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AIM: To investigate the characteristics of changes in corneal epithelial thickness at the early postoperative stage of femtosecond assisted laser in situ keratomileusis(FS-LASIK)and its related influencing factors.METHOD: Retrospective study. A total of 120 patients(240 eyes)of myopia undergoing FS-LASIK from May 2021 to June 2022 were selected. The corneal epithelium thickness in the central area, inner ring area, and outer ring area of patients before and at 1d, 1wk, 1 and 3mo after operation was recorded. The relationship between the variation of corneal epithelium thickness and spherical equivalent, optical zone diameter, depth of cut and cutting ratio was analyzed by Pearson correlation.RESULTS: There was no statistical significance in corneal epithelial thickness in the central area, inner ring area and outer ring area at 1d after FS-LASIK compared with that before operation(P>0.05). At 1wk, 1 and 3mo after surgery, the corneal epithelial thickness in the central area, inner ring area and outer ring area increased compared with that before surgery, and the corneal epithelial thickness in the central area and inner ring area at 1 and 3mo after surgery was greater than that in the outer ring area(all P<0.05). The corneal epithelial thickness in the central, inner and outer ring areas of high myopia patients was thicker than that of low and moderate myopia patients before operation. The corneal epithelial thickness in the central, inner and outer ring areas of high myopia patients was thinner than that of low and moderate myopia patients at 1wk after operation(P<0.05). At 1 and 3mo after operation, the corneal epithelial thickness in the central, inner and outer ring areas of patients with high myopia was greater than that of patients with low and moderate myopia, and the changes of corneal epithelial thickness in the central, inner and outer ring areas were greater than those of patients with low and moderate myopia(P<0.05). The results of Pearson correlation showed that the changes in corneal epithelial thickness in the central and inner ring area were positively correlated with the corneal curvature, depth of cut and cutting ratio at 3mo after surgery, and they were in negative correlation with the age, spherical equivalent and optical zone diameter(P<0.05).CONCLUSION: The corneal epithelial thickness of patients thickened after the FS-LASIK operation, and it was correlated with age, corneal curvature, preoperative depth of cut, cutting ratio, spherical equivalent and the optic zone diameter.
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Purpose: To determine the pattern of corneal thickness and epithelial thickness distribution in healthy North Indian eyes by using spectral domain optical coherence tomography (SD?OCT). Methods: The observational study measured total corneal and epithelial thickness in the central 2 mm zone and eight sectors each in paracentral 2�mm (ring 1) and midperipheral 5�mm (ring 2) zones on SD?OCT. Results: The study included 67 eyes of 67 subjects with a male:female ratio of 32:35 and mean age of 25.04 � 4.54 years. The mean central corneal and epithelial thicknesses were 505.97 � 30.12 ?m and 60.48 � 8.37 ?m, respectively. The epithelium of inferior and infero?nasal sectors in ring 1 and inferior sector in ring 2 was significantly thicker than the radially opposite sectors of the respective rings (P = 0.001; P = 0.01 and P = 0.02, respectively). Sector?wise analysis did not reveal any significant correlation between the total corneal thickness and epithelial thickness (all P > 0.05) except in the outer superior sector where there was a weak positive correlation (r = 0.28, P = 0.02). Central epithelial thickness in males (60.59 � 9.28 ?m) and females (60.37 � 7.58 ?m) was comparable (P = 0.91). Pachymetry was thinnest in the inferior, inferonasal, and inferotemporal sectors in 44.79% of eyes (n = 30), while thinnest epithelium was seen in the superior, superonasal, and superotemporal quadrants in 50.75% of eyes (n = 34). Conclusion: The epithelial thickness distribution in this sample of topographically normal healthy North Indian eyes was nonuniform and independent of the underlying corneal thickness. Epithelium was thinner in the superior cornea, whereas total corneal thickness was minimum in the inferior part
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Purpose: To compare the corneal epithelial thickness among various age groups of normal Indians with 9?mm?wide optical coherence tomography scans. Methods: This cross sectional, observational study recruited patients in the age groups of 5–20 years (group 1), 21–35 years (group 2), 36–50 years (group 3), and more than 51 years (group 4). They underwent a detailed ophthalmic examination and were excluded if found to have any ocular surface or intraocular disease (except cataract and refractive error), undergone any ophthalmic surgery, corneal topography changes suggestive of corneal ectasias, or been continuously using any topical medication in either eye for a period of 3 months or more with the last instillation being within 1 month of inclusion in the study. Corneal epithelial thickness (CET) was measured using anterior segment optical coherence tomography (AS?OCT). The CET data from 25 sectors in each eye were analyzed for each age group. Results: There were 71 subjects in group 1, 76 subjects in group 2, 59 subjects in group 3, and 57 subjects in group 4. The mean (± standard deviation) ages in the groups 1, 2, 3, and 4 were 14.04 ± 5.10, 26.63 ± 4.71, 42.66 ± 3.92, and 61.65 ± 7.47 years, respectively. The central corneal thickness in all age groups was comparable. Maximum variance in CET parameters was seen in superior cornea. Conclusion: Central corneal thickness remains fairly stable over various age groups. The maximum variance in CET over age is seen in superior cornea. The findings from the Indian population correlate well with racially and geographically distinct subjects.
