Are there special considerations for managing and treating high myopia?
It is estimated that there are almost 1.5 billion people with myopia, 163 million with high myopia and a significant proportion of the population suffering non-refractive visual consequences of the worldwide boom in myopia.1 Estimates suggest that 10 million people worldwide currently have vision impairment from myopic macular degeneration and 3.3 million suffer blindness.2 If these numbers don’t feel staggering enough, with projections based on the rising levels of myopia, this number could rise to 55 million people vision impaired and 18.5 million blind by 2050, or 0.57% and 0.19% of the world’s population respectively.2
Young children (under age 10) with high levels of myopia often have an associated general or ocular health condition of concern, and typically require co-management between optometry and ophthalmology. Read more about this in High Myopia in Childhood - Special Considerations and Safe Management. Complications of myopia are rapidly becoming a leading cause of vision impairment in children1, and myopic maculopathy is already the leading cause of monocular blindness in Japanese adults.3 As Ian Flitcroft first revealed - there is no safe level of myopia, but the risks really escalate in high myopia.4 The following describes the steps we should consider in managing our highly myopic patients.
High myopia is defined by the International Myopia Institute as 6D or more of myopia.5
1. Provide ocular health management
The risk of complications of macular maculopathy escalate exponentially with myopic dioptres: double the risk in the 1-3D group compared to the emmetrope, 10x greater risk in those with myopia of 3-5D and 40x greater risk as myopia increases beyond 5D.4
Childhood retinal detachments make up 3-13% of all retinal detachments, so these consequences of myopia are not simply an 'adult only' problem.6 Younger children can have limited capacity as observers of their own symptoms, and the consequences of this are significant: 97% of paediatric retinal detachments are macula off.7
Once axial length becomes longer than 26mm, the risk of a host of myopia-associated complications increases steeply.8 We have discussed how measuring axial length is useful in monitoring myopia progression in Six questions on axial length measurement in myopia management, however it is also useful in assessing the risk of maculopathy and other complications of myopia for the individual patient.
Any myope with an axial length exceeding 26mm could be considered a 'high myope' from the retinal perspective. The IMI Clinical Management Guidelines suggest that these patients be reviewed annually with retinal health examination through dilated pupils.9
If you don't have access to axial length measurement, even once as a single measure to gain an idea of your patient's disease risk, it's helpful to know that 26mm is approximately equivalent to 5D of myopia.8
It's also important to note, though, that variation in axial length can mean that a lower myope can have a longer axial length. Beware these patients in cases where the patient has a flatter cornea - since the cornea doesn't typically tend to change much in school-aged children,10 a flatter cornea with moderate myopia can be a particular clue to longer axial length. Read more about this in the clinical case A mismatch between myopia and axial length.
If you are an optometrist without access to mydriatic diagnostic drugs, depending on your scope of practice and appropriate clinical pathways in your country, you may need to co-manage with ophthalmology for annual retinal health examination through dilated pupils for high myopes, and other myopes on indication.
Advice on ocular health
Patients with high myopia, and their families, should be advised of the importance of regular retinal health examinations, and the symptoms of retinal detachment. Blunt trauma is responsible for 90% of giant retinal tears in children,11 so advise parents and patients on this risk and how to avoid it. Protective eye wear (especially if otherwise wearing contact lenses) can be very important for ball sports.
If the retina is at particular risk, for example through predisposing retinal degenerations or prior surgery, the patient may need to be advised to avoid or limit any sports and activities that involve excessive shaking or forces on the head: such as contact sports, extreme roller-coaster rides, trampoline jumping and bungee jumping.
2. Consider the best optical correction
For high myopia, it's important to control the vertex distance in both refraction and optical dispensing. High myopes approaching 10D and beyond can suffer reduced visual acuity12 and contrast sensitivity13 compared to lower myopes, and impaired quality of life similar to that of patients with keratoconus.12 Ensure you measure vertex distance in refraction, check acuity in a trial frame and attempt to match this in the vertex distance of the frame for best acuity.
Spectacle frame choices for stability and sturdiness; and high index lenses for improved visual quality and comfort, are vital to give high myopes the clearest possible vision. More tips on refraction and dispensing can be found in this Points de Vue article entitled High Myopia: the specificities of refraction and optical equipment.
