Management of dislocated nucleus with corneal opacity by combined deep anterior lamellar keratoplasty, pars- plana vitrectomy and phaco-fragmentation

Abstract

A 32-year-old man presented with bilateral diminution of vision for 10 years. Visual acuity was light perception in both eyes with inaccurate projection in the oculus dextrus(OD) and accurate projection in the in oculus sinister (OS). Intraocular pressure was 6 and 12 mm Hg in the OD and OS, respectively. Slit-lamp examination revealed the presence of leucomatous corneal opacification with microcornea in oculus uterque (OU). Both eyes had a dislocated nucleus in the vitreous cavity on ultrasound B-scan with advanced cupping in the right eye. Ultrasound biomicroscopy revealed ciliary body atrophy in the OD and preserved ciliary processes (two quadrants) in the OS. In view of a partially preserved ciliary body function and a potential for gaining useful vision, we planned surgical intervention in the left eye. Deep anterior lamellar keratoplasty with pars planavitrectomy (PPV) and phacofragmentation of the nucleus was done. Donor lamellar graft was sutured after completion of PPV and nucleus fragmentation. The patient regained useful ambulatory vision postoperatively with clear corneal graft.

Background

Descemet’s membrane (DM) is the strongest layer of the human cornea with a measured elastic modulus of 20–80 kPa (150–600 mm Hg).¹ We often see scleral tissue giving way in cases of globe rupture following blunt trauma, while the cornea remains intact.² This may indicate that the DM can withstand high intraocular pressure fluctuations, which may arise during pars plana vitrectomy (PPV). We report the case of 32-year-old man who had leucomatous corneal opacity and a dislocated cataractous lens in vitreous cavity. The patient underwent deep anterior lamellar keratoplasty (DALK) with PPV and phacofragmentation for the dislocated nucleus, wherein PPV was performed by visualisation through a layer of residual stroma and DM, after deep lamellar dissection of scarred corneal stroma. Owing to the mechanical strength and transparency of the DM, a complex procedure like PPV with phacofragmentation of the hard nucleus could be performed, resulting in a favourable outcome. Our approach bypasses the need for using temporary keratoprosthesis to perform PPV and eliminated the need for full-thickness penetrating keratoplasty in favour of a lamellar procedure, which remains ideal for partial thickness corneal pathologies.

Case presentation

A 32-year-old man presented with bilateral diminution of vision for 10 years, wherein the oculus dextrus (OD) was more severely affected than the oculus sinister (OS). The patient was ambulatory with the left eye until 1 year prior to presentation when he noticed a progressive deterioration of vision in the same eye. Visual acuity was light perception with inaccurate projection of rays in the right eye and light perception and accurate projection of rays in all quadrants of the left eye. On slit-lamp examination, corneal scarring with leucomatous opacity and a poor view of the anterior chamber was present in both eyes (figure 1). Slit beam revealed the presence of scarring predominantly in the corneal stroma. The vertical corneal diameter was 9 mm in both eyes. Fundus examination was not possible due to the dense corneal opacity. Intraocular pressure was 6 and 12 mm Hg in OD and OS, respectively.

Figure 1.

Slit-lamp photograph of the oculus sinister showing leucomatous opacity with poor view of the anterior chamber.

Investigations

Ultrasound B-scan of both eyes revealed a dislocated nucleus in the vitreous cavity. Advanced cupping of the optic nerve head was noted in the right eye. Additionally, ultrasound biomicroscopy revealed ciliary body atrophy in all quadrants of the right eye, whereas the ciliary processes were preserved in two quadrants of the left eye and atrophic in the remaining quadrants.

Differential diagnosis

In view of bilateral symmetrical findings with a constellation of clinical features like microcornea, corneal opacity, spontaneous dislocation of the nucleus with advanced presenile cataractous lens, we considered a syndromic or systemic association. However, detailed personal and family history and thorough systemic examination did not reveal any supportive evidence to indicate correlation with any established syndromic entities. Literature review with the above keywords did not reveal a previous documented case, having similar clinical features, reported before.

Treatment

Based on history, clinical examination, B-scan and ultrasound biomicroscopy  findings, the left eye appeared to have some useful visual potential and hence was considered for surgery. DALK with PPV and nucleus removal by phacofragmentation was planned after detailed informed consent. Under local peribulbar anaesthesia, the left eye was prepared with 5% povidone iodine and was draped using sterile technique. Corneal size was measured using callipers in order to prepare the host button. The corneal centre was marked, and the host button was cut using corneal trephine of appropriate size. Deep anterior lamellar dissection of the corneal stroma was performed using a crescent knife. The host button was removed, leaving behind DM with a thin residual layer of deep stroma. Some amount of scarring of the residual stroma was still present. At this stage, 25-gauge pars plana, transconjunctival, three sclerostomy ports were made; the infusion cannula was fixed and PPV was started. The dislocated hard nucleus was visualised; core-vitrectomy followed by induction of posterior vitreous detachment and completion of vitrectomy was done. Visualisation was found adequate; hence, the decision to perform phacofragmentation was taken because the nucleus was very hard and sclerotic. Localised peritomy was performed, and using a 20-gauge MVR knife, a fourth sclerostomy port for the insertion of a ‘phacofragmetome’ probe was created. Phacofragmentation of the nucleus was completed in the midvitreous cavity, and the fourth port was closed using 6–0 Vicryl suture.

