Posterior Corneal Characteristics of Cataract Patients with High Myopia

Epidemiology and Burden of Astigmatism: A Systematic Literature Review

SIGNIFICANCE

This is the first literature review to report the epidemiology, patient burden, and economic burden of astigmatism in the general adult population. The unmet needs of astigmatism patients with coexisting ocular conditions (cataract, glaucoma, dry eye, presbyopia, or macular degeneration) and risks associated with untreated astigmatism are also reviewed and reported.

PURPOSE

This study aimed to identify, report, and summarize the published literature on epidemiology, patient burden, and economic burden of astigmatism using a systematic literature review.

METHODS

MEDLINE, EMBASE, and Cochrane Library databases were searched (January 1996 to May 2021). Search results were limited to the English language. Proceedings (2018 to 2021) from ophthalmology congresses were searched along with gray literature using the Google Scholar platform.

RESULTS

The literature search yielded 6804 citations, of which 125 met the inclusion criteria (epidemiology, 68; patient burden, 60; economic burden, 6). Astigmatism prevalence in the general population varied from 8 to 62%, with higher rates in individuals 70 years or older. The prevalence of with-the-rule astigmatism was higher in individuals 40 years or younger, whereas rates of against-the-rule and oblique astigmatism increased with age. Astigmatic patients experienced decreased vision quality, increased glare (53 to 77%), haloes (28 to 80%), night-time driving difficulties (66%), falls, and spectacle dependence (45 to 85%). Astigmatic patients performed vision-related tasks slower (1 D, 9% slower; 2 D, 29% slower) and made more errors (1 D, 38% more errors; 2 D, 370% more errors) compared with fully corrected individuals. In cataract patients with astigmatism, the annual mean per-patient productivity loss costs ranged from €55 ($71) to €84 ($108), and mean informal care costs ranged from €30 ($39) to €55 ($71) with a mean of 2.3 to 4.1 hours spent on informal care.

CONCLUSIONS

Uncorrected astigmatism decreases patients' vision-related quality of life, decreases productivity among working-age adults, and poses an economic burden on patients and their families.

Agreement of Anterior Segment Parameters Between Schiempflug Topography and Swept-Source Optic Coherence Based Optic Biometry in Keratoconus and Healthy Subjects

PURPOSE

The aim of this study is to compare anterior segment parameters, including corneal thickness (CCT), keratometry and anterior chamber depth (ACD), and white to white corneal diameter (WTW), obtained by Pentacam Schiempflug imaging and intraocular lens (IOL) Master 700 swept-source optic coherence tomography biometry in keratoconus patients and healthy subjects.

METHODS

This prospective cross-sectional instrument agreement analysis includes 88 eyes of 50 keratoconus patients and 87 eyes of 50 healthy subjects. Biometry was performed using IOL Master 700, and topography was performed using Pentacam. The keratometry values (Kf, Ks, Km, and Kmax), ACD, WTW, CCT, axial length (AL), anterior chamber angle (ACA), and lens thickness (LT) were evaluated. Levels of agreement between devices were evaluated by Bland-Altman plots with 95% limits of agreement.

RESULTS

Intraocular lens Master 700 showed higher WTW, ACD, pupil diameter, and CCT values than Pentacam in both the keratoconus and control groups. However, there were no statistically significant differences in flat keratometry (Kf) and steep keratometry (Ks) values between the groups.

CONCLUSION

Pentacam and IOL Master 700 may be used interchangeably in normal eyes and keratoconus eyes for the measurement of keratometry values and axis; however, these two devices should not be considered interchangeable for WTW, ACD, pupil diameter, and CCT measurements in both keratoconus patients and healthy subjects.

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 (s_r = 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.

Evaluation of preoperative corneal astigmatism using swept-source optical biometry in Chinese cataract surgery candidates with high myopia: a prospective, comparative observational study

Background

High myopia and cataracts are major causes of blindness in East and Southeast Asia. Corneal astigmatism is a major contributor to uncorrected poor vision after cataract surgery in patients with high myopia. The purpose of the present study was to evaluate the demographic characteristics and distribution of preoperative corneal astigmatism in Chinese cataract surgery candidates with high myopia.

Methods

Swept-source optical coherence tomography-based optical biometry was performed preoperatively in consecutive cataract surgery candidates who were classified by axial length (AL) into a high myopia group (defined as AL ≥26.0 mm) and a control group (normal ALs). The demographics, ALs, and keratometry values were recorded.