Contact lenses can improve distance acuity and field of view in high myopia, and hence are a crucial correction option. Contact lenses, though, require increased accommodative and vergence effort at near compared to strongly powered myopic spectacles. This may not be an issue for children, teens and young adults with normal binocular vision function, but can lead to earlier presbyopic correction required by contact lens-wearing high myopes compared to those wearing spectacles.14
Contact lenses can also have significant functional and psychological benefits for children and teens - read more on these topics in Kids And Contact Lenses – Benefits, Safety And Getting To ‘Yes’.
3. Consider myopia control
Since each dioptre increases the risk of myopic pathology and visual impairment,15 it makes sense to discuss myopia control with all myopes at risk of progression.
Most myopia control studies, though, exclude children with more than 5D of myopia which does mean we have to extrapolate the evidence base for these patients. There is a small amount of evidence for high myopia control intervention with orthokeratology and low-concentration atropine.
The only optical intervention with evidence for high myopes is partial correction orthokeratology, which showed a myopia control effect equivalent to at any other level of myopia. In the study, myopes between 6 and 8D were partially corrected to around 4D with the residual refractive error corrected with glasses during the day time.16 The Low-concentration Atropine for Myopia Progression (LAMP) study enrolled children up to around 8D of myopia, with around 10-15% being high myopes. It showed a concentration-dependent myopia control impact of 0.05% and 0.025% atropine, with minimal effect of 0.01%.17 It did not report specific outcomes relating to baseline refraction.
Other myopia control methods, where available for high myopia correction, can still be discussed with parents and patients, with the caveat that results can't necessarily be predicted for that individual's situation.
Do high myopes progress more quickly?
There isn't actually a lot of data on this. The main relationship between faster myopia progression is the child's current age - younger children progress more quickly, regardless of their level of myopia at the time.18
A recent large-scale European study showed faster progression in children aged 7-9 years with more than 4D of myopia. The authors also noted that regardless of baseline myopia, the 7-9 year olds progressed most quickly. Children younger or older than this, or with lower baseline myopia, didn't progress as quickly.19
Another recent large study, this time in India, similarly showed fastest progression in children aged 6-10 years. High myopes (6 to 9D) showed faster progression than low and moderate myopes (0.50 to 3D and 3 to 6D respectively), who were similar. Severe myopes (over 9D) showed the fastest progression over one year, even in their later teens and early adulthood.
- In myopes under 15 years, the mean annual progression in low and moderate myopes was just under 0.50D. High myopes were around 0.62D and severe myopes 0.75D.
- In myopes over 15 years of age, low, moderate and high myopes all progressed similarly, by less than 0.25D. The severe myopes over 15 years, though, progressed by around 0.50D in one year.20
The sum total is that children under age 10 will progress most quickly, and high myopes probably will progress a little faster. Severe myopes (9D or more) progress more quickly than the rest, even in late childhood and adulthood.
- Manage ocular health in high myopes, by ensuring retinal examination through dilated pupils occur yearly. For optometrists, this may require co-management with ophthalmology, especially in younger children.
- The best optical correction for high myopes is likely to be contact lenses, which can provide improved acuity, field of view and quality of life. Spectacles are a necessity for all contact lens wearers, though (even if as a backup) so remember to manage vertex distance, dispense a sturdy frame and high index lenses for best vision and comfort outcomes.
- Every dioptre is important - discuss the options of myopia control for children, teens and young adults with progressive myopia, but be cautious in considering how the results of clinical studies may not directly apply to that particular patient.
