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| BRIEF REPORT |
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| Year : 2000 | Volume
: 48
| Issue : 3 | Page : 233-4 |
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Unilateral pellucid marginal degeneration
SK Basak, TK Hazra, D Bhattacharya, TK Sinha
Disha Eye Hospitals and Research Centre, Barrackpore, West Bengal-743 001, India
Correspondence Address:
S K Basak
Disha Eye Hospitals and Research Centre, Barrackpore, West Bengal-743 001
India
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 11217258 
Keywords: Astigmatism, etiology, Cornea, pathology, ultrasonography, Corneal Dystrophies, Hereditary, complications, diagnosis, Corneal Topography, Diagnosis, Differential, Disease Progression,
How to cite this article:
Basak S K, Hazra T K, Bhattacharya D, Sinha T K. Unilateral pellucid marginal degeneration. Indian J Ophthalmol 2000;48:233 |
Pellucid marginal degeneration (PMD) is a rare and usually a bilateral condition. We report a case of typical PMD with a unilateral presentation.
Indian J Ophthalmol 2000;48:233-34
Pellucid marginal degeneration (PMD) is characterised by non-ulcerative, non-inflammatory, clear thinning of the inferior portion of the peripheral cornea. [1,2] It occurs in both men and women, presenting between second and the fourth decade, with chief complaints of progressive dimness of vision caused by high "against the rule" astigmatism.
| Case report | |  |
A 46-year-old male presented, complaining of progressive dimness of vision in the left eye for past 12 years. There was no history of excessive eye rubbing, trauma, contact lens wear or episodic redness of the eye. His general medical history was not contributory. Two of his sisters had a history of myopia. The patient had worn myopic spectacles correction for the past 12 years. Earlier he was diagnosed with keratoconus in the left eye. On examination, his best corrected visual acuity in the right eye was 6/6 (-0.50 Dsph with -0.75 Dcyl @ 95ø) and in the left eye, 6/36 (-7.50 Dcyl @ 90ø). Keratometric measurements in the right eye were 42.50 @ 95ø and 43.50 @ 5ø, and in the left eye, 39.50 @ 95ø and 48.50 @ 180ø. Slitlamp examination of the right cornea revealed normal features without any thinning or protrusion. However, in the left eye a clear band of peripheral thinning about 1-2 mm wide, was noted inferiorly extending from the 4.30 to 8.30 o' clock meridian, with anterior protrusion of the cornea just above the thinned area [Figure - 1]. A 2 mm zone of normal-thickness cornea was seen between the thinned area and the limbus. The epithelium overlying this thinning was intact and showed no evidence of vascularisation or lipid deposition. Ocular adenexa were healthy without any congestion or chemosis. Ultrasonic pachometry readings of the right eye were 542 μm centrally and 718 μm peripherally; in the left eye, the readings were 548 μm centrally, 514 μm at the zone of thinning, and 712 μm at the periphery.
Corneal topography (EYE SYS - Technologic, Version 8.04, Houston, Texas) of the right eye showed normal features with mild "against the rule" astigmatism at 95ø [Figure:2a]. In the left eye the lowest corneal power was located along a narrow corridor of the central and paracentral cornea; the axis of this narrow corridor was at 90ø. The corneal power was highest along the inferior peripheral cornea and in the mid peripheral cornea along the inferior-oblique corneal meridians, conditions typical of PMD [Figure:2b].
| Discussion | | |
Pellucid marginal degeneration is a non-inflammatory thinning of the inferior peripheral cornea without any vascularisation, scarring or lipid deposition. It is a bilateral condition. Most cases present with "against the rule" astigmatism. On corneal topography it is seen as marked steepening of the inferior corneal periphery, which also extends into mid-peripheral inferior corneal meridians. The mid-peripheral cornea is gradually decreased in power above the inferior oblique meridians.[3] This patient had all these features only in the left eye; the right eye was normal in all respects except for mild "against the rule" astigmatism. Absence of vascularisation and lipid deposition, marginal ulceration, or protrusion in the zone of thinning distinguishes this case from Terrien's marginal degeneration, Mooren's ulcer or keratoconus.
Atypical presentations of PMD have been reported in the literature. The various presentations include the superior PMD, or in association with keratoconus or keratoglobus.[4] A similar presentation of unilateral typical PMD has been reported by Wagenhorst in an elderly black patient.[5] Although bilateral conditions often present asymmetrically, the right eye in this case did not reveal any signs of corneal involvement at presentation. This unusual unilateral affection of typical PMD in this patient is reported to differentiate this condition from other ectatic corneal disorders.
| References | | |
| 1. | Krachmer JH. Pellucid marginal corneal degeneration. Arch Ophthalmol 1978;96:1217-21.  [ PUBMED] |
| 2. | Krachmer JH, Feder RS, Belin MW. Keratoconus and related noninflammatory corneal thinning disorders. Surv Ophthalmol 1984;28:293-322. [ PUBMED] |
| 3. | Maguire LJ, Klyce SD, McDonald MB, Kaufman HE. Corneal topography of pellucid marginal degeneration. Ophthalmology 1987;94:519-24. |
| 4. | Bower KS, Dhaliwal DK, Barnhorst DA Jr, Warnicke J. Pellucid marginal degeneration with superior corneal thinning. Cornea 1997;16:483-85. [ PUBMED] |
| 5. | Wagenhorst BB. Unilateral pellucid marginal degeneration in an elderly patient. Br J Ophthalmol 1996;80:927-28. [ PUBMED] |
[Figure - 1], [Figure - 2], [Figure - 3]
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