Treatment Diabetic Retinopathy Study circle in the macula. Peripheral TRL and ganglion cell complex thickness on the temporal outside the vascular arcades were lower than on the other sides. The peak latency of a-wave and b-wave in scotopic and photopic 3.0 ERG was 14.78 ± 1.00 and 32.89 ± 1.81 ms, and 12.91 ± 1.03 and 31.79 ± 2.16 ms, respectively. The n2 wave peak latency of VEP was 15.21 ± 8.07 ms. The a-wave peak latency of ERG and the n2 wave peak latency of VEP negatively correlated with age. Conclusions The normative ocular biometric, electrophysiological test, and OCT parametric data of cynomolgus monkeys could serve as reference values for further preclinical studies. Translational Relevance We present normative data of cynomolgus monkeys’ eyes, an adequate animal model for preclinical studies.
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Affiliation(s)
- Kwang-Eon Choi
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
| | - Vu Thi Que Anh
- Department of Ophthalmology, Hanoi Medical University, Hanoi, Vietnam
| | - Cheolmin Yun
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
| | - Young-Jin Kim
- Medical Device Development Center, Osong Medical Innovation Foundation, Cheongju, Chungbuk, Korea
| | - Hachul Jung
- Medical Device Development Center, Osong Medical Innovation Foundation, Cheongju, Chungbuk, Korea
| | - Heejong Eom
- Laboratory Animal Center, Osong Medical Innovation Foundation, Cheongju, Chungbuk, Korea
| | - Dongkwan Shin
- Laboratory Animal Center, Osong Medical Innovation Foundation, Cheongju, Chungbuk, Korea
| | - Seong-Woo Kim
- Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
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Lin KH, Tran T, Kim S, Park S, Chen J, Stout JT, Chen R, Rogers J, Yiu G, Thomasy S, Moshiri A. Age-related changes in the rhesus macaque eye. Exp Eye Res 2021; 212:108754. [PMID: 34506802 PMCID: PMC8785649 DOI: 10.1016/j.exer.2021.108754] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 08/26/2021] [Accepted: 08/30/2021] [Indexed: 11/26/2022]
Abstract
PURPOSE To assess age-related changes in the rhesus macaque eye and evaluate them to corresponding human age-related eye disease. METHODS Data from eye exams and imaging tests including intraocular pressure (IOP), lens thickness, axial length, and retinal optical coherence tomography (OCT) images were evaluated from 142 individuals and statistically analyzed for age-related changes. Quantitative autofluorescence (qAF) was measured as was the presence of macular lesions as related to age. RESULTS Ages of the 142 rhesus macaques ranged from 0.7 to 29 years (mean = 16.4 years, stdev = 7.5 years). Anterior segment measurements such as IOP, lens thickness, and axial length were acquired. Advanced retinal imaging in the form of optical coherence tomography and qAF were obtained. Quantitative assessments were made and variations by age groups were analyzed to compare with established age-related changes in human eyes. Quantitative analysis of data revealed age-related increase in intraocular pressure (0.165 mm Hg per increase in year of age), ocular biometry (lens thickness 7.2 μm per increase in year of age; and axial length 52.8 μm per increase in year of age), and presence of macular lesions. Age-related changes in thicknesses of retinal layers on OCT were observed and quantified, showing decreased thickness of the retinal ganglion cell layer and inner nuclear layer, and increased thickness of photoreceptor outer segment and choroidal layers. Age was correlated with increased qAF by 1.021 autofluorescence units per increase in year of age. CONCLUSIONS The rhesus macaque has age-related ocular changes similar to humans. IOP increases with age while retinal ganglion cell layer thickness decreases. Macular lesions develop in some aged animals. Our findings support the concept that rhesus macaques may be useful for the study of important age-related diseases such as glaucoma, macular diseases, and cone disorders, and for development of therapies for these diseases.
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Affiliation(s)
- Kira H Lin
- William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, 1 Garrod Drive, Davis, CA, 95695, USA
| | - Tu Tran
- Department of Ophthalmology & Vision Science, School of Medicine, U.C. Davis, Sacramento, CA, 95817, USA
| | - Soohyun Kim
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA
| | - Sangwan Park
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA
| | - Jiajia Chen
- Department of Ophthalmology & Vision Science, School of Medicine, U.C. Davis, Sacramento, CA, 95817, USA
| | - J Timothy Stout
- Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Rui Chen
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA; Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Jeffrey Rogers
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Glenn Yiu
- Department of Ophthalmology & Vision Science, School of Medicine, U.C. Davis, Sacramento, CA, 95817, USA
| | - Sara Thomasy
- Department of Ophthalmology & Vision Science, School of Medicine, U.C. Davis, Sacramento, CA, 95817, USA; Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA, 95616, USA
| | - Ala Moshiri
- Department of Ophthalmology & Vision Science, School of Medicine, U.C. Davis, Sacramento, CA, 95817, USA.
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Effect of eyedrops and applanation tonometry on optical biometry. J Cataract Refract Surg 2021; 47:706-712. [PMID: 33278235 DOI: 10.1097/j.jcrs.0000000000000499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 10/21/2020] [Indexed: 11/25/2022]
Abstract
PURPOSE To determine whether eyedrops (phenylephrine, tropicamide, and fluorescein-proparacaine) and Goldmann applanation tonometry (GAT) have an effect on optical biometry measurements for preoperative cataract surgery workup. SETTING George Washington University, Washington, DC. DESIGN Nonrandomized controlled trial. METHODS Participants older than 18 years with no contraindications to eyedrops or tonometry were recruited. Optical biometry measurements were obtained on a single eye using the Lenstar LS900. One drop each of phenylephrine, tropicamide, and fluorescein-proparacaine was applied to the same eye, and measurements were repeated. GAT was performed, and measurements were repeated. For controls, the contralateral eye was also measured at each interval. RESULTS There was no statistically significant difference in mean predicted postoperative refraction (PPOR) keratometry (K) 1, K2, or axis postdrops and post-GAT 62 eyes (n = 62). After drops were applied, mean central corneal thickness increased from 540 to 542 µm (P = .0002), mean anterior chamber depth (ACD) increased from 3.68 to 3.70 mm (P < .0001), and lens thickness (LT) decreased from 3.66 to 3.65 (P = .001). After GAT, ACD increased to 3.76 mm (P < .0001), and LT increased to 3.60 mm (P < .0001). There was no statistically significant difference in PPOR or other parameters for the control eyes (n = 5). CONCLUSIONS GAT and phenylephrine, tropicamide, and fluorescein-proparacaine drops did not affect the primary outcome of PPOR. This suggests that cataract surgery candidates do not need to return for a separate preoperative visit for optical biometry.
