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Spasm of accommodation

A spasm of accommodation (also known as a ciliary spasm, an accommodation, or accommodative spasm) is a condition in which the ciliary muscle of the eye remains in a constant state of contraction. Normal accommodation allows the eye to "accommodate" for near-vision. However, in a state of perpetual contraction, the ciliary muscle cannot relax when viewing distant objects. This causes vision to blur when attempting to view objects from a distance. This may cause pseudomyopia or latent hyperopia.

Although antimuscarinic drops (homatropine 5%) can be applied topically to relax the muscle, this leaves the individual without any accommodation and, depending on refractive error, unable to see well at near distances. Also, excessive pupil dilation may occur as an unwanted side effect. This dilation may pose a problem since a larger pupil is less efficient at focusing light (see pupil, aperture, and optical aberration for more.)

Patients who have accommodative spasm may benefit from being given glasses or contacts that account for the problem or by using vision therapy techniques to regain control of the accommodative system.

Possible clinical findings include:

Treatments

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Cycloplegic Eye Drops (Dilation)

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Spasm of accommodation is frequently resistant to treatment. However, some patients do find relief through the use of daily eye dilation with cycloplegic drops. One side effect of cycloplegic drops is that they often have BAK as a preservative ingredient, which, with daily use, can erode the tear shield:

At each administration of an eye drop containing benzalkonium chloride, its detergent effect disrupts the lipid layer of the tear film. This cannot be regenerated and can no longer protect the aqueous layer of the tear film, which evaporates easily. In these circumstances, the cornea is exposed and eye dryness occurs. In addition, benzalkonium chloride has a cellular toxicity on caliciform cells, entailing a reduction in the amount of mucin, an additional reason for disrupting the tear film.[1]

In fact, none of the cycloplegic drops used to treat Spasm of Accommodation in the United States are available without BAK. This unfortunately makes treatment much more difficult as the side effect of dry eyes and corneal damage can occur. France, Australia, Canada, and the United Kingdom do have limited availability of BAK-free eye drops available in unidose, and they must be imported to the United States with a physician's letter to the FDA[2] enclosed with the imported prescription.

Due to the high potential of tear shield damage with long-term use and the associated dry eye condition caused by cycloplegic eye drops with BAK (preservative), many physicians do not recommend cycloplegic eye drops. In difficult cases, "cycloplegic agents are highly favored to break spasm quickly and may be more economical compared to other conventional therapies"[3]

Cyclopentolate, Atropine, Tropicamide, and Homatropine are the typical cycloplegic eye drops used once daily to treat spasm of accommodation by relaxing the ciliary muscle. One side effect is blurred vision since these induce dilation.

Vision Training

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Vision therapy administered by a trained optometrist has shown a success rate of over 70%.[4]

Surgery

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Multifocal intraocular lens implantation is a new possible treatment involving clear lens extraction and multifocal intraocular lens implantation[5] but it may not be appropriate for patients who have had resistant spasm of accommodation for a long period of time.

Research

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Experimental Nitroglycerin and Nitric Oxide

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Animal studies[6][7] have found nitroglycerin, a vasodilator used to treat angina, relaxes the ciliary muscle and may hold hope for those suffering from spasm of accommodation. Nitroglycerin is currently being investigated as a treatment for glaucoma, and has shown to decrease intraocular pressure and relax the ciliary muscle. According to Investigative Ophthalmology & Visual Science Journal. "In a nonhuman primate study, topical administration of nitroglycerin at a dose of 0.1% significantly decreased IOP in normotensive animals after 90 minutes".[7] Further, according to Wiederholt, Sturm, and Lepple-Wienhues,[8] "The data indicate (indicates [sic]) that an increase of intracellular cGMP by application of cGMP and organic nitrate or non-nitrate vasodilators induces relaxation of the bovine trabecular meshwork and ciliary muscle".

