Oversized corneal grafts for corneal opacities with iridocorneal adhesions

Preoperative Structural Risk Factors for Glaucoma After Penetrating Keratoplasty for Congenital Corneal Opacity: An Observational Study

INTRODUCTION

Post-keratoplasty glaucoma (PKG) is a major complication following penetrating keratoplasty (PKP) for congenital corneal opacity (CCO). This study aims to assess the preoperative structural risk factors for PKG following PKP for CCO using ultrasound biomicroscopy (UBM).

METHODS

Pediatric patients with CCO who underwent preoperative UBM and primary PKP were enrolled. Patients with anterior segment operation history or with a follow-up duration less than 12 months were excluded. The structural features of the anterior segment including central corneal thickness, anterior chamber depth, angle closure range (ACR), anterior synechia range, maximum iridocorneal adhesion length, abnormal iridocorneal synechia, and lens anomalies were identified on UBM images. The medical histories were reviewed to identify clinical features. The incidence of PKG was assessed to determine significant structural and clinical risk factors.

RESULTS

Fifty-one eyes of 51 pediatric patients with CCO were included. The median age at surgery was 8.0 months, and the mean follow-up duration was 33 ± 9 months. Eleven (21.6%) eyes developed PKG. The main structural risk factors were abnormal iridocorneal synechia (P = 0.015), lens anomaly (P = 0.001), and larger ACR (P = 0.045). However, a larger range of normal anterior synechia without involvement of the angle was not a significant risk factor. Preoperative glaucoma (P < 0.001) and higher intraocular pressure (P = 0.015) were clinical risk factors. A shallow anterior chamber was a unique risk factor for sclerocornea (P = 0.019).

CONCLUSIONS

Detailed preoperative examination of iridocorneal synechia, lens, and angle closure using UBM is critical for PKG risk assessment, surgical prognosis evaluation, and postoperative management in patients with CCO.

Penetrating Keratoplasty in Dogs using Acellular Porcine Corneal Stroma (BioCorneaVet™): A prospective pilot study of five cases

OBJECTIVE

This prospective pilot study was conducted to evaluate the outcome of a commercially available corneal stroma substitute, Acellular Porcine Corneal Stroma (APCS), in dogs undergoing penetrating keratoplasty (PK) to restore corneal integrity after having deep ulcers.

METHOD

Five dogs (1 eye in each dog) underwent a PK using APCS (BioCorneaVet™) as a graft. The surgical procedure and peri- and postoperative treatment were standardized. All cases required a minimum 6 months follow-up. Ease of keratoprosthetic tissue handling, graft survival, anterior chamber stability, corneal opacity, neovascularization and re-epithelialization were noted. Presence of secondary uveitis was investigated.

RESULTS

BioCorneaVet™ was easy to handle and, at all-time points, provided adequate tectonic support. Graft survival was achieved in all 5 cases. A minimum follow-up period of 10 months was available for the five eyes (22 months maximum). Degree and area of corneal graft opacity progressively improved resulting in minimal to moderate loss of transparency in all cases but one, where it was severe. Neovascularization degree was most severe 0.5-1 month after surgery and fully resolved 4-6 months post-surgery. Re-epithelialization was complete in the majority of grafts in 1 month. Secondary uveitis was not detected at any time in 4 of 5 dogs.

CONCLUSION

BioCorneaVet™ seems to be an effective graft for PK in the dog. In this case series, APCS was convenient to handle during surgery and provided excellent tectonic support. The material showed good tissue biocompatibility and resulted in the majority of cases in minimal to moderate graft opacity, that ameliorates with time.

Suturing large therapeutic corneal grafts based on donor size: A simplified technique for the novice corneal surgeon

Purpose:

We describe a simple technique for achieving radial and equally spaced sutures by novice corneal surgeon in cases of large penetrating keratoplasties.

Method:

A simple mathematical equation was derived for precise calculation of spacing between interrupted sutures in large grafts ( n = 50). The ubiquitous and easily available Castroviejo calipers were used to mark the donor cornea according to the derived formula. Interrupted sutures were passed over the pre-marked points and tied. Radiality was assessed in the post-operative period.

Results:

A total of 50 eyes undergoing therapeutic keratoplasty with graft size between 9 and 12 mm were enrolled. Equally spaced and radially aligned sutures were achieved in all cases postoperatively with watertight apposition of the graft host junction using our simple technique.

Conclusion:

The Castroviejo caliper can be effectively used for equidistant spacing of interrupted sutures in large therapeutic grafts by a novice surgeon thereby simplifying the procedure and reducing the surgical time.

Anterior segment analysis and intraocular pressure elevation after penetrating keratoplasty and posterior lamellar endothelial keratoplasty

BACKGROUND

Peripheral anterior synechiae (PAS) is a common problem after penetrating keratoplasty (PK) and leads to intraocular pressure (IOP) elevation. This study examines the risk factors for IOP elevation and post-keratoplasty glaucoma.

METHODS

A retrospective analysis was performed of 47 eyes following PK and of 65 eyes following Descemet's stripping endothelial keratoplasty (DSEK) between 2009 and 2011. The assessment included preoperative history of corneal disease and glaucoma, response to treatment, IOP, and visual acuity. Irido-trabecular contacts (ITC), the angle opening distance (AOD 500) and the anterior chamber angle (ACA 500) were calculated.

RESULTS

The incidences of IOP elevation and post-keratoplasty glaucoma were 27-36% and 10-29%, respectively. The incidence did not differ significantly between both procedures. Pre-existing glaucoma increased the risk for developing IOP elevation and post-DSEK glaucoma. Eyes with bullous keratopathy (BK) developed significantly more IOP elevation (p = 0.01, d.f. = 1, χ(2) = 6.11) and post-keratoplasty glaucoma (p = 0.01, d.f. = 1, χ(2) = 6.22) than eyes with Fuchs' endothelial dystrophy. Eyes with ITC developed post-keratoplasty glaucoma significantly more often than eyes without ITC (p = 0.01, d.f. = 1, χ(2) = 6.63).