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Streckenbach F, Stachs O, Langner S, Guthoff RF, Meinel FG, Weber MA, Stahnke T, Beller E. Age-Related Changes of the Human Crystalline Lens on High-Spatial Resolution Three-Dimensional T1-Weighted Brain Magnetic Resonance Images In Vivo. Invest Ophthalmol Vis Sci 2020; 61:7. [PMID: 33270843 PMCID: PMC7718815 DOI: 10.1167/iovs.61.14.7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Purpose To reveal age-related changes of the human crystalline lens by using high-spatial resolution T1-weighted brain magnetic resonance imaging of patients under general anesthesia. Methods We retrospectively identified 47 children (2–17 years) and 30 adults (18–70 years) without diabetes or eye disease, who required brain magnetic resonance imaging examinations under general anesthesia between 2012 and 2019. Normalized signal intensity of the crystalline lens and vitreous body, as well as equatorial diameter and axial thickness of the lens were assessed by using a three-dimensional T1-weighted magnetization prepared rapid acquisition gradient echo sequence of the brain with 0.9-mm spatial resolution. Patient dossiers were reviewed to record indication for magnetic resonance imaging examination and hypertension. Results Advancing age was significantly correlated with increasing equatorial diameter of the infantile lens (r = 0. 74; 95% confidence interval, 0.58–0.85; P < .0001) and increasing crystalline lens signal intensity of the adult lens (r = 0.38; 95% confidence interval, 0.02–0.65; P = .0382), which remained significant after accounting for potential confounding variables. There was no significant correlation between age and axial thickness or vitreous body signal intensity in the children and adult cohort. Conclusions The present study demonstrated that advancing age was significantly correlated with an increasing equatorial diameter of the infantile lens and with increasing crystalline lens signal intensity of the adult lens. These normative data can contribute to our understanding of age-related changes in eye health and function, especially in regard to the emmetropization process and should also be taken into account when investigating lens pathologies.
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Affiliation(s)
- Felix Streckenbach
- Institute of Diagnostic and Interventional Radiology, Pediatric Radiology and Neuroradiology, Rostock University Medical Center, Rostock, Germany.,Centre for Transdisciplinary Neurosciences Rostock, University of Rostock, Rostock, Germany
| | - Oliver Stachs
- Department of Ophthalmology, Rostock University Medical Center, Rostock, Germany
| | - Sönke Langner
- Institute of Diagnostic and Interventional Radiology, Pediatric Radiology and Neuroradiology, Rostock University Medical Center, Rostock, Germany
| | - Rudolf F Guthoff
- Department of Ophthalmology, Rostock University Medical Center, Rostock, Germany
| | - Felix G Meinel
- Institute of Diagnostic and Interventional Radiology, Pediatric Radiology and Neuroradiology, Rostock University Medical Center, Rostock, Germany
| | - Marc-André Weber
- Institute of Diagnostic and Interventional Radiology, Pediatric Radiology and Neuroradiology, Rostock University Medical Center, Rostock, Germany
| | - Thomas Stahnke
- Department of Ophthalmology, Rostock University Medical Center, Rostock, Germany
| | - Ebba Beller
- Institute of Diagnostic and Interventional Radiology, Pediatric Radiology and Neuroradiology, Rostock University Medical Center, Rostock, Germany.,Department of Ophthalmology, Rostock University Medical Center, Rostock, Germany.,https://orcid.org/0000-0002-5268-151X
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Shah M, Cabrera-Ghayouri S, Christie LA, Held KS, Viswanath V. Translational Preclinical Pharmacologic Disease Models for Ophthalmic Drug Development. Pharm Res 2019; 36:58. [PMID: 30805711 PMCID: PMC6394514 DOI: 10.1007/s11095-019-2588-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 02/08/2019] [Indexed: 12/14/2022]
Abstract
Preclinical models of human diseases are critical to our understanding of disease etiology, pathology, and progression and enable the development of effective treatments. An ideal model of human disease should capture anatomical features and pathophysiological mechanisms, mimic the progression pattern, and should be amenable to evaluating translational endpoints and treatment approaches. Preclinical animal models have been developed for a variety of human ophthalmological diseases to mirror disease mechanisms, location of the affected region in the eye and severity. These models offer clues to aid in our fundamental understanding of disease pathogenesis and enable progression of new therapies to clinical development by providing an opportunity to gain proof of concept (POC). Here, we review preclinical animal models associated with development of new therapies for diseases of the ocular surface, glaucoma, presbyopia, and retinal diseases, including diabetic retinopathy and age-related macular degeneration (AMD). We have focused on summarizing the models critical to new drug development and described the translational features of the models that contributed to our understanding of disease pathogenesis and establishment of preclinical POC.
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Affiliation(s)
- Mihir Shah
- Biological Research, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612, USA
| | - Sara Cabrera-Ghayouri
- Biological Research, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612, USA
| | - Lori-Ann Christie
- Biological Research, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612, USA
| | - Katherine S Held
- Biological Research, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612, USA
| | - Veena Viswanath
- Biological Research, Allergan plc, 2525 Dupont Drive, Irvine, California, 92612, USA.
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Anterior chamber indices in a population-based study using the Pentacam. Int Ophthalmol 2018; 39:2033-2040. [PMID: 30382464 DOI: 10.1007/s10792-018-1037-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 10/26/2018] [Indexed: 10/28/2022]
Abstract
PURPOSE To determine the distribution of anterior chamber depth (ACD), anterior chamber volume (ACV), and anterior chamber angle (ACA) values in a rural population over 5 years of age using the Pentacam. METHODS In this cross-sectional study, samples were selected from over 1-year-old inhabitants of two villages in Iran using a multistage cluster sampling approach. All participants underwent the measurement of uncorrected and corrected visual acuity and auto-refraction, retinoscopy, subjective refraction, and slit lamp examination. Finally, corneal imaging was done for all subjects over 5 years of age using the Pentacam. RESULTS Of 3851 selected individuals, 3314 participated in the study, of whom 2681 met the inclusion criteria. The mean age of the sample was 36.03 ± 18.5 years (range 6-90 years). The mean ACD, ACA, and ACV values were 3.37 mm (95% CI: 3.37-3.39), 34.82° (95% CI: 34.45-35.2), and 159.17 µL (95% CI: 156-161.36), respectively. The results of multiple linear regression models showed that ACD, ACA, and ACV values reduced with age, and ACD and ACV values were significantly higher in males. ACA and ACV values correlated inversely with central corneal thickness, while the ACA value correlated directly with keratometry and inversely with the ACV value. CONCLUSION This study is one of the few studies in the world showing changes in ACD values in different age groups using the Pentacam. According to the results, aging was associated with a decline in the mean ACD, ACA, and ACV values. These parameters were the largest in patients with emmetropia and smallest in hyperopic subjects.
