Table 2 Instruments used at baseline and follow-up for examination, including rationale for change where appropriate
From: The Nakuru eye disease cohort study: methodology & rationale
Procedure | Baseline Instrument (2007/08) | Follow-up instrument (2013/14) | Rationale for change |
|---|---|---|---|
Near Vision Test | Continuous Text “Read in Style®” diopter chart | Unchanged | N/A |
Personal Interview | Questionnaire developed by the survey ophthalmologist (WM) | Questionnaire developed by the survey ophthalmologist (AB) see Additional file 1: Appendix | N/A |
Weight | The Seca 761 Medical Class 4 Scales mechanical ground scale (Williams Medical Supplies, London) | Tanita Segmental Body Composition Monitor | Combined weight and bioimpedence device – approved for medical studies |
Bioimpedence | Not performed | Tanita Segmental Body Composition Monitor | Combined weight and bioimpedence device – approved for medical studies |
Height | Leicester Height Measure (Stadiometer) (Chasmors Ltd, London) | SECA Height Measure | Better stability on uneven grounds |
Waist and Hip circumference | Chasmors WM02 Body Tape measure | SECA Measuring tape | Availability |
Blood pressure | Omron® Digital Automatic Blood Pressure Monitor Model HEM907 | Unchanged | N/A |
Visual Acuity | ETDRS LogMAR chart | Unchanged | N/A |
Auto refraction | Topcon® Auto refractor RM8800 | Welch Allyn SureSight | Improved portability |
Corrected Visual Acuity | Frames and standard refraction lenses | Unchanged | N/A |
Undilated eye exam including imaging (SL-OCT) | Haag-Streit® Slit lamp BD900 with SL-OCT | Haag-Streit® Slit lamp BM900 – no SL-OCT | Availability |
Tonometry | Haag Streit® Goldmann Applanation tonometer on above slit lamp | Haag Streit® Goldmann Applanation tonometer on above slit lamp | N/A |
Gonioscopy | Not performed | Four-mirror non-coupling gonioscopy lens (Zabby’s) | For glaucoma sub-typing and angle evaluation in normal population |
Visual fields | Humphrey Field Analyzer II -720 i series(Zeiss®) | Henson 8000 Visual Field Analyser (TopCon, Inc) | Deemed more suitable for epidemiological data collection |
Pupil Dilation | Mydriacyl drops (Alcon®) | G. Tropicamide 1% + G. Phenylepherine 2.5% (Minims) | Single units and better shelf life |
Blood sugar | Accutrend GCT and test strips (Roche®) | OneTouch Select, Lifescan | Availability. Approved for medical studies |
Blood Cholesterol | Accutrend GCT and test strips (Roche®) | Not performed | Cost prohibited inclusion |
HbA1c | Not performed | (A1C Now+, Bayer) | Increase accuracy of Diabetes Mellitus diagnosis as participants non-fasted |
Examination of anterior and posterior segments through a dilated pupil | 90D lens and slit lamp(Volk®) | Superfield and 60D Lens (Volk) and Slit Lamp | Study ophthalmologist preference |
Retinal Photo | Topcon® NW6S Non Mydriatic camera model | Haag-Streit DRS Retinal Camera | Suitability for travel and ease of use. |