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Managing Acute Corneal Hydrops

2T CPD in Australia | 0.75CD in New Zealand | 8 December 2018

By David Foresto

Acute corneal hydrops are uncommon and often selflimiting. When suspected, clinicians should be careful in their slit lamp assessment to rule out other more sinister and sight threatening pathologies. Once diagnosed, diligent management of acute corneal hydrops is important to limit permanent corneal damage. If not treated effectively, this condition can lead to vision loss, corneal scarring and even the need for corneal transplantation.

LEARNING OBJECTIVES

1. Recognise the typical signs and symptoms of acute corneal hydrops.
2. Understand the appropriate available treatments of acute corneal hydrops.
3. Become mindful of the impact that corneal hydrops has on a patient’s quality of life.
4. Be aware of which other pathologies can have similar presentations to acute corneal hydrops.
5. Correctly identify whether topical therapy or surgical intervention is indicated.

Acute corneal hydrops is the development of significant corneal oedema due to a rupture in Descemet’s membrane, followed by leakage of aqueous into the stroma, and sometimes the corneal epithelium.

Presentation typically includes a sudden decrease in vision, photophobia, and pain. Occasionally the patient will have noted that their cornea has taken on a blue or white appearance.

Acute corneal hydrops is most commonly found in patients with diseases involving corneal thinning, such as keratoconus and pellucid marginal degeneration. It can also occur in patients with other corneal disorders, such as post-surgical ectasia, keratoglobus, Terrien’s marginal degeneration and trauma. The condition is typically unilateral in presentation, however there are documented cases of bilateral corneal hydrops.1,2

Eye rubbing is a significant risk factor for the development of acute corneal hydrops,3,4 therefore hydrops may occur in patients with other non-corneal eye diseases. Hydrops events have been documented in children with severe atopic or vernal conjunctivitis.5 Slit lamp examination shows significant stromal oedema, which may be focal or diffuse, as well as conjunctival hyperaemia, and occasionally epithelial microcystic oedema. Continuous accumulation of the aqueous into the corneal stroma may lead to the separation of the collagen lamellae and the formation of large fluid filled stromal pockets. In rare cases, corneal neovascularisation or perforation may occur.6,7

Corneal hydrops is a self-limiting condition, however it may result in corneal scarring. Therefore, diligent management of the hydrops event will lead to a better visual outcome than if left untreated and will reduce the need for subsequent corneal transplantation. Treatment duration varies depending on severity of episode, timeliness of intervention, patient response to therapeutic agents and severity of the underlying corneal condition.

Corneal topography is helpful for the diagnosis and monitoring of acute corneal hydrops, however given that much of the corneal curvature change will be posterior in nature, corneal topography will be limited in imaging the total corneal change.

Anterior optical coherence tomography (OCT) is very helpful for the diagnosis and monitoring of acute corneal hydrops. The OCT corneal scans will show both the anterior and posterior corneal changes, and are useful in monitoring the resolution of the hydrops throughout the treatment course.

Figure 1. A typical hydrops presentation.

DIFFERENTIAL DIAGNOSES OF CORNEAL HYDROPS

Penetrating Corneal Injury

It is important for clinicians to differentiate the presentation of acute corneal hydrops from penetrating corneal injuries, which will have an area of focal epithelial staining and the possible presence of aqueous leakage.

Herpetic Disciform Keratitis

This viral keratitis also shares a similar presentation to acute corneal hydrops in the form of stromal and epithelial oedema, pain, a blue or white corneal hue, and conjunctival hyperaemia. In cases of Herpetic Disciform Keratitis, corneal stromal infiltrates and keratic precipitates on the endothelium may be present.

Chronic Endothelial Disease

Failure of the corneal endothelium to maintain stromal hydration may lead to stromal oedema. The most common of these diseases are Fuch’s endothelial dystrophy, posterior polymorphous dystrophy and iridocorneal endothelial syndrome. In these cases, the stromal oedema is most commonly more diffuse
and slower in onset than that found in acute corneal hydrops. It is nevertheless important for the clinician to carefully observe the corneal endothelium away from the oedematous area for evidence of a broader endothelial disease such as those listed.

