None listed
Conditions
Brief summary
This study will investigate the changes that occur in the cornea following collagen cross linking. Recent studies have demonstrated that this procedure is effective in reducing the progression of keratoconus, however very little is known about the microstructural changes that occur during this procedure. This study aims to investigate both the clinical outcomes of this procedure (for example vision and corneal shape (topography)); as well as the cellular changes that occur in the cornea. This information will allow us to better understand the procedure and its outcomes, hence allowing us to identify the patients that are most likely to benefit.
Interventions
The treatment aims to target the pathogenesis of keratoconus by stimulating collagen cross linking in the cornea using ultra violet light (UVA) and the photosensitiser riboflavin. The process involves stimulating covalent bonds between corneal collagen fibrils, aiming to improve the mechanical rigidity of the cornea and increase its resistance to the ectatic process.
The procedure will be conducted in a sterile procedure room in the Department of Ophthalmology, Greenlane clinical centre by a re
The treatment aims to target the pathogenesis of keratoconus by stimulating collagen cross linking in the cornea using ultra violet light (UVA) and the photosensitiser riboflavin. The process involves stimulating covalent bonds between corneal collagen fibrils, aiming to improve the mechanical rigidity of the cornea and increase its resistance to the ectatic process. The procedure will be conducted in a sterile procedure room in the Department of Ophthalmology, Greenlane clinical centre by a registered Ophthalmologist. 1. Eye selection based on initial work up and randomisation strategies 2. Insertion of a lid speculum 3. Instillation of tetracaine 1% and/or oxybuprocaine 0.4% in the treatment eye. 4. The central 7 mm of the cornea will be mechanically removed using a blade. 5. Instillation of riboflavin drops q. 5 mins , starting 5 mins prior to the treatment procedure (2-4 drops of 0.1% solution 10 mg riboflavin-5-phosphate in 10 mls dextran-T- 500 solution) 6. Commencement of UVA light irradiation using a UVA double diode 370 nm, located 10-12 mm in front of the corneal apex to obtain radiant energy of 3 mW/cm² or 5.4 J/ cm² (monitored via a potentiometer/ UV power metre). A Irradiation time of 5 minutes will be repeated 5 times (For a total of 30 minutes), with the lamp being switched off and instillation of the riboflavin drops between each 5 minute irradiation occurring. 7. During the procedure balanced salt solution will be instilled every 2 minutes to moisten the cornea. 8. Upon completion of the procedure the eye will be flushed with balanced salt solution. 9. Following the procedure slit lamp examination will be performed 10. A bandage contact lens will be inserted (To improve comfort for the patient while healing occurs) 11. Prophylactic broad spectrum antibiotic ointment (chloramphenicol 0.5% minims) will be instilled and dispensed to the patients. Patients will be reviewed at day 1, 1 week, 1 month, 2 months, 3 and 6 months.
Sponsors
University of Auckland
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Treatment
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
14 Years to 30 Years
Healthy volunteers
No
Inclusion criteria
1. Patient with bilateral keratoconus 2. Patients with documented progressive keratoconus: 3. At least 2 years of follow up data available to accurately map out the rate of progression. Classified as: i. Increase in maximal keratometry readings over a period of up to three months ii. change in refraction reported by patient or referring clinician, over the last 12 months (>0.75 Dioptres ) iii. Several increases of corneal keratometry readings over a period of six months (>0.75 Dioptres) iv. Progression measured indirectly via by using rigid contact lenses of varying base curves to achieve apical clearance. Ii.e. change in documented contact lens fit in the last 6-12 months. v. Demonstrated pachyometrical keratoconus worsening over the last six months 4. Participants must be >14 yrs of age < 30 yrs of age. 5. Maximal corneal keratometry reading of no more than 60 Dioptres 6. Minimal corneal thickness measurement of at least 400 µm 7. Preserved best spectacle corrected visual acuity of > 20/80 (6/24) 8. Clear corneas, clinically 9. Well informed patients with the ability to understand the implications of the intervention, such that they are able to consent for themselves 10. Documented rigid gas permeable contact lens intolerance
Exclusion criteria
1. Previous episodes of corneal hydrops 2. Ocular surgery or trauma 3. Systemic disease which may affect cornea. 4. Demonstrated clinical topographical keratoconus stability in the last 24 months 5. Previous herpetic disease of the cornea. 6. Severe corneal dryness 7. Significant corneal desiccation staining (Grade 2 on the Cornea and Contact Lens Research Unit (CCLRU) grading scale). 8. Minimal corneal thickness of less than 400 µm 9. Evidence of sub-epithelial or mid anterior stromal scarring or opacities 10. Slit lamp examination of marked Vogt striae or confocal evidence of a deep reticular pattern of dark bands (more prone to stromal oedema and corneal haze, due to the procedure) 11. Inability to give informed consent 12. Inability to maintain repeat visits to the Ophthalmology department over a period of months
Outcome results
None listed