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Optical Coherence Tomography Reveals Sigmoidal Crystalline Lens Changes during Accommodation. Vision (Basel) 2018; 2:vision2030033. [PMID: 31735896 PMCID: PMC6835499 DOI: 10.3390/vision2030033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 08/15/2018] [Accepted: 08/17/2018] [Indexed: 12/02/2022] Open
Abstract
This study aimed to quantify biometric modifications of the anterior segment (AS) during accommodation and to compare them against changes in both accommodative demand and response. Thirty adults, aged 18–25 years were rendered functionally emmetropic with contact lenses. AS optical coherence tomography (AS-OCT) images were captured along the 180° meridian (Visante, Zeiss Meditec, Jena, Germany) under stimulated accommodative demands (0–4 D). Images were analysed and lens thickness (LT) was measured, applying a refractive index correction of 1.00. Accommodative responses were also measured sequentially through a Badal optical system fitted to an autorefractor (Shin Nippon NVision-K 5001, Rexxam, Japan). Data were compared with Dubbelman schematic eye calculations. Significant changes occurred in LT, anterior chamber depth (ACD), lens centroid (i.e., ACD + LT/2), and AS length (ASL = ACD + LT) with accommodation (all p < 0.01). There was no significant change in CT with accommodation (p = 0.81). Measured CT, ACD, and lens centroid values were similar to Dubbelman modelled parameters, however AS-OCT overestimated LT and ASL. As expected, the accommodative response was less than the demand. Interestingly, up until approximately 1.5 D of response (2.0 D demand), the anterior crystalline lens surface appears to be the primary correlate. Beyond this point, the posterior lens surface moves posteriorly resulting in an over-all sigmoidal trajectory. he posterior crystalline lens surface demonstrates a sigmoidal response with increasing accommodative effort.
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Evaluating relaxed ciliary muscle tone in presbyopic eyes. Graefes Arch Clin Exp Ophthalmol 2017; 255:973-978. [PMID: 28238194 DOI: 10.1007/s00417-017-3621-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 01/29/2017] [Accepted: 02/09/2017] [Indexed: 12/27/2022] Open
Abstract
PURPOSE Studies of age-related changes in ciliary muscle (CM) morphology and contractility have variously reported that CM weakens or strengthens with age. In response, the aim of this study was to evaluate relaxed CM tone in vivo in pre-presbyopic and presbyopic patients using a predictor value (PCM). METHODS Two groups of eyes-40 eyes of 40 healthy volunteers with a mean age of 28.1 ± 5.8 years and 40 eyes of 40 healthy volunteers with a mean age of 56.6 ± 7.3 years-formed the sample for this prospective, observational cross-sectional study. Used to evaluate relaxed CM tone, PCM was calculated as the difference between the change in mean anterior chamber depth (ACD) and lens thickness (LT) before and after cycloplegia, as measured with swept-source optical biometry. RESULTS The PCM for relaxed CM tone was 0.04 ± 0.04 mm in pre-presbyopic participants, 0.06 ± 0.03 mm in presbyopic ones, and significantly greater in presbyopic patients (p = .018). CONCLUSION The statistical significance of PCM between pre-presbyopic and presbyopic eyes might not signify clinical significance, since the difference was close to the repeatability limits for swept-source optical biometry. When relaxed, CM tone does not diminish with presbyopia according to changes in anterior chamber parameters due to cycloplegia.
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Özyol P, Özyol E, Baldemir E. Changes in Ocular Parameters and Intraocular Lens Powers in Aging Cycloplegic Eyes. Am J Ophthalmol 2017; 173:76-83. [PMID: 27702623 DOI: 10.1016/j.ajo.2016.09.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 09/25/2016] [Accepted: 09/25/2016] [Indexed: 10/20/2022]
Abstract
PURPOSE Age-related changes in lens elasticity and ciliary muscle contractility can affect how ocular parameters respond to cycloplegia, and therefore intraocular lens (IOL) power measurements calculated by formulas using anterior chamber depth (ACD), lens thickness (LT), or white-to-white (WtW) for effective lens position prediction can vary. In response, using swept-source optical biometry in prepresbyopic and presbyopic eyes, we investigated changes in ocular parameters and IOL power calculations attributable to cycloplegia. DESIGN Cross-sectional study. METHODS In 38 prepresbyopic and 42 presbyopic eyes, we measured pupil diameter, radius of corneal curvature values, central corneal thickness, WtW, ACD, LT, and axial length both before and after cycloplegia. We determined IOL power calculations with the Sanders-Retzlaff-Kraff/theoretical, Holladay 2, and Haigis formulas. To pinpoint the effect of cycloplegia, we recorded refractive predictions in pre- and postdilation conditions according to the same IOL power calculations, even if postdilation IOL power calculations had changed. RESULTS With cycloplegia, pupil diameter changed significantly more in presbyopic eyes (P < .001). Central corneal thickness decreased in prepresbyopic eyes (P = .048), whereas WtW increased in presbyopic eyes (P = .02). In both groups, ACD and LT changed significantly (P < .001). IOL power calculations according to the Holladay 2 formula differed in prepresbyopic eyes (P = .042), and refractive predictions with the Holladay 2 and Haigis formulas differed significantly in prepresbyopic eyes (P = .043 and P = .022, respectively). CONCLUSION Surgeons should consider the effect of cycloplegia on refractive prediction errors and IOL power calculations determined with Haigis and Holladay 2 formulas, especially in prepresbyopic ages.
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Abstract
PURPOSE To examine ocular growth in nonhuman primates (NHPs) from measurements on ex vivo eyes. METHODS We obtained NHP eyes from animals that had been killed as part of other studies or because of health-related issues. Digital calipers were used to measure the horizontal, vertical, and anteroposterior globe diameters as well as corneal horizontal and vertical diameters of excised globes from 98 hamadryas baboons, 551 cynomolgus monkeys, and 112 rhesus monkeys, at ages ranging from 23 to 360 months. Isolated lens sagittal thickness and equatorial diameter were measured by shadowphotogrammetry. Wet and fixed dry weights were obtained for lenses. RESULTS Nonhuman primate globe growth continues throughout life, slowing toward an asymptotic maximum. The final globe size scales with negative allometry to adult body size. Corneal growth ceases at around 20 months. Lens diameter increases but thickness decreases with increasing age. Nonhuman primate lens wet and dry weight accumulation is monophasic, continuing throughout life toward asymptotic maxima. The dry/wet weight ratio reaches a maximum of 0.33. CONCLUSIONS Nonhuman primate ocular globe and lens growth differ in several respects from those in humans. Although age-related losses of lens power and accommodative amplitude are similar, lens growth and properties are different indicating care should be taken in extrapolating NHP observations to the study of human accommodation.