Interstitial Keratitis

Any swelling or infiltration of the corneal stroma as a result of a pathogen or autoimmune response may present similarly to acute corneal hydrops. Clinicians should observe for any presence of elevated immunity, such as anterior chamber cells, or corneal infiltrates.

Congenital Glaucoma

Any paediatric patient presenting with a cloudy cornea should be assessed for the possibility of a Descemet’s membrane break secondary to glaucoma.

Acute Angle Closure and Severe Ocular Hypertension

Patients with severe ocular hypertension, including those found in acute angle closure, may present with significant corneal oedema. Clinicians must always assess angles as part of a comprehensive slit lap assessment of any acute eye presentation.

CORNEAL HYDROPS IN KERATOCONUS

While known as a disease resulting in corneal thinning, keratoconus affects the corneal properties in more complex ways than thinning alone. The three dimensional irregularity of the collagen lamellae within a cornea with keratoconus profoundly alters that cornea’s biomechanical properties. Corneas with keratoconus have also been noted to express an increase in lysosomal and proteolytic enzymes and a decreased concentration of protease inhibitors.8

Approximately 5 per cent of patients with keratoconus will experience a corneal hydrops event.9

With the advent of corneal collagen cross-linking, less patients will progress to severe stage keratoconus than before and therefore, it is likely that the incidence of hydrops events in keratoconus patients will decrease with time. However, it should be noted that collagen cross-linking is not totally protective against acute corneal hydrops. Cases have been reported of hydrops occurring some time after corneal cross-linking for keratoconus.10

Corneal collagen cross-linking principally strengthens the anterior two thirds of the cornea11 and given that acute corneal hydrops originates from a split in Descemet’s membrane, cross-linking cannot be totally effective in removing the risk of hydrops in keratoconus patients. Despite this, cross-linking may reduce a patient’s risk of future corneal hydrops by reducing the future steepening of the cornea, and therefore the strain placed on Descemet’s membrane.

While acute corneal hydrops is generally a negative event in patients with keratoconus, in some cases a small amount of corneal scarring can have the positive benefit of flattening the apex of the cornea. As long as the scarring does not cross into the visual axis, the patient’s unaided and spectacle corrected acuities can improve in these cases.

Contact lens wear is typically contraindicated during treatment of acute corneal hydrops given the decreased oxygen permeation to the cornea. In cases of epithelial compromise during hydrops, a bandage soft contact lens may be considered for a short time, however the increased risk of hypoxia and infection must be carefully considered.

The management of acute events, such as corneal hydrops in keratoconus patients, is commonly complicated by their difficulties functioning without being able to wear their contact lens correction. Additionally, they have a high propensity for scarring and risk proceeding to require corneal transplant. This makes it important for clinicians who have relevant experience to manage acute corneal hydrops in patients with keratoconus.

TOPICAL TREATMENT OF ACUTE CORNEAL HYDROPS

The basis of topical treatment for most cases of acute corneal hydrops are steroid and hypertonic saline drops.

Steroid eye drops decrease stromal oedema, decrease propensity for corneal scarring and provide some level of pain relief. With regards to the pain associated with acute corneal hydrops, much of it occurs due to ciliary spasm, and hence cycloplegic agents can be prescribed as part of the patient’s pain management plan.

A typical therapeutic dose for the management of acute corneal hydrops would be:

  • Prednisolone acetate 1 per cent, fourtimes daily
  • Homatropine 2 per cent or Atropine1 per cent, once daily

Topical hypertonic saline may be helpful, however even at doses of 5 per cent it is primarily effective in reducing epithelial oedema with a small benefit in reducing stromal oedema.6

In cases of epithelial compromise, a topical broad spectrum antibiotic, such as chloramphenicol 0.5 per cent or ofloxacin 0.3 per cent, may be considered as prophylaxis against secondary corneal infection, although this is not routinely required.

