Central and bullous Descemet membrane detachment during cataract wound hydration: an insightful complication in a post-DALK eye

Abstract

A 54-year-old man, with history of undergoing deep anterior lamellar keratoplasty (DALK) 20 months ago, presented with mature senile cataract in the same eye. While undergoing phacoemulsification, a large, central Descemet membrane detachment (DMD) was noted, separating the donor cornea from the host predescemetic layer. No DM tears were noted. Stromal puncture was done at the graft host junction to reduce the extent of DMD. This was followed by a large intracameral air bubble insertion, which resulted in complete resolution of DMD on the first postoperative day. DMD during hydration of wound is a unique complication to be anticipated while doing cataract surgery in an operated DALK eye.

Background

Descemet membrane detachment (DMD) is a frequent complication encountered during cataract surgery.¹ Usually peripheral and self-limiting in nature, they may occasionally lead to sight threatening complications like corneal oedema, corneal opacity and permanent endothelial damage. Hence, patients with peripheral DMD are kept on regular follow-up to monitor its progression. Central DMD, on the other hand, needs to be attended to, at the earliest, as they pose the risk of significant morbidity and visual impairment secondary to endothelial dysfunction and corneal decompensation.

Due to its ubiquity, DMD has been noted during almost all steps of cataract surgery, including capsulorrhexis, hydro manoeuvres, phacoemulsification, irrigation-aspiration and intraocular lens (IOL) insertion.² Herein, we report a case of a central, bullous DMD which occurred while hydration of the main entry wound during cataract surgery, a step not known to cause this particular complication, in a previously operated deep anterior lamellar keratoplasty (DALK) patient undergoing phacoemulsification, managed effectively with descemetopexy under direct visualisation through intraoperative optical coherence tomography (iOCT).

Case presentation

A 54-year-old man presented to our outpatient department with complaints of diminution of vision in the left eye (LE) since the last 6 months. He had undergone DALK in the LE 20 months back at our tertiary eye care centre for leucomatous corneal opacity, secondary to healed fungal keratitis (culture proven Aspergillus flavus). On examination, Snellen’s visual acuity (VA) of 6/12 and hand movements close to face (HMCF) with accurate projection of rays in the right and left eye, respectively, was recorded. Previous hospital records demonstrated LE preoperative VA of counting fingers close to the face with accurate projection of rays before DALK was performed. He gained a best corrected VA (BCVA) of 6/60, the subnormal vision contributed by presence of immature senile cataract at that time. The cataract progressed and VA dropped to HMCF, necessitating cataract surgery. Intraocular pressure was 18 mm Hg in both eyes. Anterior segment evaluation of LE revealed a clear corneal graft with well apposed graft host junction (GHJ), suture marks, broken sutures embedded in the cornea layers at three places and few Descemet membrane (DM) folds along mature senile cataract precluding a detailed posterior segment evaluation. Axial length measured with immersion A scan ultrasonography was 22.9 mm. Ultrasonography B scan of the LE was unremarkable. The preoperative endothelial cell counts were 2045 cells/mm². In vivo confocal microscopy revealed healthy epithelium, keratocytes scattered in the anterior and posterior corneal stroma and tightly packed sheet of hexagonal endothelial cells, demonstrating mild pleomorphism and polymegathism with absence of any drop out areas (figure 1A–D). The patient was planned for LE phacoemulsification under topical anaesthesia.

Figure 1.

In vivo confocal microscopic imaging of the left eye revealed (A) normal epithelial morphology, and (B) numerous keratocytes scattered as hyperreflective bodies in the anterior stroma. The posterior corneal stroma (C) revealed larger keratocytes and the endothelial cells (D) were arranged as a single sheet of hexagonal cells with few cells displaying pleomorphism and polymegathism.