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Affiliation(s)
- Robert C Augusteyn
- Vision Cooperative Research Centre, Sydney, Australia 2School of Optometry and Vision Science, University of New South Wales, Sydney, Australia 3Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miam
| | - Bianca Maceo Heilman
- Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States 4Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida, United States
| | - Arthur Ho
- Vision Cooperative Research Centre, Sydney, Australia 2School of Optometry and Vision Science, University of New South Wales, Sydney, Australia 3Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miam
| | - Jean-Marie Parel
- Vision Cooperative Research Centre, Sydney, Australia 3Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States 4Department of Biomedical Engineering, University of Miami Colle
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Greenwood M, Bafna S, Thompson V. Surgical Correction of Presbyopia: Lenticular, Corneal, and Scleral Approaches. Int Ophthalmol Clin 2016; 56:149-166. [PMID: 27257729 DOI: 10.1097/iio.0000000000000124] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
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16
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The effect of pupil dilation on AL-Scan biometric parameters. Int Ophthalmol 2015; 36:179-83. [DOI: 10.1007/s10792-015-0097-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 06/22/2015] [Indexed: 10/23/2022]
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17
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Ramasubramanian V, Glasser A. Can Ultrasound Biomicroscopy Be Used to Predict Accommodation Accurately? J Refract Surg 2015; 31:266-73. [DOI: 10.3928/1081597x-20150319-06] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 01/30/2015] [Indexed: 11/20/2022]
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18
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Computer-animated model of accommodation and presbyopia. J Cataract Refract Surg 2015; 41:437-45. [DOI: 10.1016/j.jcrs.2014.07.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 07/25/2014] [Accepted: 07/30/2014] [Indexed: 12/20/2022]
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19
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Lindbloom-Brown Z, Tait LJ, Horwitz GD. Spectral sensitivity differences between rhesus monkeys and humans: implications for neurophysiology. J Neurophysiol 2014; 112:3164-72. [PMID: 25253473 DOI: 10.1152/jn.00356.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spectral sensitivity of humans and rhesus monkeys was compared using identical displays and similar procedures. Detection thresholds were measured for the following: 1) 15-Hz modulation of a blue and a green cathode-ray tube phosphor; 2) 15-Hz modulation of all three phosphors together; and 3) slow (<1 Hz) modulations of a blue and a green phosphor under scotopic conditions. Monkeys had lower blue-to-green threshold ratios than humans at all eccentricities tested (0.5 to 7°), consistent with a lower lens optical density in monkeys. In addition to apparently having a lower lens density than humans, monkeys were more sensitive to 15-Hz red-green isoluminant modulations than humans, an effect that cannot be explained by optical factors.
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Affiliation(s)
- Zachary Lindbloom-Brown
- Department of Physiology and Biophysics and Washington National Primate Research Center, University of Washington, Seattle, Washington
| | - Leah J Tait
- Department of Physiology and Biophysics and Washington National Primate Research Center, University of Washington, Seattle, Washington
| | - Gregory D Horwitz
- Department of Physiology and Biophysics and Washington National Primate Research Center, University of Washington, Seattle, Washington
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20
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Ostrin LA, Garcia MB, Choh V, Wildsoet CF. Pharmacologically stimulated pupil and accommodative changes in Guinea pigs. Invest Ophthalmol Vis Sci 2014; 55:5456-65. [PMID: 25097245 DOI: 10.1167/iovs.14-14096] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The guinea pig is being used increasingly as a model of human myopia. As accommodation may influence the effects of manipulations used in experimental myopia models, understanding the accommodative ability of guinea pigs is important. Here, nonselective muscarinic agonists were used as pharmacological tools to study guinea pig accommodation. METHODS Measurements were made on 15 pigmented guinea pigs. For in vivo testing, animals were anesthetized and, following baseline measurements, 2% pilocarpine was applied topically. Measurements included A-scan ultrasonography, optical coherence tomography (OCT) imaging, corneal topography, and refraction. In vitro lens scanning experiments were performed using anterior segment preparations, with measurements before and during exposure to carbachol. Anterior segment structures were examined histologically and immunohistochemistry was done to characterize the muscarinic receptor subtypes present. RESULTS In vivo, pilocarpine induced a myopic shift in refractive error coupled to a small, but consistent decrease in anterior chamber depth (ACD), a smaller and more variable increase in lens thickness, and a decrease in pupil size. Lens thickness increases were short-lived (10 minutes), while ACD and pupil size decreased over 20 minutes. Corneal curvature was not significantly affected. Carbachol tested on anterior segment preparations in vitro was without effect on lens back vertex distance, but did stimulate pupil constriction. Immunohistochemistry indicated the presence of muscarinic receptor subtypes 1 to 5 in the iris and ciliary body. CONCLUSIONS The observed pilocarpine-induced changes in ACD, lens thickness, and refraction are consistent with active accommodation in the guinea pig, through cholinergic muscarinic stimulation.
