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Coutinho CP, Schiano-Lomoriello D, Mazzotta C, Ferrise M, Hoffer KJ, Ribeiro FJ, Dias JM, Savini G. Differences Between Simulated Keratometry and Total Corneal Power in Eyes With Keratoconus and a Formula to Improve IOL Power Calculation Results. J Refract Surg 2024; 40:e253-e259. [PMID: 38593262 DOI: 10.3928/1081597x-20240311-06] [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: 04/11/2024]
Abstract
PURPOSE To compare simulated keratometry (SimK) and total corneal power (TCP) in keratoconic eyes, to determine whether the differences are systematic and predictable and to evaluate an adjusted TCP-based formula for intraocular lens (IOL) power calculation. METHODS In a consecutive series of keratoconic eyes, measurements of SimK, TCP, posterior keratometry, and anterior and posterior corneal asphericities (Q-values) were retrospectively collected. The difference between SimK and TCP was linearly correlated to the biometric parameters. In a separate sample of keratoconic eyes that had undergone cataract surgery, IOL power was calculated with the Barrett Universal II, Hoffer QST, Holladay 1, Kane, and SRK/T formulas using the SimK and an adjusted TCP power. The respective prediction errors were calculated. RESULTS A total of 382 keratoconic eyes (271 patients) were enrolled. An increasing overestimation of SimK by TCP was detected from stage I to III, with a significant correlation between the SimK and TCP difference and SimK in the whole sample (P < .0001, r2 = 0.1322). Approximately 7% of cases presented an underestimation of SimK by TCP. IOL power calculation with the adjusted TCP improved outcomes, achieving a maximum of 80% of eyes with a prediction error within ±0.50 diopters with the Hoffer QST, Holladay 1, and Kane formulas. CONCLUSIONS Overall, SimK overestimated TCP. Such a difference could not be predicted by any variable. The proposed TCP-adjustment formula (TCPadj = TCP + 0.56 diopters) in keratoconic eyes for IOL power calculation might be valuable for improving refractive outcomes. [J Refract Surg. 2024;40(4):e253-e259.].
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Camellin U, Ninotta I, Latino G, Alibrandi A, Aragona P, Roszkowska AM. Prediction of total corneal power in keratoconus using anterior surface data. Clin Exp Optom 2024; 107:274-280. [PMID: 37271161 DOI: 10.1080/08164622.2023.2215382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 05/09/2023] [Accepted: 05/12/2023] [Indexed: 06/06/2023] Open
Abstract
CLINICAL RELEVANCE Keratoconus results in an increase in anterior and posterior curvatures and a reduction in corneal thickness. Anterior corneal ectasia is partially compensated by remodelling the corneal epithelium. Therefore, there is an alteration in the relationship between corneal surfaces and variation in corneal power. The variation in corneal power is one of the sources that induces errors in IOL power calculation. BACKGROUND This study aimed to assess a method for predicting total corneal power in keratoconus using several anterior surface parameters at 3 mm and 4 mm. METHODS Tomographic data obtained using Pentacam (Oculus, Germany) were analysed from 280 eyes of 140 patients with keratoconus using anterior and posterior keratometry, anterior Q-value at 8 mm, central corneal thickness, Kmax location and value, and true net power at 4 mm (TNP). Calculated total corneal power (TCPc) at 3 mm was obtained using the Gauss formula. Predicted total corneal power at 3 mm (TCPp3) and 4 mm (TCPp4) was obtained from univariate (TCPp3u and TCPp4u) and multivariate linear regression formulae (TCPp3m and TCPp4m). SimK, anterior Q-value, vertical location, and Kmax value were used in the multivariate formulae. Mean absolute error (MAE) and median absolute error (MedAE) were also calculated. Absolute frequencies within dioptric ranges of all formulas divided for keratoconus grading were evaluated. RESULTS TCPc and TNP exhibited a good correlation (R2 = 0.58, p < 0.05) with a higher dispersion above 50 D of corneal power. Highly significant correlations were observed between TCPp3u and TCPc (R2 = 0.978, p < 0.05) and TCPp3m and TCPc (R2 = 0.989, p < 0.05). Lower but significant correlations were observed between TCPp4u and TNP (R2 = 0.692, p < 0.05) and between TCPp4m and TNP (R2 = 0.887, p < 0.05). The best results for TCP prediction at 3 and 4 mm were obtained with TCPp3m and TCPp4m as follows: MAE of TCPp3m was 0.24 ± 0.20 (SD) D with MedAE of 0.20 D, while MAE of TCPp4m was 0.96 ± 0.77 D with MedAE of 0.80 D. The 3 mm multivariate regression formula results in higher absolute frequencies of prediction errors in the total eyes within 0.5 D (93%) than the univariate formula (81%). At 4mm, the multivariate regression formula has a lower percentage within 0.5 D (32%) than the univariate formula (41%), but the percentage of the multivariate formula is higher within 1 D (63%) than the univariate formula (56%). CONCLUSION All formulas show a decrease in accuracy with increasing grades of keratoconus. Multivariate linear regression formulae using only anterior surface data can predict TCP with good approximation in eyes with keratoconus in cases where posterior surface parameters are unavailable. The vertical location of Kmax and the anterior asphericity could play a relevant role in the prediction of total corneal power in keratoconus.
