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Title
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Complications of laser refractive surgery : prevention, diagnosis, and treatment
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Author
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Abstract
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| Laser refractive surgery helps patients with refraction errors to correct their vision acuity without spectacles or contact lenses. By applying a high-powered laser beam to the cornea, the tissue can be remodeled, altering the corneal refraction to allow a clear image to be projected on the retina. Although these techniques have been continuously improved over the past three decades, laser refractive surgery still sees some complications. The most serious complications are postoperative ectasia and postoperative infectious keratitis. Keratoconus is a strong contraindication for laser refractive surgery as the laser ablation can trigger postoperative ectasia. This ectasia is caused by the decompensation of the corneal material properties and is diagnosed based on postoperative tomography. The main purpose of preoperative examinations is therefore to screen for keratoconus using devices based such as Scheimpflug tomography, optical coherence tomography (OCT), and air-puff tonometry. These devices use different techniques to assess the in-vivo shape and material properties of the cornea for signs of early keratoconus. OCT provides higher resolution images than Scheimpflug tomography, which allows studying the corneal epithelial layer thickness. This can be used detect keratoconus early and tp stage the condition using artificial intelligence (AI). Although OCT only provides morphological information, its abilities can be extended by combining it with an air-puff device and AI to achieve a very high diagnostic sensitivity for the earliest form of keratoconus, referred to as forme fruste keratoconus (FFKC). Postoperative ectasia is typically treated using corneal cross-linking (CXL), which strengthens the impaired mechanical properties of the cornea. This technique comes in two variants in which the corneal epithelium is either removed (epi-off) or left in place (epi-on). Although epi-off was considered more effective, modern epi-on protocols have overcome limitations such as oxygen diffusion, riboflavin penetration, and UV-A light blocks to ensure a similar biomechanical effect as the accelerated epithelium-off CXL protocol. Postoperative infectious keratitis is rare and is cause by the laser ablation that makes the cornea thinner and more susceptible to perforation. Photo-activated chromophore for keratitis-CXL (PACK-CXL) treats infectious keratitis from different perspectives, but the protocols should be updated based on our keratoconus-oriented treatment experience. The PACK-CXL protocols may be accelerated while maintaining the same bacterial killing rate. In conclusion, the focus of laser refractive surgery complications should still be on prevention, both for ectasia and infectious keratitis. Both can seriously threaten vision, but properly adjusted protocols for CXL and PACK-CXL can help to improve prognosis. |
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Language
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English
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Publication
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Antwerp
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University of Antwerp, Faculty of Medicine and Health Sciences
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2023
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Volume/pages
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230 p.
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Note
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Koppen, Carina [Supervisor]
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Hafezi, Farhad [Supervisor]
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Rozema, Jos J. [Supervisor]
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Full text (open access)
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