Human Excmier Laser Keratectomy: Clinical and Histopathologic Correlations

doi:10.1016/S0161-6420(94)31202-4

Ophthalmology

Volume 101, Issue 6, June 1994, Pages 979-989

https://doi.org/10.1016/S0161-6420(94)31202-4 Get rights and content

Purpose: To understand the healing capabilities of the diseased human cornea after excimer laser photoablation by morphologic analysis of laser-treated corneas.

Methods: Twelve corneal specimens were obtained 5 to 16 months after lamellar or full-thickness keratoplasty following phototherapeutic keratectomy for undercorrected myopic epikeratoplasty (2 eyes), corneal leukomas (2 eyes), herpes zoster corneal scarring (1 eye), band keratopathy (2 eyes), adenoviral subepithelial opacity (1 eye), keratoconus (1 eye), herpes simplex corneal scarring (2 eyes), granular corneal dystrophy (1 eye), and recurrent lattice dystrophy (1 eye). The morphology of the corneas was examined by light and electron microscopy.

Results: Epithelial hyperplasia, abnormal epithelial attachment, and disorganized stromal matrices were observed. Evidence of residual disease frequently observed in these specimens indicated that the pathology either was not excised at the time of laser keratectomy or was recurrent.

Conclusions: The response of the diseased cornea to excimer laser treatment has similar characteristics to the responses previously observed in animal studies. Incomplete ablation of diseased tissue and/or recurrence of the initial disease was the major reason for failure of the treatment. Possible causes for the inability to remove diseased tissues and superficial scars with the excimer laser include (1) insufficiently achieved ablation depth and/or diameter and (2) decreased laser ablation rates of scarred cornea.

References (35)

DS Aron Rosa et al.
Wound healing following excimer laser radial keratotomy
J Cataract Refract Surg
(1988)
T Seiler et al.
Excimer laser keratectomy for correction of astigmatism
Am J Ophthalmol
(1988)
DM Taylor et al.
Experimental corneal studies with the excimer laser
J Cataract Refract Surg
(1989)
DS Aron Rosa et al.
Corneal wound healing after excimer laser keratotomy in a human eye
Am J Ophthalmol
(1987)
DM Taylor et al.
Human excimer laser lamellar keratectomy. A clinical study
Ophthalmology
(1989)
JS Englanoff et al.
In situ collagen gel mold as an aid in excimer laser superficial keratectomy
Ophthalmology
(1992)
MB McDonald et al.
One-year refractive results of central photorefractive keratectomy for myopia in the nonhuman primate cornea
Arch Ophthalmol
(1990)
RW Zabel et al.
Myopic excimer laser keratectomy: a preliminary report
Refract Corneal Surg
(1990)
NA Sher et al.
Clinical use of the 193-nm excimer laser in the treatment of corneal scars
Arch Ophthalmol
(1991)
GL Goodman et al.
Corneal healing following laser refractive keratectomy
Arch Ophthalmol
(1989)

JC Liu et al.

Myopic excimer laser photorefractive keratectomy: an analysis of clinical correlations

Refract Corneal Surg

(1990)

DS Gartry et al.

Photorefractive keratectomy with an argon fluoride excimer laser: a clinical study

Refract Corneal Surg

(1991)

SJ Tuft et al.

Corneal repair following keratectomy. A comparison between conventional surgery and laser photoablation

Invest Ophthalmol Vis Sci

(1989)

KD Hanna et al.

Corneal stromal wound healing in rabbits after 193-nm excimer laser surface ablation

Arch Ophthalmol

(1989)

N SundarRaj et al.

Healing of excimer laser ablated monkey corneas. An immunohistochemical evaluation

Arch Ophthalmol

(1990)

G-B van Setten et al.

Expression of tenascin and fibronectin in the rabbit cornea after excimer laser surgery

Graefes Arch Clin Exp Ophthalmol

(1992)

PS Binder et al.

Highvoltage electron microscopy of normal human cornea

Invest Ophthalmol Vis Sci

(1991)

Cited by (39)