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Affiliation(s)
- Umberto Camellin
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
| | - Ivan Ninotta
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
| | - Gianluigi Latino
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
| | | | - Pasquale Aragona
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
| | - Anna M Roszkowska
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Messina, Italy
- Department of Ophthalmology, Andrzej Frycz Modrzewski Krakow University, Kraków, Poland
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D'Oria F, Bagaglia SA, Alio Del Barrio JL, Alessio G, Alio JL, Mazzotta C. Refractive surgical correction and treatment of keratoconus. Surv Ophthalmol 2024; 69:122-139. [PMID: 37774800 DOI: 10.1016/j.survophthal.2023.09.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/01/2023]
Abstract
Keratoconus is an ectatic corneal disorder that causes severe vision loss. Surgical options allow us to correct, partially or totally, the induced refractive error. Intracorneal ring segments (ICRS) implantation represents a minimally invasive surgical option that improves visual acuity, with a high success rate and a low overall complication rate. Corneal allogenic ICRS consists of ring segments derived from allogenic eye bank-processed donor corneas. Selective topography-guided transepithelial photorefractive or phototherapeutic keratectomy combined with CXL is another way in selected cases to improve spectacles corrected distance visual acuity. The microphotoablative remodeling of the central corneal profile is generally planned by optimizing the optical zones and minimizing tissue consumption. Phakic intraocular lens (PIOL) implant is considered in patients with stable disease and acceptable anatomical requirements. The two types of pIOLs, depending on their implantation inside the eye, are anterior chamber-pIOLs, which fixate to the anterior surface of the iris by using a polymethomethacrolate claw at the two haptics, and posterior chamber-pIOLs. In patients with both cataracts and keratoconus, the correct IOL power is difficult to obtain due to the irregular corneal shape and K values. Toric IOL is recommended, but carefully judging the topography and the possible need of subsequent keratoplasties.
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Affiliation(s)
- Francesco D'Oria
- Section of Ophthalmology, Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari, Bari, Italy.
| | - Simone A Bagaglia
- Departmental Ophthalmology Unit, Sant' Andrea Hospital, USL Toscana Sud-Est, Massa Marittima, Italy
| | - Jorge L Alio Del Barrio
- Vissum Miranza, Alicante, Spain; Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain
| | - Giovanni Alessio
- Section of Ophthalmology, Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari, Bari, Italy
| | - Jorge L Alio
- Vissum Miranza, Alicante, Spain; Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain.
| | - Cosimo Mazzotta
- Departmental Ophthalmology Unit, AUSL Toscana Sud Est, Campostaggia, Siena, Italy; Department of Medicine, Surgery and Neurosciences, Postgraduate Ophthalmology School, Siena University, Siena, Italy; Siena Crosslinking Center, Siena, Italy
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Wei J, He R, Wang X, Song Y, Yao J, Liu X, Yang X, Chen W, Li X. The Corneal Ectasia Model of Rabbit: A Validity and Stability Study. Bioengineering (Basel) 2023; 10:bioengineering10040479. [PMID: 37106666 PMCID: PMC10135747 DOI: 10.3390/bioengineering10040479] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/12/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Keratoconus is a bilateral progressive degenerative corneal disease characterized by localized corneal thinning and dilatation. The pathogenesis of keratoconus is not fully elucidated. To gain a better understanding of the pathophysiology of this disease and to explore potential treatments, animal models are essential for basic research. Several attempts have been made to establish animal models of corneal ectasia by using collagenase. However, continuous changes of the cornea have not been well-tracked for the model. In this study, corneal morphology and biomechanical behavior in vivo were determined before and after collagenase Ⅱ treatment at 2, 4, and 8 weeks. The elastic modulus and histology of cornea tissues ex vivo were measured at 8 weeks postoperatively. The results showed that the posterior corneal curvature (Km B) increased and central corneal thickness (CCT) decreased after collagenase treatment. The mechanical properties of ectatic corneas weakened significantly and the collagen fiber interval in the stromal layer was increased and disorganized. This study provides insights into the changes of corneal morphology and biomechanical properties in a rabbit model of corneal ectasia. Changes observed at 8 weeks indicated that the cornea was still undergoing remodeling.
