Impact of Ocular Residual Astigmatism On Anterior Corneal Astigmatism In Children With Low And Moderate Myopia

Background: To assess the influence of ocular residual astigmatism to anterior corneal astigmatism in children with low and moderate myopia.Methods: Refractive astigmatism was obtained by subjective manifest refraction. Anterior corneal astigmatism was obtained by IOL Master. Using Thibos vector analysis to calculate ocular residual astigmatism. Correlation analysis was used to assess the relationship between the magnitude of ocular residual astigmatism and anterior corneal astigmatism. The influence of ocular residual astigmatism to anterior corneal astigmatism was evaluated by Physical method.Results: The study analyzed 241 right eyes of 241 children aged 8 to 18 years old. In this study, the median magnitude of ocular residual astigmatism was 1.02 D, with interquartile range was 0.58 D. Against-the-rule ocular residual astigmatism was seen in 232 eyes (96.3%). There was a significant and moderate correlation between ocular residual astigmatism and anterior corneal astigmatism (r = 0.50, P < 0.001). The ocular residual astigmatism in 240 eyes (99.6%) had a compensatory effects on anterior corneal astigmatism. The mean compensation value was 1.00 ± 0.41 D (rang 0.02 D to 2.34 D). Based on this effect, 37 eyes had different axial classification of anterior corneal astigmatism and refractive astigmatism. By contrast, one eye (0.4%) had oblique ocular residual astigmatism and superimposed with-the-rule anterior corneal astigmatism.Conclusions: The magnitude of ocular residual astigmatism was relatively huge in myopia children and predominantly compensated anterior corneal astigmatism. The ocular residual astigmatism should be assessed first before fitting orthokeratology.

Distribution and internal correlations of corneal astigmatism in cataract patients

The aim of the study is to explore the distribution patterns and internal correlations of the morphological parameters of the cornea in patients with age-related cataract. The Pentacam HR was used to measure anterior corneal astigmatism (ACA), posterior corneal astigmatism (PCA), total corneal astigmatism (TCA) and keratometric corneal astigmatism (KCA). With age, the proportion of with-the-rule (WTR) ACA decreased from 65.31% to 23.63%, while the against-the-rule (ATR) ACA increased from 26.53% to 56.20%. PCA exceeded 0.50 D in 9.14% of eyes, while 76.35% of them were ATR. The magnitude of ACA was positively correlated with PCA in the whole sample, with a more significant correlation in WTR eyes (sr = 0.349, P < 0.001). The vector summation effect of PCA to ACA changed from compensation to augmentation with aging. In 57.53% of WTR eyes, KCA was overestimated by an average of 0.21 ± 0.17 D, while it was underestimated by 0.38 ± 0.27 D in 87.62% of ATR eyes. In conclusion, among age-related cataract patients, ACA and TCA gradually shifted from WTR to ATR with aging, while most PCA remained as ATR. Ignoring the age-related changes and real PCA might cause overestimation of WTR astigmatism and underestimation of ATR astigmatism.

Long-term ocular biometric variations after scleral buckling surgery in macula-on rhegmatogenous retinal detachment

Background Myopic shift and biometric ocular changes have been previously observed after scleral buckling (SB) surgery in rhegmatogenous retinal detachment (RRD), but long term-term outcomes had not yet been explored. The purpose of present study is to evaluate long term ocular biometric changes in patients with primary macula-on RRD treated with SB. Methods In this retrospective, observational study, we reviewed the medical records of patients undergoing SB surgery for macula-on RRD. Ocular biometry was performed before and at the most recent visit after surgery. Axial length (AXL), anterior chamber depth (ACD), anterior corneal astigmatism and spherical equivalent in treated eyes were compared before and after surgery as well as with those of fellow eyes. Results Thirty-four eyes of 17 patients with a mean age of 57.0 ± 8.9 years were included. The mean follow-up duration was 50.9 ± 21.9 months (median 53.0; range 12 to 82 months). A significant postoperative AXL increase of 0.83 mm and a concomitant myopic shift of 1.35 diopters was observed in the operated eyes (p < 0.0001). The preoperative AXL was the only predictive factor of AXL change after surgery (B = 0.152, 95% CI 0.059 to 0.245, β = 0.668, P = 0.003). Compared to fellow eyes, a postoperative ACD shallowing of 0.1 mm was found in operated eyes (p < 0.05), while there were no long-term changes of anterior corneal astigmatism. Conclusions We show that the preoperative AXL is the only predictive factor of AXL increase after SB surgery. Scleral encircling induces a concomitant long-term shallowing of the AC, therefore fourth generation intraocular lens (IOL) power calculation formulae should be used for patients requiring cataract surgery after SB.

Contribution of Ocular Residual Astigmatism to Anterior Corneal Astigmatism in Children with Low and Moderate Myopia

To assess the contribution of ocular residual astigmatism (ORA) to anterior corneal astigmatism (ACA) in children with low and moderate myopia. Refractive astigmatism (RA) were received by subjective manifest refraction. ACA were obtained by IOL Master. Using Thibos vector analysis to calculate ORA. Correlation analysis was used to assess the relationship between the magnitude of ORA and ACA. The contribution of ORA to ACA was evaluated by Physical method. The study analyzed 241 right eyes of 241 children aged 8 to 18 years old. In this study, the median magnitude of ORA was 1.02 D, with interquartile range was 0.58 D. Against-the-rule ORA was seen in 232 eyes (96.3%). There was a significant and moderate correlation between ORA and ACA (r = 0.50, P < 0.001). The ORA in 240 eyes (99.6%) had a compensatory effects on ACA. The mean compensation value was 1.00 ± 0.41 D. Based on this effect, 37 eyes had different axial classification of ACA and RA. By contrast, one eye (0.4%) had oblique ORA and superimposed with-the-rule ACA. The magnitude of ORA was relatively huge in myopia children and predominantly compensated ACA. The ORA should be assessed first before fitting orthokeratology.

