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A 29-year-old man with bilateral megalocornea
Digital Journal of Ophthalmology 2021
Volume 27, Number 2
April 18, 2021
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John Mark S. de Leon, MD | Department of Health Eye Center, East Avenue Medical Center, Quezon City, Philippines Marc Alfred C. Mangahas | Department of Health Eye Center, East Avenue Medical Center, Quezon City, Philippines
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| Diagnosis and Discussion | Megalocornea, a rare nonprogressive enlargement of a normal cornea to 13 mm can occur, according to Waring et al,(1) in three patterns: (1) simple megalocornea unassociated with other ocular abnormalities, (2) anterior megalophthalmos with megalocornea, and (3) iris and angle abnormalities as well as buphthalmos in infantile glaucoma. Our case was associated with other ocular findings, and the enlargement of both corneas was probably congenital, but because they were clear, the corneal enlargement was most likely nonprogressive. These findings rule out infantile or congenital glaucoma. The recent symptoms of headache and blurring of vision in the right eye that prompted consultation were probably due to the high IOP and progressing glaucoma. Anterior megalophthalmos is characterized by bilateral congenital enlargement of the corneas and anterior segments; increased anterior chamber depth in both eyes was observed in our patient.(2) Anterior megalophthalmic eyes present with a very deep anterior chamber and a vitreous index (vitreous length/axial length × 100) below 69%.(3) Our patient had a vitreous index of 60.75% in the right eye and 60.39% in the left eye.
Bilateral iridodonesis and phacodonesis in our patient was probably due to the zonular stretching caused by enlarged ciliary rings. The unilateral advanced glaucoma in the right eye (with unilateral hyper-pigmented PTM), without any of the other typical characteristics of pigment dispersion syndrome, was noteworthy, as was the lack of evidence of glaucoma in the contralateral eye, despite both eyes presenting with megalocornea, phacodonesis, and iridodonesis. We had difficulty making a definitive diagnosis of pigmentary glaucoma in the right eye, and we were uncertain whether the left eye would develop glaucoma. During initial presentation with high IOP, there were no signs of active pigment dispersion. We hypothesize that the glaucoma in the right eye was probably due to another secondary open-angle glaucoma etiology, such as an abundance of trabecular meshwork mesenchymal tissue or goniodysgenesis;(4) however, we could not entirely rule out a pigment dispersion component because of the hyperpigmented PTM in the right eye. Weak zonules could cause angle closure glaucoma by forward movement of the lens-iris diaphragm, but the angles were wide open in our case. Our patient has been doing well with the implant in the right eye, with IOP of 18 mm Hg without glaucoma medication. After more than 1 year, the vision in the right eye has deteriorated because of cataract development.
This case highlights the fact that patients with megalocornea should be monitored for glaucoma, especially those with other ocular findings. LPI was performed in the left eye, even though we were unsure whether this was a PDS case, because this was the patient’s good (glaucoma-free) eye, and the patient was very young. On UBM of the left eye, the reverse pupillary block seemed to have reversed after LPI. | |
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