Have you heard of a hyperopic myope? PC shared an interesting case with the Myopia Profile Facebook community that involved an aphakic hyperopic patient, who in reality is a high myope with Marfan Syndrome and an incredibly long axial length.
Marfan syndrome is a connective tissue disorder that affects the cardiovascular, ocular and skeletal organ systems.1 Patients with this condition usually have high myopia. Other ocular features1 can include:
- Amaurosis (2%)
- Amblyopia (3%)
- Cataract (12%)
- Ectopia lentis (30%)
- Ectopia pupillae (3%)
- Glaucoma (5%)
- Lens in vitreous (2%)
- Optic nerve atrophy (1%)
- Retinal detachment (4%)
- Retinal rupture (1%)
- Strabismus (9%)
The average axial length of healthy person is 24.73mm.2 The crystalline lens usually contributes approximately 15-20D to the optics of the eyeball.
With the crystalline lens removed, one would expect an aphakic patient to have a refractive error of approximately +15 to +20D. Hence, with a refractive error in the high +4’s, this patient is much less hyperopic (or more myopic) than she should be. This is further supported by her 30.9mm axial length reading.
Managing progression in an adult myope with Marfan syndrome can be complicated, as the condition predisposes him/her to such progression. As the current evidence base does not include such patients, practitioners should be cautious when making recommendations on the efficacy of myopia control.
Whether myopia control strategies are implemented or not, with such high axial length, this patient is at a much higher risk of ocular disease. Hence, annual follow up is necessary to monitor ocular health, and the patient should be educated as such.
Do anti-glaucoma drugs help in slowing myopia?
YCC shared data of a patient with high myopia and progressive axial elongation They offered an interesting approach in arresting axial length progression by prescribing anti-glaucoma drugs in order to slow myopia progression. Qi et al showed less myopic regression with 0.5% timolol on progressing post-LASIK patients.3 However, the biomechanics of myopic regression in post-LASIK patients are not directly comparable to that of normal myopic progression as the former can be influenced by corneal thickness, ablation depth, optical zone size and more.4 On the other hand, Goldschmidt et al showed that 0.25% timolol drop twice daily for a year had no myopia control effect (n=10).5.Therefore, further research about the efficacy of timolol in myopia control is needed.
Other pharmaceutical strategies for myopia control
In addition to timolol (and apart from atropine), other drugs under research for myopia control efficacy include 7-methylxanthine and pirenzepine. A pilot study by Trier et al showed that 7-methylxantine was effective in slowing myopia progression in Danish myopes.6 Pirenzepine has also been shown to be effective in slowing myopia, though not without adverse effects.7-9
Hence, low-dose atropine remains to be most commonly used pharmacological agent in children for myopia control. It has minimal side effects and has a great safety profile. To learn more about atropine, read the The latest and greatest research on atropine and When to prescribe atropine for myopia control.
Take home messages:
- In complex presentations with a history of pathology and/or ocular surgery, there is more than meets the eye – remember that refractive error may only one part of the story. The clinical picture still needs to make sense. If an aphakic patient is only +4.00, they are not really as hyperopic as one may be led to believe.
- Atropine remains to be the only proven pharmacological form of myopia control. Other drugs such as timolol, 7-methylxanthine and pirenzepine require more robust studies before they can be used with confidence.
- In atypical cases of myopia such as this - due to the patient's age, pathological source of myopia and high level of myopia - myopia control strategies cannot be expected to work as demonstrated in scientific studies. Proceed with a focus on informed consent and educating the patient on the importance of ongoing ocular health monitoring.
- Konradsen TR, Zetterström C. A descriptive study of ocular characteristics in Marfan syndrome. Acta ophthalmologica. 2013 Dec;91(8):751-5. (link)
- Chang JS, Lau SY. Correlation between axial length and anterior chamber depth in normal eyes, long eyes, and extremely long eyes. The Asia-Pacific Journal of Ophthalmology. 2012 Jul 1;1(4):213-5. (link)
- Qi H, Gao C, Li Y, Feng X, Wang M, Zhang Y, Chen Y. The effect of Timolol 0.5% on the correction of myopic regression after LASIK. Medicine. 2017 Apr;96(17). (link)
- Wang XC, Zhao GQ, Lin J, Jiang N, Wang Q, Xu Q. Efficacy and safety of topical timolol eye drops in the treatment of myopic regression after laser in situ keratomileusis: A systematic review and meta-analysis. J Ophthalmol. 2015: 985071. (link)
- Goldschmidt E, Jensen H, Marushak D, Østergaard E. Can timolol maleate reduce the progression of myopia?. Acta Ophthalmologica. 1985 Jul;63(S173):90. (link)
- Trier K, Ribel-Madsen SM, Cui D, Christensen SB. Systemic 7-methylxanthine in retarding axial eye growth and myopia progression: a 36-month pilot study. Journal of ocular biology, diseases, and informatics. 2008 Dec 1;1(2-4):85. (link)
- Tan DT, Lam DS, Chua WH, Shu-Ping DF, Crockett RS, Asian Pirenzepine Study Group. One-year multicenter, double-masked, placebo-controlled, parallel safety and efficacy study of 2% pirenzepine ophthalmic gel in children with myopia. Ophthalmology. 2005 Jan 1;112(1):84-91. (link)
- Siatkowski RM, Cotter S, Miller JM, Scher CA, Crockett RS, Novack GD. Safety and Efficacy of 2% Pirenzepine Ophthalmic Gel in Children WithMyopia: A 1-Year, Multicenter, Double-Masked, Placebo-Controlled ParallelStudy. Archives of ophthalmology. 2004 Nov 1;122(11):1667-74. (link)
- Siatkowski RM, Cotter SA, Crockett RS, Miller JM, Novack GD, Zadnik K, US Pirenzepine Study Group. Two-year multicenter, randomized, double-masked, placebo-controlled, parallel safety and efficacy study of 2% pirenzepine ophthalmic gel in children with myopia. Journal of American Association for Pediatric Ophthalmology and Strabismus. 2008 Aug 1;12(4):332-9. (link)