Stromal wound healing explains refractive instability and haze development after photorefractive keratectomy

Møller‐Pedersen, Torben; Cavanagh, Harrison D; Petroll, Walter M; Jester, James V.

doi:10.1016/s0161-6420(00)00142-1

Cited by 272 publications

(185 citation statements)

References 25 publications

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“…It has been recognized that the anterior stromal cell density decreases after PRK correction (15,25) , and the depletion of keratocytes in the anterior stroma has been shown to be higher after MMC application (14) . It is also known that stromal corneal fibroblasts and keratocytes contribute to the total amount of ocular light scattered (26) . Thus, we believe that the observed changes in ocular straylight values in the early two-month period after PRK occurred due to a reduction of the anterior stromal cell density.…”

Section: Discussionmentioning

confidence: 99%

Intraocular straylight before and after low myopic photorefractive keratectomy with and without mitomycin C

Torricelli¹,

Parede²,

Netto³

et al. 2016

Arquivos Brasileiros De Oftalmologia

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Purpose: To evaluate ocular straylight before and after photorefractive keratectomy (PRK) for low myopia with and without topical mitomycin (MMC) treatment. Methods: Patients who underwent PRK for low myopia were enrolled into the study. PRK without MMC was performed in 21 eyes (12 patients), whereas PRK with topical 0.02% MMC was performed in 25 eyes (14 patients). Both groups were treated using the NIDEK EC5000 excimer laser. Measurements were performed using the C-Quant straylight meter preoperatively and at two and four months postoperatively. Results: The mean patient age was 30 ± 4 years, and the mean spherical equivalent refractive error was -2.2 ± 0.75 D. The mean preoperative intraocular straylight values were 1.07 ± 0.10 in the PRK without MMC group and 1.07 ± 0.11 log(s) in the PRK with topical MMC group. At two months after surgery, there was a decrease in mean intraocular straylight values in both groups. However, a significant difference was only reached in the PRK with MMC group [0.98 ± 0.09 log(s), p=0.002] compared with preoperative values, which was likely due to a greater scatter of measurements in the PRK without MMC group [1.03 ± 0.13 log(s), p=0.082]. At four months postoperatively, ocular straylight values were not significantly different compared with those at baseline in either the PRK without MMC group [1.02 ± 0.14 log(s), p=0.26] or in the PRK with topical MMC group [1.02 ± 0.11 log(s), p=0.13]. Conclusion: PRK for low myopia decreases ocular straylight, and MMC application further reduces straylight in the early postoperative period. However, ocular straylight values do not significantly differ at four months after surgery compared with those at baseline. (1,02 ± 0,14 log(s), p=0,26) quanto no grupo com MMC tópica (1,02 ± 0,11 log(s), p=0,13). Keywords meses da cirurgia houve uma diminuição na média da dispersão de luz intraocular em ambos os grupos. Entretanto uma diferença estatisticamente significante, comparado com os valores préoperatórios, foi observada apenas no grupo PRK com MMC (0,98 ± 0,09 log(s), p=0,002), provavelmente devido as medidas com maior espalhamento de luz no grupo sem MMC (1,03 ± 0,13 log(s), p=0,082). Após 4 meses de pósoperatório, os valores de dispersão de luz não apresentavam diferença estatisticamente significantes quando comparados com os valores iniciais, tanto no grupo sem MMC Conclusão: PRK para baixa miopia diminui a dispersão de luz ocular e a aplicação de MMC contribui para uma ainda menor dispersão de luz no período pósoperatório inicial. Entretanto, quatro meses após a cirurgia a dispersão de luz intraocular não é significantemente diferente das medidas préoperatórias.Descritores: Ceratectomia fotorrefrativa; Miopia/cirurgia; Mitomicina; Cicatrização this as a troubling symptom, at least in the early postoperative period, following procedures such as photorefractive keratectomy (PRK).Disability glare is the veiling of vision due to the forward scattering of light in the eye (5,6) . Straylight is a known source of disability glare (7) . Th...

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Section: Discussionmentioning

confidence: 99%

Intraocular straylight before and after low myopic photorefractive keratectomy with and without mitomycin C

Torricelli¹,

Parede²,

Netto³

et al. 2016

Arquivos Brasileiros De Oftalmologia

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“…The severity of haze has been related to the photoablation depth in higher corrections. Thereby, higher corrections involve an increase in cellularity, and hypercellularity produces increased haze (Moller-Pedersen et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

“…Based on our previous studies, loss of transmittance is related to increased light scattering (Mar et al, submitted for publication). The photons travel through the cell and the cellular components scatter light depending on their size and shape and the size and shape of its organelles (Moller-Pedersen, 2004;Moller-Pedersen et al, 2000). Fibroblasts and myofibroblasts are larger and present greater quantities of organelles than keratocytes; in addition, myofibroblasts have bundles of actin microfilaments (Fig.…”

Section: Discussionmentioning

confidence: 99%

Wound healing following refractive surgery in hens

Martínez-García¹,

Merayo‐Lloves

Blanco–Mezquita

et al. 2006

Experimental Eye Research

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The wound-healing response is critical to the outcome of refractive surgery and studying wound healing contributes to an understanding of the pathophysiology of other corneal injuries. Animal models allow research to be conducted with sufficient samples and under controlled parameters. We studied the hen to determine the healing process from clinical, biophysical, and biological standpoints after photorefractive keratectomy (PRK). PRK (ÿ6.0 diopters) was performed in hen eyes. At 3, 6, 12, 24, 48, and 72 h and 5, 7, 15, 30, and 60 days postoperatively, we studied the clinical follow-up, objective measurements of light transmission (direct transmittance), apoptosis by TUNEL assay, proliferation by immunocytochemical analysis of 5-bromo-2 0 -deoxyuridine, and expression of alpha smooth muscle actin (SMA) in myofibroblasts in the corneas. Hen corneas reepithelialize quickly. Haze developed from 5 to 60 days after surgery and was correlated with the appearance and finalization of the expression of SMA. The direct transmittance of light was low during the first 15 days and improved at 30 and 60 days. TUNEL-positive cells were observed 3 h after surgery and the numbers decreased thereafter. Epithelial proliferation began at 12 h and was greater at 48 h, while stromal cell proliferation began at 24 h and was greater at 72 h. The hen cornea is anatomically similar to the human cornea, and the manner in which it heals is a good model for studying different surgical techniques and pharmacologic assays.

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“…25,26 Cornea oedema An understanding of structure and transparency changes when the cornea swells is dependent on our knowledge of where imbibed water is situated, both at the level of the tissue as a whole and within the lamellae themselves.…”

Section: Direct Summation Of Fields Methodsmentioning

confidence: 99%

“…40 Various authors have ascribed the observed haze to irregularities in the epithelium, 41,42 to subepithelial deposits, 43 to the presence of vacuoles, 44 to the deposition of poorly organised collagen, 45,46 or to the presence of activated keratocytes. 25,26 However, none of these suggestions have been experimentally or theoretically shown to account for increased light scattering. We have used PTK in rabbits to predict the percentage transmission of visible light through the newly deposited collagen using the DSF method and hence to see if this collagen could account for the observed haze.…”

Section: Phototherapeutic Keratectomymentioning

confidence: 99%