Lens Power, Axial Length-to-Corneal Radius Ratio, and Association with Diabetic Retinopathy in the Adult Population with Type 2 Diabetes

The relationship between refractive error and the risk of diabetic retinopathy: a systematic review and meta-analysis

Purpose

This meta-analysis was conducted to collect all available data and estimate the relationship between refractive error and the risk of diabetic retinopathy (DR) in patients with diabetes, and to assess whether vision-threatening DR (VTDR) is associated with refractive error.

Methods

We systematically searched several literature databases including PubMed, Embase, Cochrane Library, Web of Science, CNKI, CBM, Wan Fang Data, and VIP databases. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated using fixed or random effects models. Four models were developed to assess the relationship between refractive error and the risk and DR, VTDR: hyperopia and DR, VTDR; myopia and DR, VTDR; spherical equivalent (SE per D increase) and DR, VTDR; and axial length (AL per mm increase) and DR, VTDR. The included literature was meta-analyzed using Stata 12.0 software, and sensitivity analysis was performed. Publication bias in the literature was evaluated using a funnel plot, Begg's test, and Egger's test.

Results

A systematic search identified 3,198 articles, of which 21 (4 cohorts, 17 cross-sectional studies) were included in the meta-analysis. Meta-analysis showed that hyperopia was associated with an increased risk of VTDR (OR: 1.23; 95% CI: 1.08-1.39; P = 0.001), but not with DR (OR: 1.05; 95% CI: 0.94-1.17; P = 0.374). Myopia was associated with a reduced risk of DR (OR: 0.74; 95% CI: 0.61-0.90; P = 0.003), but not with VTDR (OR: 1.08; 95% CI: 0.85-1.38; P = 0.519). Every 1 diopter increase in spherical equivalent, there was a 1.08 increase in the odds ratio of DR (OR: 1.08; 95% CI: 1.05-1.10; P<0.001), but not with VTDR (OR: 1.05; 95% CI: 1.00-1.10; P = 0.06). AL per mm increase was significantly associated with a decreased risk of developing DR (OR: 0.77; 95% CI: 0.71-0.84; P<0.001) and VTDR (OR: 0.63; 95% CI: 0.56-0.72; P<0.001). Analysis of sensitivity confirmed the reliability of the study's findings.

Conclusion

This meta-analysis demonstrates hyperopia was associated with an increased risk of VTDR in diabetes patients. Myopia was associated with a reduced risk of DR. AL is an important influencing factor of refractive error. Every 1 mm increase in AL reduces the risk of DR by 23% and the risk of VTDR by 37%.

Systematic review registration

identifier: CRD42023413420.

Diabetic retinopathy in China: Epidemiology, screening and treatment trends-A review

Diabetic retinopathy (DR) is the leading cause of vision impairment in the global working-age population. In China, with one-third of the world's diabetes population estimated at 141 million, the blindness prevalence due to DR has increased significantly. The country's geographic variations in socioeconomic status have led to prominent disparities in DR prevalence, screening and management. Reported risk factors for DR in China include the classic ones, such as long diabetes duration, hyperglycaemia, hypertension and rural habitats. There is no national-level DR screening programme in China, but significant pilot efforts are underway for screening innovations. Novel agents with longer durations, noninvasive delivery or multi-target are undergoing clinical trials in China. Although optimised medical insurance policies have enhanced accessibility for expensive therapies like anti-VEGF drugs, further efforts in DR prevention and management in China are required to establish nationwide cost-effective screening programmes, including telemedicine and AI-based solutions, and to improve insurance coverage for related out-of-pocket expenses.

Is myopia accelerated in type 1 diabetes mellitus children? Analyses from the ocular parameters

BACKGROUND

This study compares the ocular biometry with or without myopia in children with type 1 diabetes mellitus (T1DM) and healthy children in China to analyse the difference between myopia in T1DM and healthy children.

METHODS

A case-control study was conducted at the Children's Hospital of Fudan University. The children were divided into four subgroups depending on myopia or non-myopia, T1DM or non-DM. The participants were evaluated for anterior chamber depth (ACD), lens thickness (LT), axial length (AL), average keratometry (K) and lens power (P). Furthermore, cycloplegic refraction was performed and the spherical equivalent (SE) was acquired.