Isolated Bowman layer transplantation to manage persistent subepithelial haze after excimer laser surface ablation
2010, Journal of Cataract and Refractive Surgery
Citation Excerpt :
Without this barrier, epithelial–stromal interaction is recognized as inducing an abnormal wound-healing response, clinically observed as subepithelial stromal scarring.4,7–10 Nonanatomical organization of the stromal lamellae may interfere with the concept of “constructive interference” by which a normal cornea obtains its optical transparency.4,7–10 The application of mitomycin 0.02% has been described as a method to reduce the epithelial–stromal wound-healing response after secondary haze removal.15–18
In a 21-year-old patient with persistent dense subepithelial haze after photorefractive keratectomy, unresponsive to retreatment, a stromal flap, 9.0 mm in diameter and approximately 60 μm in thickness, was excised and an unsutured 9.0 mm donor Bowman layer was transplanted onto the stromal bed. The corrected distance visual acuity improved from 20/40 (0.5) before surgery to 20/18 (1.2) with a scleral-supported contact lens 2 months after transplantation. With optical coherence tomography, the transplanted Bowman layer was seen as a fine white line bordering the anterior host stroma. No recurrence of stromal haze was seen throughout the 6-month follow-up. Isolated Bowman layer transplantation may be a new technique for the management of anterior stromal opacities or complicated epithelial wound healing such as persistent corneal haze after excimer laser surface ablation.
No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes.
Effects of topical tranilast on corneal haze after photorefractive keratectomy
2005, Journal of Cataract and Refractive Surgery
Citation Excerpt :
Therefore, the mechanism of corneal haze and prophylactic therapies have been investigated, and new therapeutic agents have been proposed and tested.26–36 Previous histologic studies indicated that corneal haze was restricted to the area directly beneath the ablated area and contained some atypical extracellular matrix components including type III, IV, and VII collagens, fibronectin, laminin, and tenascin, along with proteoglycans and proliferating keratocytes.37–39 A variety of growth factors and cytokines including epidermal growth factor, keratinocyte growth factor, fibroblast growth factor, and vascular endothelial growth factor as well as TGF-β are known to regulate this corneal stromal wound-healing process after PRK.9–11
To determine whether topical tranilast might reduce corneal haze through suppression of transforming growth factor (TGF)-β1 synthesis in keratocyte after photorefractive keratectomy.
Department of Ophthalmology, Korea University College of Medicine, Seoul, Republic of Korea.
Photorefractive keratectomy was performed on 48 eyes of 28 white rabbits and 24 eyes in a tranilast group were treated with tranilast solution, and the other 24 eyes in control group were treated with saline after laser ablation. The grades of corneal haze at 1, 2, 4, and 8 weeks after surgery were evaluated in 10 eyes of each group for comparison. Immunohistochemistry was performed on 10 eyes of each group, and Western blot analysis was done on 4 eyes of each group for studying TGF-β1 expression at postoperative day 7.
There was no statistically significant difference in corneal haze between 2 groups from week 1 to week 4 after surgery, but a significant difference was found at week 8 after photorefractive keratectomy (P = .02). The mean number of keratocytes that expressed TGF-β1 in the tranilast group was 58.3 (±17.2), which showed significant difference, compared with that of the control group, 104.5 (±23.0) (P<.01). Western blot analysis also revealed that the amount of TGF-β1 in tranilast group was slightly less than the control group.
Topical tranilast could reduce corneal haze by suppressing TGF-β1 expression in keratocytes after photorefractive keratectomy.
Phototherapeutic keratectomy in the treatment of lattice corneal dystrophy type I
2004, Journal Francais d'Ophtalmologie
La dystrophie cornéenne grillagée de type I est due à des mutations du gène BIGH3 et se caractérise par la présence de dépôts stromaux linéaires superficiels et profonds entraînant une baisse de l’acuité visuelle et/ou des épisodes d’érosions récidivantes. Dans les formes évoluées, une kératoplastie transfixiante était classiquement indiquée. Actuellement, la photo-ablation thérapeutique au laser excimer est une alternative à la chirurgie classique, utilisée pour traiter les opacités cornéennes superficielles.
Les auteurs présentent les résultats d’une série de 19 yeux atteints d’une dystrophie grillagée de type I (13 dystrophies primaires et 6 récidives sur greffons) et traités par cette technique (après avoir établi leur génotype et mesuré la profondeur des opacités centrales en caméra Scheimpflug).
La profondeur centrale des dépôts mesurée avec la caméra Scheimpflug est en moyenne de 74,14 ± 31,03 μm dans les dystrophies primaires et de 30,1 ± 10 μm dans les récidives. Nous avons noté une nette amélioration de l’acuité visuelle corrigée de loin, qui a progressé de 0,257 ± 0,120 à 0,600 ± 0,178 dès le troisième mois et s’est stabilisé à 0,684 ± 0,257 jusqu’au 36 mois. La profondeur d’ablation centrale moyenne est de 69 μm et l’hypermétropisation induite est de + 0,71 ± 1 D à 36 mois. Une disparition des ulcérations récidivantes est observée jusqu’au 30^e mois. Nous avons trouvé une corrélation statistiquement significative (r = 0,6776 ; p = 0,0109) entre le gain d’acuité visuelle (en lignes) et la profondeur des opacités (avec la caméra Scheimpflug).
Ces résultats confirment que la photokératectomie thérapeutique est efficace dans la dystrophie grillagée de type I.
Lattice corneal dystrophy type I is an autosomal dominant corneal dystrophy caused by allelic mutations of the BIGH3 gene. Type I dystrophy is recognized clinically by the characteristic net of linear opacities within the corneal stroma that results from an accumulation of amyloid. This study was designed to evaluate the therapeutic potential of phototherapeutic keratectomy (PTK) for the treatment of lattice corneal dystrophy type I.
PTK was performed with the Chiron Technolas Chiron Keracor 217c on a series of 19 eyes of 13 patients with lattice dystrophy type I. Mean patient age was 38.9 years. The mean follow-up period was 36 months. Localization of central opacities was determined by analyzing Scheimpflug images. The changes in spherical equivalent and best corrected visual acuity were evaluated at 1, 3, 6, 9, 12, 18, 24 and 36 months.
The central depth of the deposits measured with the Scheimpflug camera was on average 74.14±31.03μm in the primary dystrophies and 30.1±10μm in graft recurrence. We noted a clear improvement in visual acuity, which increased by 0.257±0.120 to 0.600±0.178 as of the 3rd month and stabilized at 0.684±0.257 until the 36th month. A disappearance of repeating ulcerations was observed at month 30. We found a statistically significant correlation (R=0.6776; p=0.0109) between the improvement in vision (in lines) and the depth of opacities (with the Scheimpflug camera). The mean hyperopic shift caused by photoablation (69±15±μm) was +0.71±1 D at 36 months.
These results confirm that PTK is an effective method of managing corneal lattice dystrophy type I.
Late corneal scarring after retinal detachment surgery 42 months after photorefractive keratectomy
2004, Journal of Cataract and Refractive Surgery
A 42-year-old man had uneventful bilateral nonsimultaneous photorefractive keratectomy (PRK) for severe myopia. Thirty-nine months after the procedure, the patient presented with a retinal detachment (RD) in the right eye. Cerclage, vitrectomy, endolaser, and intravitreal silicone oil tamponade were performed, and the RD was successfully repaired. Three months after vitrectomy and 42 months after PRK, the patient complained of visual impairment in the right eye and photophobia. On slitlamp examination, marked reticular scarring of the central anterior cornea was observed. The occurrence of late-onset corneal haze highlights the need for special attention to patients who have vitrectomy after PRK.
Laser in situ keratomileusis flap tear during lifting for enhancement in the presence of post-photorefractive keratectomy corneal haze
2004, Journal of Cataract and Refractive Surgery
A patient who had photorefractive keratectomy for low myopia 6 years earlier had an enhancement by hyperopic laser in situ keratomileusis (LASIK). Moderate reticular corneal haze developed after LASIK. An attempted flap lift 4 months after LASIK resulted in a flap tear at the edge of the zone of corneal haze. Because haze can indicate an area of exuberant wound healing that can result in flap adhesion to the bed, recutting a LASIK flap may be safer than lifting it in the presence of haze.
Laser in situ keratomileusis in human corneas: New organ culture model
2004, Journal of Cataract and Refractive Surgery
Purpose: To establish an in vitro model of laser in situ keratomileusis (LASIK) in human donor eyes and to test its validity in comparison with animal models.
Setting: Department of Anatomy, Friedrich-Alexander Unviersity, Erlangen, Germany.
Methods: Laser in situ keratomileusis was performed on 20 organ-cultured human corneal buttons. The excimer laser ablations ranged from 0 to 12.0 diopters. The corneas were maintained in culture for up to 6 months and then evaluated with light microscopy and transmission electron microscopy. In addition, corneal sections were immunohistochemically stained for collagen type III, laminin, and fibronectin. The main outcome measures were the ultrastructural and immunohistochemical features of the stromal incision interface.
Results: Ultrastructural investigations in the peripheral cornea revealed a disarrangement of collagen fibers, indicating scar formation. These findings were not observed in the central area. Immunohistochemical staining for fibronectin and collagen type III was detected over the entire stromal incision interface, whereas laminin staining was related to the ingrowth of epithelial cells.
Conclusions: The morphological changes after LASIK in an organ culture model can simulate the in vivo situation. Therefore, this model appears appropriate to use in further study of corneal wound-healing changes after LASIK.

