Evaluation of Macular Vascular Changes in Behcet's Disease Using Optical Coherence Tomography Angiography

Behcet's disease is an important cause of retinal vasculitis and vision loss in Egypt. Fluorescein angiography is the standard method of diagnosis of retinal vasculitis. OCT angiography (OCT-A) is a recently developed method that can be used in the evaluation of retinal circulation. In this study, we will test the utility of OCT-A in diagnosis and follow up of retinal vascular changes in cases diagnosed with Behcet's disease that visit the outpatient uveitis clinic of Assiut University hospital, a major tertiary center in southern Egypt, over a one year duration. Also, correlation of OCT-A changes with visual acuity and hence prognosis will be described.

Aim of the research To describe macular retinal vascular changes in patient with retinal vasculitis secondary to Behcet's disease both qualitatively and quantitatively.

Research design Type of the study: cross sectional analytical study Study Setting: Assuit University Hospital (Ophthalmology Department)

Study subjects:

1. Inclusion criteria:

   • Patients diagnosed with Behcet's disease with or without active uveitis
2. Exclusion criteria:

   * Patients less than 18 years old
   * Hazy media precluding clear fundus view.
   * Patients with very poor fixation.
3. Sample Size Calculation:

We will aim at recruiting all patients diagnosed with Behcet's disease in outpatient clinic who will meet the inclusion criteria within one year from the start of our project.

Methods Subject recruitment and obtaining consent Study subjects (Behcet's patients) will be recruited from patients attending uveitis and retina clinic of the ophthalmology Department, Faculty of Medicine, Assiut University. Written informed consent form will be obtained from each patient.

Baseline evaluation:

1. Full ocular examination including slit lamp and dilated fundus examinations. Also, measurement of the best corrected visual acuity (BCVA) using Snellen's chart will be done.
2. Thorough clinical history and review of other systems involvement as well as full drug history including use of topical and systemic medications.
3. Retinal vasculitis will be diagnosed by fundus examination. Additionally, fluorescein angiography may be done according to the discretion of the investigators to confirm the diagnosis.

Optical coherence tomography angiography imaging OCT imaging will be performed after pupillary dilatation using Topcon DRI OCT Triton platform which utilizes invisible 1050 nm light and obtains images at a speed of 100,000 A scans/sec.

First, B scans of the macula will be obtained and anatomical alterations of retinal architecture will be noted. Next, OCT angiography scans in a 4.5x 4.5 mm circle centered on the fovea will be then obtained. Analysis and interpretation of the enface images of the superficial and deep retinal capillary plexus as well as choriocapillaries will be performed. Areas of capillary dropout, abnormalities of retinal capillaries and vessels such as looping, dilated segments, microaneurysms as well as FAZ area will be documented.

Research outcome measures:

A. Primary (main):

1- Qualitative description of the retinal capillary plexus changes in the macular area

B. Secondary:

1. Quantification of the extent of macular ischemia by measuring the area of foveal avascular zone (FAZ).
2. Correlation between extent of macular vascular changes and visual acuity

Data management and analysis:

Data collection data will be recorded in the form of excel spreadsheets Computer software SPSS and Prism graphpad Statistical tests chi square test and Pearson correlation coefficient

Eligibility Criteria:
Inclusion Criteria:

* • Patients diagnosed with Behcet's disease

Exclusion Criteria:

* • Patients less than 18 years old

  * Hazy media precluding clear fundus view.
  * Patients with very poor fixation.