RESULTS

One hundred and ten patients with T1DM and 102 healthy subjects were included in this study. In the age-sex adjusted analysis, the myopia T1DM subgroup showed thicker LT (p = 0.001), larger P (p = 0.003) and similar ACD, AL, K and SE (all p > 0.05) compared to the myopia control subgroup. Additionally, the myopia T1DM subgroup showed longer AL (p < 0.001) and similar ACD, LT, K and P (all p > 0.05) as the non-myopia T1DM subgroup. In the multivariate linear regression, for T1DM patients, eyes with longer AL, shallower ACD, and larger P were associated with a decrease in SE (p < 0.001, p = 0.01, and p < 0.001, respectively). Meanwhile, for healthy controls, eyes with longer AL and larger P were associated with a decrease in SE (all p < 0.001).

CONCLUSIONS

The ACD and LT of myopia T1DM children remained unchanged compared to non-myopia T1DM children. This means that the lens in the former group could not lose power as compensation for AL growth, thus providing evidence for the acceleration of myopia in T1DM children.

Surgeon effects on cataract refractive outcomes are minimal compared with patient comorbidity and gender: an analysis of 490 987 cases

AIM

To investigate effect of patient age, gender, comorbidities and surgeon on refractive outcomes following cataract surgery.

METHODS

Study population: patients on UK national ophthalmic cataract database on cataract operations undertaken between 1 April 2010 and 31 August 2018. Variables examined included gender, age, diabetic retinopathy, glaucoma, high myopia, inherited retinal disease, optic nerve disease, uveitis, pseudoexfoliation, vitreous opacities, retinal pathology, cataract type, previous surgery and posterior capsular rupture. A multivariate normal cross-classified model was fitted to the refractive outcome using Markov Chain Monte Carlo (MCMC) methods with diffuse priors to approximate maximum likelihood estimation. A MCMC chain was generated with a burn-in of 5000 iterations and a monitoring chain of 50 000 iterations.

RESULTS

490 987 cataract operations were performed on 351 864 patients by 2567 surgeons. Myopic and astigmatic errors were associated with posterior capsule rupture (-0.38/+0.04×72), glaucoma (-0.10/+0.05×95), previous vitrectomy (-0.049/+0.03×66) and high myopia (-0.07/+0.03×57). Hyperopic and astigmatic errors were associated with diabetic retinopathy (+0.08/+0.03×104), pseudoexfoliation (+0.07/+0.01×158), male gender (+0.12/+0.05×91) and age (-0.01/+0.06×97 per increasing decade). Inherited retinal disease, optic nerve disease, previous trabeculectomy, uveitis, brunescent/white cataract had no significant impact on the error of the refractive outcome. The effect of patient gender and comorbidity was additive. Surgeons only accounted for 4% of the unexplained variance in refractive outcome.

CONCLUSION

Patient comorbidities and gender account for small but statistically significant differences in refractive outcome, which are additive. Surgeon effects are very small.

Artificial Intelligence in Community-Based Diabetic Retinopathy Telemedicine Screening in Urban China: Cost-effectiveness and Cost-Utility Analyses With Real-world Data

BACKGROUND

Community-based telemedicine screening for diabetic retinopathy (DR) has been highly recommended worldwide. However, evidence from low- and middle-income countries (LMICs) on the choice between artificial intelligence (AI)-based and manual grading-based telemedicine screening is inadequate for policy making.

OBJECTIVE

The aim of this study was to test whether the AI model is more worthwhile than manual grading in community-based telemedicine screening for DR in the context of labor costs in urban China.

METHODS

We conducted cost-effectiveness and cost-utility analyses by using decision-analytic Markov models with 30 one-year cycles from a societal perspective to compare the cost, effectiveness, and utility of 2 scenarios in telemedicine screening for DR: manual grading and an AI model. Sensitivity analyses were performed. Real-world data were obtained mainly from the Shanghai Digital Eye Disease Screening Program. The main outcomes were the incremental cost-effectiveness ratio (ICER) and the incremental cost-utility ratio (ICUR). The ICUR thresholds were set as 1 and 3 times the local gross domestic product per capita.

RESULTS

The total expected costs for a 65-year-old resident were US $3182.50 and US $3265.40, while the total expected years without blindness were 9.80 years and 9.83 years, and the utilities were 6.748 quality-adjusted life years (QALYs) and 6.753 QALYs in the AI model and manual grading, respectively. The ICER for the AI-assisted model was US $2553.39 per year without blindness, and the ICUR was US $15,216.96 per QALY, which indicated that AI-assisted model was not cost-effective. The sensitivity analysis suggested that if there is an increase in compliance with referrals after the adoption of AI by 7.5%, an increase in on-site screening costs in manual grading by 50%, or a decrease in on-site screening costs in the AI model by 50%, then the AI model could be the dominant strategy.

