![]() ![]() This retrospective study included 15 eyes of 15 patients, eleven males and four females, with a diagnosis of pellucid marginal degeneration (PMD) in whom MyoRing was implanted using the PocketMaker Microkeratome for PMD correction at Bina eye hospital, Tehran, Iran, between October 2012 and November 2013. The use of the MyoRing implantation has proven safe and effective in patients with high myopia, post LASIK ectasia, and keratoconus ( 25- 32). The MyoRing (Dioptex GmbH) is a 360º continuous intracorneal ring that is implanted into the cornea using the PocketMaker Microkeratome or femtosecond laser. Due to the unsatisfactory results of the available treatments for PMD, the use of intracorneal ring segments (ICRS) has been proposed, in order to improve visual outcomes ( 18- 24). However, all of these techniques are irreversible which require a long period of rehabilitation with unpredictable visual results ( 13- 17). ![]() In patients who cannot tolerate contact lenses or in those who do not achieve adequate visual acuity with contact lenses because of the degree of ectasia, several surgical procedures including penetrating keratoplasty, deep anterior lamellar keratoplasty, crescentic wedge resection, thermokeratoplasty, epikeratoplasty, and crescentic lamellar keratoplasty, have been proposed. Patients with high or irregular astigmatism cannot be corrected with spectacles in these cases, contact lens fitting is more difficult in pellucid eyes than keratoconic eyes as a result of central flattening and peripheral steepening ( 9- 12). The non-surgical management of PMD includes spectacles and different groups of contact lenses ( 6- 8), yet these procedures lose their effectiveness as the disease progresses. The management of PMD depends on the severity of the disease. Visual symptoms include long-standing poor visual acuity, which results from high irregular against-the-rule astigmatism ( 2- 5). The topographic appearance is a classical “butterfly” pattern demonstrating a large amount of against-the-rule astigmatism that makes the fitting of contact lenses difficult. The gold standard diagnostic test for PMD is corneal topography. The area of thinning is typically around 1 or 2 mm in width, which extends from 4 to 8-o’clock positions ( 1- 4). Pellucid marginal corneal degeneration (PMD) is a rare, non-inflammatory ectatic disorder of the inferior peripheral cornea characterized by a crescent-shaped band of inferior corneal thinning. ![]()
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