Acute Corneal Hydrops 3 Years after Intra-corneal Ring Segments and Corneal Collagen Cross-linking.

This case report describes a 15-year-old male with allergic conjunctivitis and keratoconus, who underwent uneventful intra-corneal ring segment (ICRS) implantation and corneal collagen cross-linking (CXL) in the right eye. During the follow-up periods, the patient was noted to have several episodes of allergic conjunctivitis that were treated accordingly. At the 2 years postoperatively, he presented with another episode of allergic conjunctivitis and progression of keratoconus was suspected on topography. However, the patient was lost to follow-up, until he presented with acute hydrops at 3 years postoperatively. There are no reported cases of acute corneal hydrops in cross-linked corneas. We suspect the young age, allergic conjunctivitis and eye rubbing may be a risk factors associated with possible progression of keratoconus after CXL. Prolonged follow-up and aggressive control of the allergy might be necessary in similar cases.

INTRODUCTION

Keratoconus is a progressive, noninflammatory, thinning disorder resulting in irregular corneal astigmatism and poor visual acuity.1 Acute hydrops is a rare manifestation of severe progressive disease. With the advent of corneal collagen cross-linking (CXL), disease progression can be halted due to increased crosslinks between corneal collagen fibrils.12 Yet, keratoconus progression, as depicted by increased keratometric values on topography and changes in topographic patterns, can still occur despite CXL.345 Acute hydrops has not been reported to occur in cross-linked corneas. We describe a patient with keratoconus that presented with acute corneal hydrops 3 years after intra-corneal ring segment (ICRS) implantation and CXL.

CASE REPORT

On February 2010, a 15-year-old male presented to our center for management of his advanced keratoconus disease. On examination, the uncorrected distance visual acuity (UCVA) was counting fingers bilaterally. The corrected distance visual acuity (CDVA) was 20/50 OD (manifest refraction: −15.50 + 4.50 × 165) and 20/25 OS (manifest refraction: −7.10 + 5.00 × 60). On corneal topography (Pentacam, Oculus Optikgerate GmbH, Wetzlar, Germany), the keratometric values were 52.90/60.10 D and Kmax 65.10 D-right eye and in the left eye: 42.60/48.00 D with Kmax of 50.90 D [Figure 1a]. The thinnest central pachymetry measured with the Pentacam was, 365 mm for the right eye and 418 mm for the left eye. Otherwise, the patient had a history of recurrent ocular allergy associated with eye rubbing the patient denied any other significant medical condition, and was not on any medications or eye drops.

Figure 1

Corneal topography of right eye (a) before intra-corneal ring segment implantation, (b) 10 months post- and intra-corneal ring segment-collagen cross-linking procedures showing improvement of keratometry-readings. (c) Corneal topography of right eye at 2 years after intra-corneal ring segment implantation and corneal collagen cross-linking performed when the patient presented with exacerbation of allergic conjunctivitis, showing superior steepening with inferior flattening

For the right eye, patient underwent an ICRS implantation (February 2010) using the Intralase femtosecond laser (Abbott Medical Optics Inc., Santa Ana, California, USA), followed by CXL 1-month later (March 2010). According to our topo-guided nomogram for ICRS insertion,6 a single 0.35 mm thick-210 Keraring SK (Mediphacos, Belo Horizonte, Brazil was inserted from an incision at 75°. A standard epithelium-off CXL procedure was performed under sterile conditions using a hypo-osmotic riboflavin 0.1% solution by diluting Vitamin B2-riboflavin-5-phosphate 0.5% with physiological sodium chloride 0.9% solution, and an ultraviolet (UV) lamp ([3.0 ± 0.3 mW/cm2, 30 min], [UV-X illumination system, version 1000; IROC AG, Zurich, Switzerland]). The left eye was scheduled for CXL in February 2010.

At the 5 months post-ICRS implantation follow-up, the patient presented with an episode of severe allergic conjunctivitis with limbal hypertrophy that was treated with topical fluorometholone 0.1%. At this visit, CDVA was 20/30 OD (manifest refraction −14.50 + 5.00 × 160) and 20/25 OS (manifest refraction −6.50 + 5.50 × 50) (topography not available). On November 2010 (10 months post-ICRS), the patient had another episode of allergic conjunctivitis OU also treated with topical fluorometholone 0.1%. The presenting CDVA at this visit was 20/30 OD and 20/25 OS (manifest refraction −13.50 + 5.00 × 100 OD and −5.50 + 3.50 × 50 OS), with keratometric readings of 47.50/52.70 D with Kmax of 50.40 D in the right eye and 41.30/46.50 D with Kmax of 48.60 D in the left eye. The thinnest pachymetry readings were 356 mm in the right eye and 398 mm in the left eye [Figure 1b]. Although, the patient was scheduled to undergo phakic intra-ocular lens implantation and was informed that regular monitoring was imperative to document stability, he was lost to follow-up. In June 2012 (2 years post-ICRS), the patient presented with another episode of allergic conjunctivitis OU and CDVA 20/50 OD and 20/30 OS (manifest refraction −14.00 + 4.50 × 110 OD and −7.25 + 3.00 × 65 OS). Superior steepening with inferior flattening was present on topography, but the interpretation was not reliable because of the ocular surface conditions due to the severe allergic conjunctivitis associated with limbal hypertrophy [Figure 1c]. At that visit, the patient was discharged with instruction to instill fluorometholone 0.1% and advised to present for a repeat topography. He was lost to follow-up again until he presented to the emergency room on March 2013 (3 years post-CXL), with a complaint of recent sudden onset visual loss in the right eye. Examination revealed a dense cloudy thick cornea, with no signs of corneal perforation, corneal melting or ICRS migration [Figure 2]. These findings were consistent with the diagnosis of acute corneal hydrops in the right eye rather than corneal decompensation from endothelial failure, which tends to occur within a few weeks of the CXL procedure.7 The corneal edema persisted despite management with topical hypertonic 5% saline solution, topical steroids, and anti-glaucoma medications, and full-thickness penetrating keratoplasty was performed.