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Affiliation(s)
- Lisa A Ostrin
- University of Houston College of Optometry, Houston, Texas, United States
| | - Mariana B Garcia
- University of California Berkeley School of Optometry, Berkeley, California, United States
| | - Vivian Choh
- University of Waterloo Optometry and Vision Science, Waterloo, Ontario, Canada
| | - Christine F Wildsoet
- University of California Berkeley School of Optometry, Berkeley, California, United States
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Comparison between carbachol iontophoresis and intravenous pilocarpine stimulated accommodation in anesthetized rhesus monkeys. Exp Eye Res 2013; 115:123-30. [DOI: 10.1016/j.exer.2013.06.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 06/13/2013] [Accepted: 06/30/2013] [Indexed: 11/19/2022]
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de Castro A, Birkenfeld J, Maceo B, Manns F, Arrieta E, Parel JM, Marcos S. Influence of shape and gradient refractive index in the accommodative changes of spherical aberration in nonhuman primate crystalline lenses. Invest Ophthalmol Vis Sci 2013; 54:6197-207. [PMID: 23927893 PMCID: PMC3771709 DOI: 10.1167/iovs.13-11996] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 07/17/2013] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To estimate changes in surface shape and gradient refractive index (GRIN) profile in primate lenses as a function of accommodation. To quantify the contribution of surface shape and GRIN to spherical aberration changes with accommodation. METHODS Crystalline lenses from 15 cynomolgus monkeys were studied in vitro under different levels of accommodation produced by a stretching system. Lens shape was obtained from optical coherence tomography (OCT) cross-sectional images. The GRIN was reconstructed with a search algorithm using the optical path measured from OCT images and the measured back focal length. The spherical aberration of the lens was estimated as a function of accommodation using the reconstructed GRIN and a homogeneous refractive index. RESULTS The lens anterior and posterior radii of curvature decreased with increasing lens power. Both surfaces exhibited negative asphericities in the unaccommodated state. The anterior surface conic constant shifted toward less negative values with accommodation, while the value of the posterior remained constant. GRIN parameters remained constant with accommodation. The lens spherical aberration with GRIN distribution was negative and higher in magnitude than that with a homogeneous equivalent refractive index (by 29% and 53% in the unaccommodated and fully accommodated states, respectively). Spherical aberration with the equivalent refractive index shifted with accommodation toward negative values (-0.070 μm/diopter [D]), but the reconstructed GRIN shifted it farther (-0.124 μm/D). CONCLUSIONS When compared with the lens with the homogeneous equivalent refractive index, the reconstructed GRIN lens has more negative spherical aberration and a larger shift toward more negative values with accommodation.
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Affiliation(s)
- Alberto de Castro
- Instituto de Óptica “Daza de Valdés,” Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Judith Birkenfeld
- Instituto de Óptica “Daza de Valdés,” Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Bianca Maceo
- Ophthalmic and Biophysics Center, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida
- Biomedical Optics Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida
| | - Fabrice Manns
- Ophthalmic and Biophysics Center, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida
- Biomedical Optics Laboratory, Department of Biomedical Engineering, University of Miami College of Engineering, Coral Gables, Florida
| | - Esdras Arrieta
- Ophthalmic and Biophysics Center, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida
| | - Jean-Marie Parel
- Ophthalmic and Biophysics Center, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida
| | - Susana Marcos
- Instituto de Óptica “Daza de Valdés,” Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
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Abstract
Recent discoveries suggest that aging is neither driven by accumulation of molecular damage of any cause, nor by random damage of any kind. Some predictions of a new theory, quasi-programmed hyperfunction, have already been confirmed and a clinically-available drug slows aging and delays diseases in animals. The relationship between diseases and aging becomes easily apparent. Yet, the essence of aging turns out to be so startling that the theory cannot be instantly accepted and any possible arguments are raised for its disposal. I discuss that these arguments actually support a new theory. Are any questions remaining? And might accumulation of molecular damage still play a peculiar role in aging?
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Affiliation(s)
- Mikhail V Blagosklonny
- Department of Cell Stress Biology, Roswell Park Cancer Institute, BLSC, L3-312, Elm and Carlton Streets, Buffalo, NY 14263, USA.
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Croft MA, McDonald JP, Katz A, Lin TL, Lütjen-Drecoll E, Kaufman PL. Extralenticular and lenticular aspects of accommodation and presbyopia in human versus monkey eyes. Invest Ophthalmol Vis Sci 2013; 54:5035-48. [PMID: 23745002 DOI: 10.1167/iovs.12-10846] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To determine if the accommodative forward movements of the vitreous zonule and lens equator occur in the human eye, as they do in the rhesus monkey eye; to investigate the connection between the vitreous zonule posterior insertion zone and the posterior lens equator; and to determine which components-muscle apex width, lens thickness, lens equator position, vitreous zonule, circumlental space, and/or other intraocular dimensions, including those stated in the objectives above-are most important in predicting accommodative amplitude and presbyopia. METHODS Accommodation was induced pharmacologically in 12 visually normal human subjects (ages 19-65 years) and by midbrain electrical stimulation in 11 rhesus monkeys (ages 6-27 years). Ultrasound biomicroscopy imaged the entire ciliary body, anterior and posterior lens surfaces, and the zonule. Relevant distances were measured in the resting and accommodated eyes. Stepwise regression analysis determined which variables were the most important predictors. RESULTS The human vitreous zonule and lens equator move forward (anteriorly) during accommodation, and their movements decline with age, as in the monkey. Over all ages studied, age could explain accommodative amplitude, but not as well as accommodative lens thickening and resting muscle apex thickness did together. Accommodative change in distances between the vitreous zonule insertion zone and the posterior lens equator or muscle apex were important for predicting accommodative lens thickening. CONCLUSIONS Our findings quantify the movements of the zonule and ciliary muscle during accommodation, and identify their age-related changes that could impact the optical change that occurs during accommodation and IOL function.
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Affiliation(s)
- Mary Ann Croft
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53792-3220, USA.
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25
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Palamar M, Alkan Z, Egrilmez S, Yagci A. Influences of Tropicamide on Anterior Segment Parameters with Pentacam in Healthy Individuals. J Ocul Pharmacol Ther 2013; 29:349-52. [DOI: 10.1089/jop.2012.0145] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Melis Palamar
- Department of Ophthalmology, Faculty of Medicine, Ege University, Izmir, Turkey
| | - Zerrin Alkan
- Department of Ophthalmology, Faculty of Medicine, Ege University, Izmir, Turkey
| | - Sait Egrilmez
- Department of Ophthalmology, Faculty of Medicine, Ege University, Izmir, Turkey
| | - Ayse Yagci
- Department of Ophthalmology, Faculty of Medicine, Ege University, Izmir, Turkey
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Richdale K, Sinnott LT, Bullimore MA, Wassenaar PA, Schmalbrock P, Kao CY, Patz S, Mutti DO, Glasser A, Zadnik K. Quantification of age-related and per diopter accommodative changes of the lens and ciliary muscle in the emmetropic human eye. Invest Ophthalmol Vis Sci 2013; 54:1095-105. [PMID: 23287789 DOI: 10.1167/iovs.12-10619] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To calculate age-related and per diopter (D) accommodative changes in crystalline lens and ciliary muscle dimensions in vivo in a single cohort of emmetropic human adults ages 30 to 50 years. METHODS The right eyes of 26 emmetropic adults were examined using ultrasonography, phakometry, anterior segment optical coherence tomography, and high resolution magnetic resonance imaging. Accommodation was measured both subjectively and objectively. RESULTS In agreement with previous research, older age was linearly correlated with a thicker lens, steeper anterior lens curvature, shallower anterior chamber, and lower lens equivalent refractive index (all P < 0.01). Age was not related to ciliary muscle ring diameter (CMRD) or lens equatorial diameter (LED). With accommodation, lens thickness increased (+0.064 mm/D, P < 0.001), LED decreased (-0.075 mm/D, P < 0.001), CMRD decreased (-0.105 mm/D, P < 0.001), and the ciliary muscle thickened anteriorly (+0.013 to +0.026 mm/D, P < 0.001) and thinned posteriorly (-0.011 to -0.015, P < 0.01). The changes per diopter of accommodation in LED, CMRD, and ciliary muscle thickness were not related to subject age. CONCLUSIONS The per diopter ciliary muscle contraction is age independent, even as total accommodative amplitude declines. Quantifying normal biometric dimensions of the accommodative structures and changes with age and accommodative effort will further the development of new IOLs designed to harness ciliary muscle forces.
