The analysis of corneal asphericity (Q value) and its related factors of 1,683 Chinese eyes older than 30 years

Xiong, Ying; Li, Jing; Wang, Ke; Xue, Le; Wang, Zhao; Tsai, Frank F.; Wan, Xiuhua

doi:10.1371/journal.pone.0176913

Cited by 24 publications

(40 citation statements)

References 23 publications

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“…Regarding posterior surface Q, not all available studies including the present investigation found a significant relationship with sex. 23,30 Thus, corneal asphericity appears to be equivalent in men and women.…”

Section: Discussionmentioning

confidence: 99%

“…2 Various reasons can be proposed for these discrepancies in the reported Q values, including differences in ethnicity, age distribution, sample size, measurement equipment and chord diameter. As seen in Table 6, most previous investigations had a small sample size with only two studies 4,30 having a sample of more than 1,000 eyes. This reduces the generalizability of the findings to some extent, although the sample size is, in part, dependent on the study aims, objectives and context.…”

Section: Discussionmentioning

confidence: 99%

“…4,26 Indeed, the ocular factors associated with corneal asphericity have not yet been definitively identified. The relationship between the Q value and ocular factors such as refractive error, 3,4,6,17,19,20,24,26,30,31,34,35 corneal radius of curvature, 4,27,29,31,36 axial length, 20 anterior chamber depth, 2 corneal diameter 6,30,37 and corneal astigmatism 3 were evaluated in various studies. It should be noted that there are significant inconsistencies between the results of different studies in this regard.…”

Section: Introductionmentioning

confidence: 99%

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Corneal asphericity and related factors in the geriatric population: A population‐based study

Hashemi

Nabovati

Aghamirsalim

et al. 2021

Ophthalmic Physiologic Optic

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Purpose: To determine the distribution of the corneal asphericity coefficient (Q value) and related factors in an Iranian geriatric population. Methods: This population-based study was conducted in 2019 in Tehran, using stratified multistage random cluster sampling. The study population was ≥60 years of age. Participants underwent corneal imaging using a Pentacam HR. Mean keratometry, corneal astigmatism, central corneal thickness, anterior chamber depth and the overall anterior and posterior Q values (for 8 mm chord diameter) were recorded. Axial length measurements were performed using the IOL Master 500. Results: 2457 eyes of 2457 individuals were analysed. The mean age was 67.3 AE 5.82 years and 1479 (60.2%) were female. The mean Q value for the anterior corneal surface was À0.35 AE 0.17 (95% CI: À0.35 to À0.34). The anterior Q value showed a statistically significant inverse relationship with axial length and mean keratometry, and a significant direct association with anterior chamber depth and corneal astigmatism. The mean posterior Q value was À0.41 AE 0.15 (95% CI: À0.42 to À0.40). The posterior Q value had a significant direct relationship with age, anterior chamber depth, mean keratometry and corneal astigmatism. Conclusion:The corneal Q values in this geriatric Iranian population were more negative than the values reported in most previous studies. Corneal asphericity was greater affected by ocular biometry and corneal curvature than demographic factors and refractive status.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Corneal asphericity and related factors in the geriatric population: A population‐based study

Hashemi

Nabovati

Aghamirsalim

et al. 2021

Ophthalmic Physiologic Optic

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“…Without the influence of the corneal flap, the comparison between the SMILE and LASEK is more like the comparison of femtosecond laser and excimer laser, and the different corneal-tissue-removing pattern, and which treatment inducing less asphericity change and better visual quality remained unclear. The corneal ashphericity could be represented by the corneal Q value, and could also be reflected by the change of corneal power from center to periphery [10, 11].…”

Section: Introductionmentioning

confidence: 99%

Comparative study of wave-front aberration and corneal Asphericity after SMILE and LASEK for myopia: a short and long term study

