Active clinical trials for "Keratoconus"

To investigate a possible benefit of Orthokeratology contact lenses to improve uncorrected visual acuity of keratoconus patients

Corneal ectasia is a relative weakness in the structure of the cornea, which produces a progressive change in its shape which results in visual distortion. It is known that collagen cross-linking in the cornea occurs naturally with age, and in diabetes, both of which seem to prevent progressive ectasia. Corneal collagen cross-linking with riboflavin on corneas thicker than 400 microns has been shown to stabilize the cornea in keratoconus, and prevent progression of the disease. The purpose of this study is to determine whether corneal collagen cross-linking with riboflavin in a hypotonic solution, with UV light, on corneas less than 400 microns thick, leads to stabilisation of corneal ectasia.

patients with keratoconus in one eye and forme fruste keratoconus in the fellow eye compared to normal subjects .the patients were examined by schemipflug imaging system (Pentacam)

The purpose of this study is the investigation of biomechanical properties of the cornea using computer-aided data analysis. Currently, it is known that keratoconus and glaucoma are ocular disease that are associated with biomechanical alterations of the cornea. Corneal ectasia, especially keratoconus, is a corneal disease that leads to an irreversible loss of visual acuity while the cornea becomes steeper, thinner and irregular. For these patients, surgical intervention (e.g. corneal cross-linking) is performed, in case of disease progression. In glaucoma, the information about corneal alterations serves in two ways, first, correct measurement of intra ocular pressure (IOP); second, early diagnosis of suspects before visual field defects are detectable. Especially, the Corvis ST is an air-puff tonometer that measures intraocular pressure, corneal thickness (CCT) as well as dynamic corneal response (DCR) parameters. Most of the DCR parameters are affected by IOP and CCT: Therefore, algorithm are needed to determine parameters without impact of IOP and CCT that are describe the biomechanical properties of the cornea.

The primary goal of the trial is to show that optical coherence tomography (OCT) technology can be used to effectively screen for diseases of the eye including glaucoma, macular diseases and keratoconus. Glaucoma is a disease that causes permanent vision loss and is usually accompanied by increased eye pressure. Macular diseases affect sharp, central vision. Keratoconus is a disease that affects the cornea (clear surface covering the colored part of the eye).