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Affiliation(s)
- Kathryn Richdale
- College of Optometry, State University of New York, New York, NY, USA.
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Wendt M, Bockhorst K, He L, Glasser A. Accuracy and resolution of in vitro imaging based porcine lens volumetric measurements. Exp Eye Res 2011; 93:741-52. [PMID: 21963717 DOI: 10.1016/j.exer.2011.09.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 08/30/2011] [Accepted: 09/16/2011] [Indexed: 11/24/2022]
Abstract
There is considerable interest in determining lens volume in the living eye. Lens volume is of interest to understand accommodative changes in the lens and to size accommodative IOLs (A-IOLs) to fit the capsular bag. Some studies have suggested lens volume change during accommodation. Magnetic Resonance Imaging (MRI) is the only method available to determine lens volume in vivo. MRI is, by its nature, relatively low in temporal and spatial resolution. Therefore analysis often requires determining lens volume from single image slices with relatively low resolution on which only simple image analysis methods can be used and without repeated measures. In this study, 7 T MRI scans encompassing the full lens volume were performed on 19 enucleated pig eyes. The eyes were then dissected to isolate and photograph the lens in profile and the lens volumes were measured empirically using a fluid displacement method. Lens volumes were calculated from two- and three-dimensional (2D and 3D) MR and 2D photographic profile images of the isolated lenses using several different analysis methods. Image based and actual measured lens volumes were compared. The average image-based volume of all lenses varied from the average measured volume of all lenses by 0.6%-6.4% depending on the image analysis method. Image analysis methods that use gradient based edge detection showed higher precision with actual volumes (r(2): 0.957-0.990), while threshold based segmentation had poorer correlations (r(2): 0.759-0.828). The root-mean-square (RMS) difference between image analysis based volumes and fluid displacement measured volumes ranged from 8.51 μl to 25.79 μl. This provides an estimate of the error of previously published methods used to calculate lens volume. Immobilized, enucleated porcine eyes permit improved MR image resolution relative to living eyes and therefore improved image analysis methods to calculate lens volume. The results show that some of the accommodative changes in lens volume reported in the literature are likely below the resolution limits of imaging methods used. MRI, even with detailed image analysis methods used here, is unlikely to achieve the resolution required to accurately size an A-IOL to the capsular bag.
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Affiliation(s)
- Mark Wendt
- College of Optometry, University of Houston, 505 J. Davis Armistead Building, Houston, TX 77204, USA.
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28
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Palamar M, Egrilmez S, Uretmen O, Yagci A, Kose S. Influences of cyclopentolate hydrochloride on anterior segment parameters with Pentacam in children. Acta Ophthalmol 2011; 89:e461-5. [PMID: 21332970 DOI: 10.1111/j.1755-3768.2011.02122.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To investigate the effects of cyclopentolate hydrochloride 1% on the main numerical parameters of anterior segment with Pentacam rotating Scheimpflug camera in children. SETTING Ege University Faculty of Medicine, Department of Ophthalmology. METHODS Pentacam measurements of 50 (23 boys and 27 girls) children before and after 45 min of cyclopentolate hydrochloride 1% instillation were performed and compared with 31 (17 boys and 14 girls) no medication instilled control group. Measurements of the control group (cycloplegia-free) were taken at two separate sessions with 45-min intervals. For comparison of the test parameters, paired t-test in the groups and unpaired t-test in between the groups were used. RESULTS Mean ages in the study and control groups were 10.06 ± 2.87 (range 6 and 16 years) and 9.87 ± 2.72 (range 6 and 16 years), respectively, and the difference was statistically insignificant (p > 0.05). In the study group, measurements between two sessions were significantly different for the parameters of anterior chamber depth (ACD), anterior chamber volume (ACV) and central corneal thickness (CCT) (p < 0.05), whereas none of the parameters was different between two sessions for control group. CONCLUSIONS Cyclopentolate hydrochloride 1% instillation leads to significant decrement in CCT. ACD and ACV are the other important refractive parameters that increase significantly after cycloplegia. Effects of cycloplegia on these parameters for Pentacam measurements should be regarded for proper clinical interpretation in children.
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Affiliation(s)
- Melis Palamar
- Faculty of Medicine, Department of Ophthalmology, Ege University, Izmir, Turkey.
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29
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Augusteyn RC, Mohamed A, Nankivil D, Veerendranath P, Arrieta E, Taneja M, Manns F, Ho A, Parel JM. Age-dependence of the optomechanical responses of ex vivo human lenses from India and the USA, and the force required to produce these in a lens stretcher: the similarity to in vivo disaccommodation. Vision Res 2011; 51:1667-78. [PMID: 21658404 DOI: 10.1016/j.visres.2011.05.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 05/16/2011] [Accepted: 05/17/2011] [Indexed: 11/25/2022]
Abstract
The purpose of this study was to study the age-dependence of the optomechanical properties of human lenses during simulated disaccommodation in a mechanical lens stretcher, designed to determine accommodative forces as a function of stretch distance, to compare the results with in vivo disaccommodation and to examine whether differences exist between eyes harvested in the USA and India. Postmortem human eyes obtained in the USA (n=46, age=6-83 years) and India (n=91, age=1 day-85 years) were mounted in an optomechanical lens stretching system and dissected to expose the lens complete with its accommodating framework, including zonules, ciliary body, anterior vitreous and a segmented rim of sclera. Disaccommodation was simulated through radial stretching of the sectioned globe by 2mm in increments of 0.25 mm. The load, inner ciliary ring diameter, lens equatorial diameter, central thickness and power were measured at each step. Changes in these parameters were examined as a function of age, as were the dimension/load and power/load responses. Unstretched lens diameter and thickness increased over the whole age range examined and were indistinguishable from those of in vivo lenses as well as those of in vitro lenses freed from zonular attachments. Stretching increased the diameter and decreased the thickness in all lenses examined but the amount of change decreased with age. Unstretched lens power decreased with age and the accommodative amplitude decreased to zero by age 45-50. The load required to produce maximum stretch was independent of age (median 80 mN) whereas the change in lens diameter and power per unit load decreased significantly with age. The age related changes in the properties of human lenses, as observed in the lens stretching device, are similar to those observed in vivo and are consistent with the classical Helmholtz theory of accommodation. The response of lens diameter and power to disaccommodative (stretching) forces decreases with age, consistent with lens nuclear stiffening.
