![]() PMD has no sex or racial predilection, and does not appear to be hereditary, but moderate to high astigmatism has been noted in families with affected patients. PMD typically presents in the second to fifth decade of life. It has not been elucidated whether keratoconus, keratoglobus, and PMD are different diseases or phenotypic variations of the same disease. In series performed in Japan, 17 of 27 cases of unilateral PMD revealed keratoconus or suspected keratoconus in the fellow eye. Ten percent of PMD cases are associated with keratoconus and 13% are associated with keratoglobus. Keratoconus, keratoglobus, and PMD are postulated to be related because these conditions coexist in families. Some people postulate, however, that this prevalence might be underestimated as the condition is often misdiagnosed as keratoconus. PMD, while rare, is the second most common noninflammatory corneal thinning disorder after keratoconus. Also, patients who undergo refractive surgery with PMD can have deleterious results, so it is important to consider prior to refractive surgery. ![]() ![]() It is important to recognize as it can cause severe deterioration in visual function. PMD is disease of peripheral corneal thinning that is slowly progressive over many years. There is no associated inflammation and the central cornea is of normal thickness. The usual tendency of an increase in "against the rule astigmatism" that occurs when PK alone is done for PMD was eliminated.PMD is uncommon and is characterized by a crescent-shaped band of inferior corneal thinning approaching 20% of normal thickness that is 1 to 2 mm in height, 6 to 8 mm in horizontal extent, and 1 to 2 mm from the limbus. Low to moderate levels of postkeratoplasty astigmatism were achieved in all the eyes treated. The short-term results with this technique are excellent in that it provides early and stable visual rehabilitation in patients with advanced PMD. ![]() Two patients had elevations of intraocular pressure that responded to reduction in topical steroid dose. A tendency for an increase in "with the rule astigmatism" after the rehabilitation period was noted. The time required for visual rehabilitation ranged from 5.13 to 10.93 (mean, 9.92) months, and the amount of corneal astigmatism at the end of this period ranged from 0.3 diopters (D) to 5.3 D. The latter two had decreased acuity from posterior subcapsular cataract formation, which may have been caused by topical steroid use. Visual acuity results were 20/40 in three eyes, 20/80 in one eye, and 20/400 in one eye. Measuring the change in corneal astigmatism by videokeratography over the subsequent follow-up period after spectacle correction had been prescribed assessed stability of the achieved refraction. These included interval of time required for visual rehabilitation, best spectacle-corrected visual acuity achieved, and amount of corneal astigmatism, as measured by videokeratography. Simultaneous peripheral crescentic LK and central PK followed by selective suture removal and astigmatic keratotomy in the postoperative period. Retrospective, noncomparative, interventional case series. To determine the efficacy of simultaneous peripheral crescentic lamellar keratoplasty (LK) and central penetrating keratoplasty (PK) for advanced pellucid marginal degeneration (PMD).
0 Comments
Leave a Reply. |