Results

Among 15,063 cataract surgery candidates (15,063 eyes), 1,921 patients (12.8%, 1,921 eyes) in the high myopia group and 11,880 patients (11,880 eyes) in the control group were enrolled. In the high myopia group, the mean age was 59.8±12.6 (standard deviation) years, which was younger than that in the control group (69.1±11.0 years, P<0.001). In the high myopia group, the mean corneal astigmatism was 1.20±0.83 dioptre (D), which was greater than that in the control group (0.93±0.69 D, P<0.001). In the high myopia group, 82.2% had corneal astigmatism ≥0.50 D, 51.4% ≥1.00 D, 27.4% ≥1.50 D and 14.4% ≥2.00 D, all of which were higher than the respective proportions in the control group (P<0.001 for all). In the high myopia group, 66.8% had moderate to high corneal astigmatism, and 42.8% had “with-the-rule” astigmatism, and both of these proportions were higher than the respective proportions in the control group (P<0.001 for both). In the high myopia group, corneal astigmatism tended to increase with increasing age (r =0.134, P<0.001) after the age of 50, which was consistent with the tendency in the control group.

Conclusions

A significant burden of preoperative corneal astigmatism was observed in Chinese cataract surgery candidates with high myopia. Moderate to high corneal astigmatism was more common in highly myopic eyes than in normal AL eyes.

Crossed versus conventional pseudophakic monovision for high myopic eyes: a prospective, randomized pilot study

BACKGROUND

Aiming at spectacle independence, conventional pseudophakic monovision has been widely used in myopia patients with bilateral monofocal intraocular lens implantation. However, the crossed monovision, which is to correct the dominant eye for near vision and the non-dominant eye for distant vision, has been mentioned preferable for high myopic cataract patients by some studies. We have conducted this study to compare clinical results to assess the feasibility of conventional and crossed monovision for high myopic pseudophakic patients by comparing patient satisfaction, visual function and spectacle independence.

METHOD

Forty-sixth high myopia patients were divided into two groups: 22 in crossed monovision group with patients whose refraction targeted to - 2.00 diopters (D) in the dominant eye and - 0.50D in the non-dominant eye; 24 in conventional monovision group with patients whose refraction targeted to - 0.50D in the dominant eye and - 2.00D in the non-dominant eye. Binocular uncorrected distance visual acuity (BUDVA), binocular uncorrected near visual acuity (BUNVA), binocular corrected distant visual acuity (BCDVA), binocular corrected near visual acuity (BCNVA), contrast visual acuity and stereoacuity were examined at postoperative 2 weeks, 1 month and 3 months. Questionnaires were completed by patients 3 months after binocular surgery to evaluate patients' satisfaction and spectacle independence.

RESULTS

The conventional monovision and the crossed monovision group showed no significant differences of mean BUDVA, BUNVA, BCDVA, BCNVA 2 weeks, 1 month or 3 months postoperatively (P > 0.05). There was no difference in the bilateral contrast sensitivity or stereoscopic function between the convention conventional and crossed monovision groups (P > 0.05). Patient satisfaction with near and distant vision, as well as spectacle dependence did not differ significantly between the two groups (P > 0.05).

CONCLUSION

Crossed pseudophakic monovision exhibited similar visual function when compared with conventional monovision technique, which indicates that it is an effective option to improve the visual functionality and quality of life for high myopic patients who considering bilateral cataract surgery.

TRIAL REGISTRATION

The Institutional Review Board and Ethics committee of the First Affiliated Hospital of Chongqing Medical University, Chongqing, China. The trial registration was submitted in September 2018 and passed on March 18, 2020, and the registration number is: ChiCTR2000030935 .

Comparison of Q-value-guided laser-assisted in situ keratomileusis and standard laser in situ keratomileusis for myopia: A meta-analysis

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.

Measurement of crystalline lens tilt in high myopic eyes before cataract surgery using swept-source optical coherence tomography

Background

To measure the crystalline lens tilt in eyes with various degrees of myopia before cataract surgery using swept-source optical coherence tomography (SS-OCT).

Methods

We used SS-OCT (IOLMaster 700) to scan 131 emmetropic eyes (axial length < 24.5 mm), 25 mild/moderate myopic eyes (axial length 24.5-26 mm), and 123 high myopic eyes (52, 29, and 42 eyes with axial lengths of 26-28, 28-30, and > 30 mm, respectively) as part of the routine preoperative examination before cataract surgery. SS-OCT involved B-scans along six meridians. The data were analyzed to assess the magnitude and orientation of the lens tilt and their correlation with other optical biometric parameters.

