Myopia linked to lower AMD and DR risk, higher glaucoma risk

Paper title: Positive and Negative Associations of Myopia with Ocular Diseases in Population-Based Studies

Authors: Jonas JB (1,2,3), Bikbov MM (4), Kazakbaeva GM (4,5), Wang YX (6), Xu J (6), Nangia V (7), Nangia PV (7), Panda-Jonas S (1,3,8)

1. Institut Français de Myopie, Hôpital Fondation Adolphe de Rothschild, Paris, France 
2. Singapore Eye Research Institute, Singapore 
3. Privatpraxis Prof Jonas und Dr Panda-Jonas, Heidelberg, Germany
4. Ufa Eye Research Institute, Ufa, Russia
5. Ufa Eye Research Institute, Ufa, Russia; Ufa Eye Institute, Ufa, Russia
6. Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, China
7. Suraj Eye Institute, Nagpur, India
8. Department of Ophthalmology, Medical Faculty Heidelberg, Heidelberg University, Heidelberg, Germany

Date: Published online July 5, 2024

Reference: Jonas JB, Bikbov MM, Kazakbaeva GM, Wang YX, Xu J, Nangia V, Nangia PV, Panda-Jonas S. Positive and Negative Associations of Myopia with Ocular Diseases in Population-Based Studies. Ophthalmology. 2024 Dec;131(12):1427-1435.

[Link to paper abstract] 

Previous studies have demonstrated that myopia, particularly high myopia, is associated with increased risks of complications such as myopic macular degeneration and optic neuropathies.^1–4 Conversely, evidence also suggests the risk of other ocular pathologies is lower in myopes compared to hyperopes, including diabetic retinopathy (DR)^5,6, age-related macular degeneration (AMD)^7,8, and angle-closure glaucoma (ACG).^9,10 Associations with these conditions are less well-established. To address this gap, the authors conducted a comparative analysis of three large population-based studies to explore whether axial myopia is consistently associated with major ocular diseases.

This study analysed data from three population-based cohorts involving adults in the Ural Eye and Medical Study (UEMS; age>40 years), the Beijing Eye Study (BES; age >40 years), and the Central India Eye and Medical Study (CIEMS; age >30 years). Axial length was used as a surrogate for myopia, and all participants underwent a series of comprehensive ophthalmological and general medical examinations. High myopia was defined as spherical equivalent refraction of more than -8D or axial length of 26.5 mm or more. 

Key findings were as follows.

• Longer axial length was associated with lower prevalence of DR (OR 0.73 in Russia, 0.64 in China) and lower 10-year incidence of DR (OR 0.48 in China).
• Longer axial length was also associated with lower prevalence and incidence of AMD (ORs 0.85 in Russia, 0.81 in India; 5-year AMD incidence OR 0.996 in China).
• ACG prevalence decreased with longer axial length across all three cohorts (e.g., OR 0.55 in India).
• In contrast, longer axial length was linked to higher prevalence and incidence of open-angle glaucoma (OAG) (e.g., ORs 1.65 in Russia; 10-year OAG incidence OR 1.40 in China).
• The increase in OAG risk was nonlinear, with a steep rise in highly myopic eyes.

These findings highlight the nuanced relationship between myopia and ocular disease. While myopia is well recognised as a risk factor for open-angle glaucoma and myopic macular degeneration, it is offset by a relatively lower risk of developing other major age-related ocular diseases (compared to hyperopia). 

For eye care practitioners, these findings should not diminish the importance of existing practice patterns. For example, myopia control remains essential in childhood to reduce the future burden of high myopia and its associated complications.

The increased prevalence and incidence of OAG in eyes with long axial length reinforces the utility of ocular biometry in the clinical assessment of myopic adults. Axial length measurements can be used to quantify disease risk to assist eye care practitioners in educating patients about the importance of ongoing ocular health assessment.

Eyes with axial lengths exceeding 26 mm especially warrant close surveillance for evidence of glaucoma and other myopia-related conditions. The latter is important, as the authors appeared to convey lower prevalence of DR, AMD, and ACG as an advantage of myopia. However, it should be remembered that myopic maculopathy, retinal detachment, and cataract, are established disease associations of high myopia as well.¹¹

Several limitations resulted from the three studies selected for comparison. The three population-based studies were not equivalent in design. The longitudinal analyses of DR, AMD, and OAG were based on the Chinese cohort only, introducing potential survival bias over a 10-year follow-up period. The remaining two studies (Russia and India) were cross-sectional in design, limiting causal inference between axial length and ocular disease prevalence. 

With regards to the study populations used, the UEMS (Russia), CIEMS (India), and BES (China), were not fully representative of the countries in which they were conducted. For example, the ethnic composition of the UEMS, is half Central Asian and half Eastern European. This limits the ability to generalise the study’s findings to other countries in similar regions.

The authors cited that the prevalence of AMD may have been underestimated in myopic eyes due to anatomical alterations. Choroidal thinning and tessellated fundus are a common characteristic of highly myopic eyes.¹² Drusenoid changes – a hallmark of AMD, may be more difficult to detect in myopic eyes, which can have less fundus contrast due to retinal pigment epithelium and choroidal changes. 

Future studies should aim to clarify causality, explain why axial length is associated with higher or lower prevalence of certain ocular diseases, and investigate more diverse populations.

Purpose: Prevalence of myopia and vision impairment due to myopic macular degeneration and myopia-related optic neuropathies have markedly increased worldwide. We evaluated whether myopia is associated with other ocular disorders.

Methods: The participants underwent a series of ophthalmological and general medical examinations.

Results: In the UEMS, DR prevalence (odds ratio [OR], 0.73), AMD prevalence (OR, 0.85), and ACG prevalence (OR, 0.72) decreased, and OAG prevalence (OR, 1.65) increased with longer axial length in multivariable analyses. In the CIEMS, lower AMD prevalence (OR, 0.81) and lower ACG prevalence (OR, 0.55), and higher OAG prevalence (OR, 1.45) were associated with longer axial length. Diabetic retinopathy prevalence (0.33%) was too low for statistical analysis in the CIEMS. In the BES, prevalence (OR, 0.64) and 10-year incidence of DR (OR, 0.48) and prevalence (OR, 0.83) and 5-year incidence of AMD (OR, 0.996) decreased, and prevalence (OR, 1.35) and 10-year incidence of OAG (OR, 1.40) increased with longer axial length. In all 3 studies, the association between higher OAG prevalence and longer axial length was nonlinear with a slight increase for the moderate myopia range and a steep increase in the highly myopic range.

Conclusions: Myopia is associated with a lower prevalence of DR, AMD, and ACG and a lower incidence of DR and AMD, whereas high myopia more than moderate myopia is associated with a higher prevalence and incidence of OAG. Future studies may assess whether in myopia (in particular, in moderate myopia), the myopia-related advantages, that is, lower prevalence of DR, AMD, and ACG, may outweigh the increased risks for OAG and other myopia-related disorders.

[Link to paper abstract]

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