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Affiliation(s)
- Robert C Augusteyn
- Vision Cooperative Research Centre, Brien Holden Vision Institute, Sydney, Australia.
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Ni Y, Liu XL, Wu MX, Lin Y, Sun YY, He C, Liu YZ. Objective evaluation of the changes in the crystalline lens during accommodation in young and presbyopic populations using Pentacam HR system. Int J Ophthalmol 2011; 4:611-5. [PMID: 22553730 DOI: 10.3980/j.issn.2222-3959.2011.06.07] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Accepted: 10/31/2011] [Indexed: 11/02/2022] Open
Abstract
AIM To quantify the changes in the lens profile with accommodation in different age groups. METHODS The Pentacam HR system was used to obtain the images of the anterior eye segment from 23 young and 15 presbyopic emmetropic subjects in unaccommodated (with an accommodation stimulus of 0.0D) and accommodated (with an accommodation stimulus of 5.0D for the young group and 1.0D for the presbyopic group) states. The phakic crystalline lens shape, including curvature of crystalline lens and central lens thickness (CLT), and the measurements of anterior segment length (ASL), central anterior chamber depth (CACD) were investigated. The anterior chamber volume (ACV) was also measured. RESULTS The reduction of CACD and ACV were significant in both groups after accommodation stimulus. From the profile of anterior eye segment, a significant decrease in anterior crystalline lens radii of curvature (-2.52mm) and a mean increase in CLT (0.222mm) and ASL (0.108mm) were found in the young group with an accommodation stimulus of 5.0D. However, no statistically significant changes of CLT, ASL, or crystalline lens radii of curvature were found in the presbyopic group. CONCLUSION Our data showed that the shallowing of anterior chamber during accommodation was caused by the forward bulging of the anterior lens surface, rather than by anterior shifting of lens position in either young or presbyopic subjects.
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Affiliation(s)
- Yao Ni
- Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-sen University, Guangzhou 510060, Guangdong Province, China
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He L, Donnelly WJ, Stevenson SB, Glasser A. Saccadic lens instability increases with accommodative stimulus in presbyopes. J Vis 2010; 10:14.1-16. [PMID: 20465334 PMCID: PMC2913422 DOI: 10.1167/10.4.14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 02/22/2010] [Indexed: 11/24/2022] Open
Abstract
An SRI dual Purkinje image (dPi) eye tracker was used to measure lens wobble following saccades with increasing accommodative effort as an indirect measure of ciliary muscle function in presbyopes. Ten presbyopic subjects executed 32 four-degree saccades at 1-s intervals between targets arranged in a cross on illuminated cards at each of 9 viewing distances ranging from 0.5- to 8-D accommodative demands. Post-saccadic lens wobble artifacts were extracted by subtraction of P1 (H(1)/V(1)) position signals from P4 signals (Theta(H)/Theta(V)), both of which were sampled by the eye tracker at 100 Hz. A ray tracing eye model was also employed to model the fourth Purkinje image shifts for a range of lens translations and tilts. Combining all saccades from all subjects showed a significant positive relationship between lens wobble artifact amplitude and accommodative demand. Eye model simulations indicated that artifacts of the amplitude measured could arise from either lens tilts (in the range of 2-4 degrees) or lens translations (in the range of 0.1 to 0.2 mm). Saccadic lens wobble artifacts increase with accommodative effort in presbyopes, indicating preserved ciliary muscle function and greater relaxation of zonular tension with accommodative effort. Variation across subjects may reflect differences in accommodative effort, ciliary muscle function for a given effort, and/or in intraocular anatomy.
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Affiliation(s)
- Lin He
- College of Optometry, University of Houston, 4901 Calhoun Road, Houston, TX 77204, USA.
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Wendt M, Glasser A. Topical and intravenous pilocarpine stimulated accommodation in anesthetized rhesus monkeys. Exp Eye Res 2010; 90:605-16. [PMID: 20159011 DOI: 10.1016/j.exer.2010.02.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 02/09/2010] [Accepted: 02/10/2010] [Indexed: 10/19/2022]
Abstract
Many studies have used pilocarpine to stimulate accommodation in both humans and monkeys. However, the concentrations of pilocarpine used and the methods of administration vary. In this study, three different methods of pilocarpine administration are evaluated for their effectiveness in stimulating accommodation in rhesus monkeys. Experiments were performed in 17 iridectomized, anesthetized rhesus monkeys aged 4-16 years. Maximum accommodation was stimulated in all these monkeys with a 2% pilocarpine solution maintained on the cornea for at least 30 min in a specially designed perfusion lens. In subsequent topical pilocarpine experiments, baseline refraction was measured with a Hartinger coincidence refractometer and then while the monkeys were upright and facing forward, commercially available pilocarpine (2, 4, or 6%) was applied topically to the cornea as 2 or 4 drops in two applications or 6 drops in three applications over a five minute period with the eyelids closed between applications. Alternatively, while supine, 10-12 drops of pilocarpine were maintained on the cornea in a scleral cup for 5 min. Refraction measurements were begun 5 min after the second application of pilocarpine and continued for at least 30 min after initial administration until no further change in refraction occurred. In intravenous experiments, pilocarpine was given either as boluses ranging from 0.1mg/kg to 2mg/kg or boluses followed by a constant infusion at rates between 3.06 mg/kg/h and 11.6 mg/kg/h. Constant 2% pilocarpine solution on the eye in the perfusion lens produced 10.88+/-2.73 D (mean+/-SD) of accommodation. Topically applied pilocarpine produced 3.81 D+/-2.41, 5.49 D+/-4.08, and 5.55 D+/-3.27 using 2%, 4%, and 6% solutions respectively. When expressed as a percentage of the accommodative response amplitude obtained in the same monkey with constant 2% pilocarpine solution on the eye, the responses were 34.7% for 2% pilocarpine, 48.4% for 4% pilocarpine, and 44.6% for 6% pilocarpine. Topical 4% and 6% pilocarpine achieved similar, variable accommodative responses, but neither achieved maximum accommodation. IV boluses of pilocarpine achieved near maximal levels of accommodation at least ten times faster than topical methods. Doses effective for producing maximum accommodation ranged from 0.25mg/kg to 1.0mg/kg. IV pilocarpine boluses caused an anterior movement of the anterior lens surface, a posterior movement of the posterior lens surface, and a slight net anterior movement of the entire lens. Considerable variability in response amplitude occurred and maximum accommodative amplitude was rarely achieved with topical application of a variety of concentrations of commercially available pilocarpine. Intravenous infusion of pilocarpine was a rapid and reliable method of producing a nearly maximal accommodative response and maintaining accommodation when desired.
