By Mok Hao Ting, Yong Loo Lin School of Medicine, National University of Singapore
With the rise in the prevalence of myopia globally, myopic complications are real and rising concerns in society. Severe myopia increases the risk of developing a variety of macular and peripheral retinal complications, potentially compromising one’s quality of life.
Dr Au Eong Kah Guan, Medical Director and Senior Consultant Ophthalmologist in International Eye Cataract Retina Centre at Mount Elizabeth Medical Centre and Farrer Park Medical Centre, delivered a lecture at the Singapore Primary Eye Care Symposium (SPECS) 2019 held at One Farrer Hotel on 23 and 24 July 2019. His lecture on ‘Complications of Myopia: Macular and Peripheral Retinal Pathology’ highlights the common and severe pathological changes associated with high myopia.
The different degrees of myopia are characterised based on the severity of the refractive error, ranging from low myopia (-3.00 dioptres or less) to moderate myopia (-3.25 to -5.00 or -6.00 dioptres) and high myopia (greater than -5.00 or -6.00 dioptres). Axial length elongation, which causes a stretch in the retina is commonly associated with high myopia. Moreover, posterior staphyloma, the outpouching of the ocular wall with a smaller radius, is often present in highly myopic individuals with long axial length. Dr Au Eong focussed on various myopia-related complications, including myopic choroidal neovascularisation, foveoschisis, macular hole, lattice degeneration, retinal holes, retinal tears and retinal detachment.
Studies have shown a link between high myopia and choroidal neovascularisation, which affects 5 to 11% of high myopes. During the initial stages, bleeding and formation of new blood vessels may lead to direct damage to photoreceptors, causing central visual loss. As the choroidal neovascularisation regresses, a fibrous pigmented scar known as Fuch’s spot forms. If left untreated, it may result in the atrophy of the retina, leading to long-term vision loss. Further assessments of such a condition can be carried out using fundus fluorescein angiography and optical coherence tomography (OCT) to detect any lesion and determine its pathological nature.
Moving on, myopic foveoschisis is defined as the intraretinal cleavage in the fovea, and is a prevalent complication related to high myopia. Myopic foveoschisis affects 9 to 34% of highly myopic patients with posterior staphyloma and its symptoms include metamorphopsia and blurred vision.
Myopic macular hole occurs more commonly in eyes with increased axial length in conjunction with posterior staphyloma. It may be associated with retinal detachment. Myopia also increases the possibility of lattice degeneration, the thinning of peripheral retina, which causes focal degeneration. Furthermore, myopia is a major risk factor for retinal holes, retinal tears and rhegmatogenous retinal detachment, and related symptoms are floaters and peripheral loss of vision.
To conclude, Dr Au Eong emphasised on the importance of being on a constant lookout for these myopia-related macular and peripheral retinal complications and the urgency of treatment for some of these conditions. Slit-lamp examination and the use of imaging modalities such as fundus fluorescein angiography and OCT can help in identifying any underlying retinal changes and aid in its proper diagnosis and management.