This study attempts to compare Corneal Hysteresis (CH) and Corneal Resistance Factor (CRF) in a series of keratoconic eyes before and after Corneal collagen cross-linking (CXL). Furthermore, among the objectives of the study is to reveal correlations between CH and CRF and a series of corneal indexes like the Corneal Thickness (CT), mean keratometry (Km) and corneal astigmatism (Astig). The study adhered to the tenets of the Declaration of Helsinki and written informed consent was given by all participants. The study was conducted at the Eye Institute of Thrace (ΕΙΤ), in Alexandroupolis, Greece. EΙΤ is a Democritus University research institute focusing primarily on the conditions of the anterior segment of the eye. Participants were recruited from the Outpatients Cornea service of the EIT in a consecutive if eligible basis. Fifty (50) eyes of thirty (30) patients with keratoconus were recruited for the sake of the study and formed the keratoconus group (KG). Eligible subjects for the keratoconus group had to present progressive keratoconus in consecutive corneal topographies, changes in refractive power, and deterioration of the visual acuity within a period of two years. Exclusion criteria included glaucoma, glaucoma suspicion, and intraocular pressure (IOP) lowering drugs administration. Further to glaucoma, exclusion criteria included central corneal thickness (CCT) less than 400μm, K-readings more than 60D, a history of herpetic keratitis, corneal scarring, severe eye dryness, pregnancy or nursing, current corneal infection, or underlying autoimmune disease. Fifty (50) eyes of fifty (50) non-keratoconic, age-matched, individuals who visited our outpatient service formed the control group (CG). Further to keratoconus, and a spherical equivalent error above 3D, the same exclusion criteria applied to the control group members, as well. All participants wearing contact lenses were instructed to discontinue contact lens wear at least a month before measurements. CRF and CH parameters were obtained while the patient was sitting on a chair in front of the Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Buffalo, NY, USA) device. Upon successful fixation of the patient's eye on a red blinking target, the operator activated the device. An air puff was released by a non-contact probe, which scanned the central area of the eye and sent a signal to the ORA. In brief, the air puff causes the cornea to move inward, past applanation, and into slight concavity. After milliseconds, the air pumps shut off, the pressure decreases, and the cornea begins to return in its normal state. The system monitors the entire process and measures two pressure values, which are determined from the inward and outward applanation processes. The aforementioned measuring procedure enables the determination of CH which is related to the viscoelastic structure of the corneal tissue, and is calculated as the difference between the two pressure values at the two applanation processes, and CRF which is indicative of the overall resistance of the cornea and is calculated as a linear function of the two pressures associated with the two applanation. In order to ensure accurate results, ORA was done four times for each eye, by the same operator. Signals that differ significantly in appearance from the other signals from the same eye were deleted. The same surgical procedure was applied to all keratoconus patients that included: Instillation of proparacaine hydrochloride 0.5% drops for topical anaesthesia, application of a sponge saturated with 10% alcohol to the central cornea for 30 seconds and subsequent de-epithelialization by means of a hockey knife. Following de-epithelialization, a mixture of 0.1% riboflavin in 20% Dextran solution was instilled to the cornea for 30 minutes (2 drops every 2 minutes) prior to the irradiation, until the stroma was completely penetrated and aqueous was stained yellow. The ultraviolet A (UVA) radiation source that was used is UV-XTM (IROC AG, Zurich, Switzerland). In details, an 8.0mm diameter of central cornea was irradiated for 30 minutes by UVA light with a wavelength of 370nm and an irradiance of 3mW/cm2. Instillation of riboflavin drops (1 drop every 2 minutes) was continued during irradiation, as well, in order to sustain the necessary concentration of the riboflavin. Moreover, balanced salt solution (BSS) was applied every 6 minutes to moisten the cornea. After treatment all patients were prescribed topical ofloxacin drops qid, fluorometholone qid and diclofenac nitrate qid, accompanied by frequent instillation of artificial tears. Soft therapeutic lens was applied until complete re-epithelialization of the cornea was detected. Follow up visits were performed on the 1st day, 7th day, 1st, 3rd, 6th and 12th month after the operation.

The purpose of this study is to investigate changes in corneal innervation during scleral contact lens wear in a keratoconic population. Specifically, changes in corneal sensitivity and nerve fiber density from baseline in the central and mid-peripheral corneal locations will be measured over a 6-month lens wear period. An additional aim of the study is to investigate the impact of scleral lens wear on corneal inflammation within the same study group. This will be achieved by comparing dendritic cell density change from baseline over the study period.

A retrospective study has shown the association between the inflammatory bowel diseases (IBD) and the presence of a keratoconus. This new study will measure the prevalence of keratoconus and follow its activity in patients affected by IBD and followed up in hepatology-gastroenterology department at Nancy Hospital. The prevalence of keratoconus will be compared to known data of literature about general population. The secondary purpose is to search for a relationship between the presence of a keratoconus and activity criteria of IBD. Perspectives are a systematic screening for keratoconus in patients affected by IBD with the amelioration of the ophthalmologic care of IBD patients and confirmation of the recent hypothesis of inflammatory origin of keratoconus.

Study Hypothesis: Former investigators indicated that keratoconus has a negative impact on vision-specific quality of life. This study attempts to confirm this statement and assess whether cross-linking and cross-linking combined with photorefractive keratectomy improve vision-specific quality of life, in a sample of keratoconus patients with 3-years follow-up.

The purpose of this study will be to determine optimal surgical technique for performing FLAK including laser parameters, keratoplasty shape and suture technique in order to standardize surgical technique and to collect safety and efficacy data. This will be compared to data of patients with full thickness PKP to measure visual outcomes, refraction, astigmatism, surgical methods and wound healing.