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@#AIM: To evaluate the changes in corneal epithelial thickness in corneal grafts following penetrating keratoplasty(PK)using anterior segment optical coherence tomography(AS-OCT), and to determine the role of epithelial thickness mapping in the early detection of graft rejection.<p>METHODS: This prospective comparative observational study included 20 patients(20 eyes)who underwent PK as study group and 16 patients(16 eyes)as control group. Corneal epithelial thickness mapping using AS-OCT was performed at 2wk, 1 and 3mo postoperatively. The parameters of epithelial thickness and distribution at the 3mo were compared to 16 patients(16 eyes)with allograft rejection following PK.<p>RESULTS: There was significant decline in the superior, inferior, maximum, and minimum epithelial thickness values of the study group at 1mo compared to 2wk(<i>P</i>=0.0004, 0.0001, 0.0001, 0.04 respectively)with no significant differences at 3mo compared to 1mo(<i>P</i>=0.4, 0.1, 0.8)respectively. Percentage of reduction in epithelial thickness was significantly higher than that of stromal thickness at 1mo compared to 2wk(<i>P</i>=0.04). The epithelial thickness maps showed a similar pattern of epithelial thickness distribution in the study group and in the rejection group showing considerable corneal edema. However, the allograft rejection group showed irregular pattern of epithelial thickness distribution in patients showing relatively higher central corneal thickness(CCT)as measured by pachymetry map.<p>CONCLUSION: Quantitative assessment of graft epithelial remodeling following PK shows early changes that contribute to significant corneal graft thickness changes. Changes in corneal epithelial thickness and pattern of distribution could be used as an indicator for corneal graft rejection.
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Objective To evaluate the application of the lower tear meniscus parameters measured by anterior segment optical coherence tomography (AS-OCT) in dry eye diagnosis.Methods A prospective randomized clinical controlled study was conducted.One hundred and thirteen dry eye patients (226 eyes) and 206 healthy volunteers (410 eyes) were enrolled from May 2015 to October 2016 in Shanxi Eye Hospital.The lower tear meniscus height (LTMH),lower tear meniscus area (LTMA),lower tear meniscus depth (LTMD),the corneal epithelial thickness (CET) at central 6 mm and the corneal thickness at central 6 mm were measured by RTVue-XR.The measurement results of the two groups were compared and the ROC curve was drawn.The dry eye group and the control group were divided into four age groups:＞20-30 years old,＞30-40 years old,＞40-50 years old and ＞50-60 years old.The changes of the parameters of the tear crescent in different age groups were compared.The changes of the lower tear meniscus with age were analyzed by linear regression equation.This study was approved by the Ethics Committee of Shanxi Eye Hospital.All operations were performed in accordance with the Helsinki Declaration,and written informed consent was obtained from each subject prior to any medical examination.Results The values of LTMH,LTMD and LTMA in dry eye group were (216.08±67.26) μm,(116.50±29.13) μm,(0.012 9±0.006 7) mm2,respectively,which were lower than (333.71±50.38) μm,(139.56±28.76) μm,(0.026 6±0.007 4)mm2 in control group,with statistical significance between the two groups (all at P＜0.05).The CET values of each quadrant in the central area of 2 mm,2-5 mm and 5-6 mm in the dry eye group were significantly lower than those in the control group,with statistically significant differences between the two groups (all at P＜0.05).The corneal thickness of central 5-6 mm region,1/8 above the superior nasal quadrant in the central range of 2-5 mm and 1/8 above the superior quadrant was not statistically significant between the two group (all at P＞0.05);the corneal thickness values of the other quadrant in dry eye groups were lower than those in control group,the differences were statistically significant (all at P＜0.05).The cut-off values of LTMH,LTMD,LTMA,CET at central 2 mm and corneal thickness at central 2 mm were 269.83 μm,122.02 μm,0.023 2 mm2,54.16 μm,531.50 μm,respectively,the sensitivity were 85.4％,88.9％ 96.5％,77.0％,66.8％,respectively;the specificity were 91.7％,70.5％,75.1％,56.8％,59.8％,respectively.The values of LTMA,LTMH and LTMD in each age group of dry eye group were significantly lower than those of the control group (all at P＜0.05).Linear regression analysis showed that LTMH was decreased by 3.966 μm and LTMD was decreased by 2.381 μm along with the increase of 1 year age in the control group,while LTMH was decreased by 1.293 μm along with the increase of 1 year age in the dry eye group.Compared with the control group,the area of the lower tear crescent image in the dry eye group was reduced,the boundary line was blurred and the coherence was poor in varying degrees,and the turbidity of the tear was increased.Conclusions AS-0CT can objectively reflect the shape of the lower tear meniscus parameters,central CET and central corneal thickness changes.The LTMH and LTMD of normal people are decreased with the increase of age.LTMA and LTMH have high diagnostic efficacy for dry eye and are expected to become one of the important methods for dry eye screening.