Residual vitrectomy and base dissection were completed, and peripheral fundus examination was performed. Sclerostomy ports were closed. The host corneal bed was irrigated, and the donor lamellar graft button was prepared to size for grafting. Cardinal sutures were placed, and the donor corneal graft button was secured using 10–0 nylon interrupted sutures. Pad and patch were applied (video 1).

Video 1.

Download video file ^{(23.5MB, mp4)}

DOI: 10.1136/bcr-2019-229397.video01

Video demonstrating the surgical steps.

Outcome and follow-up

The postoperative period was uneventful with normal intraocular pressure and good graft uptake. The patient was started on topical and oral steroids with topical antibiotic drops and tear substitutes. The best corrected visual acuity at 1-month follow-up was counting fingers at 3 m. On slit-lamp examination, the graft button and the graft–host interface were clear with some amount of scarring at the level of deep residual stroma, sutures were healthy and the anterior chamber was well formed and quiet.

Intraocular pressure was 14 mm Hg (figures 2 and 3).

Figure 2.

Postoperative photograph showing the clear graft button.

Figure 3.

Postoperative photograph showing the clear graft–host interface.

Discussion

Good visualisation is one of the great challenges faced while performing PPV in the eyes with corneal opacity. Earlier open-sky vitrectomy was used in similar situations, but the outcomes were poor; therefore, it is not a favoured approach in modern vitreoretinal surgery.³ Various visualisation techniques have evolved in the past few decades, in an attempt to get a better intraoperative view in the eyes with corneas having compromised clarity. Currently, endoscopic visualisation-assisted and, more commonly, temporary keratoprosthesis-assisted PPVs are being performed.^{4 5}

In the present case, PPV with phacofragmentation of the posteriorly dislocated nucleus was performed by visualisation through DM after deep anterior lamellar dissection of the scarred corneal stroma. This helped us to achieve an adequate view in order to perform PPV.

During vitrectomy, DM, along with a deeper layer of residual stroma, was resilient enough to withstand fluctuating intraocular pressure, fluidic currents and turbulence generated due to the operation of fragmetome and the relatively longer duration of the combined anterior–posterior segment surgery. In the postoperative period, graft clarity was maintained, and there was no intraocular pressure spike. The inflammation was controlled with topical and systemic corticosteroids.

Endoscopic vitreous surgery is not commonplace because of infrequent availability of equipment and poor stereoscopic view with endoscopes over a television screen. The small size of the cornea in our case would have made the use of temporary keratoprosthesis difficult with the possibility of a very limited view during surgery. In addition, placement of keratoprosthesis would have required a full-thickness penetrating keratoplasty, which is associated with a higher chance of graft rejection and failure.³

Previous studies have reported allograft survival rates of 27%–73% in the eyes treated by keratoprosthesis-assisted vitreous surgery.^6–10 Postoperative inflammation and raised intraocular pressure are mainly responsible for graft failure in these cases.⁶ By performing a DALK in this case, an external device in the form of a keratoprosthesis and a full-thickness penetrating keratoplasty was avoided. This would result in lesser postoperative inflammation and fewer surgical steps resulting in reduced surgical time.

Our technique provides an advantage in using lamellar grafts, wherein one donor graft has a potential to benefit more than one host and reduces the risk of graft rejection and failure.^{11 12} It avoids the intraoperative complications associated with the use of temporary keratoprosthesis. Temporary keratoprosthesis-assisted PPV requires placement of keratoprosthesis after trephination of the host button, its removal following vitrectomy and finally suturing the donor graft in place.⁴ However, in the present technique, PPV was performed after deep anterior lamellar dissection of the corneal stroma, which was followed by suturing of the donor corneal tissue. The final result was a reduced number of surgical steps, lesser related complications and shorter surgical time.

In the present case, a non-contact viewing system was used for visualisation of the posterior segment, and we found it adequate for performing PPV, base dissection and phacofragmentation.

A contact viewing system using a wide-angle lens can also be used following deep stromal dissection, as reported by Muraine et al, who achieved good intraoperative visualisation. However, they could not achieve reattachment of the retina due to the severity of damage following trauma at presentation, which was not attributable to the surgical technique.¹³

To the best of our knowledge, this is the first case being reported in which PPV with phacofragmentation of a dislocated nucleus has been performed, along with DALK, without using temporary keratoprosthesis. However, Muraine et al have previously reported that PPV could be done with good visualisation under the bared DM, and they were able to perform delicate steps like epiretinal membrane peeling with precision as visualisation was good.¹³

We feel that in a situation where stromal scarring precludes visualisation during PPV, this technique can be a practical alternative for carrying out all the steps of a simple to moderately complex vitreoretinal procedure. It provides good visualisation of the surgical field through residual stroma and DM without using temporary keratoprosthesis and obviates the requirement of penetrating keratoplasty. Such a technique cannot replace the use of temporary keratoprosthesis but is a viable and practical alternative if DALK is the procedure of choice in combination with vitreous surgery, in the presence of partial thickness corneal pathologies.

Learning points.

• Deep anterior lamellar  keratoplasty with pars plana vitrectomy can be considered for patients with corneal stromal scarring.

• This technique provides good intraoperative visualisation and lesser postoperative inflammation.

• Chances of graft survival is more since the host endothelium is not subjected to transplantation.

• Obviates the need for an external device in the form of temporary keratoprosthesis, resulting in reduced surgical steps, fewer intraoperative complications and effective surgical time.