PNEUMATIC DESCEMETOPEXY (INTRACAMERAL INJECTION)

In situations of hydrops that are not responsive to topical therapy, or in cases where aggressive management is required, another treatment option is via the administration of intracameral air or gas. The mechanisms of action in this form of treatment are dual fold:

1. The tamponade effect created by the gas agent applies pressure force to Descemet’s layer, causing the membrane to stretch across the area of rupture.

2. The air/gas creates a pocket and therefore a separation between the aqueous in the anterior chamber and the cornea.12

Various agents are available for intracameral use, namely air, 20 per cent sulfur hexafluoride and 14 per cent perfluoropropane. Each of the gas options will remain in the anterior chamber for longer compared to air alone, and hence will require less repeated applications. However, perfluoropropane may lead to some reduction in endothelial function with time, and both sulfur hexafluoride and perfluoropropane increasing the risk of secondary glaucoma compared to air.12

Viscoelastic injections, such as sodium hyaluronate, are contraindicated in hydrops as the solution may enter the corneal stroma and exacerbate the corneal oedema.

Intracameral injection has some potential drawbacks including infection, elevation of intraocular pressure, pupillary block, cataract and endothelial damage.12 The patient is also required to lie flat for two weeks so that the gas pocket can create the required tamponade. During this time, topical therapy is continued in the form of prophylactic antibiotics, hypertonic saline, and steroids.

SURGICAL MANAGEMENT

In cases of severe corneal hydrops involving wide separations between the edges of Descemet’s membrane, topical therapy and intracameral injections of air or gas may not be sufficient to treat the acute hydrops event. The persistent corneal oedema may lead to stromal scarring and neovascularisation, the latter of which will significantly increase the patient’s likelihood of graft rejection, should the cornea require keratoplasty. In these cases, the application of compressive sutures along with gas injection has been reported to be a successful option.13

The role of the compressive sutures is to physically bring the edges of the Descemet’s membrane rupture closer together and hence hasten the resolution of the hydrops event. In this technique, the surgeon applies two to five full corneal thickness sutures across the tear area immediately after the injection of gas into the anterior chamber. Full topical therapy is continued and the sutures are removed based on healing rate, which is typically at some point within six weeks of the suture date.13

CORNEAL GRAFT

Corneal graft following acute corneal hydrops is not commonly required. Typically, acute hydrops events are self-limiting, however timely and appropriate intervention with the above listed therapies will speed the resolution and reduce the likelihood of corneal scarring, neovascularisation and vision loss.

Corneal graft however, is a possible outcome in severe or non-responsive cases of corneal hydrops, and a possible outcome in patients with severe progressive keratoconus, the demographic of which are most commonly those in which hydrops events occur.

When corneal transplantation does occur, a full thickness penetrating keratoplasty is the transplant of choice. A deep anterior lamellar keratoplasty (DALK) is generally not practical given the difficulties in separating Descemet’s membrane. This is due to its compromised structure, and there being little value in the patient retaining their damaged Descemet’s membrane and endothelial layers.

There is some evidence that grafts performed following a corneal hydrops episode in patients with ectatic corneas have a lower survival rate than in non-hydrops patients, however there is contention as to the underlying reason for this decrease in survival rate. It has been postulated that the pre-operative inflammation caused by the hydrops event heightens the likelihood of graft rejection, however it has also been suggested that patients with weaker Descemet’s membranes suffer hydrops events and given that some peripheral endogenous Descemet’s membrane is retained after penetrating keratoplasty, these corneas are more likely to result in rejection.14,15

Descemet membrane endothelial keratoplasty (DMEK) is not a typical treatment in managing vison loss related to corneal hydrops. This is because this form of graft only replaces the Descemet membrane and endothelial layer, and hence any stromal scarring will remain. It has however, been cited as a possible treatment to reduce recurrences in patients with persistent corneal hydrops events.16

 

Patient Case Study

Figure 2. The patient’s cornea at time of presentation.

