Evaluation of the Pentacam Ray Tracing Method for the Measurement of Central Corneal Power After Myopic Photorefractive Keratectomy

Oh, Jung Hyun; Kim, Sung Hyun; Chuck, Roy S.; Park, Keun

doi:10.1097/ico.0000000000000034

Cited by 29 publications

(31 citation statements)

References 15 publications

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“…Assessing corneal power in patients who have previously undergone keratorefractive surgery has been the subject of a significant amount of research over the past several years . Keratometry and computerised videokeratography fail to provide correct measurements of the corneal power after corneal surgery.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, keratometers and topographers have a central scotoma. The inherit limitations explain why these instruments give inaccurate measurements after corneal surgery . Many formulas have been suggested through the years to circumvent these issues, with The Clinical History Method being one of the most recognised calculations .…”

Section: Introductionmentioning

confidence: 99%

“…Recent studies suggest that devices employing Scheimpflug technology, such as the Sirius (Costruzione Strumenti Oftalmici, Florence, Italy), the Galilei (Ziemer Ophthalmic Systems AG, Port, Switzerland), and the Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany), may be used to accurately measure the effective refractive change for surgically treated corneas. The Pentacam HR (Oculus Optikgeräte GmbH) device uses a rotating Scheimpflug camera and presents several methods for calculating corneal power including Gaussian optics and ray tracing (http://www.pentacam.com/sites/calc_corneal_power.php#ptop).…”

Section: Introductionmentioning

confidence: 99%

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Assessing the corneal power change after refractive surgery using Scheimpflug imaging

Gyldenkerne

Ivarsen

Hjortdal

2015

Ophthalmic Physiologic Optic

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessing the corneal power change after refractive surgery using Scheimpflug imaging

Gyldenkerne

Ivarsen

Hjortdal

2015

Ophthalmic Physiologic Optic

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“…TCRP K1 and TCRP K2 with their respective meridians were used for SIA calculations from 3 mm and 4 mm zones. For SIA using both TCRP3 and TCRP4, significant differences were found between right and left eyes, with a dorsonasal incision creating more SIA than a dorsotemporal incision (Table ).…”

Section: Resultsmentioning

confidence: 99%

“…In this study, TCRP at the 3 mm and 4 mm zones was evaluated with repeated measures and used in SIA calculations. While the 3 mm zone is supposed to most closely match the standard zone of keratometric analysis, several human studies have evaluated both areas .…”

Section: Discussionmentioning

confidence: 99%

Surgically induced astigmatism in canines following sutured dorsonasal vs dorsotemporal clear corneal incisions

Pederson

Cleymaet

Hess

et al. 2019

Veterinary Ophthalmology

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Objectives: To investigate use of the Pentacam® HR for evaluation of surgically induced corneal astigmatism (SIA) in canines undergoing bilateral phacoemulsification and determine differences between dorsonasal and dorsotemporal clear corneal incisions. Animals: Client-owned canines undergoing bilateral phacoemulsification. Procedures: Patients received anterior segment imaging pre-operatively, immediately post-operatively, and 2-4 months post-operatively (follow-up). Total corneal refractive power was used to determine SIA. Surgically induced astigmatism was compared between right and left eyes, representing dorsotemporal and dorsonasal incisions, respectively. Repeated measures analyses were used between time points and paired t test compared SIA between eyes. Results: Complete imaging series were obtained for seven patients. Follow-up imaging occurred at a median of 112 days (range 60-132 days) post-operatively. For repeated measures analyses, significant differences were found between pre-and immediate post-operative values (P < 0.01), and between immediate post-operative and follow-up values (P < 0.01). There was no significant difference between preoperative and follow-up values. Surgically induced astigmatism was significantly different between right and left eyes, with values of 2.01 ± 1.24 D and 3.05 ± 1.58 D at 3 mm radius (P < 0.05), and 2.04 ± 1.18 D and 3.06 ± 1.27 D at 4 mm radius (P < 0.05) for dorsotemporal and dorsonasal incisions, respectively. Conclusions: Preliminary investigation revealed improvement of corneal SIA 2-4 months post-operatively, but development of significantly more SIA in dorsonasal vs dorsotemporal incisions. This prompts consideration of patient or microscope rotation to create a more dorsotemporal incision when possible. K E Y W O R D S canine, clear corneal incision, cornea, Pentacam, phacoemulsification, surgically induced astigmatism 800 | PEDERSON Et al.

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Panacea IOL Calculator

Flikier

2024

Intraocular Lens Calculations

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The Panacea formula is a theoretical vergence thin lens formula that can calculate the spherical and toric intraocular lens (IOL) power. There are some relevant differences over other similar IOL formulas. The lens position algorithm is based on four biometric variables: axial length, keratometry, anterior chamber depth, and lens thickness. Keratometry is modified as a function of anterior to posterior curvature ratio to avoid errors in altered corneas. The axial length is transformed correcting the bias in extreme cases. The corneal power is optimized taking into account the asphericity and the anterior-to-posterior curvature ratio. Several studies have proved better results than other IOL formulas.

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Evaluation of the Pentacam Ray Tracing Method for the Measurement of Central Corneal Power After Myopic Photorefractive Keratectomy

Abstract: Although postoperative TCRPs showed no significant difference with CHM, delta-MR was still underestimated after myopic PRK.

Cited by 29 publications

References 15 publications

Assessing the corneal power change after refractive surgery using Scheimpflug imaging

Assessing the corneal power change after refractive surgery using Scheimpflug imaging

Surgically induced astigmatism in canines following sutured dorsonasal vs dorsotemporal clear corneal incisions

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