CONCLUSIONS

Our study may provide a reference for policy making in planning community-based telemedicine screening for DR in LMICs. Our findings indicate that unless the referral compliance of patients with suspected DR increases, the adoption of the AI model may not improve the value of telemedicine screening compared to that of manual grading in LMICs. The main reason is that in the context of the low labor costs in LMICs, the direct health care costs saved by replacing manual grading with AI are less, and the screening effectiveness (QALYs and years without blindness) decreases. Our study suggests that the magnitude of the value generated by this technology replacement depends primarily on 2 aspects. The first is the extent of direct health care costs reduced by AI, and the second is the change in health care service utilization caused by AI. Therefore, our research can also provide analytical ideas for other health care sectors in their decision to use AI.

Analysis of independent risk factors for progression of different degrees of diabetic retinopathy as well as non-diabetic retinopathy among type 2 diabetic patients

Purpose

To study the independent risk factors for development of different degrees of diabetic retinopathy (DR) as well as non-DR (NDR) among type 2 diabetic patients.

Methods

This cross-sectional study included 218 patients with type 2 diabetes between January 2022 and June 2022. All the patients were divided into two groups: the DR group and the NDR group. The DR group was subdivided into the mild, moderate and severe non-proliferative DR (NPDR) group and the proliferative DR (PDR) group. Data recorded for all patients included age, gender, duration of diabetes, blood pressure, glycated hemoglobin (HbA1c), fasting blood glucose (FBG), blood lipids, best corrected visual acuity (BCVA), intraocular pressure (IOP), axial length (AL), anterior chamber depth (ACD), and renal function. Logistic regression methods were used to analyze the risk factors for DR.

Results

The prevalence of DR in type 2 diabetes was 28.44%. The duration of diabetes, age, mean arterial pressure (MAP), HbA1c, FBG, urinary albumin/creatinine ratio (UACR), BCVA, AL, and ACD were significantly different between the DR and the NDR groups (p < 0.05). Multivariate logistic regression analysis identified age, FBG, UACR, and AL as the independent risk factors for DR (OR = 0.843, 2.376, 1.049, 0.005; p = 0.034, 0.014, 0.016, p < 0.001).

Conclusion

Young age, short AL, higher levels of FBG and UACR were the independent risk factors for the progression of DR in type 2 diabetes.

A Study Linking Axial Length, Corneal Curvature, and Eye Axis With Demographic Characteristics in the Emmetropic Eyes of Bangladeshi People

Background Axial length (AL) and corneal curvature (CC) are one of the furthest critical parameters for optometry and oculoplastic surgery. These two variables are crucial in biometry for accurately measuring the power of the intraocular lens in cataract surgery. This research aimed to determine the association linking axial length and corneal curvature with demographic characteristics in emmetropic eyes of Bangladeshi people. Methods This descriptive cross-sectional research was carried out among 200 emmetropic eyes of Bangladeshi people attending the Department of Ophthalmology at Rajshahi Medical College, Bangladesh, with different eye conditions, between July 2017 and June 2018. Data was gathered by conducting person-to-person interviews, checking visual activity using the Snellen chart, and measuring corneal curvature using an auto-keratometer and axial eyeball length using A-scan ultrasonography. Results A total of 200 attendances were studied, 90 males and 110 females. All were emmetropic. The age range was 21-52 years, and the highest contributors were in the 21-30-year age group. The association between right axial length and right corneal curvature shows a negative relation among both sexes. It was -0.61 (β-coefficient (β-coff)), and highly significant in females at -0.89 (β-coff). Additionally, the association between left axial length and left corneal curvature shows a negative relation of -0.65 (β-coff), which was again highly significant in females at -0.87 (β-coff). Both were not significant in males. There was no significant association linking axial length and eye axis in both sexes. The multivariate regression model was used to assess the p-value, and the regression model was adjusted by age. Conclusion Optical parametric measurement is a noninvasive diagnostic and assessment tool that might help in the actual measurement of intraocular lens implantation in cataract surgery and may also provide supplementary information to the researcher domain.

Clinical Observation of Macular Vessel Density in Type 2 Diabetics with High Myopia

INTRODUCTION

The aim of this study was to compare the macular retinal vessel density (VD) of diabetics with high myopia, diabetics without high myopia, and healthy controls.

METHODS

This cross-sectional study recruited type 2 diabetic (T2D) people with no history of ocular treatment in our hospital. Thirty T2D people with high myopia (30 eyes) were included in group A, while 30 T2D people (30 eyes) without myopia were included in group B. Another 30 healthy volunteers (30 eyes) were included in group C. The superficial and deep capillary plexuses VD of the macula were measured in all subjects by optical coherence tomography angiography. In T2D people with high myopia, the correlation between VD in macular regions and baseline data was investigated.