Figure 2

Slit-lamp photograph of the right eye 3 years post- and intra-corneal ring segment implantation and corneal collagen cross-linking. Surrounding the intra-corneal stromal ring is dense clouding involving around 60% of the cornea, consistent with acute corneal hydrops (note the yttrium aluminium garnet laser peripheral iridotomy between 1 and 2 o’clock, as the patient was prepared for implantable collamer lens implantation)

DISCUSSION

Several studies have reported the efficacy of CXL in halting progressive keratoconus.2 Yet despite CXL, the progression of the disease can still occur. During the 1st year after CXL continued disease progression had been reported in 7.6–9.8% of cases.45 An increased failure rate of CXL is associated with a higher preoperative Kmax (>58.00 D).4 Delayed progression of keratoconus has also been reported to occur in cross-linked eyes following several years of stability despite a preoperative Kmax <58.00 D and no inciting etiology.3 Kymionis et al.,3 described a case report of two patients over 29-year-old with waning of the effect of CXL after several years of stromal remodeling and rejuvenation. Their3 case illustrates that delayed disease recurrence can occur after CXL.

In our report, a young (15 years old) keratoconic patient with severe allergic conjunctivitis underwent sequential ICRS implantation and CXL with the aim of halting the keratoconus progression, enhancing the CDVA, and decreasing anisometropia. Despite a preoperative Kmax of 65.10 D, our patient was stable clinically (in terms of manifest refraction and visual acuity) and topographically over the first postoperative year. Progression of the disease status was noted at the 2 years postoperative visit after several episodes of allergic conjunctivitis, which later resulted in acute hydrops.

The delayed progression of keratoconus in our patient might be partly attributed to the waning effect of CXL on the stroma, possibly due to the higher rate of stromal remodeling in children.8 A more obvious cause for disease progression, however, was the recurrent exacerbations of allergic conjunctivitis with eye rubbing. In fact, moderate to severe atopy and vigorous eye rubbing is known to stimulate the anterior stromal cell apoptosis resulting in disease progression secondary to increased inflammatory mediators (interleukin-6, intercellular cell adhesion molecule-1, and vascular cell adhesion molecule-1).1

It is also possible that the ICRS contributed to the exacerbations in an inflammatory reaction within the cornea. The corneal hydrops was most dense at the inferior corner of the ICRS segment at 6 o’clock [Figure 2] where it is easiest to rub the eye, and accordingly the corner of the segment would have been squeezed numerous times leading to keratoconus progression and hydrops.

Acute hydrops is a rare complication that usually occurs in patients with end-stage keratoconus. Extreme thinning and stretching of the descemet membrane (DM) is believed to cause a spontaneous break, leading to acute swelling of the cornea with subsequent loss of vision.9 The occurrence of acute hydrops after CXL can be attributed to the limited effect of CXL to the anterior (200–400 mm) corneal stroma as demonstrated by stress-strain measurements, thermo-mechanical measurements, and swelling studies.2 Limited penetration of the UVA into the deeper stroma due to riboflavin UVA-absorption causes this differential variation in stromal strength.2 In that regards, the relative sparing of the posterior thirds of the cornea after CXL will not prevent the spontaneous tear in the DM.

Acute hydrops developing in cross-linked corneas has not been reported though (PubMed search from 2003 until present using the terms: CXL, corneal CXL and corneal hydrops, acute corneal hydrops, and acute corneal hydrops keratoconus). Acute hydrops in association with an uncomplicated ICRS implantation was only reported in the immediate postoperative period in a patient with a Kmax of 50.00 D, possibly related to the mechanical effects during the ring implantation.10

CONCLUSION

Allergic conjunctivitis with eye rubbing is associated with keratoconus development, and may be associated with delayed progression of keratoconus following CXL and corneal hydrops development, especially in the presence of an ICRS. It might be important to reinforce close follow-up and aggressive control of allergic conjunctivitis/eye rubbing in patients despite undergoing CXL, to monitor disease progression and prevent possible hydrops.

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Conflicts of interest

There are no conflicts of interest.