Experimental Perilla frutescens

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Since spasm of accommodation is a result of contraction of the ciliary muscle, the goal would be to relax the ciliary muscle. New studies conducted on rats using perilla frutescens aqueous extract have shown to relax the ciliary muscle. Since there are no known drugs to treat this eye condition, perilla frutescens in an aqueous extract form may result in the relaxation of the ciliary muscle in humans as well. Perilla frutescens is currently used in traditional medicine in Korea, Japan, and China and a clinical study "showed that PFA (perilla frutescens extract) attenuates eye fatigue by improving visual accommodation"[9]

Prognosis

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For routine cases of spasm of accommodation, the American Optometric Association says the prognosis is fair and on average, the number of visits a patient needs will be 1-2 for evaluation and 10 follow up visits.[10] Additionally, the AOA recommends the following management plan for spasm of accommodation: "Begin with plus lenses and VT; if VT fails, use cycloplegic agent temporarily; educate patient".[This quote needs a citation]

For more chronic and acute cases that do not respond to vision training and cycloplegic drops, the eye muscles should weaken with advancing age providing intermittent or permanent relief from this condition.[11]

See also

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References

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  1. ^ Coroi, Mihaela Cristina; Bungau, Simona; Tit, Mirela (2015). "Preservatives from the Eye Drops and the Ocular Surface". Romanian Journal of Ophthalmology. 59 (1): 2–5. PMC 5729814. PMID 27373107.
  2. ^ Commissioner, Office of the. "FDA Basics - Is it legal for me to personally import drugs?". www.fda.gov. Retrieved 2019-01-24.
  3. ^ "CLINICAL FINDINGS AND MANAGEMENT OF; ACCOMMODATIVE SPASM". www.aaopt.org. Retrieved 2019-01-26.
  4. ^ "The Effectiveness of Vision Therapy in Improving Visual Function". Vision Help. 2014-10-30. Wold (78) reported on 100 children who had undergone accommodative vision therapy procedures. These clinically selected cases showed an 80% rate of improvement in accommodative amplitude and 76% in accommodative facility using a pre- and post-treatment ordinal criterion referenced scaling method. These results are similar to those reported by Hoffman and Cohen (168) a in which 70 patients were successfully treated for accommodative insufficiency and infacility based on clinical findings. Retrieved 2019-01-26.
  5. ^ Gedar Totuk, Ozgun Melike; Aykan, Umit (2018). "A new treatment option for the resistant spasm of accommodation: clear lens extraction and multifocal intraocular lens implantation". International Journal of Ophthalmology. 11 (1): 172–174. doi:10.18240/ijo.2018.01.28. PMC 5767676. PMID 29376009.
  6. ^ Gabelt, B’Ann T.; Kaufman, Paul L.; Rasmussen, Carol A. (September 2011). "Effect of nitric oxide compounds on monkey ciliary muscle in vitro". Experimental Eye Research. 93 (3): 321–327. doi:10.1016/j.exer.2010.12.003. PMC 3299082. PMID 21147103.
  7. ^ a b Cavet, Megan E.; Vittitow, Jason L.; Impagnatiello, Francesco; Ongini, Ennio; Bastia, Elena (14 August 2014). "Nitric Oxide (NO): An Emerging Target for the Treatment of Glaucoma". Investigative Ophthalmology & Visual Science. 55 (8): 5005–5015. doi:10.1167/iovs.14-14515. PMID 25125670.
  8. ^ Zhao, Xiujun; Pearson, Keri E.; Stephan, Dietrich A.; Russell, Paul (1 May 2003). "Effects of Prostaglandin Analogues on Human Ciliary Muscle and Trabecular Meshwork Cells". Investigative Ophthalmology & Visual Science. 44 (5): 1945–1952. doi:10.1167/iovs.02-0920. PMID 12714628.
  9. ^ Kim, Jaeyong; Kang, Huwon; Choi, Hakjoon; Jo, Ara; Oh, Dooi-Ri; Kim, Yujin; Im, Sojeong; Lee, Seul-Gi; Jeong, Kyeong-In; Ryu, Geun-Chang; Choi, Chulyung (19 July 2018). "Aqueous Extract of Perilla frutescens var. acuta Relaxes the Ciliary Smooth Muscle by Increasing NO/cGMP Content In Vitro and In Vivo". Molecules. 23 (7): 1777. doi:10.3390/molecules23071777. PMC 6100439. PMID 30029520.
  10. ^ "Care of the Patient with Accommodative and Vergence Dysfunction" (PDF). American Optometric Association. 2001. Archived from the original (PDF) on December 13, 2016. Retrieved January 25, 2019.
  11. ^ Landolt, Edmond (1926). The refraction and accommodation of the eye and their anomalies. J.B. Lippincott Co. p. 450. OCLC 651960997.
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