RESULTS

(1) Overall comparison of the 3 groups: no statistically significant differences in macular central superficial vessel density (SVD) were found in the three groups (p > 0.05). There were significant differences in the temporal, superior, nasal, inferior SVD between the 3 groups (p < 0.05). There were significant differences in macular central, temporal, superior, nasal, and inferior deep vessel density (DVD) between the three groups (p < 0.05). (2) Comparison of B (no myopia, T2D group) and C (healthy control group): inferior SVD in group B was lower than that in group C (p < 0.05). Temporal, superior, nasal, and inferior DVD in group B were lower than those in group C (p < 0.05). (3) A (high myopia group, T2D) compared with B (no myopia, T2D group), A group compared with C (healthy control group): temporal, superior, nasal, inferior SVD and DVD in group A were all lower than those in group B and C (p < 0.05), DVD in group B was lower than those in group C (p < 0.05). (4) The mean SVD and DVD were not correlated with age, IOP, anterior chamber depth, corneal curvature, but they were negatively correlated with axial length and duration of diabetes in the T2D people with high myopia.

CONCLUSION

Myopia and diabetes are two important factors affecting macular retinal VD. Comparing with the eyes of T2D people without high myopia, the VD in macular regions shows a higher decline in the eyes of T2D people with high myopia.

Beijing Pinggu Childhood Eye Study: The Baseline Refractive Characteristics in 6- to 12-Year-Old Chinese Primary School Students

Purpose

To report the design and baseline data of a 3-year cohort study in Beijing Pinggu District primary school students in China after COVID-19.

Methods

Noncycloplegic and cycloplegic spherical equivalent refraction (SER) were measured, ocular biometry, including the axial length (AL), anterior chamber depth (ACD) and corneal power (CP), were collected before cycloplegia. Corneal radius (CR), AL-to-CR ratio, and lens power (LP) were calculated.

Results

Among the 4,806 (89.1%) eligible students (51.5% male), the prevalence of emmetropia, myopia, mild hyperopia, and mild-to-high hyperopia was 12.8, 30.8, 53.0, and 3.3% after cycloplegia, respectively. Myopia increased from 2.5% in 6- to 71.6% in 12-year-old students, with 9- and 10-year-olds showing the most prominent increases. The median of cycloplegic SER was 0.50 (IQR = 1.63), and the noncycloplegic SER was −0.38 D (IQR = 1.50), which is more negative than the cycloplegic refraction. The mean AL increased with age, from 22.46 ± 0.70 mm to 24.26 ± 1.07 mm. The ACD increased from 3.38 ± 0.28 mm to 3.70 ± 0.30 mm, and the AL-to-CR ratio increased from 2.91 ± 0.08 to 3.12 ± 0.13 between 6- and 12-year-old students. AL, CR and LP explained the SER variance with R² of 86.4% after adjusting the age and gender.

Conclusions and Relevance

The myopia prevalence since emergence of COVID-19 rapidly increased from 6- to 12-year primary school Chinese children, especially after 7 years of age. The non-cycloplegia SER overestimated the prevalence of myopia, and the cycloplegic SER is a more accurate and reliable method to assess the prevalence of refractive status.

Axial myopia, a protective factor for diabetic retinopathy-role of vascular endothelial growth factor

Long axial length is one of the ocular protective factors in development of diabetic retinopathy (DR). In this study we examined the effect of axial length (AL) on aqueous humor vascular endothelial growth factor (VEGF) levels in patients with diabetes mellitus with or without DR. Forty-eight eyes of 48 participants were divided into three groups of 16 each. Group A consisted of non-diabetic patients, Group B had diabetic patients without DR, and Group C had diabetic patients with treatment-naive non-proliferative DR (NPDR). The groups were further subdivided based on axial lengths i.e., AL ≤ 23.30 mm (A1, B1, C1) and AL > 23.30 mm (A2, B2, C2). Undiluted aqueous humor was obtained during cataract surgery to measure the VEGF levels. We observed significant decrease in VEGF concentration in patients with AL ≥ 23.30 mm as compared with AL ≤ 23.30 mm in non-diabetic as well as diabetic patients. As the eye elongates, there is less secretion of VEGF in non-diabetics as well in diabetics with or without DR. Our findings strengthened the concept that an increase in AL leads to less VEGF in diabetic eyes, thus leading to less severe DR changes.

The role of peripheral ocular length and peripheral corneal radius of curvature in determining refractive error

PURPOSE

The purpose of this study was to extend the knowledge of peripheral biometric component and its relationship to refractive status in healthy individuals by determining the correlation between peripheral ocular length to peripheral corneal radius ratio and the refractive error.

