Interferometric technique to measure biomechanical changes in the cornea induced by refractive surgery

Jaycock, Philip D.; Lobo, Leon; Ibrahim, Jamal S.; Tyrer, John R.; Marshall, John

doi:10.1016/j.jcrs.2004.10.038

Cited by 104 publications

(75 citation statements)

References 24 publications

(25 reference statements)

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“…Combined with a LASIK history, the patient's cornea may have been compromised and susceptible to disruption. Myopic LASIK severs collagen bands and thins the cornea, reducing its integrity and strength [10]. The tensile strength of a cornea with a LASIK flap may be reduced significantly in comparison to a normal cornea [11].…”

Section: Discussionmentioning

confidence: 99%

Fulminant Culture Negative Endophthalmitis as a New Entity, Toxic Posterior Segment Syndrome?

LoBue¹

2016

AOVS

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Purpose: To report an unusual case of sterile versus bacterial endophthalmitis in a post cataract surgery wound leak Subject: A 58-year-old woman with a past eye medical history of LASIK underwent routine cataract extraction (CE) with lens implant of left eye and presented with a delayed, fulminant endophthalmitis OS on day 19 post CE or 3.5 days after the development of a post-op wound leak. Eye examination OS showed visual acuity (VA) of bare LP. Slit lamp examination revealed an edematous cornea with a 1mm hypopyon. A large amount of exudate filled the entire posterior segment.Results: Patient was treated with intravitreal vancomycin (1mg) and ceftazidime (2mg) and pars plana vitrectomy. Vitreal cultures were negative, but initial clinical presentation mimicked a virulent strep, staph, or pseudomonas endophthalmitis. Her postoperative course showed gradual improvement, reaching baseline VA of 20/30 OS with a normal eye exam. Conclusion:Although culture-negative bacterial endophthalmitis is common, good visual outcomes with virulent bacteria is not. Fulminant culture-negative endophthalmitis with a good visual outcome may be due to a sterile toxic insult, a variation of TASS which we call Toxic Posterior Segment Syndrome (TPSS).

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Section: Discussionmentioning

confidence: 99%

Fulminant Culture Negative Endophthalmitis as a New Entity, Toxic Posterior Segment Syndrome?

LoBue¹

2016

AOVS

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“…ESPI has been used to examine the effects of microkeratome incisions on the biomechanical behaviour of the cornea. 18 Radial speckle shearing interferometry has been used to show the effect of using different parameters during LASIK surgery such as depth and angles of incisions. 19 It has also been used to determine the changes in Young's modulus of the cornea during ageing 20 and following crosslinking.…”

Section: Laser Interferometrymentioning

confidence: 99%

The role of light in measuring ocular biomechanics

Wilson

Marshall

Tyrer

2016

Eye

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The cornea is a highly specialised tissue with a unique set of biomechanical properties determined by its complex structure. The maintenance of these mechanical properties is fundamental to maintain clear vision as the cornea provides the majority of the focussing power of the eye. Changes to the biomechanics of the cornea can occur during ageing, disease, and trauma, or as a result of surgery. Recently there has been increased interest in the mechanical properties of the cornea as knowledge of these properties has significant implications for the improvement of current ocular treatments including PRK and LASIK, and for the diagnosis and tracking of corneal diseases and therapy such as keratoconus and crosslinking. Biomechanics are also important for the development of artificial corneal replacements. This paper describes the use of a novel, non-destructive lateral electronic speckle pattern shearing interferometer (ESPSI). The data generated via this technique give a full-field view of the mechanical response of the cornea under simulated physiological loading conditions, and enables strain and displacement to be determined in three planes. The technique allows corneal stiffness to be quantified and enables changes and non-homogeneities that occur due to surgery or disease to be detected.

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“…Pre-and postcharacterization of the cornea is also useful in understanding the healing process of the eye. 16 A final example for the use of a high-resolution corneal topographer is also the motivation for the instrument described in this paper: soft contact lens metrology. The value of the contact lens market in the United States is placed at about $2.5 billion, with 39.2 million contact lens wearers, and an international market that is estimated to be about three times larger.…”

Section: Introductionmentioning

confidence: 99%

Dual interferometer for dynamic measurement of corneal topography

Micali

Greivenkamp

2016

J. Biomed. Opt

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Abstract. The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface, where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. A dual interferometer system for measuring the dynamic corneal topography is designed, built, verified, and qualified by testing on human subjects. The system consists of two coaligned simultaneous phase-shifting polarization-splitting Twyman-Green interferometers. The primary interferometer measures the surface of the tear film while the secondary interferometer tracks the absolute position of the cornea, which provides enough information to reconstruct the absolute shape of the cornea. The results are high-resolution and high-accuracy surface topography measurements of the in vivo tear film and cornea that are captured at standard camera frame rates.

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Interferometric technique to measure biomechanical changes in the cornea induced by refractive surgery

Abstract: Results show that in the formation of the microkeratome flap, collagen fibers are severed and minimal biomechanical loading is distributed through the flap. Corneal biomechanical integrity is compromised after microkeratome incisions.

Cited by 104 publications

References 24 publications

Fulminant Culture Negative Endophthalmitis as a New Entity, Toxic Posterior Segment Syndrome?

Fulminant Culture Negative Endophthalmitis as a New Entity, Toxic Posterior Segment Syndrome?

The role of light in measuring ocular biomechanics

Dual interferometer for dynamic measurement of corneal topography

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