A 43 year old female presented having been diagnosed with acute corneal hydrops in her right eye over the preceding weekend at a public hospital. The patient had experienced significant vision loss in that eye as well as moderate discomfort. Contact lens wear in that eye had been ceased and the patient had been prescribed prednisolone acetate 1 per cent four times daily.

The patient’s ocular history included:

  • Bilateral keratoconus, diagnosed as a teenager
  • Left eye full thickness penetrating keratoplasty at approximately age 25
  • Left eye re-graft at approximately age 31
  • Left eye cataract extraction and IOL placement
  • Left eye Descemet membrane endothelial keratoplasty (DMEK) at age 42
  • Left eye DMEK re-bubble
  • Left eye chronic low grade rejection and propensity for oedema
  • Scleral lens wear each eye

Slit lamp assessment showed an area of grade three stromal oedema approximately 4mm in diameter in the inferior paracentral area of the cornea in the right eye. There was the appearance of overlying epithelial cysts. Anterior chamber was quiet. Pupil was mobile and angles were wide open. There were no infiltrates present.

A diagnosis of acute corneal hydrops was confirmed and the patient was prescribed 5 per cent hypertonic saline ointment twice daily in addition to the existing prednisolone acetate 1 per cent four times daily. At the one week review, the patient’s area of stromal oedema had started to reduce. Treatment of prednisolone acetate 1 per cent and 5 per cent hypertonic saline was continued.

 Figure 3. OCT scan showing immense corneal oedema.

Figure 4. OCT scan showing total resolution of the corneal oedema and with keratoconus correcting scleral contact lens in place.

The two week review was performed by the patient’s regular ophthalmologist. At that time the patient was advised to cease the prednisolone acetate and hypertonic saline, and to use a Manuka honey based ointment instead. At the three week review, the patient had developed a sudden increase in pain and photophobia. Slit lamp assessment showed grade 1 anterior chamber cells, limbal injection and a sluggish right pupil. There were no infiltrates present and no mucous discharge. Angles were open. Intraocular pressures were normal at R 9mmHg L 10mmHg at 10am.

Figure 5. The small area of residual haze following resolution of the oedema.

A diagnosis of secondary iritis was made. The patient was prescribed prednisolone acetate 1 per cent every hour and atropine 1 per cent each morning.

A follow-up phone call the next day confirmed that the patient’s pain and photophobia had started to subside.

At the following review, the patient’s pain and photophobia had subsided. The corneal oedema had mostly resolved with only a small area visible with the slit lamp. OCT scan confirmed that the corneal oedema had mostly resolved. The atropine eyedrop was ceased and the prednisolone acetate was slowly tapered over the next four weeks. The hypertonic saline ointment was continued throughout that same period of time.

The patient was unable to wear a contact lens throughout the treatment course of the right eye acute hydrops event. Twelve weeks after the hydrops event, it was deemed safe to resume contact lens wear on the right eye. Corneal topography showed progressive flattening throughout the treatment course and eventual invagination of the cornea at the site of the mild scarring.

The patient’s right eye scleral lens, which had been successfully worn prior to the hydrops event, was now exhibiting more clearance than before. This was expected with the corneal flattening, which had taken place because of the corneal scarring.

The patient was advised to be monitored for excessive suctioning or hypoxia from the excessive scleral lens clearance, or to be refitted to a new lens.

Figure 6. Topography scans showing progressive flattening of the cornea as the hydrops resolved.

 

SUMMARY

Acute corneal hydrops events are uncommon and often self-limiting however timely diagnosis and management can reduce the morbidity attached to the event and the likelihood of vision loss. Clinicians should be careful in their slit lamp assessment of patients with suspected hydrops, to rule out other more sinister and sight threatening pathologies. It is also particularly important that clinicians are mindful when treating hydrops in patients with corneal ectasias such as keratoconus. This is because their inability to function without wearing their usual contact lens correction creates a significant loss in quality of life and hence relying on the condition to self-limit will impose unnecessary delays in restoring their ability to function normally.