CONCLUSION

IOP elevation and post-keratoplasty glaucoma showed a high incidence. Risk factors like pre-existing glaucoma, BK and PAS elevated the rate of IOP elevation and post-keratoplasty glaucoma for both procedures.

Structural and functional salvaging of eyes with anterior staphyloma using cyclodialysis with penetrating keratoplasty

PURPOSE

To evaluate the efficacy of a novel technique of anterior segment reconstruction and cyclodialysis in patients with anterior staphyloma.

METHODS

A prospective case series of 8 consecutive patients who underwent anterior segment restoration with penetrating keratoplasty and cyclodialysis was analyzed. The main parameters evaluated were structural success of the graft, improvement in visual acuity, and intraocular pressure.

RESULTS

The globe could be salvaged in all the cases, and 75% (6 of 8) of the cases had clear graft at 6-month follow-up. Best-corrected visual acuity (BCVA) ranged from hand motion close to face to 6/12. None of the patients developed glaucoma during the follow-up period.

CONCLUSIONS

Intraoperative creation of a cyclodialysis cleft can aid in adequate postoperative intraocular pressure (IOP) control and hence decrease the likelihood of graft failure because of raised IOP in eyes predisposed to development of postkeratoplasty glaucoma.

Post-penetrating keratoplasty glaucoma

Post-penetrating keratoplasty (post-PK) glaucoma is an important cause of irreversible visual loss and graft failure. The etiology for this disorder is multifactorial, and with the use of new diagnostic equipment, it is now possible to elucidate the exact pathophysiology of this condition. A clear understanding of the various mechanisms that operate during different time frames following PK is essential to chalk out the appropriate management algorithms. The various issues with regard to its management, including the putative risk factors, intraocular pressure (IOP) assessment post-PK, difficulties in monitoring with regard to the visual fields and optic nerve evaluation, are discussed. A step-wise approach to management starting from the medical management to surgery with and without metabolites and the various cycloablative procedures in cases of failed filtering procedures and excessive perilimbal scarring is presented. Finally, the important issue of minimizing the incidence of glaucoma following PK, especially through the use of oversized grafts and iris tightening procedures in the form of concomitant iridoplasty are emphasized. It is important to weigh the risk-benefit ratio of any modality used in the treatment of this condition as procedures aimed at IOP reduction, namely trabeculectomy with antimetabolites, and glaucoma drainage devices can trigger graft rejection, whereas cyclodestructive procedures can not only cause graft failure but also precipitate phthisis bulbi. Watchful expectancy and optimal time of intervention can salvage both graft and vision in this challenging condition.

Penetrating Keratoplasty for Perforated Corneal Ulcers

PURPOSE

This study was designed to study an alternative technique of lamellar separation of corneal layers for therapeutic keratoplasty in place of an en bloc removal of host corneal button in eyes with perforated corneal ulcers with pseudocornea.

METHODS

Twelve eyes with perforated corneal ulcers with pseudocornea in which therapeutic keratoplasty was planned were included in the study. A new technique was used in which the host corneal tissue was removed in layers by lamellar dissection started peripherally and proceeding centripetally with care taken to prevent perforation at the site of iris incarceration. After injection of viscoelastic into the anterior chamber with a 26-gauge needle entered tangentially, the deeper layer of the cornea was then gently dissected and peeled away from the iris tissue, with care not to avulse the fragile iris and the overlying fibrotic membrane. Adjunctive procedures were performed, and the donor tissue was secured over the host bed.

RESULTS

A complete separation of the iris tissue from corneal button and the fibrous membrane was achieved in 9 eyes. In 3 eyes, iris was partly trimmed along with the fibrous membrane, because the membrane was totally adherent to the iris tissue. Eight patients required pupilloplasty. Apart from minimal bleeding, no other complication was encountered. At the end of 3 months, 9 of 12 grafts remained clear.

CONCLUSIONS

Debulking and layer-by-layer removal of host corneal tissue is effective in preservation of iris while performing therapeutic keratoplasty in eyes with perforated corneal ulcers with pseudocornea.

Keratoplasty for keratomalacia in preschool children

AIM

To study the results of surgical management of keratomalacia in children.

METHODS

A clinical case series of all children with keratomalacia, admitted to an Indian centre during the period from June 2000 to June 2001 is presented. The parameters evaluated were demographic data, systemic associations, and results of medical and surgical intervention.

RESULTS

29 children with keratomalacia ranging from 2 months to 5 years of age (mean 1.8 (SD 1.4) years) were included in the study. All children belonged to families of lower socioeconomic status. 27 patients (93.1%) had not been immunised at all. The systemic diseases precipitating the onset of keratomalacia included measles (41.37%), pneumonia (31.03%), and acute diarrhoea (37.93%). 36 eyes (66.7%) had total corneal melting and 11 (20.3%) eyes had paracentral corneal melting. In 15 eyes (27.8%) an emergency tectonic penetrating keratoplasty was performed of which only five grafts (33.3%) remained clear at a mean follow up of 7.3 (6.8) months (range 3-24 months). Seven eyes underwent optical penetrating keratoplasty, of which four grafts (57.14%) remained clear at a mean follow up of 6.4 (3.6) months (range 3-12 months). None of these could achieve a visual acuity better than 6/60.

CONCLUSIONS

Corneal grafting surgery in keratomalacia is associated with poor visual outcome.