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Affiliation(s)
- Junchao Wei
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Rui He
- School of Ophthalmology, Shanxi Medical University, Taiyuan 030002, China
| | - Xiaogang Wang
- School of Ophthalmology, Shanxi Medical University, Taiyuan 030002, China
| | - Yaowen Song
- School of Ophthalmology, Shanxi Medical University, Taiyuan 030002, China
| | - Jinhan Yao
- School of Ophthalmology, Shanxi Medical University, Taiyuan 030002, China
| | - Xiaona Liu
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Xin Yang
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Weiyi Chen
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
| | - Xiaona Li
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
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Singh C, Joshi VP. Cataract surgery in Keratoconus revisited - An update on preoperative and intraoperative considerations and postoperative outcomes. Semin Ophthalmol 2023; 38:57-64. [PMID: 35996343 DOI: 10.1080/08820538.2022.2112702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
PURPOSE This review aims to evaluate and simplify the recent literature on preoperative surgical planning, intraoperative considerations, postoperative surprises, and their management in patients with keratoconus undergoing cataract surgery. METHODS A review of the literature was done to analyze all the pertinent articles on Keratoconus and cataract surgery. RESULTS The surgical planning of cataracts in eyes with keratoconus needs a multifaceted approach. Preoperatively, techniques such as cross-linking or the use of intra-corneal rings help stabilize the progression. Unreliable biometric measurements are a significant problem in keratoconus patients, especially in an advanced stage of the disease. It is better to consider actual K readings if the K value is less than 55D but for a K value, more than 55D using standard K values will prevent postoperative refractive surprises. For calculation of K values, an elevation-based device like pentacam gives better repeatability in mild to moderate cases whereas for advanced keratoconus none of the keratometers is reliable. Recently, the Kane keratoconus formula performed better in all stages of disease whereas previous studies showed good results with SRK/T formula is a mild and moderate disease. Monofocal intraocular lenses are a better choice in these patients. Toric lenses can be used in mild and stable keratoconus. Intraoperatively, the use of a customized RGP lens can overcome the challenge of image distortion and loss of visual perspective. Despite taking necessary measures, postoperative refractive surprise can occur and can be managed with IOL exchange or Secondary IOLs. CONCLUSION There is a spectrum of challenges in managing cataracts in keratoconus which makes thorough preoperative planning important for good surgical outcomes. Despite the measures, there might be post-operative surprises and the patients need to be informed regarding the same.
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Affiliation(s)
- Charul Singh
- Academy of Eye Care Education, L V Prasad Eye Institute, Hyderabad, India.,The Cornea Institute, L V Prasad Eye Institute, Hyderabad, India
| | - Vineet P Joshi
- The Cornea Institute, L V Prasad Eye Institute, Hyderabad, India.,Centre for Innovation, L V Prasad Eye Institute, Hyderabad, India
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Cataract surgery considerations in patients with prior history of keratoconus and ectasia. Curr Opin Ophthalmol 2023; 34:41-47. [PMID: 36165405 DOI: 10.1097/icu.0000000000000908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW Preoperative workup for cataract surgery in patients with keratoconus poses certain challenges, particularly in patients with moderate-to-severe disease. This review aims to outline the appropriate preoperative, intraoperative, and postoperative considerations and provides an algorithm to help guide the workup prior to surgery. RECENT FINDINGS A new system for keratoconus progression and staging has been proposed and additional studies comparing intraocular lens (IOL) formulas calculations and biometry devices have been conducted. SUMMARY Patients with severe keratoconus have unpredictable results and have an increased risk of a hyperopic refraction postoperatively. Although studies have compared IOL calculation formulas, there is no consensus on management. Clinical considerations and an approach to the workup are presented; however, additional studies are required to determine the most appropriate management of cataracts in severe keratoconus.