View all citing articles on Scopus

: Presented as a poster at the American Academy of Ophthalmology Annual Meeting, Dallas, November 1992.

View full text

Human Excmier Laser Keratectomy: Clinical and Histopathologic Correlations

J Cataract Refract Surg

Am J Ophthalmol

J Cataract Refract Surg

Am J Ophthalmol

Ophthalmology

Ophthalmology

One-year refractive results of central photorefractive keratectomy for myopia in the nonhuman primate cornea

Arch Ophthalmol

Myopic excimer laser keratectomy: a preliminary report

Refract Corneal Surg

Clinical use of the 193-nm excimer laser in the treatment of corneal scars

Arch Ophthalmol

Corneal healing following laser refractive keratectomy

Arch Ophthalmol

Myopic excimer laser photorefractive keratectomy: an analysis of clinical correlations

Refract Corneal Surg

Photorefractive keratectomy with an argon fluoride excimer laser: a clinical study

Refract Corneal Surg

Corneal repair following keratectomy. A comparison between conventional surgery and laser photoablation

Invest Ophthalmol Vis Sci

Corneal stromal wound healing in rabbits after 193-nm excimer laser surface ablation

Arch Ophthalmol

Healing of excimer laser ablated monkey corneas. An immunohistochemical evaluation

Arch Ophthalmol

Expression of tenascin and fibronectin in the rabbit cornea after excimer laser surgery

Graefes Arch Clin Exp Ophthalmol

Highvoltage electron microscopy of normal human cornea

Invest Ophthalmol Vis Sci