Reduction of Foveal Sensitivity in Eyes With Diabetic Macular Edema
Condition: Diabetic Retinopathy; Clinically Significant Macular Edema
MeSH terms: Macular Edema; Retinal Diseases; Diabetic Retinopathy; Hypersensitivity; Edema
Study type: Observational [Patient Registry]

Summary: 
      Clinically significant macular edema (CSME) is a thickening of the macula associated with the
      risk of visual loss, which increases its centre is involved. Functional evaluation of the
      macula relies on best corrected visual acuity; however, neural dysfunction in diabetic eyes
      appears before retinal thickening and visual loss. Retinal sensitivity decreases in eyes with
      CSME, but it is unknown whether it differs between eyes with and without centre thickening.

      Aim: To compare the reduction of foveal sensitivity in eyes with CSME, with and without
      centre thickening.
    

Detailed description: 
      A non-experimental, comparative, prospective, cross-sectional study was conducted. Target
      population were type 2 diabetics, from Mexico City and its metropolitan area, and available
      population were type 2 diabetics who attended an Ophthalmology service from a general
      hospital in Mexico City, from September 2011 to May 2012.

      Type 2 diabetic patients aged 30-85 years, from any gender, with central fixation, whose
      ocular media allowed obtaining an adequate quality Optical Coherence Tomography, who had CSME
      with focal angiographic pattern were included. Eyes with optic nerve or visual pathways
      diseases or any other ocular disease that decreased Best corrected visual acuity, were
      excluded. Diabetic patients without retinopathy who fulfilled the remaining selection
      criteria were evaluated as the reference group.

      Sixty degrees colour fundus photographs were obtained in all the patients using a Visucam
      lite ocular fundus camera; in group 1 it was verified that no signs of diabetic retinopathy
      existed in the photographs; CSMO was diagnosed by biomicroscopy under mydryasis, according to
      the ETDRS criteria.

      Retinal thickness was measured using Stratus optical coherence tomography (OCT), version
      4.0.1 (Zeiss). The 6 mm fast macular map strategy was used, according to the following
      standardised operating procedure: mydriasis ≥6mm, inclusion of the spherical equivalent and
      anteroposterior axis, and optimisation of z axis and of polarisation; the photograph was
      taken with flash between 9:00 and 11:00, using an acquisition strategy for dark irises. The
      maps were obtained by the same investigator, independent from the one who evaluated the
      patients clinically; any deviation of the OCT line regarding the actual retina boundary was
      considered as a measurement error.

      A 10° macular perimetry was obtained in all the patients, using a Humphrey field analyser
      model 750i (software version 4.1); the sixteen points evaluated were arbitrarily labelled.
      Retinal thickness within 3 mm from the centre of the fovea was measured in 9 fields,
      according to the fast macular map.
    

Observational model: Case-Control
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        target population were type 2 diabetics, from Mexico City and its metropolitan area, and
        available population were type 2 diabetics who attended an Ophthalmology service from a
        general hospital in Mexico City, from September 2011 to May 2012
      
Keywords: clinically significant macular edema; foveal thickness; foveal sensitivity; perimetry; diabetic retinopathy