The contribution of ocular residual astigmatism to anterior corneal astigmatism in refractive astigmatism eyes

To determine the distribution of ocular residual astigmatism (ORA) in astigmatic eyes and the influence on the anterior corneal (ACA) and refractive astigmatism (RA). A total of 165 children met the inclusion criteria. Right eyes’ data were analyzed. Using Thibos vector analysis to calculate ORA. Spearman correlation analysis was used to obtain the correlation between the magnitude of ORA, ACA and RA. The median magnitude of ORA in astigmatic eyes was 0.57 D, with interquartile range was 0.42 D. And they were main against-the-rule (57.6–75.8%) and oblique astigmatism (13.9–34.5%) ORA. The ORA in 140 eyes (84.8%) acted as an offset to ACA, meanwhile, 25 eyes (15.2%) superimposed it. About 98% (97.9–98.4%) against-the-rule and 75% (73.9–82.5%) oblique ORA counteracted ACA, nevertheless, all with-the-rule ORA had a superimposed effect on ACA. For with-the-rule ACA, about 86% (85.4–85.9%) ORA worked to offset it. There was statistically correlations between ORA and ACA (r = 0.17, P = 0.03), ORA and RA (r = − 0.27, P = 0.001). The magnitude of ocular residual astigmatism was relatively small in children’s astigmatic eyes. Both against-the-rule and oblique ORA can counteract with-the-rule ACA.

Does pterygium morphology affect corneal astigmatism?

Purpose: The purpose of this study was to evaluate the correlation between corneal astigmatism and the morphology of pterygium with anterior segment optic coherence tomography (AS-OCT). Material and Methods: The size of pterygium (horizontal length, vertical width) was measured manually; pterygium area and percentage extension of the pterygium onto the cornea were calculated. Anterior and posterior corneal astigmatism, Sim K, K1, K2 were measured using a dual Scheimpflug analyzer. Morphological patterns of the pterygium analyzed with AS-OCT were determined according to the extension of the pterygium apex below the corneal epithelium. Two tomographic patterns were identified: continuous and nodular. Correlation between anterior corneal astigmatism and pterygium size, percentage extension of the pterygium, and morphological pattern of the pterygium was analyzed. Results: The mean ages of the 47 patients were 49.4 ± 16.6 (22–80) years. Mean horizontal pterygium length, vertical width, pterygium area, and percentage extension of the pterygium were 2.8 ± 1.2 mm, 4.8 ± 1.6 mm, 7.42 ± 5.6 mm2 and 24.5 ± 10.4%, respectively. Mean anterior corneal astigmatism was 2.3 ± 2.3 D and simulated keratometry was 43.4 ± 2.02 D. In terms of the morphological pattern of the pterygium, 24 eyes had continuous, 23 eyes had a nodular pattern and the median (interquartile range) anterior corneal astigmatism was 1.87 (1.01–3.80) and 1.22 D (0.58–2.35), respectively ( p = 0.102). Other topographic and pterygium size parameters were similar between groups. Analyzing the correlations in groups separately, a positive moderate statistically significant correlation was present between vertical width, percentage extension, pterygium area, and anterior corneal astigmatism in both continuous and nodular groups. Conclusions: Although not statistically significant, anterior corneal astigmatism was higher in continuous group. Using AS-OCT to standardize the morphology of pterygium could provide additional clinical information.

Characteristics of corneal high-order aberrations in adolescents with mild to moderate myopia

Background This study investigated the characteristics of corneal higher-order aberrations (HOAs) of the anterior surface, posterior surface, and total cornea in adolescents with mild to moderate myopia. Methods A total of 183 patients with myopia (183 eyes) aged 8 to 18 years were enrolled in this study. The axial length (AL) of the eyes was measured by an IOL-Master, and corneal curvatures (K-values) and HOAs were measured by a Pentacam anterior segment diagnostic analyzer. Results Results of this study showed that the anterior, posterior and total corneal horizontal coma Z31 were − 0.1249 ± 0.105 μm, 0.0009 ± 0.001 μm, and − 0.1331 ± 0.116 μm, respectively; the anterior, posterior and total corneal vertical coma Z3− 1 were − 0.0212 ± 0.164 μm, 0.0003 ± 0.043 μm, and − 0.0216 ± 0.168 μm, respectively; and spherical aberration (SA) Z40 values were 0.2244 ± 0.091 μm, 0.1437 ± 0.029 um, and 0.1889 ± 0.090 μm, respectively. Total corneal Z31 was statistically correlated with posterior corneal astigmatism (K2b − K1b) (p = 0.038). Total corneal Z3− 1 was correlated with anterior corneal astigmatism (K2f − K1f) (p = 0.027). Anterior, posterior, and total corneal Z40 were correlated with anterior and posterior corneal curvature (K1f, K2f, K1b, K2b) (p = 0.001). Posterior corneal Z40b was also significantly correlated with AL. Conclusions In adolescents with mild to moderate myopia, the posterior corneal surface shape may play a compensatory role in the balance of corneal aberrations, and the posterior corneal SA tended to become less negative as the AL increased. The corneal coma may also play a compensatory role in posterior corneal surface astigmatism, which was valuable for the treatment for improving visual quality. This conclusion still needs to be verified.