 

     David Foresto is an optometrist who works predominantly with custom contact lenses and is the practice owner of Foresto EyeQ Optometrists. He is also a lecturer and clinical supervisor at QLD University of Technology and a former President of Optometry Australia's QLD/NT Division. Mr. Foresto is one of Queensland's most experienced optometrists in the management of contact lenses for keratoconus and corneal transplants, having treated over 1,000 patients with these conditions. Mr. Foresto provides advisory services for contact lens and pharmaceutical companies and is also involved in the development of new contact lens designs.   

 

References:
1. Downie, L. (2014). The necessity for ocular assessment in atopic children: bilateral corneal hydrops in an 8 year old. Pediatrics, 134(2), e596. doi:10.1542/peds.2013-3750
2. Bilgin, B., Unal, B., Unal, M., Do?an, E., Cetinkaya, A., Akyol, M., Yücel, I., et al. (2013). Keratoconus presenting with bilateral simultaneous acute corneal hydrops. Contact lens & anterior eye : the journal of the British Contact Lens Association, 36(2), 98.
3. S. Grewal, P.R. Laibson, E.J. Cohen, C.J.Rapuano Acute hydrops in the corneal ectasias: associated factors and outcomes. Transactions of the American Ophthalmological Society, 97 (1999), pp. 187-203
4. Jhanji V, Sharma N, Vajpayee RB. Management of keratoconus: current scenario. Br J Ophthalmol 2011; 95:1044–1050.
5. U. Rehany, S. Rumelt Corneal hydrops associated with vernal conjunctivitis as a presenting sign of keratoconus in children. Ophthalmology, 102 (12) (1995), pp. 2046-2049
6. Tuift SJ, Gregory WM, Buckley RJ. Acute corneal hydrops in keratoconus. Ophthalmology. 1994;101:1738–44.
7. Nicoli C, Wainsztein RD, Trotta LP. Corneal topography of spontaneous perforation of acute hydrops in keratoconus. J Cataract Refract Surg 1999; 25:871–872.
8. Raiskup-Wolf, F., Hoyer, A., Spoerl, E., & Pillunat, L. (2008). Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: Long-term results. Journal of Cataract & Refractive Surgery, 34(5), 796–801.
9. Rabbanikhah, A., Javadi, A., Rostami, A., Aghdaie, A., Yaseri, A., Yahyapour, A., & Katibeh, A. (2011). Association Between Acute Corneal Hydrops in Patients With Keratoconus and Mitral Valve Prolapse. Cornea, 30(2), 154–157.
10. Antonios R, Dirani A, Fadlallah A, Chelala E, Hamadeh A, Jarade E. Acute Corneal Hydrops 3 Years after Intra-corneal Ring Segments and Corneal Collagen Crosslinking. Middle East African Journal of  Ophthalmology. 2016;23(1):156-159.
11. M. Kohlhaas, E. Spoerl, T. Schilde, et al. Biomechanical evidence of the distribution of cross-links in corneas treated with riboflavin and ultraviolet A light. J Cataract Refract Surg, 32 (2006), pp. 279-283
12. Miyata K, Tsuji H, Tanabe T, et al. Intracameral air injection for acute hydrops in keratoconus. Am J Ophthalmol 2002; 133:750–752.
13. Rajaraman R, Singh S, Raghavan A, Karkhanis A. Efficacy and safety of intracameral perfluoropropane (C3F8) tamponade and compression sutures for the management of acute corneal hydrops. Cornea 2009; 28:317–320.
14. Tuft SJ, Gregory WM, Buckley RJ. Acute corneal hydrops in keratoconus. Ophthalmology. 1994;101(10):1738-44.
15. Akova YA, Dabil H, Kavalcioglu O, Duman S. Clinical features and keratoplasty results in keratoconus complicated by acute hydrops. Ocul Immunol Inflamm. 2000;8(2):101-9.
16. Tu, Y. (2017). Descemet Membrane Endothelial Keratoplasty Patch for Persistent Corneal Hydrops. Cornea, 36(12), 1559–1561.

' Treatment duration varies depending on severity of episode, timeliness of intervention, patient response to therapeutic agents and severity of the underlying corneal condition '