METHODS

This prospective study was conducted on thirty-three healthy adult participants. Refractive error was assessed objectively and subjectively and recorded as the mean spherical equivalent. Central and peripheral ocular lengths at 30° were assessed using partial coherence interferometry under dilation with 1% tropicamide. Central and peripheral corneal radius of curvature was assessed using Scheimpflug topography. Peripheral ocular lengths at 30° were paired with peripheral corneal curvatures at the incident points of the IOLMaster beam (3.8mm away from corneal apex) superiorly, inferiorly, temporally and nasally to calculate the peripheral ocular length-peripheral corneal radius ratio. Descriptive statistics were used to describe the distribution and spread of the data. Pearson's correlation analysis was used to present the association between biometric and refractive variables.

RESULTS

Refractive error was negatively correlated with the axial length-central corneal radius ratio (r=-0.91; p<0.001) and with 30° peripheral ocular length-peripheral corneal radius ratio in all four meridians (r≤-0.76; p<0.001). The strength of the correlation was considerably lower when only axial length or peripheral ocular lengths were used.

CONCLUSION

Using the ratios of peripheral ocular length-peripheral corneal radius to predict refractive error is more effective than using peripheral corneal radius or peripheral ocular length alone.

Analysis of Iris volume using swept-source optical coherence tomography in patients with type 2 diabetes mellitus

PURPOSE

To evaluate iris volume before and after pupil dilation using swept-source anterior segment optical coherence tomography (SS-ASOCT) and investigate the associated factors of iris volume and iris volume change after pupil dilation in patients with type 2 diabetes mellitus (T2DM).

METHODS

A cross-sectional study was conducted in Zhongshan Ophthalmic Center among T2DM registered patients in the community of Guangzhou, China. Anterior chamber volume (ACV), iris volume, anterior chamber depth (ACD), angle opening distance at 500 μm (AOD 500) and pupil diameter were estimated using SS-ASOCT (CASIA; Tomey, Nagoya, Japan). Venous blood was taken for the measurement of glycosylated haemoglobin A1c (HbAlc). All biometric measurements were performed before and after pharmacologic pupil dilation.

RESULTS

A total of 117 subjects were included in the analysis. The mean age (±SD) was 64.96 ± 7.75 years, and 62.4% were females. After pupil dilation, iris volume decreased in all eyes. Shorter duration of diabetes (p = 0.035), longer axial length (p < 0.001) and smaller pupil diameter (p < 0.001) were associated with larger iris volume. The change in iris volume per millimetre change in pupil diameter was 1.35mm³ /mm. Smaller baseline iris volume (p = 0.002) and higher HbA1c level (p = 0.010) were associated with smaller change in iris volume per millimetre change in pupil diameter, after adjusting for other factors.

CONCLUSION

Iris volume can be estimated by SS-ASOCT. Diabetic duration was associated with static anatomy of iris volume, while HbA1c level indicated the dynamic response of iris volume. It is likely that diabetic duration and HbA1c level could affect the macroscopic and microscopic composition of the iris in the diabetic population.

Associations between anterior segment biometry and high axial myopia in 3438 cataractous eyes in the Chinese population

Background

To investigate the associations between anterior segment biometry and high axial myopia in cataractous eyes in the Chinese population.

Methods

Data on 3438 eyes from 3438 subjects were analyzed in this cross-sectional study. Anterior segment biometry, axial length measurements, and intraocular pressure evaluation were implemented using an Oculus Pentacam HR, a Zeiss IOLMaster 500, and a Nidek TonoRef II, respectively. A multivariate-adjusted logistic model and a multivariate-adjusted linear model were used for statistical analysis.

Results

The mean age of the subjects was 62.2 ± 10.6 years, and 56.4% were female. There were 2665 subjects with high axial myopia (axial length, ≥26.50 mm) and 773 without (axial length, < 26.50 mm). The characteristics independently associated with high axial myopia included lower total corneal refractive power, a more negative Q value, greater total corneal astigmatism, greater white-to-white corneal diameter, greater anterior chamber depth, and higher intraocular pressure (all P <  0.05). In addition, greater axial length correlated with a thicker temporal cornea and a thinner nasal cornea (both P <  0.001).

Conclusions

For cataractous eyes, high axial myopia was associated with corneal flattening, increased total corneal astigmatism, anterior segment enlargement, and intraocular pressure elevation. The findings may inform the choice of intraocular lenses and the calculation of their power, help improve the surgical practice of refractive cataract procedures, and provide useful information on the centration and stability of intraocular lenses.