Result

The mean tilt was 3.36 ± 0.98° in emmetropic eyes, 3.07 ± 1.04° in mild/medium myopic eyes, and 2.35 ± 1.01° in high myopic eyes. Tilt correlated significantly and inversely with axial length (Pearson's r = - 0.427, P < 0.001). The crystalline lens tilt predominantly faced the upper outer quadrant relative to the visual axis, symmetrically in both eyes, with mean angles of 24.32° and 147.36° in the right and left eyes, respectively. The variability in the lens tilt direction increased with increasing axial length (χ² test, P < 0.001).

Conclusion

The magnitude of crystalline lens tilt decreased with increasing axial length. The direction of tilt was predominantly towards the upper outer quadrant in both eyes. The variability in the tilt orientation increased with increasing axial length.

Trial registration

NIH (clinicaltrial.gov), NCT03062085. Registered 23 February 2017.

Analysis of corneal higher-order aberrations in cataract patients with high myopia

PURPOSE

To evaluate the differences in corneal higher-order aberrations (HOAs) between cataract patients with high axial myopia and normal cataract patients, and to identify the associated factors.

SETTING

Department of Ophthalmology and Vision Science of the Eye and ENT Hospital of Fudan University, Shanghai, China.

DESIGN

Retrospective case series.

METHODS

Corneal aberrations and axial lengths (ALs) were measured using a rotating Scheimpflug camera (Pentacam) and partial coherence interferometry (IOLMaster) in the high myopia group and the control group.

RESULTS

The study comprised 287 patients (520 eyes). There were 194 eyes in the high myopia group and 326 eyes in the control group. The 5 anterior corneal aberrations-vertical coma, vertical trefoil, horizontal coma, oblique trefoil, and primary spherical aberration-in the high myopia group were 0.07 μm ± 0.38 (SD), -0.11 ± 0.23 μm, 0.07 ± 0.28 μm, -0.02 ± 0.18 μm, and 0.39 ± 0.19 μm, respectively. No negative primary spherical aberrations of the total or anterior corneal surface were found in the high myopia group. Differences between the 2 groups were found in terms of central corneal thickness, astigmatism, primary spherical aberration, vertical coma, and oblique trefoil; however, these differences were not consistent between different age subgroups. Higher-order aberrations were correlated with age. Posterior corneal vertical coma was correlated with AL (Pearson correlation = -0.188, P = .047).

CONCLUSIONS

Negative primary spherical aberrations of the anterior or total corneal surface were not found in the high myopia group. Age showed a strong relationship with HOAs. For cataract patients with high myopia, aspheric intraocular lens implantation is recommended.

Comparing surgically induced astigmatism calculated by means of simulated keratometry versus total corneal refractive power

Purpose:

To evaluate surgically induced astigmatism as computed by means of either simulated keratometry (KSIM) or total corneal refractive power (TCRP) after temporal incisions.

Methods:

Prospective observational study including 36 right eyes undergoing cataract surgery. Astigmatism was measured preoperatively during the 3-month follow-up period using Pentacam. Surgically induced astigmatism was computed considering anterior corneal surface astigmatism at 3 mm with KSIM and considering both corneal surfaces with TCRP from 1 to 8 mm (TCRP3 for 3 mm). The eyes under study were divided into two balanced groups: LOW with KSIM astigmatism <0.90 D and HIGH with KSIM astigmatism ≥0.90 D. Resulting surgically induced astigmatism values were compared across groups and measuring techniques by means of flattening, steepening, and torque analysis.

Results:

Mean surgically induced astigmatism was higher in the HIGH group (0.31 D @ 102°) than in the LOW group (0.04 D @ 16°). The temporal incision resulted in a steepening in the HIGH group of 0.15 D @ 90°, as estimated with KSIM, versus 0.28 D @ 90° with TCRP3, but no significant differences were found for the steepening in the LOW group or for the torque in either group. Differences between KSIM- and TCRP3-based surgically induced astigmatism values were negligible in LOW group.

Conclusion:

Surgically induced astigmatism was considerably higher in the high-astigmatism group and its value was underestimated with the KSIM approach. Eyes having low astigmatism should not be included for computing the surgically induced astigmatism because steepening would be underestimated.