A Centurion Vision System (Alcon Labs) device was used for phacoemulsification, via a standard 2.2 mm temporal clear corneal incision. A straight headed coaxial tip was used for irrigation-aspiration, and a posterior chamber hydrophilic IOL (+21.5D;I-VISION, Aurolab, India) was placed in the capsular bag. On completion of the surgery, the main 2.2 mm corneal incision was hydrated with balanced salt solution (BSS). iOCT revealed a large bullous DMD characterised by the separation of the predescemetic layer (PDL) from the grafted corneal stroma, with sparing of the periphery corresponding to the area of host corneal rim (figure 2). The detachment was progressive in nature that advanced from the wound site to occupy nearly the complete anterior chamber (AC) (figure 3A–C).

Figure 2.

Intraoperative anterior optical coherence tomography image of the patient showing separation of the predescemetic layer (PDL; white arrow) from the stroma. Note the region of attached PDL in the periphery, corresponding to the area of host corneal rim. Descemet membrane folds, present preoperatively in the patient, can also be seen (yellow arrow).

Figure 3.

Intraoperative image of the patient, showing progression of Descemet membrane detachment (DMD) while hydration of the entry wound during cataract surgery, as delineated by white arrows (A–C). Note that the DMD is limited to the area of the graft, with no extension beyond the graft host junction into the recipient corneal rim. Following stromal puncture (D), there is a reduction in the size of DMD (E). Descemetopexy with intracameral air and resultant tamponade led to resolution of DMD postoperatively (F).

Treatment

Reattachment of the DMD was attempted by injecting a large air bubble (AB) in the AC, but it failed owing to the large DMD preventing entry of AB into the AC. iOCT-guided stromal puncture was done with the help of a 1.3 mm ophthalmic knife (Alcon Labs), with the site of incision being at the GHJ (figure 3D). Fluid causing the DMD was slowly ‘milked out’ from between the corneal layers, with the help of gentle counter pressure applied on the cornea with an iris repositor, at a site opposite to the stromal entry. This resulted in a reduction in the extent of DMD, with an area of residual detachment in the superior cornea (figure 3E). A large AB was injected and left in the AC (figure 3F), and the patient was advised to lie supine for a period of 6 hours after the surgery.

Outcome and follow-up

On the first postoperative day, the patient had an uncorrected visual acuity (UCVA) of 3/60, improving to 6/60 with pin hole. Slit lamp examination revealed temporal corneal oedema with multiple DM folds (figure 4A). There was complete resolution of DMD with no areas of residual detachment (figure 4B). He was prescribed topical moxifloxacin 0.3% thrice daily, prednisolone acetate 1% four times a day gradually tapered to once a day after 4 weeks, topical hypertonic saline 10% and carboxymethyl cellulose 1% four times a day. On completion of 4 weeks after surgery, he attained a BCVA of 6/12. Anterior segment OCT performed 4 weeks after the cataract surgery demonstrated complete resolution of DMD with well attached graft stroma and host PDL and DM and absence of corneal oedema (figure 4C). There were no events of delayed redetachment of the PDL.

Figure 4.

Clinical photograph of the patient taken on the first postoperative day (A) multiple DM folds can be seen. note that the PDL is firmly attached to the stroma, with complete resolution of DMD (B) postoperative anterior segment optical coherence tomography confirmed complete resolution of DMD with no interface fluid (C). DMD, Descemet membrane detachment; PDL, predescemetic layer.

Discussion

The incidence of DMD following cataract surgery has been reported between 36.7% and 82.0%, as noted on the first postoperative day.³ A recent iOCT-based study by Dai et al conducted on 133 patients reported the intraoperative DMD rate to be as high as 94%.⁴ The pathogenesis involves loosening of the association between the DM and posterior stromal layers, subsequently leading to the detachment of the former. The first step is the creation of a gap between the two layers while making the primary incision for cataract surgery, greatly accentuated in the event of improper placement of the incision, inadvertent friction caused by instrumentation, use of improper techniques and blunt instruments. The risk of DMD is increased in events of a shallow AC, complicated surgery, prolonged surgical time, small size of the incision or the presence of an unhealthy endothelium. The role of endothelium in DMD was well illustrated by Ti et al and SSamarawickrama et al, who noted an increased incidence of DMD in patients with pre-existing corneal guttae.^{5 6} However, we could only find a single report in literature of DMD following DALK that occurred during automated irrigation and aspiration of cortical matter.⁷ To the best of our knowledge, complete central DMD in a case of operated DALK during hydration of the main entry wound of cataract surgery, as seen in our patient, has not been reported yet.

