Timing of Glaucoma Drainage Device Implantation With Boston Keratoprosthesis Surgery
试验速览
- 阶段
- 不适用
- 发起方
- 入组人数
- 40
- 试验地点
- 2
- 主要终点
- Visual field mean deviation
研究概览
简要总结
Boston keratoprosthesis (KPro) is a piece of specialized plastic that replace sick cornea (transparent structure at the front of the eye) in patients who have failed or those who are expected to have poor results with traditional corneal transplantation. While the Kpro can offer dramatic improvement in vision, it is also associated with several complications. Glaucoma (optic nerve damage due to high pressure inside the eye) is one of the most common complications after KPro surgery and can potentially cause irreversible vision loss. The implantation of a glaucoma drainage device (GDD), a tiny tube that drains the liquid inside the eye by bypassing the natural drainage system, is an effective option to lower the eye pressure in patients with KPro. Given the frequency and potentially devastating effects of glaucoma among KPro patients, some surgeons recommend to put in a GDD as a preventative measure. However, there is no consensus on when is the best timing to perform such surgery in relation to the Boston Kpro surgery.
Hypothesis:
For patients undergoing the Boston KPro surgery, implanting a GDD simultaneously, at the time of surgery, is more efficacious than at 6 months later, in the prevention of the progression of glaucoma and in maintaining better visual functions.
Methods:
The investigators aim to recruit 40 patients over 4 years. Recruited patients will be randomly assigned to 2 groups: 1) simultaneous GDD implantation at the Boston KPro surgery, and 2) GDD implantation 6 months after the Boston KPro surgery.
Once recruited, patients will be followed before the KPro surgery, postoperative day 1, week 1, month 1, 3, 6 and 12. Standard ophthalmological exam will be performed at each visit. Additional non-invasive glaucoma tests and evaluation (visual fields and optic nerve photo) will be performed on day 1, month 1, 3, 6 and 12.
For patients assigned to group 2, a GDD will be implanted 6 months after the KPro surgery. They will have additional follow-ups on post-GDD surgery day 1, week 1 and month 1.
Results of visual acuity, visual fields, optic nerve evaluation and complications will be compared between the two groups to determine the better timing of GDD implantation.
详细描述
INTRODUCTION:
Glaucoma is a major problem for KPro candidates. Indeed, many diagnostic indications for KPro such as aniridia, chemical burns, trauma and repeated graft failure imply alteration of the iridocorneal angle, and consequently high intraocular pressure (IOP) and glaucoma. Accordingly, the prevalence of glaucoma before KPro surgery lies between 27% and 77%, with most studies showing a prevalence above 50%. The diagnosis and management of glaucoma is particularly challenging in the KPro population. Preoperatively, the measurement of IOP is possible through Goldmann tonometry and pneumotonometry but this measurement may be erroneous due to corneal scarring and irregularity. Furthermore, corneal opacification usually prevents visualization of the optic nerve head, and visual field assessment is not possible due to poor vision. Therefore, while glaucoma is often suspected in patients undergoing KPro, this diagnosis may be only confirmed postoperatively. While optic nerve head and visual field examination become possible following KPro surgery, the determination of IOP can only be accomplished through digital palpation. The shortcomings of this method, including its very poor inter- and intra-observer reliability, are well recognized. Because IOP reduction is the basis of glaucoma treatment, it is exceedingly difficult to manage glaucoma in the KPro population. In the face of such complexity, some KPro surgeons have suggested that Glaucoma Drainage Device (GDD) implantation could be performed during KPro surgery in all patients with marginal preoperative IOP control. With this approach, the GDD could prevent postoperative IOP rise and the need for subsequent surgical and medical intervention.
RATIONALE:
The decision to implant a GDD in a patient with pre-existing or prospective KPro must be weighed carefully. The insidious development or progression of glaucoma is the most common blinding complication of KPro implantation. Indeed, the course of glaucoma is a major determinant of KPro surgery prognosis and specifically of the visual result. On the other hand, complications associated with concomitant GDD and KPro surgeries may in themselves lead to severe and irreversible vision loss and thus, prevent the visual rehabilitation of these patients. With the increasing use of the KPro, it is important to evaluate the optimal timing of GDD implantation.
HYPOTHESIS:
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Treatment
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Candidate for corneal transplantation due to loss of corneal clarity
- •Verifiable history of one or more previous full thickness donor corneal transplantation failure
- •Pre-operative visual acuity of ≤20/80 or worse in the surgical eye
- •Age ≥18 years
- •Physical condition suitable for undergoing surgery
排除标准
- •Terminal glaucoma
- •Terminal retinal diseases
结局指标
主要结局
Visual field mean deviation
时间窗: Change from baseline visual field mean deviation at 12 months
Humphrey Visual Field 24-2 (SITA-Fast) (or Goldmann if poor vision/reliability)
次要结局
- Disc Damage Likelihood Scale (DDLS) on clinical examination(Change from baseline DDLS on clinical examination at 12 months)
- Disc Damage Likelihood Scale (DDLS) on stereoscopic photographs of the optic nerve(Change from baseline DDLS on optic nerve photographs at 12 months)
- Change of visual acuity(12 months after KPro)
- Incidence of ocular complications(12 months after KPro)