OM t of c.iii - Vision Research Coordinating Center - Washington ...

More documents

Recommendations

Info

2/1/99 Chapter 1 Background page 1-8 of Keratoconus (CLEK) Study, characterizes keratoconus patients cross-sectionally at various stages of the disease and follows them for at least three years to assess changes in the disease over time. The goal is to characterize the disease across its course and to identify risk factors and protective factors that determine the severity and progression of the disease. 1.2.1 General Description of the Course of Keratoconus The Collaborative Longitudinal Evalution of Keratoconus (CLEK) Study will describe the distribution and rate of change in best corrected high and low contrast visual acuity, corneal curvature, the proportion of patients developing incident corneal scarring, and the proportion of patients progressing to surgical intervention. 1.2.2 Factors Related to Vision in Keratoconus The CLEK Study will characterize the association between best corrected visual acuity and visual quality of life and each of several pre-defined covariates. Best corrected and habitual visual acuity will be measured using high and low contrast Bailey-Lovie charts. Visual quality of life will be measured using the SF-36 and Javitt Visual Function Questionnaire and the NEI VFQ. The covariates of interest are corneal curvature, corneal irregularity, corneal scarring, the patient’s age, whether the patient wears spectacles or contact lenses, the type of contact lens worn, and the first definite apical clearance contact lens base curve. We will determine what measure of visual acuity—high or low contrast with best correction, habitual correction, or manifest refraction—best predicts visual quality of life. 1.2.3 Factors Related to Disease Progression (Corneal Curvature) in Keratoconus The CLEK Study will characterize the relationship between corneal curvature, as measured by keratometry, and each of several pre-defined covariates. The covariates of interest are corneal irregularity, corneal scarring, the patient’s age, whether the patient wears spectacles or contact lenses, and the type of contact lens worn. (Although contact lenses will influence our measurement of these variables, it has been previously established that it would be unethical to conduct an observational study of keratoconus that would prohibit the use of rigid contact lenses in optical management of the disease.) 1.2.4 Factors Related to Corneal Scarring The CLEK Study will describe the relationship between corneal scarring, as determined by a standardized photography and reading method, and each of several pre-defined covariates. The covariates of interest are corneal curvature, the patient’s
2/1/99 Chapter 1 Background page 1-9 age, high and low contrast best corrected and habitual visual acuity, whether the patient wears spectacles or contact lenses, the type of contact lens worn, and the first definite apical clearance contact lens base curve. It is expected that the results of these four sets of evaluations, and the relationship between those results will lead to a better understanding of the clinical course of keratoconus and will provide the framework for new approaches to the management of keratoconus. 1.3 Diagnosis of Keratoconus Keratoconus is a progressive disease characterized by steepening and distortion of the cornea, thinning of the apical cornea, scarring, and treatment-related sequelae, such as abrasions from contact lenses and surgical complications. Although various geometries of keratoconus have been described (Caroline et al., 1978; Perry et al., 1980) it is not usually possible to identify these types in the early stages of the disease, except keratoglobus, which is actually a separate disease (Krachmer et al., 1984). The diagnosis of early keratoconus depends primarily on assessment of the corneal topography (Krachmer et al., 1984). An irregular, scissoring motion can be detected by viewing the retinoscopic reflex (Swann and Waldron, 1986). Inferior corneal steepening (Edmund, 1987b; Zabala and Archila, 1988) and irregular mires are observed with the keratometer. Devices which more accurately depict corneal topography, such as a hand-held Placido disc, photokeratoscope, or videokeratography system show inferior corneal steepening as well as irregular astigmatism. Documented increases in keratometric curvature of the cornea over time are valuable in diagnosing early keratoconus (Krachmer et al., 1984). Lack of agreement between corneal toricity and refractive astigmatism is also a sign of early keratoconus, especially when accompanied by documented irregular astigmatism. There are several characteristic biomicroscopic signs which increase as the disease progresses (Krachmer et al., 1984). These include an inferiorly displaced, thinned protrusion of the cornea, visually evident corneal thinning over the apex, Vogt’s (1919) striae at the level of Descemet’s membrane, superficial scars at the level of Bowman’s membrane, and Fleischer’s ring (of iron) at the base of the cone, either full or partial. Vogt’s striae and Fleischer’s ring are considered pathognomonic for keratoconus. The CLEK Study protocol requires a patient to have at least one of these two classic biomicroscopic findings or corneal scarring in at least one eye in order to be eligible for the study. This stringent eligibility criterion confirms the diagnosis of keratoconus and excludes alternative conditions such as irregular corneal surface without these signs (Rabinowitz et al., 1990), pellucid marginal degeneration, and keratoglobus. 1.4 Course of Keratoconus
Page 1 and 2: 2/22/96 CLEK OM Table of Contents p
Page 7 and 8: 2/1/99 CLEK OM Table of Contents pa
Page 9 and 10: 2/1/99 Chapter 1 Background page 1-
Page 15: 2/1/99 Chapter 1 Background page 1-
Page 33 and 34: 2/1/99 Chapter 2 Study Design page
Page 55 and 56: 2/22/96 Chapter 3 Entry and Enrollm
Page 57 and 58: 2/22/96 Chapter 3 Entry and Enrollm
Page 59 and 60: 2/1/99 Chapter 4 Recruitment, Educa
Page 67 and 68:
2/1/99 Chapter 5 Scheduling page 5-
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
2/22/96 Chapter 6 Vision Assessment
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
2/22/96 Chapter 7 Slit Lamp, Fundus
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
1/1/2005 Chapter 8 Corneal Curvatur
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
2/22/96 Chapter 9 Contact Lens Fit
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
2/22/96 Chapter 10 Fluorescein Phot
Page 127 and 128:
2/22/96 Chapter 10 Fluorescein Phot
Page 129 and 130:
2/22/96 Chapter 11 Corneal Photogra
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
2/22/96 Chapter 12 Certification pa
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
2/2/99 Chapter 13 Chairman and Clin
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
2/1/99 Chapter 14 CPRC page 14-2 Fi
Page 151 and 152:
2/1/99 Chapter 14 CPRC page 14-4 Th
Page 153 and 154:
2/1/99 Chapter 14 CPRC page 14-6 Pr
Page 155 and 156:
2/22/96 Chapter 15 Coordinating Cen
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
2/22/96 Study Organization page 16-
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
show all

OM t of c.iii - Vision Research Coordinating Center - Washington ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?