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OBJECTIVE@#To assess the lower tear meniscus height (LTMH), central tear film thickness (CTFT), and central corneal epithelial thickness (CCET) after deep anterior lamellar keratoplasty (DALK).@*METHODS@#This was a retrospective cross-sectional study of 20 patients who had DALK in one eye over a three-month period. LTMH, CTFT, and CCET of the operated eyes and the unoperated fellow eyes were measured using high-definition optical coherence tomography (HD-OCT). Correlations between three OCT assessments and age, time following surgery, graft size, bed size, and the number of residual sutures were analyzed.@*RESULTS@#Compared to patients with keratoconus, patients with other corneal conditions had significantly higher CCET in the fellow eye (P=0.024). For all patients, CCET in the operated eye was significantly negatively correlated with the number of residual sutures (R=-0.579, P=0.008), and was significantly positively correlated with time following surgery (R=0.636, P=0.003). In the fellow eye, a significant positive correlation was found between age and CCET (R=0.551, P=0.012), and a significant negative correlation between age and CTFT (R=-0.491, P=0.028). LTMH was found to be significantly correlated between operated and fellow eyes (R=0.554, P=0.011). There was no significant correlation between LTMH and age, bed/graft size, time following surgery, or residual sutures (all possible correlations, P>0.05).@*CONCLUSIONS@#Patients with keratoconus tend to have a thinner central corneal epithelium. Corneal epithelium keeps regenerating over time after DALK. DALK did not induce a significant change in tear volume compared with the fellow eye. Postoperative tear function might depend on an individual's general condition, rather than on age, gender, bed/graft size, time following surgery, or residual sutures.
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Adult , Female , Humans , Male , Middle Aged , Corneal Transplantation , Cross-Sectional Studies , Epithelium, Corneal/pathology , Retrospective Studies , Tears , Tomography, Optical CoherenceABSTRACT
Objective To analyze the thickness of cornea and corneal epithelium in healthy subjects by optical coherence tomography angiography (OCTA).Methods Totally 100 healthy subjects aged between 20 and 30 years were analyzed by OCTA technique.Using AngioVue OCTA system of retinal imaging mode,and using SSADA algorithm for imaging,the cornea and the corneal epithelium in the central corneal diameter range of 9 mm were measured.The differences of corneal and corneal epithelial thickness in different gender regions were compared.Results In the male and female group,the corneal central total thickness were (559.92 ±33.26) μm and(540.06 ±31.63)μm,and the corneal epithelial thickness were(57.78 ±4.88) μm and(56.88 ±4.57) μm,The total central corneal thickness and central corneal epithelial thickness of the male were greater than those of the female,the difference was statistically significant (t =3.06,2.10;all P ＜ 0.05).The cornea of male was the thickest at S5,S7 and SN9,there were significant differences at S5 and S7 compared with female (t =2.93,2.83;all P ＜ 0.05);The female cornea was the thickest at S5,SN7 and SN9,and the difference was significant at S5 compared with male.The cornea of male subjects was the thinnest at IT,which was statistically significant only at IT5 compared with female subjects in the same area (t =2.02,P ＜ 0.05);The cornea of female subjects was the thinnest at T5,IT7 and T9,which was statistically significant only at T5 and T9 compared with male subjects in the same region (t =2.63,2.20;all P ＜ 0.05);There was significant difference in corneal thickness between male and female at ST (t =3.1 1,2.79,2.33;all P ＜ 0.05).The corneal epithelium was the thickest at IT5,I7,and I9,and the lowest at S5,S7 and S9,and there was no significant difference compared with female in the same region (all P ＞ 0.05).The corneal epithelium of female at the IT5,T7,N9 were the thickest,SN5,S7,S9 were the thinnest;Except for M2 and SN5,there was no significant differences in corneal epithelium between male and female groups (all P ＞ 0.05).Corneal central epithelium accounted for the largest percentage of total corneal thickness,and gradually decreased from inside to outside.Conclusion OCTA can be used to measure the thickness of corneal and corneal epithelial regions.
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PURPOSE: To investigate the effects of an amniotic membrane patch on corneal epithelial thickness and formation of hemidesmosomes during corneal stromal wound healing. METHODS: A stromal wound 9 mm in diameter and 130 microm in depth was created on rabbit cornea using a microkeratome. The changes in corneal epithelial thickness and hemidesmosome formations were compared between the amniotic membrane, contact lens, and control groups. Changes in the corneal epithelium were examined using H&E staining and hemidesmosome formation was examined using an electron microscope at 2 and 4 weeks after flap removal. RESULTS: Two weeks after treatment, the corneal epithelial thickness was 95.3 +/- 6.3 microm in the amniotic membrane group being significantly thicker than 76.4 +/- 5.1 microm in the contact lens group and 68.3 +/- 6.1 microm in the control group. Furthermore, more hemidesmosome formations were observed in the amniotic membrane group compared to the other 2 groups. However, there were no significant differences in corneal epithelial thickness or hemidesmosome formation among the 3 groups at week 4. CONCLUSIONS: The amniotic membrane group showed a thicker corneal epithelium and more hemidesmosome formation than the other 2 groups 2 weeks after flap removal. Thus, the use of an amniotic membrane patch appears to be effective in the early stages of corneal stromal wound healing.