Measurement of Gamma-Irradiated Corneal Patch Graft Thickness After Aqueous Drainage Device Surgery

The best thickness of cornea graft from SMILE surgery as patch graft in glaucoma drainage implant surgery

OBJECTIVE

The aim of this study was to determine the best thickness of corneal slices acquired from femtosecond laser surgery-small incision lenticule extraction (SMILE surgery) as patch graft in glaucoma drainage implantation surgery.

METHODS

This study is a prospective randomized study. Patients who received glaucoma drainage implantation from September 2016 to November 2018 were observed. The patients were randomly divided into 3 groups. Group A included 102 cases (104 eyes), receiving 1 layer (120-150 μm) of allogeneic lamellar corneal tissue as the graft. Group B included 117 cases (120 eyes), receiving 2 layers of lamellar corneal tissue from one donor. Group C included 109 cases (111 eyes), using 3 layers of lamellar corneal tissue from 2 donors. The intraocular pressure, corneal graft, conjunctiva stromalysis, drainage tube exposure, and drainage plate were observed.

RESULTS

Patients were followed up for 6 to 33 months. The intraocular pressure was significantly reduced after surgery in all three groups. Conjunctiva stromalysis and drainage tubes were exposed in 3 eyes (3%) in group A and 1 eye (0.8%, a special case which has nystagmus and the plate was placed infratemporally) in group B, whereas no conjunctiva stromalysis or tube exposure was reported in group C.

CONCLUSIONS

The corneal graft acquired from SMILE surgery can effectively prevent drainage tube exposure and give patients a better cosmetic appearance. Two layers of lamellar corneal tissue (240-300 μm) may be the best suitable thickness because it can effectively reduce tube exposure and rejection. In some special cases, 3 layers of lamellar corneal tissue are needed.

Review of Gamma-Irradiated Sterile Cornea: Properties, Indications, and New Directions

ABSTRACT

Gamma-irradiated sterile cornea (GISC) is a relatively new graft tissue that follows the 30-year success of irradiation to other tissues (bone and sclera) to lessen antigenic load and infection transmission. It can serve as a graft to cover glaucoma drainage devices, as graft tissue for frank or impending corneal perforations in tectonic keratoplasty, as graft tissue in lamellar keratoplasty, and as carrier tissue for keratoprosthesis. With the limited availability of fresh corneal tissue in less developed countries, GISC may fill a need for corneal tissue worldwide. It can be used in situations where corneal endothelium is not needed and with a greatly reduced risk of rejection and infection because of the effect of irradiation on corneal tissue.

Assessing patient cosmetic satisfaction after glaucoma drainage device surgery for different patch grafts

BACKGROUND

The use of a tissue patch graft is common practice with a glaucoma drainage device (GDD). Patch grafts can be visible in the palpebral fissure and may be cosmetically displeasing for some patients. The aim of this study was to report the cosmetic satisfaction of pericardial, scleral, and corneal patch grafts related to superior GDD surgery.

METHODS

Baseline clinical data were collected for consecutive patients with glaucoma operated between 2014 and 2019 at two tertiary eye care institutions (for superiorly-placed) Ahmad glaucoma valve implant using sclera, cornea and pericardium patch graft. A patient questionnaire that contained 4 concise questions, with a Likert-scale grading relating to cosmetic satisfaction was administered by a telephone-based interview. Responses and scores for each question were compared across patients who received the three different types of graft. A binominal logistic regression analysis was used to assess the effects of age, gender, type of graft, number of previous ocular surgeries, and final visual acuity to explain differences.

RESULTS

We included 92 patients who met our inclusion criteria (24 patients received a corneal patch graft, 30 who received sclera and 38 who received pericardium). The mean (±SD) age was 50 (±17.5) years, and the average follow up was 20.7 (± 18.6) months. Regardless of the type of patch graft, most (67-84%) of patients were satisfied with the appearance of their eyes. Patients who received cornea or sclera were more likely to report that their eye looked 'abnormal' by others. Younger age was significantly associated with the response to this question.

CONCLUSION

Patients are generally satisfied with the appearance of their eye following GDD surgery with each of the patch grafts for superiorly-placed GDDs. Younger patients with cornea or sclera were more likely to report that their eyes looked abnormal.

Outcomes of the Shunt Tube Exposure Prevention Study: A Randomized Clinical Trial

PURPOSE

To compare the long-term safety and efficacy of amniotic membrane-umbilical cord (AM-UC) and pericardium patch grafts in reducing glaucoma shunt tube exposure.

DESIGN

Multicenter, prospective, randomized clinical trial.

PARTICIPANTS

Adults with uncontrolled glaucoma undergoing glaucoma drainage device (GDD) implantation.

METHODS

Patients were randomized to receive GDD with either AM-UC or pericardium patch grafts to cover GDD tubes. Patients were followed up clinically with anterior segment (AS) OCT to assess patch graft stability and host-tissue integration prospectively.

MAIN OUTCOME MEASURES

Tube exposure, graft thinning, and graft-related complications.

RESULTS

A total of 81 eyes of 81 patients (50 women, 31 men) with a mean age of 67±13 years underwent GGD implantation using Baerveldt (n = 72) or Ahmed valve (n = 9). Tubes were inserted in the anterior chamber (n = 71), sulcus (n = 6), or pars plana (n = 4). Tube ligation was performed with Baerveldt GDD along with fenestration (n = 51) or orphan trabeculectomy (n = 21). Tubes were covered with AM-UC (n = 41) or pericardium (n = 40). The mean follow-up time was 29±8 months (range, 13-40 months). Tube exposure occurred in 1 eye (2%) in the AM-UC group at 3 months and in 2 eyes (5%) in the pericardium group at 2 and 6 months (P = 0.54). Sequential AS OCT showed better host-tissue integration and significantly less graft thinning in the AM-UC group. Early graft thinning (≤3 months) occurred in 5 eyes (12%) in the AM-UC group and in 17 eyes (43%) in the pericardium group (P = 0.002). Late thinning occurred in 2 eyes (5%) and 11 eyes (28%) in the AM-UC and pericardium groups, respectively (P = 0.007). Graft translucency and cosmetic appearance of the AM-UC graft were superior to those of the pericardium graft. No evidence of graft rejection or infection was associated with the patch grafts in either group.

CONCLUSIONS

Amniotic membrane-umbilical cord grafts are well tolerated and offer an alternative to pericardium for safe and stable tube shunt coverage. Its high-tensile strength, low immunogenicity, and excellent host-tissue integration significantly reduced graft thinning.