Longitudinal associations of ocular biometric parameters with onset and progression of diabetic retinopathy in Chinese adults with type 2 diabetes mellitus

AIMS

To investigate the associations of ocular biometric parameters with incident diabetic retinopathy (DR), incident vision-threatening DR (VTDR) and DR progression.

METHODS

This community-based prospective cohort study recruited participants with type 2 diabetes aged 35-80 years from 2017 to 2019 in Guangzhou, China. Refractive error and ocular biometric parameters were measured at baseline, including axial length (AL), axial length-to-corneal radius (AL/CR) ratio, corneal curvature (CC), lens thickness (LT), anterior chamber depth (ACD), lens power and corneal diameter (CD).

RESULTS

A total of 1370 participants with a mean age of 64.3±8.1 years were followed up for two consecutive years. During the follow-up period, 342 out of 1195 (28.6%) participants without DR at baseline had incident DR, 15 out of 175 (8.57%) participants with baseline DR had DR progression and 11 of them progressed to VTDR. After multiple adjustments, a longer AL (OR=0.76; 95% CI, 0.66 to 0.86; p<0.001) and a larger AL/CR ratio (OR=0.20; 95% CI, 0.07 to 0.55; p=0.002) were associated with significantly reduced risks of incident DR but were not associated with incident VTDR or DR progression. Refractive status and other ocular biometric parameters investigated, including ACD, CC, CD, lens power and LT were not associated with any of the DR outcomes (all p>0.05).

CONCLUSIONS

A longer AL and a larger AL/CR ratio are protective against incident DR. These parameters may be incorporated into future DR risk prediction models to individualise the frequency of DR screening and prevention measures.

Choroidal Thickness and Its Association With Age, Axial Length, and Refractive Error in Chinese Adults

Purpose

To identify the association between the choroidal thickness (ChT) with age and axial length (AL) under different refractive errors (REs) in Chinese adults.

Methods

Swept-source optical coherence tomography was used to measure ChT in 2126 right eyes of 2126 participants. The participants were classified as having pathologic myopia (PM), high myopia without PM (HM), low myopia (LM), and nonmyopia (non-M) according to their REs and META-PM (the Meta-Analysis of Pathologic Myopia) classification criteria.

Results

The mean age was 52.49 ± 20.39 years (range, 18−93 years), and the mean RE was −5.27 ± 5.37 diopters (D; range, −25.5 to +7.75 D). The mean average ChT was 159.25 ± 80.75 µm and decreased in a linear relationship from non-M to PM (190.04 ± 72.64 µm to 60.99 ± 37.58 µm, P < 0.001). A significant decline in ChT was noted between 50 and 70 years (r = −0.302, P < 0.001) and less rapidly after the age of 70 years (r = −0.105, P = 0.024). No correlation was noted between age and ChT under 50 years (P = 0.260). A significantly higher association with AL was noted in the central fovea (β^HM = −23.92, β^LM = −23.88, β^Non-M = −18.80, all P < 0.001) and parafoveal ChT (β^HM = −22.87, β^LM = −22.31, β^Non-M = −18.61, all P < 0.001) when compared with the perifoveal region (β^HM = −19.80, β^LM = −18.29, β^Non-M = −13.95, all P < 0.001). Within each group of PM, HM, LM, and non-M, regression analysis showed that the coefficients of age and AL with different macular regions of ChT varied significantly.

Conclusions

ChT was negatively correlated with age after 50 years. The thinning of the choroid was more prominent in the center and parafoveal regions as AL increased. Varied distributions of ChT decrease associated with AL and age were noted among different refractive groups.

Association of Myopia With Microvascular Alterations in Patients With Type 2 Diabetes: An Optical Coherence Tomography Angiography Study

Purpose: To determine the association of myopia with peripapillary and macular microvasculature in eyes with type 2 diabetes using optical coherence tomography angiography (OCTA).

Methods: Diabetic patients with and without diabetic retinopathy (DR) were recruited and grouped according to myopic status in this cross-sectional study. Axial length, refractive error, and OCTA parameters were measured. OCTA parameters were analyzed with adjustment of confounding factors and further Bonferroni analysis was performed to determine the differences in multiple group comparisons.