This peculiar complication in our patient seemed to stem from previous DALK surgery performed 20 months prior to the phacoemulsification. In DALK, the corneal stroma is dissected till the level of DM or the PDL and is replaced with the donor corneal button. This creates a plane of cleavage between the host DM and the transplanted donor stroma, a potential space that could be split open by mechanical force. In our patient, hydration of main port led to BSS entering the corneal lamellae to reach the graft host interface, where the hydrostatic force of the fluid forced the host DM and donor stroma apart, owing to the plane of cleavage mentioned above and fluid following the path of least resistance. This resulted in a pocket of fluid between the graft and host cornea, clinically manifesting as a complete central DMD. This was supported by the continuity of DM and absence of DM tears seen on iOCT, ruling out the possibility of DM tear and DMD being created perioperatively during cataract surgery that got extended during wound hydration. The peripheral PDL remained attached to the host corneal rim due to stronger interlamellar collagen cross links and adhesions in the host cornea, relatively unaltered by the DALK surgery.

Peripheral DMDs tend to resolve over time and require close observation and follow-up. Early attempt at reattachment is warranted in case of large central DMDs and/or the presence of corneal oedema involving the visual axis. This is best achieved with the help of injection of intracameral AB, with a reported reattachment rate of 87.5%–95%.^{5 8} Since the primary attempt of large AB insertion was unsuccessful in our patient, we went ahead with anterior stromal puncture at the site of GHJ to reduce the extent of DMD and the amount of fluid enclosed by it. This manoeuvre has been used previously to great success in resolving large DMDs encountered during phacoemulsification and DALK surgeries.^{9 10} This reduced the volume of fluid contained within the DMD, allowing the entry of AB in AC. This large AB tamponade eventually resulted in effective resolution of DMD. The use of viscoelastic substances for tamponade, was not considered in our patient, as it is reported to be useful in cases with rhegmatogenous DMDs where it facilitates unrolling of DM in scrolled DMD, and in recalcitrant DMDs refractory to pneumatopexy.¹¹ Alternatively, descemetotomy or rupturing the DM has been described for bullous DMD so as to avoid complications such as corneal scarring, astigmatism, epithelial ingrowth and infectious keratitis associated with anterior stromal puncture.¹² However, the ease of manipulation and availability of space for egress of predescemet fluid at the site of the GHJ, circumvented the need for creating an unnecessary DM incision. Moreover, the described limbal manoeuvre may not have been successful in our patient as the PDL was adequately adhered to the host DM in the peripheral region along with an added theoretical complication of double chamber formation.

Non-rhegmatogenous DMD is a rare entity and may occur during cataract surgery in cases with operated DALK due to the presence of a cleavage plane, even years after the initial corneal surgery. Surgeons need to be aware of this cause of DMD while hydrating surgical wounds in the setting of previous DALK surgery.

Patient’s perspective.

I was apprehensive when I was asked to lie on my back for a few hours after my surgery, as this is not something you expect after a cataract surgery. I was told that there was some intraoperative complication due to my previous corneal surgery, and it scared me. Thankfully, I had good vision when my bandage was removed, and it progressively improved as the days went by (translated from Hindi).

Learning points.

• Descemet membrane detachment (DMD), a frequent and potentially devastating complication, may occur during any step of cataract surgery.

• When adequately managed, even complete DMDs have favourable outcomes.

• DMD in post deep anterior lamellar keratoplasty eyes do not involve the peripheral host cornea.

• Stromal puncture can be considered in case of complete central DMD not amenable to intracameral air bubble injection.

• Intraoperative optical coherence tomography is a useful modality for real-time management of complications during anterior segment surgeries.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s)