Analysis of Retinochoroidal Vasculature in Underweight Women Using Optical Coherence Tomography Angiography
Condition: Cachexia; Underweight
MeSH terms: Cachexia; Thinness
Study type: Observational

Summary: 
      Cachectic patients and controls undergoing a comprehensive ophthalmologic examination. The
      imaging of all subjects is undertaken using a commercial OCTA device with a scan rate of
      70,000 A-scans/s, scan beam wavelength of 840 ± 10 nm and bandwidth of 45 nm. All
      measurements are performed between 10:00 and 12:00 on the same day. The OCTA images are
      independently graded and assessed by two retinal specialists. The software automatically
      segmented these full-thickness retinal scans into the superficial and deep inner retinal
      vascular plexuses, outer retina, and choriocapillaris (CC). The vascular density in the
      superficial and deep retinal vascular zones is calculated automatically by the software, and
      the foveal avascular zone (FAZ) and foveal density (FD) are also automatically determined.
      Choroidal thickness is calculated manually by two retinal specialists, and the average value
      was used.
    

Detailed description: 
      Cachectic patients and controls undergoing a comprehensive ophthalmologic examination,
      including the measurements of best-corrected visual acuity (BCVA), refractive error (KR-8900;
      Topcon, Tokyo, Japan), intraocular pressure (IOP, Full Auto Tonometer TX-F; Topcon), axial
      length (AL, Lenstar LS 900, Haag-Streit AG, Switzerland), slit lamp examination of the
      anterior segment, dilated fundus examination, and OCTA imaging (Optovue RTVue XR 100 Avanti,
      Freemont, California, USA) are included in the study. To calculate BMI, height is measured
      using a standard anthropometric tape (Bioplus Stature Meter, model number IND/09/2005/815),
      and a certified electronic weighing scale (model number Omron HN-283) is used to measure
      weight.

      According to the national guidelines, the patients are classified into two underweight
      groups: Group 1 consisting of those with a BMI of <17.00 kg/m2 and Group 2 comprising those
      with a BMI of 17.00 to 18.49 kg/m2. The control group is formed with individuals with a
      normal BMI (18.50 to 24.99 kg/m2).

      The right eye of each participant is included in the study. If the right eye meets any of the
      exclusion criteria, then the left eye is selected for the sample. The inclusion criteria for
      the patient group is being underweight (BMI < 18.50 kg/m2). The exclusion criteria for all
      groups are as follows: refractive error >+3.0 diopters (D) or <-3.0 D spherical equivalent;
      poor image quality <60 due to unstable fixation; IOP > 21 mm Hg; longer AL (>25 mm);
      pre-existing ophthalmic pathologies; prior ocular surgery; and a systemic chronic disease
      that can cause underweight or retinopathy, such as cancer, malnutrition, and diabetes
      mellitus.

      OCTA

      The imaging of all subjects is undertaken using a commercial OCTA device with a scan rate of
      70,000 A-scans/s, scan beam wavelength of 840 ± 10 nm and bandwidth of 45 nm. This device can
      perform 70 000 A-scans/s per second to acquire volumes of 304 × 304 A-scans. All measurements
      are performed between 10:00 and 12:00 on the same day.

      To evaluate the vascular structures, 6×6 mm OCTA software is used. The split-spectrum
      amplitude decorrelation angiography (SSADA) algorithm is performed in all participants. The
      images of poor quality (signal strength index (SSI) < 8) with either significant motion
      artifact or incorrect segmentation are excluded. The OCTA images are independently graded and
      assessed by two retinal specialists. The software automatically segmented these
      full-thickness retinal scans into the superficial and deep inner retinal vascular plexuses,
      outer retina, and choriocapillaris (CC). The vascular density in the superficial and deep
      retinal vascular zones is calculated automatically by the software, and the foveal avascular
      zone (FAZ) and foveal density (FD) are also automatically determined. The same software also
      calculates the flow index rates in a central circular zone of 3.144 mm² in the outer retina
      and CC segments. Choroidal thickness is calculated manually by two retinal specialists, and
      the average value was used.
    

Intervention name(s): Comprehensive ophthalmologic examination
Intervention type(s): Diagnostic Test
Intervention description(s): Measurements of best-corrected visual acuity, refractive error, intraocular pressure, axial length, slit lamp examination of the anterior segment, dilated fundus examination, and optical coherence tomography angiography imaging.
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Study population includes a convenience sampling from the patients admitted to outpatient
        clinic between June 2020 and August 2020.