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Affiliation(s)
- Mark Wendt
- College of Optometry, University of Houston, 505 J. Davis Armistead Building, Houston, TX 77204, USA.
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Borja D, Manns F, Ho A, Ziebarth NM, Acosta AC, Arrieta-Quintera E, Augusteyn RC, Parel JM. Refractive power and biometric properties of the nonhuman primate isolated crystalline lens. Invest Ophthalmol Vis Sci 2010; 51:2118-25. [PMID: 20107174 DOI: 10.1167/iovs.09-3905] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose. To characterize the age dependence of shape, refractive power, and refractive index of isolated lenses from nonhuman primates. Methods. Measurements were performed on ex vivo lenses from cynomolgus monkeys (cyno: n = 120; age, 2.7-14.3 years), rhesus monkeys (n = 61; age, 0.7-13.3 years), and hamadryas baboons (baboon: n = 16; age, 1.7-27.3 years). Lens thickness, diameter, and surface curvatures were measured with an optical comparator. Lens refractive power was measured with a custom optical system based on the Scheiner principle. The refractive contributions of the gradient, the surfaces, and the equivalent refractive index were calculated with optical ray-tracing software. The age dependence of the optical and biometric parameters was assessed. Results. Over the measured age range isolated lens thickness decreased (baboon: -0.04, cyno: -0.05, and rhesus: -0.06 mm/y) and equatorial diameter increased (logarithmically for the baboon and rhesus, and linearly for cyno: 0.07 mm/y). The isolated lens surfaces flattened and the corresponding refractive power from the surfaces decreased with age (-0.33, -0.48, and -0.68 D/y). The isolated lens equivalent refractive index decreased (only significant for the baboon, -0.001 D/y), and as a result the total isolated lens refractive power decreased with age (baboon: -1.26, cyno: -0.97, and rhesus: -1.76 D/y). Conclusions. The age-dependent trends in the optical and biometric properties, growth, and aging, of nonhuman primate lenses are similar to those of the pre-presbyopic human lens. As the lens ages, the decrease in refractive contributions from the gradient refractive index causes a rapid age-dependent decrease in maximally accommodated lens refractive power.
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Affiliation(s)
- David Borja
- Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA
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Lütjen-Drecoll E, Kaufman PL, Wasielewski R, Ting-Li L, Croft MA. Morphology and accommodative function of the vitreous zonule in human and monkey eyes. Invest Ophthalmol Vis Sci 2009; 51:1554-64. [PMID: 19815737 DOI: 10.1167/iovs.09-4008] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To explore the attachments of the posterior zonule and vitreous in relation to accommodation and presbyopia in monkeys and humans. METHODS Novel scanning electron microscopy (SEM) and ultrasound biomicroscopy (UBM) techniques were used to visualize the anterior, intermediate, and posterior vitreous zonule and their connections to the ciliary body, vitreous membrane, lens capsule, and ora serrata, and to characterize their age-related changes and correlate them with loss of accommodative forward movement of the ciliary body. alpha-Chymotrypsin was used focally to lyse the vitreous zonule and determine the effect on movement of the accommodative apparatus in monkeys. RESULTS The vitreous attached to the peripheral lens capsule and the ora serrata directly. The pars plana zonule and the posterior tines of the anterior zonule were separated from the vitreous membrane except for strategically placed attachments, collectively termed the vitreous zonule, that may modulate and smooth the forward and backward movements of the entire system. Age-dependent changes in these relationships correlated significantly with loss of accommodative amplitude. Lysis of the intermediate vitreous zonule partially restored accommodative movement. CONCLUSIONS The vitreous zonule system may help to smoothly translate to the lens the driving forces of accommodation and disaccommodation generated by the ciliary muscle, while maintaining visual focus and protecting the lens capsule and ora serrata from acute tractional forces. Stiffening of the vitreous zonular system may contribute to age-related loss of accommodation and offer a therapeutic target for presbyopia.
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Affiliation(s)
- Elke Lütjen-Drecoll
- Institute of Anatomy II, University of Erlangen-Nuremberg, Erlangen, Germany
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Plainis S, Plevridi E, Pallikaris IG. Comparison of the ocular wavefront aberration between pharmacologically-induced and stimulus-driven accommodation. Ophthalmic Physiol Opt 2009; 29:272-80. [PMID: 19422558 DOI: 10.1111/j.1475-1313.2009.00653.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To compare the ocular wavefront aberration between pharmacologically- and stimulus-driven accommodation in phakic eyes of young subjects. METHODS The aberration structure of the tested eye when accommodating was measured using the Complete Ophthalmic Analysis System (COAS; AMO WaveFront Sciences, Albuquerque, NM, USA). It was used in conjunction with a purposely-modified Badal optometer to allow blur-driven accommodation to be stimulated by a high contrast letter E with a vergence range between +0.84 D and -8.00 D. Pharmacological accommodation was induced with one drop of pilocarpine 4%. Data from six subjects (age range: 23-36 years) with dark irides were collected. RESULTS No correlation was found between the maximal levels of accommodative response achieved with an 8 D blur-driven stimulus and pharmacological stimulation. Pharmacological accommodation varied considerably among subjects: maximum accommodation, achieved within 38-85 min following application of pilocarpine, ranged from 2.7 D to 10.0 D. Furthermore, although the changes of spherical aberration and coma as a function of accommodation were indistinguishable between the two methods for low levels of response, a characteristic break in the pattern of aberration occurred at higher levels of pilocarpine-induced accommodation. This probably resulted from differences in the time course of biometric changes occurring with the two methods. CONCLUSION Measuring the pilocarpine-induced accommodative response at only one time point after its application may lead to misleading results. The considerable inter-individual differences in the time course of drug-induced accommodative response and its magnitude may lead to overestimation or underestimation of the corresponding amplitude of normal, blur-driven accommodation. Stimulating accommodation by topical application of pilocarpine is inappropriate for evaluating the efficacy of 'accommodating' IOLs.
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Affiliation(s)
- S Plainis
- Institute of Vision and Optics, School of Health Sciences, University of Crete, Heraklion, Crete 71003, Greece.
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