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Gonzalez-Salinas R, Franco JJ, Reyes-Luis JL, Sánchez-Huerta V, de Wit-Carter G, Hernández-Quintela E, Pineda R. Cataract surgery in patients with underlying keratoconus: focused review. J Cataract Refract Surg 2023; 49:97-102. [PMID: 36194107 DOI: 10.1097/j.jcrs.0000000000001069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 09/24/2022] [Indexed: 11/07/2022]
Abstract
An underlying diagnosis of keratoconus (KC) can complicate cataract surgery. In this study, the results of a focused review of the literature pertaining to cataract surgery in patients with KC are detailed. Topics essential for the appropriate management of this patient population are discussed. First, the individual and shared epidemiology and pathophysiology of cataract and KC are reviewed. Then, the theory and approach to intraocular lens power calculation are discussed, highlighting particularities and pitfalls of this exercise when performed in patients with KC. Finally, several special-although not uncommon-management scenarios and questions are addressed, such as surgical planning in cases where corneal stabilization or tissue replacement interventions are also necessitated.
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Affiliation(s)
- Roberto Gonzalez-Salinas
- From the Anterior Segment Surgery Department, Asociación para Evitar la Ceguera I.A.P., Mexico City, Mexico (Gonzalez-Salinas); Harvard Medical School, Boston, Massachusetts (Franco, Pineda); Cornea and Refractive Surgery Service, Massachusetts Eye and Ear, Boston, Massachusetts (Reyes-Luis, Pineda); Cornea Department, Asociación para Evitar la Ceguera I.A.P., Mexico City, Mexico (Sánchez-Huerta, de Wit-Carter); Division of Comprehensive Ophthalmology, Wilmer Eye Institute, Johns Hopkins Medicine, Baltimore, Maryland (Hernández-Quintela)
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8
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Chakravarty M, Ponnam SPG, Bardoloi N, Kumar S, Saikia P. A comprehensive molecular genetic analysis of keratoconus patients from assam, a northeastern state of India. Eur J Ophthalmol 2022; 32:1361-1369. [PMID: 35296157 DOI: 10.1177/11206721221087551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Keratoconus (KC, OMIM: 148300) is a progressive corneal ectatic disorder characterized by thinning and protrusion of cornea resulting in visual decrement. MATERIALS AND METHODS In the current study, we recruited a total of 50 KC patients and 100 case-controls domiciles of Assam, based on preset inclusion and exclusion criteria. All the important and relevant signs and symptoms were recorded. Amsler-Krumeich's (AK) classification was followed to grade KC corneas. We screened for the novel as well as reported sequence variations in five candidate genes namely Lysyl oxidase (LOX), Visual system homeobox 1 (VSX1), MicroRNA 184 (MIR184), Superoxide dismutase 1 (SOD1), and exons 4 and 12 of Transforming growth factor beta-induced (TGFβ-I). RESULTS We report a novel double variant p.(Pro32Arg) and p.(Gln67Glu) in the LOX gene in a sporadic male patient with Grade I (OD) and Grade II (OS) of KC. A recurrent variant p.(His244Arg) in the VSX1 gene was also observed in a sporadic female patient with Grade I of KC in both eyes. These variants were absent in 100 unrelated ethnically matched case controls. DISCUSSION Ours is the first study on molecular genetic analysis of Keratoconus patients from Assam. The novel variants p.(Pro32Arg) and p.(Gln67Glu) observed further expand the mutational spectrum of the LOX gene associated with KC. We are also the first group to report the recurrent p.(His244Arg) variant in the VSX1 gene from India. The observed variant p.(His244Arg) in the VSX1 gene could be the result of a founder effect and may be investigated further.