Chen

Liu

et al. 2019

BMC Ophthalmol

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Background The study compares the wave-front aberration and corneal asphericity from multiple perspectives after Small Incision Lenticule Extraction and Laser-assisted Subepithelial Keratomileusis for mild to moderate myopia in a short and long time period. Methods This prospective and comparative study included 32 eyes in the SMILE group, with a mean spherical equivalent (SE) of − 4.1 ± 0.9D and 32 eyes in the LASEK group, with a mean SE of − 3.7 ± 1.0D. Visual acuity, refractive error, wave-front aberration, corneal Q value and corneal refractive power were analyzed pre-, 3 months and 3 years post-operatively. Results There was no significant difference in refractive error, wave-front aberration, corneal Q value and corneal refractive power before treatment. Three months postoperative, Q value within 6 mm (SMILE: 0.46 ± 0.27, LASEK: 0.63 ± 0.28, p = 0.02), the relative peripheral corneal power (5-8 mm: p < 0.05), change of higher order aberration (SMILE: 0.10 ± 0.16, LASEK: 0.24 ± 0.20, p = 0.004) and spherical aberration (SA, SMILE: -0.07 ± 0.30, LASEK: -0.41 ± 0.40, p < 0.001) were significantly lower in the SMILE than in LASEK group. The visual acuity, refractive error, coma, peripheral Q value, central corneal power had no significant difference between the two groups. Three years post-operation, the corneal power distribution results and SA were similar to that of 3-month, while the Q value had no significant difference between the two groups. Conclusion In the early stage after SMILE, the HOAs was lower, the corneal refractive power from central to periphery was more uniform than after LASEK; and in the long-term run, SMILE still preceded LASEK in the corneal asphericity and aberration. Electronic supplementary material The online version of this article (10.1186/s12886-019-1084-3) contains supplementary material, which is available to authorized users.

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“…[ 33 , 34 ] Q value mathematically reflects corneal asphericity, which can be defined to variations in radius of curvature from apex to periphery. [ 35 , 36 ]…”

Section: Discussionmentioning

confidence: 99%

Comparison of Q-value-guided laser-assisted in situ keratomileusis and standard laser in situ keratomileusis for myopia

Zhang

Fang²,

Yin³

et al. 2020

Medicine

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Background: Previous studies examining the safety and efficacy of Q -value-guided laser-assisted in situ keratomileusis (LASIK) for treating myopia have yielded inconsistent results. We, therefore, performed a meta-analysis to clarify this issue Methods: Various databases were conducted up to November 21, 2018. All randomized controlled trials and cohorts that compared Q -value-guided LASIK with standard LASIK were selected. Mean differences (MDs) or odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to evaluate the strength of the correlations. Additionally, different subgroup analyses and publication bias tests were performed. Data were extracted including the number of postoperative uncorrected visual acuity (UCVA) of 20/20 or better, postoperative UCVA, preoperative and postoperative Q -value, postoperative refractive spherical equivalent (SE), the number of postoperative SE within ±0.5D, higher order aberration (HOA), coma-like aberration and spherical-like aberration. Results: A total of seventeen studies with 2640 patients and 3,358 eyes were included. It has been shown that postoperative Q -value (MD = -0.42; 95% CI: -0.64, -0.21; P < .001), HOA (MD = -0.14; 95% CI: -0.23, -0.06; P = .001), spherical-like aberration (MD = -0.19; 95% CI: -0.32, -0.06; P = .004) rather than postoperative UCVA (MD = 0.04; 95% CI: 0.01, 0.07; P = .012) were significantly better in the Q -value-guided LASIK than standard LASIK. However, the pooled results revealed that no significant differences were found between the 2 paired groups of postoperative UCVA of 20/20 or better (OR = 1.09; 95% CI: 0.62, 1.92; P = .763), preoperative Q -value (MD = -0.00; 95% CI: -0.02, 0.02; P = .922), postoperative refractive SE (MD = 0.08; 95% CI: -0.09, 0.25; P = .336), coma-like aberration (horizontal: MD = -0.00; 95% CI: -0.03, 0.03; P = .966; vertical: MD = -0.01; 95% CI: -0.03, 0.01; P = .263) and postoperative SE within ±0.5 D (OR = 1.06; 95% CI: 0.48, 2.33; P = .886). Likewise, similar results were detected in some corresponding subgroups. Conclusion: Q -value-guided LASIK is a safe, effective and predictable surgical option for treating myopia, especially showing superiority over standard LASIK in postoperative Q -value, HOA and spherical-like aberration. However, more detailed studies are required to confirm our conclusions in advanced researches.

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The analysis of corneal asphericity (Q value) and its related factors of 1,683 Chinese eyes older than 30 years

Cited by 24 publications

References 23 publications

Corneal asphericity and related factors in the geriatric population: A population‐based study

Corneal asphericity and related factors in the geriatric population: A population‐based study

Comparative study of wave-front aberration and corneal Asphericity after SMILE and LASEK for myopia: a short and long term study

Comparison of Q-value-guided laser-assisted in situ keratomileusis and standard laser in situ keratomileusis for myopia

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