Further reading on high myopia
- Holden BA, Fricke TR, Wilson DA, Jong M, Naidoo KS, Sankaridurg P, Wong TY, Naduvilath TJ, Resnikoff S. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology. 2016 May;123(5):1036-42. (link)
- Fricke TR, Jong M, Naidoo KS, Sankaridurg P, Naduvilath TJ, Ho SM, Wong TY, Resnikoff S. Global prevalence of visual impairment associated with myopic macular degeneration and temporal trends from 2000 through 2050: systematic review, meta-analysis and modelling. Br J Ophthalmol. 2018 Jul;102(7):855-862. (link)
- Iwase A, Araie M, Tomidokoro A, Yamamoto T, Shimizu H, Kitazawa Y; Tajimi Study Group. Prevalence and causes of low vision and blindness in a Japanese adult population: the Tajimi Study. Ophthalmology. 2006 Aug;113(8):1354-62. (link)
- Flitcroft DI. The complex interactions of retinal, optical and environmental factors in myopia aetiology. Prog Retin Eye Res. 2012 Nov;31(6):622-60. (link)
- Flitcroft DI, He M, Jonas JB, Jong M, Naidoo K, Ohno-Matsui K, Rahi J, Resnikoff S, Vitale S, Yannuzzi L. IMI - Defining and Classifying Myopia: A Proposed Set of Standards for Clinical and Epidemiologic Studies. Invest Ophthalmol Vis Sci. 2019 Feb 28;60(3):M20-M30. (link)
- Coussa RG, Sears J, Traboulsi EI. Stickler syndrome: exploring prophylaxis for retinal detachment. Curr Opin Ophthalmol. 2019 Sep;30(5):306-313. (link)
- Nagpal M, Nagpal K, Rishi P, Nagpal PN. Juvenile rhegmatogenous retinal detachment. Indian J Ophthalmol. 2004 Dec;52(4):297-302. (link)
- Tideman JW, Snabel MC, Tedja MS, van Rijn GA, Wong KT, Kuijpers RW, Vingerling JR, Hofman A, Buitendijk GH, Keunen JE, Boon CJ, Geerards AJ, Luyten GP, Verhoeven VJ, Klaver CC. Association of Axial Length With Risk of Uncorrectable Visual Impairment for Europeans With Myopia. JAMA Ophthalmol. 2016 Dec 1;134(12):1355-1363. (link)
- Gifford KL, Richdale K, Kang P, Aller TA, Lam CS, Liu YM, Michaud L, Mulder J, Orr JB, Rose KA, Saunders KJ, Seidel D, Tideman JWL, Sankaridurg P. IMI - Clinical Management Guidelines Report. Invest Ophthalmol Vis Sci. 2019 Feb 28;60(3):M184-M203. (link)
- Mutti DO, Mitchell GL, Sinnott LT, Jones-Jordan LA, Moeschberger ML, Cotter SA, Kleinstein RN, Manny RE, Twelker JD, Zadnik K, The CLEERE Study Group. Corneal and Crystalline Lens Dimensions Before and After Myopia Onset. Optom Vis Sci. 2012;89(3):251-262. (link)
- Rahimi M, Bagheri M, Nowroozzadeh MH. Characteristics and outcomes of pediatric retinal detachment surgery at a tertiary referral center. J Ophthalmic Vis Res. 2014 Apr;9(2):210-4. (link)
- Rose K, Harper R, Tromans C, Waterman C, Goldberg D, Haggerty C, Tullo A. Quality of life in myopia. Br J Ophthalmol. 2000 Sep;84(9):1031-4. (link)
- Jaworski A, Gentle A, Zele AJ, Vingrys AJ, McBrien NA. Altered visual sensitivity in axial high myopia: a local postreceptoral phenomenon? Invest Ophthalmol Vis Sci. 2006 Aug;47(8):3695-702. (link)
- Vincent SJ. The use of contact lenses in low vision rehabilitation: optical and therapeutic applications. Clin Exp Optom. 2017 Sep;100(5):513-521. (link)
- Bullimore MA, Brennan NA. Myopia Control: Why Each Diopter Matters. Optom Vis Sci. 2019;96(6):463-465. (link)
- Charm J, Cho P. High myopia-partial reduction ortho-k: a 2-year randomized study. Optom Vis Sci. 2013 Jun;90(6):530-9. (link)
- Yam JC, Jiang Y, Tang SM et al. Low-Concentration Atropine for Myopia Progression (LAMP) Study. Ophthalmol. 2019;126:113-24. (link)
- Chua SY, Sabanayagam C, Cheung YB, Chia A, Valenzuela RK, Tan D, Wong TY, Cheng CY, Saw SM. Age of onset of myopia predicts risk of high myopia in later childhood in myopic Singapore children. Ophthalmic Physiol Opt. 2016 Jul;36(4):388-94. (link)
- Tricard D, Marillet S, Ingrand P, Bullimore MA, Bourne RRA, Leveziel N. Progression of myopia in children and teenagers: a nationwide longitudinal study. Br J Ophthalmol. 2021 Mar 12:bjophthalmol-2020-318256. (link)
- Verkicharla PK, Kammari P, Das AV. Myopia progression varies with age and severity of myopia. PLoS One. 2020 Nov 20;15(11):e0241759. (link)