Results: Compared with the diabetic eyes without myopia, those with myopia had lower rate of DR (21.82 vs. 35.90%, χ² = 6.190, P = 0.013), longer axial lengths (24.94 ± 0.75 vs. 23.16 ± 0.64, F = 311.055, P < 0.001) and reduced whole vessel density (VD) of optic nerve head (ONH) (45.89 ± 5.76 vs. 49.14 ± 4.33, F = 19.052, P < 0.001), peripapillary VD (48.75 ± 6.56 vs. 50.76 ± 4.51, F = 7.600, P = 0.006), and reduced thickness of the retinal nerve fiber layer (RNFL) (95.50 ± 12.35 vs. 100.67 ± 13.68, F = 5.020, P = 0.026). In eyes without myopia, the superficial vessel density (SVD) (46.58 ± 4.90 vs. 43.01 ± 4.25; 95% CI, 1.80–4.61; P < 0.001), deep vessel density (DVD) (45.64 ± 6.34 vs. 42.15 ± 6.31; 95% CI, 1.07–5.00; P < 0.001), and FD300 area density (50.31 ± 5.74 vs. 44.95 ± 6.96; 95% CI, 2.88–7.27; P < 0.001) were significant reduced in eyes with DR(DR eyes) comparing to those without DR (NoDR eyes). In eyes with myopia, only SVD were significantly reduced in DR eyes comparing to NoDR eyes (41.68 ± 3.34 vs. 45.99 ± 4.17; 95% CI, 1.10–7.22; P = 0.002). In NoDR eyes, both whole VD of ONH and Peripapillary VD demonstrated a significant decrease in eyes with myopia comparing to those without myopia (49.91 ± 4.36 vs. 45.61 ± 6.32; 95% CI, 1.95–6.27; P < 0.001 and 51.36 ± 4.24 vs. 48.52 ± 6.99; 95% CI, 0.56–5.11; P = 0.006, respectively).

Conclusions: In diabetic patients, myopic eyes exhibited lower prevalence of DR and thinner thickness of RNFL. The refractive status could possibly impact the retinal microvascular changes from NoDR to DR stage.

Association between ocular biometrical parameters and diabetic retinopathy in Chinese adults with type 2 diabetes mellitus

PURPOSE

The influence of myopia and ocular biometry parameters on diabetic retinopathy (DR) needs further clarification. We aimed to investigate the association between ocular biometrical parameters and DR in Chinese people with diabetes mellitus (DM) without any ocular intervention.

METHODS

This cross-sectional study recruited type 2 DM patients with no history of ocular treatment in Guangzhou, China. The ocular biometrical parameters were obtained by Lenstar (LS900, Haag-Streit AG, Koeniz, Switzerland), including corneal diameter, central corneal thickness (CCT), corneal curvature (CC), anterior chamber depth (ACD), lens thickness (LT) and axial length (AL). The lens power and axial length-to-cornea radius ratio (AL/CR ratio) were calculated. Spherical equivalent (SE) was determined by auto-refraction after pupil dilation. Multivariate logistic regression analyses were performed to explore the associations of ocular biometry with any DR and vision threatening DR (VTDR).

RESULTS

A total of 1838 patients were included in the final analysis, involving 1455 (79.2%) patients without DR and 383(20.8%) patients with DR. After adjusting confounding factors, any DR was independently associated with AL (odds ratio (OR) 0.84 per 1 mm increase, 95% confidence interval (CI): 0.74, 0.94) and AL/CR ratio (OR 0.26 per 1 increase, 95%CI: 0.10, 0.70). Similarly, the presence of VTDR was independently related to AL (OR 0.67 per 1 mm increase, 95%CI: 0.54, 0.85) and AL/CR ratio (OR 0.04 per 1 increase, 95%CI: 0.01, 0.25). The lens power may not be significantly correlated with presence of any DR or VTDR. The CC, corneal diameter and refractive status were not significantly correlated with presence of DR or VTDR.

CONCLUSION

Longer AL and higher AL/CR ratio may be protective factors against the occurrence and progression of DR. Further longitudinal studies are warranted to verify if refractive status and AL-associated parameters contribute to the occurrence and progression of DR in type 2 DM.

The associations of lens power with age, axial length and type 2 diabetes mellitus in Chinese adults aged 50 and above

Background

To investigate the associations of lens power with age, axial length (AL), and Type 2 diabetes mellitus (DM) in Chinese adults aged 50 and above.

Methods

Random clustering sampling was used to identify adults aged 50 years and above in urban regions of Shanghai. The participants underwent a comprehensive ophthalmic examination including subjective refraction, autorefraction, and IOL-Master. The crystalline lens power was calculated using Bennett’s formula.

Results

A total of 4177 adults were included. A linear decrease in lens power was observed both with age and with AL, followed by a stop of lens power loss after the age of 70 or when AL ≥ 25 mm, respectively. Participants with Type 2 DM presented higher lens power (0.43 diopter (D), p < 0.001) and thicker lens thickness (0.06 mm, p < 0.001). In multivariate regression models, there was a positive correlation between lens power and Type 2 DM when age < 75 years (p < 0.001) or AL < 25 mm (p < 0.001) after adjusting for other factors, while no significant association was found in participants aged ≥ 75 years (p = 0.122) or with AL ≥ 25 mm (p = 0.172).