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Affiliation(s)
- Mrigyanka Chakravarty
- Department of Molecular Biology & Biotechnology, 28688Tezpur University, Napaam, Sonitpur, Assam, India
| | - Surya Prakash Goud Ponnam
- Department of Molecular Biology & Biotechnology, 28688Tezpur University, Napaam, Sonitpur, Assam, India
| | - Narayan Bardoloi
- Department of Cornea and Anterior Segment Services, Chandraprabha Eye Hospital, Jorhat, Assam, India
| | - Subhash Kumar
- Department of Cornea and Anterior Segment Services, Chandraprabha Eye Hospital, Jorhat, Assam, India
| | - Prasanta Saikia
- Department of Vitreo-Retinal services, Chandraprabha Eye Hospital (CPEH), Jorhat, Assam, India
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David C, Kallel S, Trinh L, Goemaere I, Borderie V, Bouheraoua N. [Intracorneal ring segments in keratoconus management]. J Fr Ophtalmol 2021; 44:882-898. [PMID: 33895029 DOI: 10.1016/j.jfo.2020.10.021] [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: 04/19/2020] [Revised: 09/30/2020] [Accepted: 10/02/2020] [Indexed: 11/25/2022]
Abstract
Intracorneal ring segments (ICRS), used in the management of keratoconus since the 2000s, have enjoyed significant technological development. Various types of ICRS exist, whose arc length, thickness, and diameter can be chosen according to the desired effect on the spherical equivalent, keratometry and asphericity. Individualized implantation strategies, based on each patient's topographic and tomographic pattern, are constantly evolving. The surgical procedure is standardized, and complications remain very rare. Combined procedures (corneal collagen cross-linking and refractive photokeratectomy±topo-guided, phakic and pseudophakic intraocular lenses) are increasingly used and require a good knowledge of the effect of ICRS alone on the keratoconic cornea. The objective of this review is to summarize clinical practices used in the visual rehabilitation of keratoconic patients using the ICRS+- combined procedures.
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Affiliation(s)
- C David
- INSERM-DGOS CIC 1423, CHNO des Quinze-Vingts, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France
| | - S Kallel
- INSERM-DGOS CIC 1423, CHNO des Quinze-Vingts, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France
| | - L Trinh
- INSERM-DGOS CIC 1423, CHNO des Quinze-Vingts, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France
| | - I Goemaere
- INSERM-DGOS CIC 1423, CHNO des Quinze-Vingts, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France
| | - V Borderie
- INSERM-DGOS CIC 1423, CHNO des Quinze-Vingts, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France; Inserm, CNRS, Sorbonne université, institut de la Vision, 17, rue Moreau, 75012 Paris, France
| | - N Bouheraoua
- INSERM-DGOS CIC 1423, CHNO des Quinze-Vingts, IHU ForeSight, 28, rue de Charenton, 75012 Paris, France; Inserm, CNRS, Sorbonne université, institut de la Vision, 17, rue Moreau, 75012 Paris, France.
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Pan C, Tan W, Savini G, Hua Y, Ye X, Xu W, Yu J, Wang Q, Huang J. A Comparative Study of Total Corneal Power Using a Ray Tracing Method Obtained from 3 Different Scheimpflug Camera Devices. Am J Ophthalmol 2020; 216:90-98. [PMID: 32277940 DOI: 10.1016/j.ajo.2020.03.037] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 03/22/2020] [Accepted: 03/25/2020] [Indexed: 11/18/2022]
Abstract
PURPOSE We sought to assess the agreement of ray-traced corneal power values by 3 Scheimpflug tomographers tp construct the corresponding arithmetic adjustment factor in comparison with an automated keratometer (IOLMaster) and a conventional Placido-based topographer (Allegro Topolyzer). DESIGN Prospective reliability analysis. METHODS A total of 74 eyes from 74 healthy subjects who underwent corneal power measurements using Pentacam, Sirius, Galilei, IOLMaster, and Allegro Topolyzer were included. Ray-traced corneal power values, such as total corneal refractive power (TCRP), mean pupil power (MPP), total corneal power (TCP), mean keratometry (Km), and simulated keratometry (SimK) were recorded respectively and analyzed using one-way analysis of variance (ANOVA) and Bland-Altman plots. RESULTS Among the 3 ray-traced corneal power values, TCRP and MPP did not differ significantly (P = 0.81), whereas TCP presented a slightly significant larger value (P < 0.001). Compared to Km or SimK, corneal power measurements by the ray tracing method exhibited significantly lower values (P < 0.001). Bland-Altman plots disclosed that the 3 Scheimpflug tomographers showed similar 95% limits of agreement after arithmetic adjustment compared with Km (-0.40 to 0.40 D, -0.39 to 0.39 D, and -0.35 to 0.34 D) or SimK (-0.50 to 0.51 D, -0.43 to 0.42 D, and -0.46 to 0.46 D). CONCLUSIONS Ray-traced corneal power values obtained using 3 Scheimpflug tomographers with default diameter settings were similar, indicating that they could be used interchangeably in daily clinical practice. The 3 Scheimpflug tomographers were satisfactory in agreement after arithmetical adjustment compared with conventional automated keratometer or Placido-based topographer.
