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Acute Corneal Hydrops

CLINICAL DESCRIPTION:
Figure 2 Figure 1Corneal hydrops is an uncommon complication seen in patients with keratoconus. It is characterized by significant corneal edema resulting from a spontaneous rupture in Descemet's membrane. Clinical findings include dense stromal and epithelial edema with corneal protrusion, possible conjunctival hyperemia and irregular epithelium secondary to microcystic edema (Figures 1 and 2). The location and area of the involved cornea is variable.
SYMPTOMS:
Patients typically report sudden onset of monocular visual impairment, ocular irritation or pain, photophobia, and tearing. Patients frequently notice corneal opacification observable by the unaided eye.
INCIDENCE: 

Corneal hydrops is known to occur in less than 5% of keratoconic patients. It has also been reported in other ectatic disorders such as pellucid marginal degeneration, keratoglobus, Terrien's marginal degeneration, and posterior keratoconus. Studies have shown hydrops occurs more commonly in males than females.

ETIOLOGY:

The progressive corneal thinning in advanced keratoconus can lead to a rupture in Descemet's membrane as well as the overlying endothelium. An influx of aqueous into the stroma results in immediate stromal and epithelial edema, opacification, and reduced visual acuity. Possible predisposing factors for the development of hydrops include the presence of systemic allergies, eye rubbing, Down's syndrome, rapid progression of ectasia, and eccentric cones.

MANAGEMENT:

The management of corneal hydrops is primarily observation and topical therapy to relieve patient discomfort. Topical medications will not necessarily decrease the duration of corneal hydrops. Hyperosmotic agents aid in reducing epithelial edema, but have little effect beyond the epithelium. If there is significant corneal compromise, a topical antibiotic can be considered to prevent a secondary infection. Corticosteroids or non-steroidal anti-inflammatory agents may be utilized for pain and inflammation. The use of corticosteroids may help reduce corneal scarring often seen in hydrops. Cycloplegics may also be used to ease pain while also reducing the potential for a secondary anterior chamber reaction. Anti-glaucoma medications may be used to decrease the hydrodynamic force on the posterior cornea.

Figure 3 - Four weeks after onset of hydrops

With time, endothelial cells will enlarge to cover the break and Descemet's membrane will be restored. Once this occurs, the endothelial pump can work to clear the edema from the cornea. The time necessary for complete resolution of hydrops is variable and depends on the size of the break in Descemet's membrane. Slow improvement is generally seen over two to four months.

While a resultant scar is typical, most cases of corneal hydrops resolve without the need for penetrating keratoplasty. Many patients are able to resume contact lens wear and achieve visual acuity similar to that obtained prior to the onset of hydrops. In many cases, contact lens wear post-hydrops is more successful due to resultant topographical flattening. For cases in which resultant corneal scarring precludes adequate visual acuity or in which corneal edema persists, penetrating keratoplasty may be necessary. It is best to allow corneal edema to maximally resolve before scheduling such a procedure.

BEST REFERENCES:
Tuft SJ, Gregory WM, Buckley, RJ. Acute corneal hydrops in keratoconus. Ophthalmology 1994; 101:1738-1744.
Grewal S, Laibson PR, Cohen EJ, et al. Acute hydrops in the corneal ectasias: associated factors and outcomes. Tr Am Ophthalmol Soc 1999; 97:187-203.
Thoat S, Miller WL, Bergmanson JPG. Acute corneal hydrops: a case report including confocal and histopathological considerations. Contact Lens & Anterior Eye 2006; 29:69-73.
OTHER REFERENCES:
Caroline PJ, Andre MP. Hydrops helps. Contact Lens Spectrum 1999;14(3):56
Kabat AG, Sowka J. Battle of the bulge. Review of Optometry 2007; 144(12):72-73.
Melton R and Thomas R. Acute Corneal Hydrops. Clinical & Refractive Optometry. Http://eyeupdate.com/pages/case_studies.html. Last accessed 4/16/2008.
Shovlin JP. Treatment of hydrops focuses on comfort. Review of Optometry 2000; 135(6):109.v

Kimberly Layfield, O.D.
Vinita Allee Henry, O.D., F.A.A.O.

University of Missouri-St. Louis College of Optometry