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Epithelial basement membrane dystrophy(EBMD)is a common anterior corneal dystrophy with hidden and easily missed clinical manifestations. Patients usually complain of mild blurred vision or foreign body sensation, or occasional pain at night or immediately after opening the eyelid in the morning. Slit-lamp examination revealed irregular, amorphous corneal surfaces, fingerprint-like linear lesions, and punctate or bubble-like lesions. EBMD has a significant impact on preoperative biometrics and intraocular lens power calculation, which can lead to inaccurate measurement and postoperative refractive accident, and cataract surgeons must be aware of this. This article reviews recent research and conference reports on the impact of EBMD on cataract surgery, as a reference for refractive cataract surgeons, thus improving the preoperative diagnosis and detection rate, so as to provide the optimal treatment plan for patients.
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Basement membranes (BMs) are highly specialized extracellular matrices, which widely exist in various tissues of the human body.Since BMs were discovered in the 19th century, the structures and functions of BMs have been gradually recognized.The corneal epithelial basement membrane (EBM) participates in the regulation of corneal scar formation by limiting the activation of fibrotic factors.After an injury, the formation and duration of corneal stromal fibrosis are determined by the degree of EBM injury and the speed of EBM regeneration.Corneal epithelium and stroma participate in the process of EBM regeneration.The rapid regeneration of corneal epithelium is beneficial to the assembly of the nascent EBM.Functional corneal stromal cells provide the rest assembly components for the nascent EBM.The regular surface of corneal stroma is beneficial to the continuous regeneration of EBM, which provides positions for stromal cells.This paper reviewed the understanding of BMs, the composition and function of EBM, the relationship between corneal EBM regeneration and corneal stroma remodeling, the influencing factors of EBM regeneration and related clinical treatment methods to discuss the influence of corneal epithelium and stroma on EBM regeneration.
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Objective@#To describe the procedure for early corneal epithelial basement membrane(EBM) repair and regeneration in rabbits with corneal penetrating injury.@*Methods@#Forty-two New Zealand white rabbits were divided into modeling 1-, 3-, 5-, 7-, 14-, 21-, and 30-day groups using a random number table method, with 6 rabbits in each group; the right eyes were selected as the experimental eyes.Another 6 New Zealand white rabbits without any treatment were taken as the normal control group.A 2.0-mm trephine was used to ablate a full-thickness button of the central corneal tissue of each rabbit.The corneas were observed by slit lamp biomicroscopy at the respective time points after the trephined injury.Corneal epithelial fluorescein staining was used to evaluate re-epithelialization with Image J software and haze grading was evaluated with the Fantes classification.Hematoxylin-eosin staining was used to observe the healing process of the cornea.Transmission electron microscopy was conducted to assess the regeneration of the EBM and the reconstruction of the cornea.The study protocol was approved by the Ethics Committee of Guangxi Medical University (No.201811031). The use and care of the experimental animals complied with the Statement for the Use of Animals in Ophthalmic and Vision Research.@*Results@#The corneal epithelial fluorescein areas in modeling 1-, 3-, 5-, 7-, and 14-day group were (4.00±0.10), (3.11±0.10), (2.00±0.06), (0.90±0.04) and (0.67±0.03)mm2, respectively, with a significant difference among them (F=3 398.88, P<0.01). With the increasing of time after modeling, the corneal epithelium fluorescein area was gradually reduced, showing significant differences between any two groups (all at P<0.05), and the staining was disappeared at 21 and 30 days after modeling.The corneal haze grades were 3.44±0.53, 0.67±0.25, 1.33±0.50, 2.11±0.60, 2.44±0.53, 3.22±0.44 and 3.78±0.44 in modeling 1-, 3-, 5-, 7-, 14-, 21-, and 30-day group, respectively. The corneal opacity score gradually decreased during 1-5 days after modeling and gradually increased during 5-30 days after modeling, with a significant difference among them (F=51.182, P<0.01). Hematoxylin-eosin staining revealed that a fibrin clot formed in the wound area, and a single layer of epithelium covered the area at initial 3 days after modeling, and a large number of fibroblasts and some extracellular matrix were found at 5 days after modeling.At 21 and 30 days after modeling, the collagen fibers were tightly arranged in the anterior stroma.Transmission electron microscopy showed that the wound was filled with irregular collagen fibers and myofibroblasts.The stroma was remodeled at 21 days after modeling, and defective regeneration of the EBM was detected at 21 and 30 days after modeling.@*Conclusions@#Corneal fibrosis initiates after corneal penetrating injury in rabbits and gradually aggravates, the EBM regenerates defectively.
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Objective To describe the procedure for early corneal epithelial basement membrane (EBM) repair and regeneration in rabbits with corneal penetrating injury.Methods Forty-two New Zealand white rabbits were divided into modeling 1-,3-,5-,7-,14-,21-,and 30-day groups using a random number table method,with 6 rabbits in each group;the right eyes were selected as the experimental eyes.Another 6 New Zealand white rabbits without any treatment were taken as the normal control group.A 2.0-mm trephine was used to ablate a full-thickness button of the central corneal tissue of each rabbit.The corneas were observed by slit lamp biomicroscopy at the respective time points after the trephined injury.Corneal epithelial fluorescein staining was used to evaluate re-epithelialization with Image J software and haze grading was evaluated with the Fantes classification.Hematoxylin-eosin staining was used to observe the healing process of the cornea.Transmission electron microscopy was conducted to assess the regeneration of the EBM and the reconstruction of the cornea.The study protocol was approved by the Ethics Committee of Guangxi Medical University (No.201811031).The use and care of the experimental animals complied with the Statement for the Use of Animals in Ophthalmic and Vision Research.Results The corneal epithelial fluorescein areas in modeling 1-,3-,5-,7-,and 14-day group were (4.00±0.10),(3.11±0.10),(2.00±0.06),(0.90±0.04) and (0.67 ± 0.03)mm2,respectively,with a significant difference among them (F =3 398.88,P ＜ 0.01).With the increasing of time after modeling,the corneal epithelium fluorescein area was gradually reduced,showing significant differences between any two groups (all at P＜0.05),and the staining was disappeared at 21 and 30 days after modeling.The corneal haze grades were 3.44±0.53,0.67±0.25,1.33±0.50,2.11±0.60,2.44±0.53,3.22±0.44 and 3.78±0.44 in modeling 1-,3-,5-,7-,14-,21-,and 30-day group,respectively.The corneal opacity score gradually decreased during 1-5 days after modeling and gradually increased during 5-30 days after modeling,with a significant difference among them (F =51.182,P＜0.01).Hematoxylin-eosin staining revealed that a fibrin clot formed in the wound area,and a single layer of epithelium covered the area at initial 3 days after modeling,and a large number of fibroblasts and some extracellular matrix were found at 5 days after modeling.At 21 and 30 days after modeling,the collagen fibers were tightly arranged in the anterior stroma.Transmission electron microscopy showed that the wound was filled with irregular collagen fibers and myofibroblasts.The stroma was remodeled at 21 days after modeling,and defective regeneration of the EBM was detected at 21 and 30 days after modeling.Conclusions Corneal fibrosis initiates after corneal penetrating injury in rabbits and gradually aggravates,the EBM regenerates defectively.