Conclusions

The lens power in adults aged 50 and above exhibited two stages with age and with AL. Type 2 DM caused an increase in lens power, which was not seen in participants aged ≥ 75 years or with AL ≥ 25 mm.

Ratio of Axial Length to Corneal Radius in Japanese Patients and Accuracy of Intraocular Lens Power Calculation Based on Biometric Data

PURPOSE

To evaluate the features of the axial length-to-corneal radius (AL/CR) ratio in Japanese patients with cataracts and to determine the accuracy of intraocular lens (IOL) power calculation formulas according to the AL/CR features and the axial length (AL).

DESIGN

Retrospective observational case series.

METHODS

Setting was a clinical practice. Patient population was a total of 1,135 eyes (1,135 patients) with cataracts. Observation procedures included measurement of the AL and corenal radius (CR) by optical biometry and evaluation of the refractive outcomes by using the SRK/T, Holladay 1, Hoffer Q, Haigis, and Barrett Universal II formulas. Main outcome measurements were the features of the AL/CR ratio and the accuracy of IOL power calculations based on the AL/CR ratio and the AL.

RESULTS

The mean AL/CR ratio was 3.15 ± 0.19. Significant weak negative correlations were observed between the spherical equivalent (SE) and AL (r = -0.7489; P < .001) and between the SE and AL/CR ratio (r = -0.8069; P < .001); no correlation was found between the SE and CR (r = 0.0208, P = .483). For medium ALs and high AL/CR ratios, the SRK/T formula performed less accurately. For long ALs and high AL/CR ratios, the Holladay 1 and Hoffer Q formulas performed less accurately. The Barrett Universal II formula performed well across a range of ALs and AL/CR ratios.

CONCLUSIONS

The AL/CR ratio explained the total variation in the SE better than the AL alone. Surgeons should pay attention to the selection of IOL power calculation formulas in eyes with high AL/CR ratios.

Refractive Errors, Ocular Biometry and Diabetic Retinopathy: A Comprehensive Review

Purpose: To summarize the association between diabetic retinopathy and refractory status as well as ocular biometric parameters; To review the theories of the protective effect of high myopia against diabetic retinopathy. Methods: A comprehensive literature search on MEDLINE, EMBASE, Web of Science and Scopus databases as well as reference list search, and systematic review of relevant publications.  Results: Myopia may delay the onset and progression of diabetic retinopathy. Increased axial length in myopia is associated with reduced risk of any diabetic retinopathy and vision-threatening diabetic retinopathy. The possible mechanisms for the protective effect of myopia against diabetic retinopathy may include posterior vitreous detachment, change in retinal blood flow and oxygen demand, choroidal thinning and altered cytokine profiles.  Conclusions: High myopia may be a protective factor against the onset and progression of diabetic retinopathy. Further studies about the mechanisms of how myopia, axial length and ocular biometrics influence the onset and progression of DR are needed.

Genome-wide analysis of DNA methylation identifies S100A13 as an epigenetic biomarker in individuals with chronic (≥ 30 years) type 2 diabetes without diabetic retinopathy

Background

This study aimed to determine the epigenetic biomarkers of diabetic retinopathy (DR) in subjects with type 2 diabetes mellitus (T2DM). This retrospective study is based on the Shanghai Xinjing community prevention and treatment administrative system of chronic diseases. The subjects enrolled herein were T2DM patients who had undergone long-term follow-up evaluation in the system. Two consecutive studies were conducted. In the discovery cohort, among 19 subjects who had developed DR with a DM duration < 3 years and 21 subjects without DR > 30 years after being diagnosed with DM, an Infinium Human Methylation 850 Beadchip was used to identify differential methylation regions (DMRs) and differential methylation sites (DMSs). The function of the genes was assessed through KEGG enrichment analysis, Gene Ontology (GO) analysis, and pathway network analysis. In the replication cohort, 87 DR patients with a short DM duration and 89 patients without DR over a DM duration > 20 years were compared to assess the association between DMSs and DR upon pyrosequencing.

Results

A total of 34 DMRs were identified. Genes containing DMSs with the top 5 highest beta value differences between DR and non-DR participants were located on chromosome 1 and were present in the S100A13 gene, which was associated with 71 GO terms. Two S100A13 gene sites, i.e., cg02873163 and cg11343894, displayed a good correlation with DR on pyrosequencing.

Conclusions

DMSs in the S100A13 gene may be potential biomarkers of DR.