High myopia glaucoma surgery
New options may address scleral thinning, other long-term complications.
Antonio M Fea MD, PhD
High myopia presents special challenges for advanced glaucoma treatment. And while surgical approaches ranging from trabeculectomy to minimally invasive procedures (MIGS) have pluses and minuses, their wide variety means it’s often possible to find an option that meets individual patient needs, said Antonio M Fea MD, PhD, at the ESCRS Glaucoma Day 2019 in Paris, France.
“Are we afraid of glaucoma surgery? I would say in general, yes. In the case of myopic patients, it is even more difficult,” said Dr Fea, of the University of Turin, Italy.
High myopia glaucoma patients often present a treatment conundrum. On one hand, they are typically young, phakic and likely to progress with intraocular pressures (IOP) in the high teens – factors favouring trabeculectomy to sustain a target IOP low enough for long-term vision preservation.
On the other hand, highly myopic patients are at higher risk for hypotony maculopathy following filtration surgery – gravitating against trabeculectomy (Costa VP, Arceiri ES. Acta Ophthalmol 2007;586-597. Fannin LA et al. Ophthalmology. Jun 2003;110(6):1185-91). Male patients are at even higher risk as are those who underwent trabeculectomy with antifibrotics, Dr Fea said. (Stamper RL et al. Am J Ophthalmol 1992; 114(5):544-53)
The risk is long-lived. In a recently published case, a 34-year-old man developed hypotony maculopathy 14 years after trabeculectomy, apparently due to progressive scleral thinning and morphologic change leading to collapse of the scleral wall during hypotony (Kao ST et al. J Glaucoma 2017;26:e137-e141). Therefore, trabeculectomy, when used in myopic patients, should be done with minimal or no antimetabolites, sutured tightly and checked to ensure complete conjunctival sealing, and followed closely, Dr Fea said.
Similarly, hypotony may be a significant risk for high myopia patients in other glaucoma surgeries. About one-third experience it after deep sclerectomy (Hamel M et al. J Cataract Refract Surg. 2001 Sep;27(9):1410-7.), while myopia-related morphological responses in drainage channels may limit the effectiveness of trabecular MIGS (Chen Z et al. Ophthalmic Physiol Opt 2018;38:266-272).
Dr Fea recently treated a 53-year-old male with -6.25 dioptres myopia with -2.75 dioptres cylinder and glaucoma that progressed about -10.0dB in 10 years in his right eye, with IOP of 18-24mmHg on four medications. To avoid hypotony, Dr Fea ruled out trabeculectomy, while ab interno MIGS didn’t offer enough potential IOP reduction. To avoid possible clogs requiring needling and complications with the patient’s contact lenses, he decided against a XEN (Allergan), opting for a PreserFlo (Santen) shunt implanted through a scleral incision.
Nine months after a surgical revision, the patient’s IOP is around 10-14mmHg. Whether that is enough remains to be seen, Dr Fea said, though the possibility of additional surgeries was preserved.
Antonio Fea: email@example.com