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Affiliation(s)
- Chao Pan
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China; Hankou Aier Eye Hospital, Jianghan District, Wuhan, China
| | - Weina Tan
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China; Hankou Aier Eye Hospital, Jianghan District, Wuhan, China
| | | | - Yanjun Hua
- Department of Ophthalmology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Xiuhong Ye
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Wenjin Xu
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Jinjin Yu
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Qinmei Wang
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China.
| | - Jinhai Huang
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, China.
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Abstract
PURPOSE OF REVIEW Intraocular lens (IOL) calculations in patients with keratoconus and other keratoectatic disorders continues to be a challenge for today's cataract surgeon. In this article, we review data published over the past 18 months (June 2018 to January 2020). RECENT FINDINGS Cataract surgery in keratoconus patients has the potential to greatly improve patients' vision. However, keratoconic eyes are notorious for unpredictable outcomes because of difficulty in obtaining proper preoperative biometry and lack of data and consensus on IOL calculation formulas that can reliable in providing the desired outcome. Recent studies suggest the Barrett II Universal calculation is the most accurate in mild-to-moderate keratoconic eyes. All studies note the level of predictability decreases with the steepness of keratometric readings. Historically, the SRK/T has been shown to provide the most reliable calculations. SUMMARY There is still no consensus on which formula is best for IOL calculation in keratoconic eyes. On the basis of the most recent literature, we recommend using the Barrett II Universal in conjunction with the SRK/T formula for mild-to-moderate eyes. Preoperative counseling of expectations with the patient is the key to achieving a satisfied patient and avoiding an unpleasant situation in the result of refractive surprise.
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Accuracy of Intraocular Lens Formulas in Eyes With Keratoconus. Am J Ophthalmol 2020; 212:26-33. [PMID: 31770511 DOI: 10.1016/j.ajo.2019.11.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 11/11/2019] [Accepted: 11/14/2019] [Indexed: 01/10/2023]
Abstract
PURPOSE To evaluate the refractive accuracy of current intraocular lens (IOL) formulas in eyes with keratoconus. DESIGN Retrospective case series. METHODS Preoperative optical biometry, Pentacam topography, and postoperative outcomes were collected from eyes with keratoconus that had uncomplicated cataract surgery between 2014 and 2018 at a single institution. Exclusion criteria include postoperative best-corrected spectacle visual acuity worse than 20/40, multifocal lens, prior ophthalmic surgeries, and prior ocular trauma. The Hoffer Q, SRK/T, Holladay I, Holladay II, Haigis, and Barrett Universal II formulas were analyzed in each eye stratified by keratoconus severity. RESULTS A total of 73 eyes were included. All formulas had a positive mean predicted error ranging from 0.10 to 4.38 diopters (D). The Barrett Universal II formula had the lowest median absolute error for stage I (n = 46, 0.445 D) and II (n = 22, 0.445 D) eyes, and the highest percentage of eyes with predicted error within ±0.50 D for both stage I (52%) and II (50%) eyes. In stage III eyes (n = 5), the Haigis formula had the lowest median predicated error (1.90 D) and the highest percentage of eyes with predicted error within ±0.50 D (40%). Corneal power measured by optical biometers was higher than measurements by Pentacam keratometry. CONCLUSIONS All formulas tend to have a hyperopic surprise. The Barrett Universal II formula was the most accurate for mild to moderate disease. Pentacam keratometry may help avoid hyperopic outcomes.
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Savini G, Abbate R, Hoffer KJ, Mularoni A, Imburgia A, Avoni L, D’Eliseo D, Schiano-Lomoriello D. Intraocular lens power calculation in eyes with keratoconus. J Cataract Refract Surg 2019; 45:576-581. [DOI: 10.1016/j.jcrs.2018.11.029] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/16/2018] [Accepted: 11/22/2018] [Indexed: 11/25/2022]
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