ABSTRACT
AIM: To investigate the diagnostic value of ocular morphological parameters under different corneal diameters for early keratoconus.METHODS: A retrospective case-control study. A total of 201 patients(201 eyes)who were treated in our hospital from January 2019 to March 2022 were included. They were divided into 135 cases(135 eyes)in the control group(patients with history of refractive error)and 66 cases(66 eyes)in the subclinical keratoconus group. The Pentacam anterior segment analyzer was used to determine the horizontal central curvature of corneal posterior surface(Kf), posterior vertical central curvature of corneal posterior surface(Ks), average curvature of corneal posterior surface(Km), Posterior I-S ratio, corneal posterior surface height after the thinnest point(PE at the thinnest point), maximum posterior elevation from best fit sphere(MPE from BFS), maximum posterior elevation from best fit toric ellipsoid(MPE from BFTE), posterior asphericity asymmetry index(AAI), thinnest point thickness of the cornea(TCT), central corneal thickness(CCT), depressed corneal thickness(DCT), pachymetric progression index average(PPIavg), Ambrósio relational thickness maximum(ARTmax)and Belin D value. The differences of each parameter between the two groups were analyzed. Receiver operating characteristic(ROC)curves were analyzed to determine the best diagnosis point. The control group was further divided into groups according to the corneal diameter: corneal diameter ≤11.0mm, 11.1mm≤ corneal diameter ≤11.5mm, 11.6mm≤ corneal diameter ≤12.0mm, corneal diameter ≥12.1mm. The differences of each parameter among these groups were compared. Pearson correlation analysis was used to analyze the correlation between corneal diameter and other parameters.RESULTS: There were significant differences in posterior I-S ratio, PE at the thinnest point, MPE from BFS, MPE from BFTE, posterior AAI, TCT, DCT, PPIavg, ARTmax, Belin D value between the subclinical keratoconus group and the control group(P<0.05). Sensitive index of Pentacam to diagnosis subclinical keratoconus were Belin D value, posterior I-S ratio, PPIavg, posterior AAI and MPE from BFTE(AUC≥0.9). In the control group, there was no significant difference in posterior I-S ratio, MPE from BFTE, posterior AAI, TCT, CCT, and DCT among different corneal diameter groups (P>0.05), and there was no significant correlation with corneal diameter(all P>0.05).CONCLUSION: The Belin D value, posterior I-S ratio, PPIavg, posterior AAI, MPE from BFTE obtained by Pentacam are sensitive indicators for the diagnosis of early keratoconus, among which posterior I-S ratio, posterior AAI, MPE from BFTE are less affected by corneal diameter. They play an important role in the early diagnosis of keratoconus under different corneal diameters.
ABSTRACT
AIM: To investigate the image features of dynamic changes of tear film break-up after corneal fluorescein staining(FL)combined with tear film lipid layer(TFLL)dynamic changes in patients with dry eye and its value of diagnosis in dry eye. METHODS: A prospective study. A total of 66 patients(132 eyes)with dry eye admitted to our hospital during September 2019 to December 2020 were divided area break-up group(17 cases, 28 eyes), circle break-up group(20 cases, 27 eyes), line break-up group(25 cases, 28 eyes), spot break-up group(21 cases, 24 eyes)and random break-up group(20 cases, 25 eyes)according to the different fluorescein tear film break-up patterns(BUPs). The image features of tear film break-up dynamic changes and the image features of TFLL dynamic changes were compared in each group, and the differences in the first non-invasive tear film break-up time(NIBUTf), average non-invasive tear film break-up time(NIBUTav), tear meniscus height(TMH)and fluorescein staining scores were compare,RESULTS:A statistically significant differences were observed in NIBUTf among the groups of patients(P<0.001). Except that there was no difference between spot break-up group and random break-up group(7.56±1.54s vs 8.02±1.86s, P=0.881), other groups had significant differences in pairwise comparisons(P<0.05). There were statistically differences among the groups for NIBUTav(P<0.001). Except that there was no difference between spot break-up group and random break-up group(9.54±2.12s vs 9.73±1.94s, P=0.997), other groups had significant differences in pairwise comparisons(P<0.05). There was statistically difference among the groups for TMH(P<0.001). Except that there was no difference between circle break-up group and line break-up group(0.16±0.03mm vs 0.17±0.03mm, P=0.986), there was no difference between spot break-up group and random break-up group(0.22±0.03mm vs 0.21±0.05mm, P=0.993), other groups had significant differences in pairwise comparisons(P<0.05). There were statistically significant differences among the groups for FL scores and TFLL grading(P<0.001).CONCLUSION:It is shown that different fluorescein BUPs intuitively reflects the tear film structure of the pathological changes according to evaluation and analysis of images feature of dynamic changes of FL tear film and TFLL combined with the results of static examination of tear film. It is helpful for clinicians to identify subtypes of dry eye, which has potential clinical value for the diagnosis and classification of dry eye.